Aplikácie

This white paper summarizes the advantages and benefits of automated titration in comparison to manual titration. The increase in accuracy and precision of measurements as well as significant time and cost savings are discussed.

This white paper summarizes the steps involved in converting an existing manual titration procedure to semi-automated or automated titration procedures. It discusses topics such as selecting the right electrode and titration mode. For a better understanding, the discussion topics are illustrated with three examples.

Thermometric titration can solve application problems that potentiometry cannot solve at all, or at least not satisfactorily.

The purity of sulfanilamide was determined by means of automatic potentiometric titration using sodium nitrite as the titrant. The solution was spiked with potassium bromide, because bromide ions catalyze diazotization titration.

Titration is an accurate and precise method that can be used to determine the pyrophosphate content in aqueous products. The OMNIS Titrator equipped with a dUnitrode delivers reliable determinations.

MATi 11 (MATi = Metrohm Automated Titration) is a completely configured system for water content determination in solid or liquid samples using automated volumetric Karl Fischer titration. It contains a Polytron PT 1300 D for the homogenization of the samples. Up to 53 samples are analyzed directly in 120 mL titration beakers. The samples are weighed in the titration beaker and sealed with aluminum foil and a foil holder so that they neither lose nor absorb water.

The water content determination by volumetric Karl Fischer titration is one of the most important analyses worldwide. Using an OMNIS system consisting of an OMNIS Titrator and an OMNIS Sample Robot, the fully automatic analysis of water content is possible in various products and matrices. The OMNIS Sample Robot is capable of running several different titrations in parallel. In this Application Note, we present the results of a volumetric Karl Fischer titration run in parallel to an aqueous acid-base titration on the same system. The water content is not influenced by the parallel running aqueous titration, allowing the combination of potentiometric titrations and Karl Fischer titrations on the same automated system.

This Application Bulletin provides information regarding the MATi 10 (Metrohm Automated Titration) system. MATi 10 is a completely configured system for automatic volumetric Karl Fischer titration with which the water content in liquid and solid samples can be determined. Up to 24 samples can be analyzed directly in 75 mL titration vessels. The samples are weighed into the titration vessels and covered with an aluminum foil. This prevents falsification of the water content.

MATi 4 (Metrohm Automated Titration) is a configured system for automated water content determination in liquid samples using coulometric Karl Fischer titration. The maximum sample volume is 5 mL. Up to 160 samples are filled in glass vials and sealed with lids. This ensures that the water content in the samples remains constant. The samples are aspirated and transferred into the coulometric cell through a needle. The tiamo™ software controls the system.

Nitric acid, phosphoric acid, and acetic acid are easily determined in etching baths using thermometric titration (TET). Compared to potentiometric titration, TET is faster and more convenient. Analysis is complete in less than two minutes.

A potentiometric method for the determination of nickel in gold and silver electroplating baths is described. The titration is carried out with KCN. Gold and silver are removed before titration by a reduction process. It is also possible to determine nickel in steel alloys, etc. (see the literature reference).Ni2+ + 4 KCN + 2NH4+ → (NH4)2[Ni(CN)4] + 4 K+

The determination of the total causticizer, sodium carbonate and aluminum oxide contents in (Bayer) process liquors can be accomplished with high precision and speed by using the 859 Titrotherm in a thermometric acid-base titration. A complete titration takes approximately 5 minutes.The procedure is an automated adaptation of the traditional Watts-Utley method, and is similar to the VanDalen-Ward thermometric titration method, but with the added advantage that the analysis can also be performed for the carbonate content of the liquor.

This Application Note describes the determination of aluminum in samples containing silicon dioxide using thermometric titration and EDTA as the titrant. Excess EDTA is titrated with a Cu2+ solution of known concentration. The initial, uncomplexed Cu2+ ions react immediately with the H2O2 present in the solution, leading to a recognizable sudden increase in temperature.

Direct titration is a simple and precise way to accurately measure the caffeine content in different nonaqueous products. The OMNIS Titrator equipped with a dSolvotrode reliably determines caffeine through flexible analyses combined with high-end software.

Hydrogen peroxide solutions can be determined through thermometric endpoint titration (TET) using iodometry. Iodide is oxidized to become iodine, which is then titrated with a standard thiosulfate solution in an exothermic reaction.

Carbonyl compounds (CC) occur in many products, such as bio-oils and fuels, cyclic and acyclic solvents, flavors and mineral oils. Carbonyl compounds can be responsible for the instability of these products during storage or processing. Especially pyrolysis bio-oils are known to cause issues during storage, handling and upgrading. This bulletin describes an aqueous and a non-aqueous analytical titration method for the determination of carbonyl compounds by potentiometric titration.

The total acid number (TAN) is an important parameter for assessing the acidity of oils and fuels. This Application Note determines TAN using conductometric titration.

Automated thermometric titration of the nickel content of electroless nickel plating solutions. The determination is suitable for fully automated titration employing a 814 Sample Processor.

Mannitol content determination is an important aspect of quality control in the pharmaceutical and food industries. Selective oxidative cleavage can be used to quantify the amount of 1,2-diol groups in the analyte. Determining the 1,2-diol content by iodometric titration can be fully automated for the most accurate results using an automated titrator and the dPt Titrode from Metrohm.

This Application contains information regarding titer determination in Karl Fischer titration, in particular regarding the water standard suitable for a titer determination and for the correct handling of the same.Titer determination for Karl Fischer titrants is indispensable, because the titer is subject to changes caused by the humidity in the air. The frequency of the determination depends on the titrant and the tightness of the system.The titer has the unit mg/mL in Karl Fischer titration. The value calculated in a titer determination indicates how many milligrams of water react on one milliliter of titrant.

Determination of aluminum in cement by photometric back-titration of the EDTA excess with zinc sulfate using the 610 nm Spectrode.

The standardization of the cationic surfactant TEGOtrant is performed using potentiometric titration as well as near-infrared spectroscopy (NIRS) in this application.

Determination of lauryl ether sulfate (LAES) by potentiometric/turbidimetric titration with TEGO®trant A100 using the 610 nm Spectrode.

The iodometric back titration is a precise method used to accurately measure the caffeine content in various aqueous samples. Reliable determinations are made easy using the OMNIS Titrator equipped with a dPt Titrode.

Determination of Fe3+ by iodometric titration. Useful if Fe3+ is accompanied by Al3+, Mg2+, Ca2+ and Fe2+.

Dissolution of urea in glacial acetic acid, and titration with standard 0.1 mol/L trifluoromethanesulfonic acid in acetic acid using isobutyl vinyl ether as a thermometric endpoint indicator.

Thermometric titration is used for the determination of hydrochloric acid and nitric acid in acid baths. The entire acid content is titrated with caustic soda in the initial titration; the hydrochloric acid content is then determined in a second titration using silver nitrate solution.

This Application Note treats the photometric titration of nickel using the Optrode (520 nm). Murexide was used as the indicator and EDTA as the titrant.

Mercury can be determined in alkali media using back titration with zinc sulfate. Eriochrome black T is used as the indicator for this procedure. The Optrode is used for indication at a wavelength of 502 nm.

Vitamin C is an important antioxidant and an important component of orange juice. A convenient and precise method for Vitamin C determination in fruit juices is titration, which is also described in numerous standards (ISO 6557/1, ISO 6557/2, AOAC 967.21).OMNIS enables quick and accurate determination of Vitamin C content in orange juice using potentiometric titration with iodine as titrant and a separate double Pt-sheet electrode.

Compared to the classical Epton titration, potentiometrically indicated two-phase titrations using organic-solvent-resistant Surfactrodes can be easily automated and require no toxic and environmentally hazardous chloroform. Even challenging matrices such as fats and oils in bath oils and hair conditioners or strong oxidizing agents in washing powder and industrial cleaners do not interfere with the titration of the ionic surfactants. Results obtained show excellent agreement to those of the Epton titration. Irrespective of the matrix, relative standard deviations of threefold determinations are all below 2.1%. While the Surfactrode Resistant is mainly used for oil-containing formulations, the Surfactrode Refill is ideal for washing powders and soaps. Both electrodes excel by their ruggedness and allow the rapid and precise determination of anionic and cationic surfactants.

