Методики

The presence of acidic components in volatile solvents could be a result of contamination, decomposition during storage, distribution or manufacture. An increased acid content in solvents could lead to a variety of problems like shorter storage stability or chemical corrosion. Using the Optrode for indication, the acidity is determined by photometric titration with sodium hydroxide as titrant and phenolphthalein as indicator. If the volatile solvent is water soluble, it is dissolved in deionized water, if not, it is dissolved in carbon-dioxide free ethanol.

The permanganate index (PMI) is a sum parameter that indicates the total load of oxidizable organic and inorganic matter in water. The substances concerned are mainly humic materials/acids that are primarily formed when dead organic material present in soil is further broken down and released into water sources. As it is an indicator of the water quality, testing of the PMI for drinking water is obligatory in many countries.For the determination, it is necessary to heat the stabilized water sample to 95 °C and higher for a stipulated time. Afterwards, the amount of permanganate that has remained after the reaction with the sample is determined titrimetrically. This sample preparation step requires considerable manual effort.In this Application Note, a fully automated procedure for the determination of the PMI according to GB/T 11892 is described, including all sample preparation steps. The gains in productivity because of a reduced manual workload are considerable.

The determination of the physical and chemical parameters as electrical conductivity, pH value, alkalinity, the calcium and magnesium hardness as well as the total hardness are necessary for evaluating the water quality. A fast and accurate determination in tap water is realized using an automated OMNIS System working in parallel on different workstations. An 856 Conductivity Module with Dosinos extends the system.

The bromine index is an important parameter for the determination of aliphatic C=C double bonds in petroleum hydrocarbons. For the titration, a solvent mixture of glacial acetic acid, methanol, and dichloromethane is usually used.In this Application Note, the chlorinated solvent in the solvent mixture was replaced with toluene, resulting in a more environmentally beneficial method in comparison to ASTM D2710 and IP 299.

The bromine index is an important quality control parameter for the determination of aliphatic C=C double bonds in aromatic hydrocarbons and is thus a measure for the presence of aliphatic unsaturation in these materials. In situ generated bromine reacts with the aliphatic double bonds. When the titration is finished an excess of free bromine causes a sudden change in the measured potential thus indicating the equivalence point.

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.

Ethanol, bio-ethanol and biofuel (E85) are increasingly used as substitutes for petroleum-based fuels. During storage, they often come into contact with metallic substrates or surfaces, e.g., in barrels, tanks, or other containers. Excessive concentrations of ions in the stored fuel promotes corrosion. Monitoring the total concentration of the ions present in the fuel matrix should be the first step of an effective anti-corrosion strategy.An easy, fast, and cost-effective method to determine the total amount of ions is by measuring the electrical conductivity according to DIN 15938.

This Application Note presents a potentiometric titration method for a potassium bicarbonate and potassium carbonate assay meeting all USP General Chapter <1225> requirements.

The analysis of the reductants, free and total sulfurous acid, pH and total acidity of wine can be performed fully automated on an OMNIS system based on the directive OIV-MA-AS323-04B, OIV-MA-AS313-01 and OIV-MA-AS313-15.Added components like SO2 have preserving properties and affect the microbiological environment (anti-microbacterial and enzyme-deactivating), they trap fermentation byproducts such as acetaldehyde and suppress a coloring into brown. The bound and free sulfurous acid are in an equilibrium with each other and can be determined via iodometric titration. Iodometric titration is also the method of choice to quantify other reductants, such as dyes, tanning agents, degradation products of carbohydrates and ascorbic acid. Finally, the acidity of wine is an important quality parameter, which affects the color and taste of wines. The total acidity and the pH of wine can be determined on the same system. Hence, Metrohm offers an all-in-one solution for the analysis of these mentioned key parameters.