Determination of nickel in solution by titration with standard disodium dimethylglyoximate.

Cobalt is analyzed in aqueous solutions using direct titration with EDTA at a pH value of 9. The indicator is murexide. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Determination of traces of calcium in brine by photometric titration with 1,2-diaminocyclohexanetetraacetic acid using the 610 nm Spectrode.

Gallium is determined at a pH value of 4.7 using back titration with zinc sulfate. Xylenol orange is used as the indicator for visualization of the equivalence point. The equivalence point is determined with the Optrode at a wavelength of 610 nm.

Determination of calcium in aqueous solutions by photometric titration with EDTA using the 610 nm Spectrode.

This Application Note explains how fluoride determination in acid etching baths can be performed with thermometric titration.

Barium is analyzed in alkali media using direct titration with EDTA. Phthalein purple is used as the indicator; the equivalence point is determined with the Optrode at a wavelength of 574 nm.

Nickel analysis can be carried out conveniently in alkali media using photometric titration. Murexide is used as the indicator for visualization of the endpoint. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Accurate, reliable determination of ionic surfactants with the Epton two-phase titration method can be achieved using an OMNIS system as shown in this study.

This Application Bulletin describes the determination of the total acid number in various oil samples by catalytic thermometric titration as per ASTM D8045.

This Application Bulletin shows the determination of the total base number in petroleum products by applying different titration types according to various standards.

The amine value is an important parameter and quality indicator to determine in chemical processes and pharmaceuticals. This Application Note presents the nonaqueous perchloric acid titration of triethanolamine.

Cadmium can be determined in aqueous solutions using back titration with zinc sulfate. Eriochrome black T is used as the indicator for this procedure. The equivalence point is determined with the Optrode at a wavelength of 610 nm.

The thermometric titration method presented here permits a simple and direct determination of the total acid number (TAN) in petroleum products. It is an invaluable alternative to current manual and potentiometric methods. Thermometric titration uses a maintenance-free temperature sensor that does not require rehydration and is free of fouling and matrix effects. The procedure requires minimal sample preparation. Results agree closely with those from the potentiometric titrimetric procedure according to ASTM D664, but the thermometric titration method is far superior in terms of reproducibility and speed of analysis, with determinations being complete in approximately one minute.

Determination of chlorite by direct thermometric titration with standard sodium thiosulfate solution. The procedurewas applied originally to the determination of chlorite in hide treatment solutions.

On the basis of a multitude of practical examples, this Bulletin describes the potentiometric two-phase titration of ionic surfactants in raw materials and many other formulations.Two surfactant electrodes – the Surfactrode Resistant and the Surfactrode Refill – make it possible to perform this type of surfactant titration, analogous to the classic "Epton titration", with a high degree of automation. The achieved results correlate very well with those of Epton titration. The toxic, carcinogenic and environmentally hazardous chloroform can be replaced by other solvents such as methyl iosbutyl ketone or n-hexane.

Palladium is determined at a pH value of 4 to 5 using back titration with zinc sulfate. Xylenol orange is used as the indicator for visualization of the endpoint. The equivalence point is determined with the Optrode at a wavelength of 610 nm.

Two-phase titration with potentiometric indication is a universal method for the determination of ionic surfactants in detergents. The results obtained are comparable to those with the classic two-phase titration in accordance with Epton (mixed indicator system disulfine blue / dimidium bromide). The present Bulletin addresses various parameters that could have an influence on potentiometric surfactant titration. The information provided makes it possible for the user to determine precisely the anionic surfactant content in practically all formulations.

OMNIS is the ideal system for quick and accurate determination of aluminum in aluminum chloride using complexometric back titration with an ion-selective copper electrode (Cu-ISE). Copper sulfate is used as the titrant.

In titration, the titrant reacts with the analyte either exothermically (gives off heat) or endothermically (absorbs heat). The Thermoprobe measures the temperature change during titration. When all of the analyte has reacted with the titrant, the temperature of the solution will change, and the endpoint of the titration is indicated by an inflection in the temperature curve. Catalytically enhanced titrations using paraformaldehyde as catalyst are based on the endothermic hydrolysis of the paraformaldehyde in the presence of excess hydroxide ions. Edible oils are dissolved in a mixture of toluene and 2-propanol (1:1) and titrated with standardized TBAH (0.01 mol/L) in 2-propanol to a catalytically enhanced endpoint.

This bulletin describes a procedure to determine the bromine index (BI) using coulometric titration. The bromine index is the fraction of reactive unsaturated compounds (mostly C=C double bonds) in hydrocarbons encountered in the petrochemical industry. The double bonds are split with the attachment addition of bromine.

This Application Note describes the nonaqueous acid-base titration of ketoconazole in accordance with the European Pharmacopoeia. The Solvotrode easyClean was used as the electrode.

This bulletin deals with the automated determination of mixtures of HNO3, HF and H2SiF6 in the range of approximately 200-600 g/L HNO3, 50-160 g/L HF, and 0-185 g/L H2SiF6 using thermometric titration.Etch acid mixtures containing HNO3, HF and H2SiF6 from the etching of silicon substrates can be analyzed in a sequence of two determinations using the 859 Titrotherm. The first determination involves a direct titration with standard c(NaOH) = 2 mol/L, followed by a back titration with c(HCl) = 2 mol/L. This determination yields the H2SiF6 content plus a value for the combined (HNO3+HF) contents. The second determination consists of a titration with c(Al3+) = 0.5 mol/L to determine the HF content. For freshly made up mixtures of HNO3 and HF containing no H2SiF6, a linked two-titration sequence is employed. Results from the two determinations are used by tiamoTM to yield individual results for HNO3, HF and H2SiF6.

Thermometric titration is used for the determination of hydrochloric acid and phosphoric acid in acid mixtures. Two endpoints appear on the titration curve that are used for the determination of the two acids.

The present Bulletin offers an overview of the multitude of surfactants and pharmaceuticals that can be determined with potentiometric titration. Metrohm provides five different surfactant electrodes for indicating the titration endpoint: the Ionic Surfactant, the High Sense, the Surfactrode Resistant, the Surfactrode Refill and the NIO Surfactant electrode. The manufacture of the respective titrants and their titer determination are described in detail. In addition to this, the Bulletin contains a tabular overview of more than 170 proven applications from the area of surfactant and pharmaceutical analysis. This guideline leads you reliably to your destination: At a glance you can see from the table which surfactant electrode and which titrant are optimally suitable for your product.

This bulletin discusses automated determination of sodium in milk products available to the public using a 859 Titrotherm and a 814 USB Sample Processor. The sodium content of milk can be rapidly and easily titrated thermometrically with a standard solution of Al3+ as titrant. Thermometric titrations are conducted under conditions of constant titrant addition rate. The molarity of the titrant is computed automatically in tiamoTM (software) with the SLO command. Results are reported as mg Na/100 mL. In addition to this application bulletin, you can find more information on thermometric sodium determination in foods in our application video available on YouTube:https://youtu.be/lnCp9jBxoEs

This Bulletin describes the complexometric potentiometric titration of metal ions. An ion-selective copper electrode is used to indicate the endpoint of the titration. Since this electrode does not respond directly to complexing agents, the corresponding Cu complex is added to the solution. With the described electrode, it is possible to determine water hardness and to analyze metal concentrations in electroplating baths, metal salts, minerals, and ores. The following metal ions have been determined: Al3+, Ba2+, Bi3+, Ca2+, Co2+, Fe3+, Mg2+, Ni2+, Pb2+, Sr2+, and Zn2+.

Thermometric titration can be used for the ready determination of sulfuric acid and phosphoric acid in acid mixtures. An endpoint for each acid appears on the titration curve that can be used to quantify the respective acid.

To determine water in crude oil, ASTM D4928 recommends coulometric Karl Fischer titration with the oven method, allowing full automation for high reproducibility.

This Application Note is devoted to the photometric determination of magnesium in cement using the Optrode (610 nm). After digestion of a sample aliquot, the magnesium content is determined using EDTA titration.

Thermometric titration is used to determine hydrofluoric acid and nitric acid in etching baths containing ethanol and acetonitrile. Two endpoints appear on the titration curve that are used individually for the quantification of the respective acid.

Phosphorus is a primary macronutrient for plants and is a constituent of DNA and adenosine triphosphate (ATP), which is involved in many biological processes requiring energy. In fertilizers, phosphorus is present in the form of phosphate, as the most accessible form of phosphorus for plants is dihydrogen phosphate. Knowledge of the phosphorus content helps to select the right fertilizer for the plants.Traditionally, phosphate is determined gravimetrically (a time consuming procedure) or spectrophotometrically (expensive instrumentation). In this Application Note, an alternative method is presented, where phosphate is determined by a precipitation titration with magnesium. Various solid and liquid NPK fertilizers with phosphorus contents between 6.5 and 17% were analyzed. The analysis by thermometric titration requires no sample preparation in case of liquid NPK fertilizers and only minimal sample preparation in case of solid NPK fertilizers. One determination takes about 5 minutes.

The determination of the acid number plays a significant role in the analysis of petroleum products. This is manifested in the numerous standard procedures in use over the world (internal specifications of multinational companies, national and international specifications of ASTM, DIN, IP, ISO, etc.). These procedures differ mainly in the composition of the used solvents and titrants.This bulletin describes the determination of the acid number in petroleum products by applying different types of titration.The potentiometric determination is described according to ASTM D664, the photometric according to ASTM D974 and the thermometric titration according to ASTM D8045.

If chloride and bromide are present in approximately equal molar concentrations they can be titrated directly with silver nitrate solution after addition of barium acetate. If, however, the molar ratio n(Br-) : n(Cl-) changes from 1 : 1 to 1 : 5, 1 : 10, 5 : 1 or 10 : 1 then greater relative errors must be expected with this method. The Bulletin describes an additional titration method that allows bromide to be determined in the presence of a large excess of chloride. The determination of small chloride concentrations in the presence of a large excess of bromide is not possible by titration.

This Application Note describes in detail how to determine the blank value and the titer for thermometric titrations using tiamo™.

Hypochlorite ions react with bromide ions to form hypobromite ions, which in turn rapidly oxidize ammonium ions to nitrogen. Hypobromite reacts more rapidly with ammonium than hypochlorite, and is formed in situ (Vogel, 1961). The titration is carried out with in a solution containing bromide and bicarbonate.

Thermometric titration is used to determine hydrochloric acid and hydrofluoric acid (hydrogen fluoride) in etching baths containing ethanol and acetonitrile. Two endpoints appear on the titration curve that are used individually for the quantification of the respective acid.

Sulfur is a secondary macronutrient for plants and is essential for chloroplast growth and function. In fertilizers, sulfur is usually provided in the form of sulfate. Traditionally the sulfate content is determined gravimetrically by precipitation with barium. The drawback of this method is that it requires numerous time consuming and laborious analysis steps.In this Application Note, an alternative method is presented, where sulfate is determined by a precipitation titration with barium chloride. Various solid and liquid NPK fertilizers with sulfur contents between 1 and 8% were analyzed. The analysis of sulfate in fertilizers by thermometric titration requires no sample preparation at all for liquid NPK fertilizers, and only minimal sample preparation for solid NPK fertilizers. One determination takes about 3 minutes only. To increase the sensitivity of the method, the samples are spiked with a standard sulfuric acid solution, which is then considered when calculating the result.

Determination of the sum of calcium and magnesium in cement by photometric titration with EDTA using the 610 nm Spectrode.

This bulletin deals with the automated determination of calcium and magnesium in commercially available finished milk products using a 859 Titrotherm and a 814 USB Sample Processor. Calcium and magnesium in milk can be rapidly and easily titrated thermometrically using a standard solution of Na4EDTA as titrant.Thermometric titrations are conducted under conditions of constant titrant addition rate. The molarity of the titrant is computed automatically in tiamo (software) using the SLO command. Results are reported as mg Ca and Mg/100 mL.

The water content of tablets determines the release of their active ingredients as well as their chemical, physical, microbial and shelf-life properties. Accordingly, the water content is of crucial importance and has to be accurately determined. This paper describes the straightforward determination of the water content using automated volumetric Karl Fischer titration (KFT). Tedious sample preparation steps are eliminated by using a high-frequency homogenizer that additionally serves as a stirrer. Prior to titration, the homogenizer comminutes the tablets directly in the KF solution. As the comminution process takes place directly in the hermetically sealed titration vessels, interference from atmospheric humidity does not occur. Even after 24 h in the vessels, the moisture content of four different tablet type samples was within 93…108% of the initially determined values. With a coefficient of determination of 0.99993 the KF method is highly linear for water amounts between 4 and 215 mg. For all investigated tablet types, KFT provides results that lie within the range expected by the manufacturer.

Potentiometric titration is an accurate method for determining chloride content. For detailed instructions and troubleshooting tips, download our Application Bulletin.

Vitamin C is an important antioxidant included in milk powder. The double Auring electrode provides an excellent titration curve when using 2,6-dichlorophenolindophenol (DPIP) as titrant and is easy to clean.With the OMNIS system, a fast and accurate determination of vitamin C in milk powder by a bi-voltametric titration is realized.

Determination of cationic surfactants in a household cleaner by potentiometric two-phase titration with sodium dodecylsulfate using the «Surfactrode Resistant» electrode.

Mixtures of aluminum and magnesium ions can be analyzed automatically using potentiometric titration. The excess DCTA is back-titrated with copper(II) sulfate solution after the addition of 1,2-diaminocyclohexanetetraacetic acid (DCTA) and complex formation. The ion-selective copper electrode is used here as the indicator electrode. First, the aluminum is determined in acidic solution and then the magnesium in alkali solution.

The acid value of fatty acid methyl esters (FAME) like biodiesel can be determined according to EN 14104 using photometric titration with OMNIS and the Optrode.

Metrohm has shaped moisture analysis for more than half a century. Find out about new developments in water analysis and learn how near-infrared spectroscopy in combination with Karl Fischer titration can increase your sample throughput and boost your productivity.

Weak, organic bases that are soluble in nonaqueous solvents (including nonpolar solvents) are determined in glacial acetic acid using titration with strong acids, e. g., anhydrous perchloric acid or trifluoromethanesulfonic acid. The endpoint of such titrations can be determined thermometrically, insofar as a suitable thermometric endpoint indicator exists. The exceptional suitability of isobutyl vinyl ether (IBVE) as indicator has been demonstrated.

Determination of anionic surfactants in shower oil by potentiometric two-phase titration with TEGO®trant A100 using the «Surfactrode Resistant» electrode.

An automatic titration method is described using biamperometric endpoint indication for the determination of antimony in antimony-alloyed cable lead (approx. 1% Sb). A 0.01 mol/L KBrO3 solution is used as the titrant.

The objective of validation of an analytical procedure is to demonstrate that it is suitable for its intended purpose. Recommendations for the validation of analytical methods can be found in ICH Guidance Q2(R1) Validation of Analytical Procedures: Text and Methodology and in USP General Chapter <1225> Validation of Compendial Procedures. The goal of this white paper is to provide some recommendations for the validation of titration methods.

This poster describes a method for automated and precise dosing of liquid samples into the Karl Fischer titration cell using Metrohm Dosino liquid handling technology. First, the titer was automatically determined with ultrapure water. The same dosing procedure proved valuable for the automated water determination in highly viscous water-glycol fluids and low-boiling organic solvents such as n-pentane. Lastly, the method copes with the labor-intensive and human error-prone suitability test stipulated in chapter 2.5.12 in the European Pharmacopoeia.

Determination of soaps and anionic surfactants in washing powder by potentiometric two-phase titration with TEGO®trant A100 using the «Surfactrode Resistant» electrode.