The FOS/TAC value, sometimes referred to as VFA/TA, is a meaningful parameter for assessing both the current condition and the development of anaerobic digestion processes in a digester of a biogas plant. Knowledge of this value can help decrease the risk of acidification problems, which can result in a costly crash of the entire digestion process. Therefore, an accurate and reliable determination of the FOS/TAC value is important for both efficient and cost-effective production operations. This value is determined by an acid-base titration. Using the Eco Titrator from Metrohm equipped with an Ecotrode plus electrode, a reproducible and accurate determination of the FOS/TAC value is possible.

Water treatment with ozone (O3) is a common procedure for the disinfection of swimming pools. It is important that a sufficient but not excessive amount of O3 is produced to disinfect the water. Otherwise, the remaining ozone could enter the swimming water, which could irritate the respiratory system or the skin of bathers.Ozone is also used in drinking and waste water treatment because it is significantly more effective than chlorine at inactivating or killing viruses and bacteria. This application note describes a method to determine the ozone concentration in water by potentiometric titration according to DIN 38408-3.

Nitrogen-based compounds are widely distributed in the environment and are essential growth nutrients for photosynthetic organisms. Therefore, it is important to monitor and control the amount of nitrogen compounds which are released into the environment.In this Application Note, a method to determine the nitrogen content in water by Kjeldahl digestion and distillation followed by a photometric or potentiometric titration according to ASTM D3590 is presented. The universality, precision, and reproducibility of the Kjeldahl method have made it the internationally recognized method for e.g. estimating the protein content in many matrices and it is the standard method to which all other methods are judged against.

Lithium salts (e.g., lithium carbonate and lithium hydroxide) are used in myriad applications. Lithium hydroxide is used for the production of lithium stearate, an important engine lubricant. In addition, it is utilized as an air purifier due to its ability to bind carbon dioxide. While the majority of lithium carbonate is used for aluminum production, it is also used for the glass and ceramic industry. It lowers the melting point of these materials, lowering the associated electricity costs and making it cheaper to produce them.For all of these applications, it is important to know the quality of the pure lithium salts used in the various production processes. This Application Note presents an easy method for the assay of lithium hydroxide and lithium carbonate on an automated OMNIS system.

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.

Sodium hypochlorite and sodium chloride can be effectively use as disinfectant for water and surfaces. The World Health Organization (WHO) recommends, depending on the application, concentrations in disinfectants of 1000 mg/L to 5000 mg/L NaOCl and up to 200 g/L NaCl.This Application Note demonstrates a reliable method to determine the hypochlorite and sodium chloride content in disinfectants by two subsequent argentometric titrations in the range recommended by the WHO.

The lithium-ion battery market is continuously growing due to the tremendous demand for battery powered consumer products. So-called «NCMs», a mixture of nickel, cobalt, and manganese oxides, have been gathering interest as cathode materials, replacing traditional compounds like cobalt oxides.Quality analysis of the post-sintered materials or recycled batteries can be performed by titration, as demonstrated in this Application Note. A fully automated analysis of the corresponding metals can be performed with OMNIS and its pipetting equipment.

In order to consistently manufacture high quality baked goods, it is critical to measure the pH value and acidity content in the raw materials and during the production steps. These factors have a major influence on the taste and storage lifetime of the final product. Consistent product quality is only possible with precise measurements during the process.This Application Note describes the measurement of pH value and the total titratable acidity in flour, dough, and bread using the Eco Titrator from Metrohm.

If consumed in excess, sodium may damage the cardiovascular system. It is therefore in the interest of food manufacturers to reduce the salt content and while preserving the flavor of the food.To ensure consistent quality, it is critical to know the exact salt content in the raw materials and the final products. This is only possible by performing precise measurements during the production process.This Application Note explains the determination of sodium chloride in dough and bread quickly according to AOAC 971.27 with the Eco Titrator equipped with an Ag Titrode.