This Bulletin describes a simple method for the determination of the calcium content in dairy products. The use of CuEGTA and the ion-selective copper electrode (Cu ISE) as indicator electrode allows the determination to be performed without time-consuming sample preparation. If the complexing agent EDTA is used as titrant instead of EGTA, the sum of calcium and magnesium is obtained. The magnesium content can then be calculated from the difference between the results of the two titrations.

Sulfonamides are drugs used to treat allergies and cough. They also have some antifungal and antimalarial activities. USP<451> describes nitrite titration method for the determination of numerous pharmacopeial sulfonamide drugs and their dosage forms as well as of other pharmacopeial drugs with, for example, hydrazide (e.g., in isoniazid) and amine ester groups (e.g., in procaine) or amide derivatives of amino acids.Here, for illustrating the analysis of the latter, the assay of the diagnostic agent aminohippuric acid is described.

Anionic surfactants represent, by volume, the most important group of surfactants used in cleaning products. The potentiometric two-phase titration is a universal method for the accurate and fast determination of them. Using the Surfactrode Refill, the anionic surfactants are determined by potentiometric titration with hyamine as titrant.

Zinc, such as that occurring as a constituent of light alloys, can be determined by precipitation titration with potentiometric endpoint indication. The determination of zinc in the presence of cadmium is also possible.2 K4[Fe(CN)6] + 3 ZnCl2 → K2Zn3[Fe(CN)6]2 + 6 KCl

In an acidic solution (containing NH4F * HF, Al(NO3)3 / KNO3) sodium forms NaK2AlF6 which precipitates in an exothermic solution, enabling analysis by thermometric titration. Several foods were analyzed, namely bouillon, gravy, tomato ketchup, corn chips, pretzel sticks as well as crackers. The reproducibility of the results was good. After weighing in and adding solutions, samples were crushed with a polytron to ensure homogeneity in the measuring solution. Relative standard deviations were between 0.08% and 3.75%. In addition to this application bulletin, you can find more information on thermometric sodium determination in foods in our application video available on YouTube:https://youtu.be/lnCp9jBxoEs

This method is applicable to all samples containing glycerin in the absence of other triols or other compounds that react with periodate to produce acidic products. Glycerin may be determined in the presence of glycols. A periodate solution reacts slowly with diols and triols in acidic aqueous media at room temperature. A quantitative amount of formic acid is generated from the reaction with glycerin (a triol). The reaction with diols produces neutral aldehydes. The amount of formic acid generated by this reaction is determined by titration against sodium hydroxide.

Carbonyl compounds occur in many products such as bio-oils and fuels, solvents, flavors, and mineral oils. Carbonyl compounds are often prone to oxidation and thus their content has an influence on stability during storage or processing. Especially for pyrolysis bio-oils, stability issues are observed during storage, handling, and upgrading.Oils are dissolved in isopropanol. After a reaction with the hydroxylamine hydrochloride at 50 °C, a fast and accurate determination by potentiometric titration using the dSolvotrode and tetra-n-butylammonium hydroxide as titrant is performed.

Online acid number analysis in various oil products is possible with thermometric catalytic titration according to ASTM D8045 using the 2060 TI Ex Proof Process Analyzer.

This Application Note describes the bivoltametric titration of ascorbic acid in orange juice. 2,6-dichlorophenol indophenol (DPIP) is used as titrant; endpoint determination takes place using the Double Pt-sheet electrode.

Fresh as well as used petroleum products may contain acidic components as additives or degradation products. The acid number (AN) is a measure for the relative amount of acids present expressed as mg KOH per g sample. Moreover, AN is used as a quality parameter of lubricating oils both for assessing the quality of new formulations and as an indicator for the degradation of such formulations during service. The use of a pH electrode suitable for non-aqueous titrations ensures the reliable determination of the equivalence point. A flexible sleeve diaphragm facilitates its cleaning especially after use in heavily contaminated samples, such as in used engine oils. Using the correct electrode greatly increases the precision and reliability of the results. This Application Note describes the potentiometric determination of the acid number according to ASTM D664 and IP 177 using the pH electrode Solvotrode easyClean.

Tartaric Sulfuric Anodizing (TSA) is an established technique for corrosion protection in the aerospace industry. It is an alternative to the environmentally harmful chromic anodizing process. As such, a method to monitor the levels of sulfuric acid and tartaric acid in TSA plating baths is required. Potentiometric titration methods have been developed, and are widely used across the industry. Their disadvantage is that two titrations with different electrodes and solvents are required.In this Application Note, an alternative method is presented, where the concentration of both acids is determined in sequence using a thermometric sensor. Compared to potentiometric titration, thermometric titration is faster and more convenient (no sensor maintenance required). On a fully automated system, the determination of both parameters takes about 7 minutes.

Pyrithione complexes, such as zinc pyrithione (ZnPT), copper pyrithione (CuPT), and sodium pyrithione (NaPT), are used as fungicides and bactericides. ZnPT is used in the treatment of skin conditions such as seborrheic dermatitis or dandruff. Furthermore, ZnPT is sometimes used as an antibacterial agent in paints to prevent algae and mildew growth. CuPT is primarily in use as a biocide to prevent biofouling of surfaces submerged in water. Meanwhile, NaPT is used as antifungal agent for treatment of mycosis, such as athlete’s foot. The different pyrithione complexes are determined by iodometric titration using a maintenance-free Pt Titrode for the indication.

Potassium is a primary macronutrient for plants, as it plays an important role in water regulation as well as plant growth. In NPK fertilizers, potassium is present besides nitrogen and phosphorus, which are the other two primary macronutrients. Knowing the quality and content of a NPK fertilizer allows an optimal fertilizer management for a planned culture, saving costs and increasing profitability.Traditionally potassium is determined gravimetrically or by flame photometry. In this Application Note, an alternative method is presented, where potassium is determined a precipitation titration. Various solid and liquid NPK fertilizers with potassium contents between 10 and 27% were analyzed. After the removal of any present ammonia, the potassium can be determined reliably in about 5 minutes.

This poster describes the water determination in different biodiesel samples via direct coulometric titration, the Karl Fischer oven method and an automated KF pipetting system.

Compounds with carbonyl groups can be prone to oxidation for which reason their stability often decreases during storage or processing. The method presented here is suitable for the determination of aldehydes and ketones sparingly soluble in water.Samples are dissolved in deionized water. After a reaction with the hydroxylamine hydrochloride at 50 °C, carbonyl groups are quickly and accurately determined by potentiometric titration using the dUnitrode and sodium hydroxide as titrant.

This Bulletin describes the simultaneous determination of gold and copper by potentiometric titration using an Fe(II) solution as titrant. Fe(II) reduces Au(III) directly to the free metal, whereas Cu(II) does not react. By the addition of fluoride ions the Fe(III) is complexed and a shift of the redox potential is effected. Afterwards, potassium iodide is added, thus reducing the Cu(II) to Cu(I), and the free iodine is again titrated with the Fe(II) solution using a Pt Titrode.Chemical reactions:Au(III) + 3 Fe(II) → Au + 3 Fe(III)2 Cu(II) + 2 I- → 2 Cu(I) + I2I2 + 2 Fe(II) → 2 I- + 2 Fe(III)

As much as the many types of cement may differ from one another, the characteristic that all of them have in common is the presence of the elements calcium, magnesium, iron, aluminum and silicon.Calcium, magnesium, iron and aluminum can be determined using various indicators following digestion of the cement sample using photometric titration with the Optrode at 610 nm. The determination of silicon, on the other hand, is gravimetric.

The bromine index indicates the degree of unsaturation and relies on the simple addition of bromine to the double bond of alkenes. One mole of bromine is consumed for each mol of carbon-carbon double bond. The bromine index indicates the olefin content in aromatic hydrocarbons. This Application Note describes the determination by coulometric titration according to ASTM D1492.