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

Traditional Chinese medicine (TCM) remedies are gaining popularity in other cultures. In some TCM, sulfur dioxide (SO2) is used as a preservative, antioxidant, and disinfectant. The products are treated by sulfurization with SO2 gas. However, sulfur dioxide is a very poisonous gas. Global health authorities have set strict limits for the content of SO2 in products. It is therefore of crucial importance to determine the sulfur dioxide content to comply with these limits. In this well-suited method, the SO2 content in different natural TCM products are analyzed reliably and accurately according to ISO 22590 using the Eco Titrator equipped with an Optrode and sodium hydroxide as titrant.

Electroplating processes are used in several different industry sectors to protect the surface quality of various products against corrosion or abrasion and significantly improve their working life. It is essential to check the bath composition on a regular basis to ensure that the process is operating correctly. Typical examples of electroplating baths include alkaline degreasing baths or acidic or alkaline baths containing metals e.g. copper, nickel, or chromium, or components like chloride and cyanide. It is crucial that the chosen analysis technique fulfills high safety standards for these kinds of analyses and produces reliable results. The OMNIS Sample Robot system automatically pipettes and analyzes aggressive electroplating bath samples on different workstations, increasing the safety in the lab. This provides more reliable results in comparison to manual titration and is more time efficient as different parameters can be analyzed in parallel.

Coagulation and flocculation are an essential part of treating both drinking water and wastewater. Aluminum salts such as aluminum sulfate and polyaluminum chloride (PAC) are often used for this purpose. For the precise application and exact dosage of the flocculant, it is important to accurately determine its aluminum content. In this Application Note, the aluminum content is accurately and reliably analyzed based on ABNT NBR 11176 using the 859 Titrotherm equipped with a Thermoprobe HF and sodium fluoride as titrant.

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.

Boehm titration is a quantitative analysis of functional groups on the surface of carbon materials based on their reactions with basic solutions of NaHCO3 (pKa = 6.4), Na2CO3 (pKa = 10.3), and NaOH (pKa = 15.7). This is a cost-efficient method that gives absolute values with high precision of the accessible, mainly oxygen-containing functional groups on the surface. Originally, Boehm titration was developed for carbon materials like conductive carbon black (CCB), activated carbon, porous carbon, and graphite. Modern carbon-based materials like graphene, graphene oxide (GO), or carbon nanotubes can also be analyzed this way.

Sodium lactate is a salt form of lactic acid used in many regulated industries—therefore an accurate determination of the lactate content is required and is already covered in several norms. One such monograph by the US Pharmacopoeia (USP) results in high accuracies and well-defined titration curves but uses titrants and solvents that are more costly than necessary. In comparison, the presented modified method from Metrohm requires a 1:1 mixture of water and acetone and uses aqueous hydrochloric acid as titrant, resulting in an estimated cost reduction of 40% per titration compared to the USP method (USP–NF 2021, Issue 2). Furthermore, the time needed for each analysis is reduced to just 12% of the USP method (excluding blank determination). This Application Note presents both methods to determine lactate content and shows the results obtained on an OMNIS system.

This Application Note presents a complementary method that allows a consecutive determination after the sample preparation (digestion) of both metal ions in one beaker with an optical sensor and xylenol orange as an indicator.

About 20% of our sugar comes from sugar beet crops, mostly grown in Europe and the U.S. where the climate is temperate, whereas the other 80% is produced from sugar cane in tropical areas. Lime salts and pH are very important factors which are controlled during the sugar manufacturing process. Complexometric titration is often used to determine the concentration of lime salts in such kinds of samples. This Application Note presents a more robust method for determining calcium compounds in sugar beet juice. Subjectivity of color change determination is eliminated by using an ion selective electrode (ISE).

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.

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.

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.

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.

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.

The pH value in carbon black, an essential additive in modern lithium-ion batteries, is accurately and reliably analyzed in this Application Note by using the 913 pH Meter equipped with a Unitrode easyClean according to ASTM D1512 as well as ISO 787-9 and GB/T 1717-1986.

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

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.

Alkalinity defines the acid-binding capacity of natural water. A distinction is made between total alkalinity (m-value) and carbonate alkalinity (p-value). This Application Note presents the determination of pH and alkalinity in water with a titration method conforming to EPA 310.1, Standard Methods 2320 B (Titration Method), ASTM D1067, EN ISO 9963-1, and EN ISO 9963-2.

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.

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.

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.

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.

The OMNIS Titrator equipped with a Pt Titrode accurately and reliably determines titer concentration even in diluted titrants as shown in this Application Note.

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.

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

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.

Determination of nickel, zinc, iron(II), and manganese in lithium bromide using cation chromatography with UV/VIS detection (520 nm) after post-column reaction.

Determination of bromide and nitrate in 1% sodium chloride solution using anion chromatography with UV/VIS detection (205 nm) after chemical suppression.

Determination of glycolic and lactic acid in the presence of N-methyl pyrrolidone used in drug delivery systems using ion-exclusion chromatography with UV/VIS detection.

Determination of traces of fluoride, bromide, nitrate, phosphate, and sulfate using anion chromatography with conductivity detection after chemical suppression and subsequent UV/VIS detection.

Determination of iodate, chlorite, bromate, and nitrite using suppressed anion chromatography with UV/VIS detection after post-column reaction.

Determination of nitrite, nitrate, and phosphate in seawater from a shrimp farm using anion chromatography with conductivity detection after chemical suppression and subsequent UV/VIS detection.

Determination of N-acetylcysteine and phenylalanine in tablets against sinusitis by anion chromatography with UV/VIS detection according to USP.

Determination of traces of iodide in bottled water using anion chromatography with UV/VIS detection.

Determination of HEDPA, PBTC, and NTP using anion chromatography with UV/VIS detection after post column reaction (PCR).

Determination of bromide in calcium chloride using anion chromatography with UV/VIS detection.

Determination of chromium(VI) (chromate) in leather extract using anion chromatography with UV/VIS detection after post-column reaction (PCR) and inline dialysis for sample preparation.

Determination of caffeine in a cola soft drink using RP chromatography with UV/VIS detection.

Determination of bromate in water using anion chromatography with UV/VIS detection after post-column reaction (PCR) with o-dianisidine reagent (described in EPA 317.0).

Determination of nitrite in mineral water using anion chromatography with UV detection.

Determination of nitrite, bromide, nitrate, and iodide in 10 g/L sodium chloride using anion chromatography with UV detection.

Determination of vanadium(IV) and vanadium(V) in Benfield solution using anion chromatography with UV detection.

Determination of saccharin, benzamide, and o-toluenesulfonamide in a nickel electroplating bath using RP chromatography with UV detection.

Determination of phenylalanine, aspartame, caffeine, and benzoate in a soft drink using RP chromatography with UV detection.

Determination of cefazolin in accordance with USP 28-NF 23 (Appendix 2) using RP chromatography and subsequent UV detection. Keyword: Antibiotics

Determination of salicylic acid and acetylsalicylic acid according to USP 28-NF 23 (second supplement) using RP chromatography with UV detection.

Determination of cloxacillin sodium in accordance with USP 28-NF 23 (Appendix 2) using RP chromatography and subsequent UV detection. Keyword: Antibiotics

Determination of amoxicillin in accordance with USP 28-NF 23 (Appendix 2) using RP chromatography and subsequent UV detection. Keyword: Antibiotics

Determination of sulfide and thiosulfate in a process water using anion chromatography with UV/VIS detection after chemical suppression and conductivity detection.

Determination of sulfide in a raw vanadate solution using anion chromatography with UV/VIS detection.

Determination of theophylline and theobromine according to USP 28-NF 23 (second supplement) using RP chromatography with UV detection.

Determination of valerophenone and ibuprofen according to USP 28-NF 23 (second supplement) using RP chromatography with UV detection.

Determination of thiamine hydrochloride according to USP 28-NF 23 (second supplement) using RP chromatography with UV detection.

Determination of ranitidine hydrochloride according to USP 28-NF 23 (second supplement) using RP chromatography with UV detection.