Following the addition of caustic soda, hexafluorosilic acid can be determined through back titration of excess hydroxide with hydrochloric acid. Hydrofluoric acid (hydrogen fluoride) is determined by precipitation with aluminum in the presence of sodium and potassium ions. Nitric acid is determined by subtracting the equivalence concentrations of hexafluorosilic acid and hydrofluoric acid from the total acid concentration.

The acid number (AN) is a measure for the quality of oils and their potential to enhance corrosion. When analyzing fresh, unused oils, the AN is used to ensure the specified quality from the manufacturer, whereas for used oils the AN is determined to observe its increase until a critical level is reached. Although it is generally assumed that the AN correlates to the corrosive potential of the oil, this is not exactly correct, as it is the change of the AN value which indicates this issue. Therefore it is necessary to determine the AN on a regular basis.Several standards already exist to determine AN via titration methods, however it is also possible to measure this parameter via spectroscopic (NIRS) methodology. No matter which technique you choose, Metrohm has you covered with high-performance instruments suitable for these published norms.

The vaping and electronic cigarette industries are growing. The mixtures used in these products are usually called e-liquid, e-fluid, or e-juice. Toensure the quality of these e-liquids, testing the most important parameters is required. One important quality control parameter is water or moisture content.Water/moisture content determination by Karl Fischer titration (KFT) is an established and reliable procedure. Compared to other methods the advantages of KFT are its accuracy, speed, and selectivity. For high water content samples, such as e-liquids, volumetric KFT is the method of choice.In this Application Note a system for the fast and reliable determination of the water content in E-liquids is presented. This fully automated system performs the analysis including system preparation, blank, titer, and sample determination completely unattended. Hence, the workload of the operator is reduced to only weighing in the sample and placing the sealed sample vessels on the system.

Lithium-ion batteries must be completely free of water (concentration of H2O < 20 mg/kg), because water reacts with the conducting salt, e.g., LiPF6, to form hydrofluoric acid.The water content of several materials used in lithium ion batteries can be determined reliably and precisely by coulometric Karl-Fischer titration. In this Application Bulletin the determination for the following materials is described:raw materials for the manufacture of lithium-ion batteries (e.g., solvents for electrolytes, carbon black/graphite); electrode coating preparations (slurry) for anode and cathode coating; the coated anode and cathode foils as well as in separator foil and in the combined material; electrolytes for lithium-ion batteries;

Agriculture at significant scale without fertilizers is no longer possible in the modern world. To grow a sufficient amount of produce for nearly 8 billion people as well as for domesticated animals and industrial uses, fertilizers of different nutrient compositions are available to cater to the unique needs of various soil types. Information on the fertilizer’s composition (e.g., total nitrogen, phosphorus, and potassium) is available to help select the ideal fertilizer for a specific soil. Conventionally these constituents are determined either gravimetrically (e.g., phosphorus, potassium, or sulfate) or with ICP-OES (e.g., phosphorus or potassium). These methods either have the disadvantages of long analysis times combined with laborious sample preparation (gravimetry), or require expensive instrumentation with high running costs (ICP-OES). This White Paper elaborates how thermometric titration is a fast and inexpensive alternative method to provide information on the content of various nutrients in different fertilizers.

This bulletin describes the determination of calcium, magnesium, and alkalinity in water by complexometric titration with EDTA as titrant. It is grouped into two parts, the potentiometric determination and the photometric determination.There are multiple definitions of the different types of water hardness. In this Application Bulletin, the following definitions are used: alkalinity, calcium hardness, magnesium hardness, total hardness, and permanent hardness. Explanations of these definitions and other expressions are provided in the Appendix.Determination of alkalinity during the photometric part is carried out in a separate acid-base titration before the complexometric titration of calcium and magnesium in water. Permanent hardness can be calculated from these values. The determination of calcium and magnesium in beverages (fruit and vegetable juices, wine) is also described.The photometric part includes the determinations of total and calcium hardness and thereby indirectly magnesium hardness using Eriochrome Black T and calconcarboxylic acid as indicators (in accordance with DIN 38406-3).

The rapid growth of the Earth's population has led to massive increases in the consumption of energy and resources and in the production of consumer products and chemicals. It is estimated that 17 million chemical compounds are currently on the market, of which 100,000 are produced on a large industrial scale. Many of these enter the environment. This leads to a demand for sensitive analytical procedures and high-performance analytical instruments.pH value, conductivity and oxygen requirement are important characteristics in water and soil analysis. The first two of these can be determined rapidly; for the third, the titration that is used is also the one used in numerous single determinations. This article describes several important standard-compliant determinations in water and soil analysis.

Only coulometric Karl Fischer titration can determine low water contents with sufficient accuracy.This Application Bulletin describes the direct determination according to ASTM D6304, ASTM E1064, ASTM D1533, ASTM D3401, ASTM D4928, EN IEC 60814, EN ISO 12937, ISO 10337, DIN 51777, and GB/T 11146. The oven technique is described according to ASTM D6304, EN IEC 60814, and DIN 51777.

Phosphate can be rapidly and easily titrated thermometrically using a standard solution of Mg2+ as titrant. The phosphate-containing solution is basified and buffered with NH3/NH4Cl solution before titration. The formation of insoluble MgNH4PO4 is exothermic. The method is a titrimetric adaptation of a classical gravimetric procedure. This bulletin deals with the determination of phosphate in phosphoric acid and granular fertilizers such as MAP (monoammonium phosphate), DAP (diammonium phosphate) and TSP (triple superphosphate). Results are reported as percentage of P and P2O5.

This Application Note shows the automatic pH adjustment of a mixture of acetonitrile, water and amine using a Metrohm titrator.

Test measurements on water standards are performed with an OMNIS KF Titrator and Karl Fischer reagents Aquagent® Complet 5 and Methanol Fast from Scharlau.

The phosphoric acid content can be easily titrated with a standardized solution of 2 mol/L NaOH. The interfering calcium content in phosphoric fertilizer can be eliminated by adding a saturated oxalate solution.

Sulfate can be rapidly and easily titrated thermometrically using a standard solution of Ba2+ as titrant. In industry, the widespread procedure is applied to the determination of sulfate in wet-process phosphoric acid.

The Kraft process is the dominant pulping process in the pulp and paper industry with the highest chemical recovery efficiency. In order to run each part of the papermaking process optimally, constant quality checks and analyses should be performed. This Process Application Note illustrates the straightforward online analysis of alkali (active, effective, total titratable alkali (TTA)), carbonate, hydroxide, sulfide and the causticizing degree (CE%) in pulping liquors using a 2060 Process Analyzer from Metrohm Process Analytics.

This Application Note describes the photometric determination of aluminum in cement using the Optrode (574 nm). Following breakdown of the cement sample, the dissolved aluminum is titrated with EDTA. The excess EDTA is titrated back with zinc sulfate solution.

Thorium is titrated with EDTA at a pH value of 4.9. Xylenol orange is used as the indicator for visualization of the equivalence point. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Thallium is titrated in slightly acidic medium as Tl(III). Xylenol orange is used as the indicator to determine the endpoint. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Zirconium is titrated directly with EDTA in acidic aqueous solution (buffer, pH 1). Eriochrome cyanine R is used as the indicator for this procedure. The equivalence point is determined with the Optrode at a wavelength of 520 nm.

Determination of copper, principally in copper mining and refining solutions. The method may also be used fordetermination of purity of copper metal. Optimal results are obtained when aliquots containing copper in the rangeapproximately 3 - 6 mmol Cu are titrated.

Tin with EDTA forms very stable complexes in its divalent and tetravalent forms. Hydroxo complexes form in alkali media, which is also why tin is titrated in an acidic medium (pH 2.1). Xylenol orange is used as the indicator. The equivalence point is determined with the Optrode at a wavelength of 574 nm.

Sulfate can be rapidly and easily titrated thermometrically using a standard solution of Ba2+ as titrant. In industry, the widespread procedure is applied to the determination of sulfate in wet-process phosphoric acid. This bulletin deals with the determination of sulfate in granular fertilizers such as MAP (monoammonium phosphate), DAP (diammonium phosphate) and TSP (triple superphosphate). Results are reported as percentage of elemental sulfur, %S.

This Application Note looks at the photometric determination of manganese sulfate using the Optrode (610 nm). Manganese is titrated with EDTA; Eriochrome Black T is used as indicator. The method complies with Ph. Eur. and the USP.

A method for the potentiometric determination of CaCO3 in cement raw meal is described, in which the accurately weighed-out sample is treated with HCl, heated to boiling and the excess HCl is then back-titrated with NaOH.

This Application Note describes the photometric determination of bismuth nitrate using the Optrode (520 nm). The sample is titrated with EDTA solution past the endpoint; xylene-orange is used as the indicator. The method for bismuth nitrate fulfills the directives defined in the Ph. Eur. and the USP.

This Application Note covers the photometric determination of calcium in cement using the Optrode (610 nm). After digestion of the cement sample, calcium is titrated with EDTA to the murexide endpoint.

During charge and discharge of a Li-ion battery, lithium ions are transported from one electrode through the electrolyte to the other electrode. Knowing the chemical diffusion coefficient of electrode materials is crucial. The potentiostatic intermittent titration technique (PITT) is one of the most used techniques to retrieve insights on the diffusion coefficient of the electrode active materials.

«Dissolved oxygen» describes the amount of oxygen molecules (O2) which are dissolved in a liquid phase under certain conditions. In this white paper, two different methods for the analysis of dissolved oxygen, titration and direct measurement, are compared and contrasted to help analysts determine which method is more suitable for their specific applications. Here, we primarily focus on the determination of dissolved O2 in water. However, the same principle applies for other liquid phases such as non-alcoholic or alcoholic beverages.

The Bayer Process is the method used to refine alumina from bauxite ore, as smelting aluminum directly from alumina is much more cost- and energy-effective. In this process, "aluminate liquors" are created by digesting the crushed bauxite with CaO and NaOH at high temperatures. Additionally, the CaO causticizes carbonate which forms in the alkaline solution from organic degradation and CO2 absorption from the atmosphere. Contaminations are removed at various steps in the process, and the liquor is filtered from the alumina crystals before it is recycled back to the digestion step. Before the spent liquor can be reused, a determination of the concentrations of the total hydroxyl (“caustic”), carbonate, and alumina values is required. These parameters can be determined quickly via thermometric titration with the 2035 Process Analyzer.

Basic chemicals are added to petroleum products to prevent corrosion as they neutralize acidic components that form during the use and aging of these products. The base number (BN) gives an indication regarding the amount of these basic additives present, and it can be used as a measure for the degradation of the petroleum product.This Application Note describes the potentiometric determination of the base number according to ISO 3771, ASTM D2896, and IP 276 using the Metrohm Solvotrode easyClean and a fully automated OMNIS system.

The titratable acidity gives an indication of the freshness of milk and yogurt as well as other fermented milk products. The determined titratable acidity in milk is mainly given through the absorption of hydroxyl ions by milk proteins and milk salts. The acidity increases with bacterial acidification and with enzymatic lipolysis. The titratable acidity corresponds to the amount of sodium hydroxide required to titrate 100 g sample to a pH value of 8.30.In this Application Note, an easy and accurate method to determine the titratable acidity in milk according to DIN 10316 and in yogurt according to ISO/TS 11869 and IDF/RM 150 is demonstrated.

Determination of sodium in salts, process solutions, and foods.

Determination of soluble orthophosphate ions, for example soluble phosphate in fertilizers such as DAP.

Determination of nickel in the absence of cobalt and other interferences.

Standardization of sodium fluoride titrant for determination of aluminum.

Determination of boric acid in electroless plating solutions.

Determination of aluminum in acidic, basic, and neutral solutions; including aluminum chloride, aluminum chlorohydrate (also in anti-perspirant formulations), alum, etching solutions, and aluminate solutions.

Determination of nickel in refinery and plating solutions. When other metals capable of being complexed by EDTA are present, these will interfere and enhance the result for nickel.

Determination of ammonium ions in ammonium salts and mixtures containing ammonium ion.

Standardization of titrant for direct determination of sodium.

Determination of sodium in seawater and similar brines. This procedure is suitable for the analysis of sodium in seawater contaminated with sodium aluminate solutions emanating from alumina refineries, and seawater which has been used for the neutralization of alumina refinery waste («red mud») slurries.

Determination of hydrofluoric acid in mixed acid etchant solutions.

Determination of boron in ores of the element such as borax and ulexite.

This Application Note describes the digestion of a cement sample and the photometric determination of iron in accordance with DIN EN 196-2 by means of Optrode at 610 nm. Sulfosalicylic acid is used as the indicator and EDTA as the titrant for the determination.

Determination of sodium and potassium salts of carboxylic acids in aqueous media. May be used for analysis of reagent purity.

Barium acetate is used as titrant for conductometric sulfate determination. It can be standardized with desiccated sodium sulfate.

Determination of the total sodium content of sodium aluminate liquors, such as Bayer Process liquor. This method is suitable for the analysis of all sodium aluminate solutions down to at least 1 g/L as Na2CO3. The determination may be automated by adding an 814 USB sample processor to an 859 Titrotherm.

This Application Note details the photometric determination of chondroitin sulfate with 1-hexadecylpyridinium chloride as titrant and with the Optrode (660 nm). The method is in compliance with the Ph. Eur. and the USP.

The poster describes the development of an automated Karl Fischer method for determining the water content in different edible oils.

The presented Application Bulletin describes the apparatus and methods that are used for acid-base analysis of whole blood and blood plasma by Joergensen and Stirum. Evaluation of the measured data is performed with a software sold by Komstar AG.

This Application Bulletin gives an overview of the volumetric water content determination according to Karl Fischer. Amongst others, it describes the handling of electrodes, samples, and water standards. The described procedures and parameters comply with the ASTM E203.

Polyurethanes are one of the most commonly used types of plastic. They are produced by the reaction of raw polyols with isocyanates. Depending on the starting material a wide variety of plastics can be obtained. The determination of the acid value, hydroxyl value, and isocyanate content plays an important part in the analysis of raw materials for plastics.The acid number of polyol raw material is usually used in quality control to ensure batch-to-batch uniformity. Additionally it is used as correction factor for calculating the true hydroxyl number. In this Application Bulletin the determination of the acid number according to ASTM D4662 and ASTM D7253 is described.One raw material for polyurethanes are polyols. Polyols contain multiple hydroxyl groups. Therefore, hydroxyl number of a raw material directly correlates to the amount of polyols present and it is thus an important quality control parameter. In this Application Bulletin the determination of the hydroxyl number according to ASTM E1899 and DIN 53240-3 is described.As polyols react stoichiometrically with isocyanates, the knowledge of the isocyanate content is an important quality parameter for the production of polyurethanes. In this document the determination according to EN ISO 14896 method A, ASTM D5155 method A and ASTM D2572 is described.

This Application Note outlines GITT, a key technique for studying Li-ion battery kinetics, OCV, and diffusion, using INTELLO for streamlined control and analysis.

This Application Bulletin describes methods for checking the condition of electrodes for surfactant titration. For testing electrodes used for ionic surfactant titration (Ionic Surfactant electrodes), sodium dodecyl sulfate (SDS) is determined using TEGO®trant. Conversely, for testing electrodes used for cationic surfactant titration (Cationic Surfactant electrodes), TEGO®trant is titrated with SDS.For non-ionic surfactant electrodes (NIO surfactant electrode), PEG 1000 is titrated with sodium tetraphenylborate (STPB).For testing Surfactrode Resistant and Surfactrode Refill electrodes, titrations of SDS with TEGO®trant are performed. Suitable criteria for the test are the height of the potential jump and the shape of the titration curve.Key word: NaPh4B

Iron sucrose injections are used during the treatment of iron deficiency anemia. They contain a mixture of ferric iron (Fe3+) and ferrous iron (Fe2+). Ferrous iron content may be determined by subtracting the ferric iron content from the total determined iron content. Yet, this increases the measurement error due to error propagation. Alternative determination of iron(II) with cerium(IV) by potentiometric titration may be hampered, as the equivalence point cannot be determined unequivocally. Determination by thermometric titration is a more robust and therefore more reliable alternative, as this method is unaffected by the sample matrix. Here, the endpoint of the titration is indicated by a fast responding thermometric sensor. Endpoint detection is further improved by spiking the sample with 0.2% ammonium iron(II) sulfate (FAS), increasing the reliability of the determination. Compared to potentiometric titration, thermometric titration is faster and more convenient as no sensor maintenance is required. One determination takes about 2–3 minutes.

This study presents the automatic titration of low sulfite levels in beet crystal sugar using an OMNIS Titrator and a Pt Titrode as the potentiometric sensor.

This Application Note looks at the determination of ferrous ion in acidic solutions through redox titration with potassium permanganate as titrant and thermometric titration.

Results from three separate single endpoint titrations are used to calculate the results. The mixture of H2SO4, HF, and NH4F/HF contains H+ from H2SO4, HF, and NH4F/HF, SO42- from H2SO4, and F- from HF and NH4F/HF. Analysis of total H+ («total acids») by NaOH titration, F- by titrating with Al(NO3)3 («total fluoride») and SO42- by titrating with BaCl2 provides the information required to determine the composition of the mixture.

Two separate titration sequences are required to analyze the mixture:- titration of the HF content with Al(NO3)3 (the «elpasolite» reaction)- titration of the H2SO4 with BaCl2 followed by titration with NaOH to determine the «total acids» contentThe HF, H2SO4, and «total acids» contents are converted to a HNO3 equivalent, with the HNO3 content found by subtracting the HF and H2SO4 from the «total acids» content.

This application presents the fully automated determination of acidity in jet fuel as per ASTM D3242 via photometric titration with an automatic titrator and the Optrode.

For a variety of reasons, the water content of chocolate is of crucial importance and has to be accurately determined. This poster compares an automated version of the Karl Fischer titration (KFT) using the sequential addition of various solvents with the widespread manual titration at elevated temperatures using a chloroform/methanol mixture. The water contents determined by the two procedures show excellent agreement. However, manual titration requires laborintensive sample preparation, the side reactions are difficult to quantify and hazardous halogenated solvents have to be used. In contrast, automated KFT is straightforward, uses non-hazardous solvents, allows to quantify the side reactions and is easily applicable to water determinations in sugar- and fat-containing matrices.

Anionic surfactants can be titrated with cationic surfactants and vice-versa. The Bulletin describes a multitude of substances that can be determined in this fashion and specifies the respective working conditions and parameters. In contrast to the classic two-phase titration in accordance with Epton, the titration with the anionic and cationic surfactants electrodes can be performed without chloroform. Furthermore, the equivalence point of the titration is difficult to determine in some cases with the Epton method and the titration cannot be automated.In many cases, a surfactant ISE is a remedy that is both environmentally friendly and suitable here. It was developed specially for application with potentiometrically indicated surfactant determinations.

For titrations in low conducting media (e.g., non-aqueous titrations) the potentiometric indication can be disturbed by interfering signals. When differential amplification is used, these signals are measured by both the measuring electrode and the reference electrode and thus neutralized. It is therefore possible to obtain smoother titration curves and more reproducible results.This Application Note describes the potentiometric determination of the acid number and base number in used motor oil by the differential amplification using a fully automated OMNIS system.

The water content of lyophilisates contained in vials is determined by Karl Fischer titration. Conditioned solvent (methanol) is injected into the vial to dissolve the sample and extract the water (ultrasonic bath). Afterwards the contents of the vial are transferred to the titration vessel to carry out the automatic determination.

The vaping and electronic cigarette industries have grown impressively in the past decade. The mixtures used in these products are usually called «e-liquid», «e-fluid», or «e-juice». To ensure the quality of these e-liquids, testing the most important quality parameters, such as nicotine content, is required. Nicotine in tobacco is usually determined by gas chromatography or liquid chromatography. Aqueous acid base titration is a much more affordable alternative for this determination. As e-liquids do not contain other components which might interfere with the titration, the aqueous acid base titration presented in this Application Note can be applied for nicotine determination. This method is an affordable and reliable way to determine the nicotine content in e-liquids and their nicotine starting material, ensuring the quality of these products.

Nicotine is a nitrogenous alkaloid that is hazardous to health and is characterized by a very high potential for addiction. The nicotine content in tobacco products must be determined and specified precisely. This Application Note exhibits an easy and straightforward method for nicotine determination in tobacco by non-aqueous titration.Results determined by GC and IC are given as a comparison. In comparison to chromatographic methods, titration is an «absolute method», meaning it is not necessary to calibrate the system prior to the analyses.

Hydrochloric acid is a strong, inorganic mineral acid with great significance in the chemical industry. The potentiometric titration of hydrochloric acid with sodium hydroxide is one of the most important and also most frequent analyses performed in the laboratory. In this Application Note, an acid-base titration is presented where the concentration of HCl is determined with NaOH using a pH electrode with an integrated Pt1000 temperature senor for the most accurate results

Halides interfere with most determinations of mercury or silver. However, if mercury or silver is titrated with sulfide ions, extremely insoluble sulfides are formed.A simple method is described that allows the direct titration of mercury(II) or silver(I) compounds in the presence of halides. The potentiometric titration takes place under alkaline conditions using thioacetamide as the titrant after formation of the EDTA complex.Organic compounds that are insoluble in alkaline EDTA can also be titrated after a Schoeniger digestion.

This Bulletin describes three potentiometric, one photometric, one thermometric and one conductometric titration method for sulfate determination. The question of which indication method is the most suitable depends primarily on the sample matrix.Method 1: Precipitation as barium sulfate and back titration of the Ba2+ surplus with EGTA. Use of the ion-selective calcium electrode as indicator electrode.Method 2: As with Method 1, although with the electrode combination tungsten/platinum.Method 3: Precipitation titration in semi-aqueous solution with lead nitrate in accordance with the European Pharmacopoeia using the ion-selective lead electrode as indicator electrode.Method 4: Photometric titration with lead nitrate, dithizone indicator and the Optrode 610 nm, particularly suitable for low concentrations (up to 5 mg SO42- in the sample solution).Method 5: Thermometric precipitation titration with Ba2+ in aqueous solution, particularly suitable for fertilizers.Method 6: Conductometric titration with barium acetate in accordance with DIN 53127

It is essential to know before starting the sample analysis if the electrode is in a good state or not. A well workingelectrode will increase the quality of your results, as the accuracy and precision will be increased. Furthermore, tedious error tracking can be omitted and no sample is wasted due to a defect or old electrode. There exist several ways how to check metal electrodes, e.g., measurement of redox potentials, potentiometric titration or bivoltammetric titration. This bulletin describes the best methods for the various by Metrohm available metal electrodes.

Karl Fischer titration can be used to determine the water content in N-acetyl-L-cysteine. Special solvent mixtures can be used to prevent unwanted side reactions in the Karl Fischer titration. The water content of N-acetyl-L-cysteine can thus be determined quickly and accurately, as is shown in this Application Note.

Fertilizers are applied in the agricultural sector to provide more essential nutrients to growing plants. The so-called «NPK» fertilizers provide such nutrients to plants with its three main components (N – nitrogen, P – phosphorous, K – potassium). In fertilizers, nitrogen is mainly provided in three forms: as ammonium nitrate (NH4NO3), ammonia (NH3), and urea (H2NCONH2). Determination of the individual nitrogen-contributing components is often laborious work. Thermometric titration offers the possibility to rapidly determine the amount of ammoniacal nitrogen and urea nitrogen in a single titration using sodium hypochlorite as titrant.

Phosphoric acid is a triprotic inorganic acid used for many purposes: as a raw material for the production of phosphate fertilizers, detergents, as an electrolyte in phosphoric acid fuel cells, rust removers, and for the passivation of iron and zinc to protect against corrosion. This Application Note presents an acid-base titration where the concentration of phosphoric acid is determined over all three of its dissociable protons by titrating it with sodium hydroxide.

Water content determination by volumetric Karl Fischer titration is one of the most important analyses worldwide, particularly when it comes to food quality. This parameter has a major influence on the growth of microorganisms, and thus indirectly affects the storability of the raw materials and final products. Consistent quality is only possible with precise measurements during the process. This measurement is performed with the Metrohm Eco KF Titrator for flour, dough, and baked goods.

This Application Note deals with the determination of ferric ion in acidic and copper-free solutions using thermometric titration. The ferric ion is reduced by iodide. The released iodine reacts exothermically when titrated with thiosulfate solution. The endpoint is determined through temperature plotting by the temperature sensor Thermoprobe.

The formol number represents a further parameter for the characterization of fruit and vegetable juices. As this is merely an index (the formalin number does not deal with the molecular size, nor with the quantity of amino acids), the conditions of the titration can be adapted to meet practical needs. This concerns mainly the pH value of the endpoint of the SET titration (pH = 8.5, pH = 9.0, pH = 9.2, etc.).

Purity of rare earth elements (REEs) can be determined by absolute complexometric titration with xylenol orange (ISO 23597). This approach achieves around 100% recovery, eliminates the need for calibration, and offers higher accuracy and reproducibility than techniques such as AAS (atomic absorption spectroscopy). Photometric titration with the Optrode M2 offers adjustable wavelength detection, providing a fast, precise, and cost-effective alternative to other conventional methods.

The titrimetric determination of nonionic surfactants on the basis of polyoxyethylene adducts (POE adducts) is described in the Bulletin. The basis for the determination is the transfer of the nonionic surfactant into a pseudo-cation compound and its precipitation titration with sodium tetraphenylborate (Na-TPB). The NIO electrode is used for the indication of the potentiometric titration. This Bulletin describes determinations in raw products, formulations and wastewater and draws attention to special features, possibilities, limits and disruptions.

Determination of low levels of sulfate (to approximately 20mg/L SO42-) by thermometric titration.

Peroxides are often used for disinfection and water treatment purposes due to their antiseptic properties. Lower concentrations between 0.3–3% are used in households, while higher concentrations can be used for sterilization purposes. Additionally, peroxides are utilized as oxidizing and bleaching agents. Peroxides, perborates, and percarbonates can easily be determined by titration. This application note presents two titration methods for peroxide analysis: ASTM D2180 for concentrated hydrogen peroxide solutions, and a second method for trace determination of hydrogen peroxide, suitable for concentrations as low as 0.4 mg/L.

Lithium nitrate is an oxidizing agent used in the manufacture of red-colored fireworks and flares. In addition, the lithium nitrate trihydrate compound absorbs heat well and can be used for thermal energy storage. Since lithium nitrate is a hygroscopic substance, its purity must first be verified before it is used for synthesis or other applications. The purity assay is done by a fully automated precipitation titration between lithium and fluoride in an ethanolic solution. The benefit of titration is that the lithium nitrate does not need to be diluted after dissolving in ethanol as with other techniques such as ICP-MS.

The bromine number is an important parameter for the determination of aliphatic C=C double bonds in petroleum products. The bromine number is usually determined using electrochemical titration at 5 °C, where the bromine is generated in situ from a bromide/bromate solution. For the titration, a solvent mixture of glacial acetic acid, methanol, and chloroform is used. In this Application Note, the toxic chloroform was replaced with diethyl carbonate.

The acid number (AN) of insulating, transformer, and turbine oils is crucial to ensure safe operation, operating equipment control, and corrosion prevention. These oils generally have low AN specifications and their AN determination by manual color-indicator titration is difficult, especially when analyzing colored samples.Using a Titrator with a photometric sensor to detect the end point ensures that the titrations are always carried out under the same conditions. This greatly increases the precision and reliability of the results, which in turn results in improved monitoring for your operations.

Automated mixing of a suspension and a solvent in a 50 mL dosing unit can be used to add a well-defined amount of a suspension-solvent mixture to a sample solution without clogging the dosing unit and tubing by the undiluted suspension.The method is explained by means of the TAN determination of a petroleum sample using thermometric titration. For a better endpoint recognition, small amounts of a paraformaldehyde-solvent suspension are added (catalyzed endpoint thermometric titration).

Many of the key factors that influence coffee taste correlate with chemical properties that can be measured. These include pH, titratable acidity, refractive index, and caffeine. Historically, many of these analyses have included long, manual sample preparation processes using the time-consuming, liquid chromatography (LC) technique. This Application Note looks at a faster, simpler, alternative method for analysis of key quality parameters in coffee using a single titration platform: OMNIS.

Standardization of disodium dimethylglyoximate by thermometric titration with standard Ni(II) solution.

The water content in methylcyclohexane is determined by coulometric Karl Fischer titration.

This application note shows how to determine the bismuth content automatically in aqueous solution with potentiometric titration.

Determination of chloride in canned vegetables by potentiometric titration with silver nitrate using the Ag-Titrode.

Determination of lidocaine in ointments by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

Penicillin and its related antibiotics are used to prevent and treat a number of bacterial infections, such as respiratory tract infections, urinary tract infections, meningitis, etc. It may also be used to prevent group B streptococcal infection in newborns. The β-lactam ring of penicillin binds to the enzyme DD- transpeptidase, which prevents the formation of cross links during cell wall formation of new bacterial cell, i.e., the division of bacterial cells. USP<425> describes a back-titration method to determine the assay of pharmacopeial penicillin antibiotic drugs and their dosage forms by iodometric titration. The method is illustrated by determining the aminopenicillin content in an ampicillin capsule.

Kjeldahl method is used to determine the nitrogen content in organic and inorganic samples. Kjeldahl consists of three steps: digestion, distillation, and titration. During the catalytic digestion step, organic nitrogen is converted into ammonium. Sodium hydroxide is added just before the distillation step for converting ammonium into ammonia. Through steam distillation the latter is transferred into the receiver vessel containing an absorbing agent (e.g., boric acid). Finally, the separated ammonia is titrated against sulfuric acid. Protein content in samples can also be determined from the nitrogen content obtained by Kjeldahl setup. USP describes the titration method to determine nitrogen content in organic products using Kjeldahl nitrogen setup. This Application Note illustrates nitrogen determination in heparin sodium.

The two potentiometric titration methods described here allow the determination of the content of commercial betaine solutions. Neither method is suitable for determining the betaine content of formulations. The possibilities and limits of both methods are described and distinctive features and possible sources of interference are mentioned. The Bulletin explains the most important theoretical principles and is intended to help users to develop their own product-specific titration methods.

Rare earth elements (REEs) are critical materials whose deposit viability and processing streams require accurate mass-fraction determination during ore dissolution and purification. This Application Note describes a rapid potentiometric back-titration using a copper ion-selective electrode (Cu-ISE) that enables selective quantification and partial separation of REEs in complex matrices with near-quantitative recovery. As an absolute, flexible, and cost-effective method with ICP-compatible sample preparation, back-titration is well suited both as a reference technique and for rapid on-site analysis.

Determination of sulfate in cement by indirect potentiometric titration with EDTA using platinum and tungsten electrodes.

Determination of total penicillin content through potentiometric titration with Hg(II) using the combined Au electrode. Keyword: Antibiotics

This Application Note compares the OMNIS Titrator and 888 Titrando for determinations of nitric acid, phosphoric acid, and acetic acid in an aluminum etching bath, as well as the determination of tetramethylammonium hydroxide (TMAH). Identical analysis parameters were used, showing that OMNIS delivers results on par or even better than with other established titration systems.

This application note shows how coconut oil ethoxylates can be determined via potentiometric titration.

This Bulletin describes the simultaneous potentiometric titration of free boric acid and free tetrafluoroboric acid in nickel plating baths. After addition of mannitol, the formed mannitol complexes are titrated with sodium hydroxide solution. The determination is carried out directly in the plating bath sample; nickel and other metal ions do not interfere.