Determination of penicillin G potassium and 2-phenyl acetamide in accordance with USP 28-NF 23 (Appendix 2) using RP chromatography and subsequent UV detection. Keyword: Antibiotics

Determination of sulfide in mining wastewater using anion chromatography with UV detection.

The determination of PBBE (tetrabromobisphenol A - TBBPA, octabromodiphenyl ether - OCTA and decabromodiphenyl ether - DECA) in a polymer sample was carried out with the Nucleosil EC - 250 mm column; for this purpose a methanol and phosphate buffer was used as an eluent and subjected to UV detection in accordance with the IEC 62321 method for RoHS testing.

The determination of chromium in metal plate samples using anion exchange chromatography with UV/VIS detection after post-column reaction with diphenylcarbazide as per IEC 62321 method for RoHS testing. This method provides procedures for the determination of the presence of chromium(VI) in colorless and colored chromate coatings on metallic samples.

The determination of chromium(VI) polymers using anion exchange chromatography with UV/VIS detection after post-column reaction with diphenylcarbazide as per IEC 62321 method for RoHS testing.

Determination of melamine in milk, diary products, eggs, and egg-based foodstuffs using cation chromatography.

Determination of cefadroxil in accordance with USP 28-NF 23 (Supplement 2) using RP chromatography with UV detection. Keyword: Antibiotics

Determination of arsenite and arsenate in process water using ion-exclusion chromatography with UV detection.

Determination of aluminum in phosphoric acid using cation chromatography with UV detection after post-column reaction with catechol violet.

Determination of aluminum in an acidic extract containing metals (e.g., alkali, alkaline earth, iron, chromium, molybdenum, etc.) using cation chromatography with UV detection after post-column reaction with Tiron.

Determination of nitrite and nitrate in a cooling lubricant using anion chromatography with conductivity detection (see AN S-274) and subsequent UV detection after sequential suppression and Metrohm Inline Dialysis.

Determination of silicate and hexafluorosilicate (calculated) using anion chromatography with conductivity detection after chemical suppression (see AN S-277) and subsequent UV/VIS detection with post-column reaction. Hexafluorosilicate is hydrolyzed into fluoride and silicate. Both anion concentrations may be used for the calculation of the SiF62- concentration.

Ion chromatography with PCR and UV/VIS detection provides a highly specific and sensitive method for bromate analysis, meeting EPA Method 317 and ISO 11206 requirements.

The Metrosep C 4 columns are mainly used for the separation of alkali and alkaline earth metal cations including ammonium and organic amines. Additionally transition metals may be determined.

Chromate (Cr(VI)) or hexavalent chromium is carcinogenic. Its use is restricted. Chromate has to be analyzed in a large range of products starting with drinking water, wastewater (e.g., from leather production), over toys to RoHS-regulated substances. Besides ion chromatographic determination applying conductivity detection, the method described here is suitable especially for lower concentrations.

The determination of amino acid is an important task in pharmaceutical and biochemical applications. A binary gradient separates in this example 17 amino acids of a commercially available standard solution. The post-column reaction with ninhydrin requires a temperature of 120 °C, while the samples need to be cooled for stability.

Cell culture growth media contain all required components to keep cells alive. Here the amino acid composition is analyzed. A binary gradient separates in this example amino acids. The post-column reaction with ninhydrin requires a temperature of 120 °C, while the samples need to be cooled for stability.

Seawater analysis with conductivity detection is difficult due to the high excess of chloride. Especially analyzing for nitrite and bromide, UV/VIS detection is preferred as chloride is not interfering with nitrite at 218 nm. This AN shows the determination of all three UV-absorbing anions in an artificial seawater.

Hexavalent chromium (chromate) is known to be carcinogenic if inhaled, and suspected to be carcinogenic if ingested. EPA Method 218.7 allows to determine chromate in drinking water down to the sub-µg/L range (method detection limit, MDL = 15 ng/L). Post-column reaction with 1,5-diphenylcarbazide and subsequent visible detection at 530 nm is applied.

Dye samples are analyzed for trace chromate. Chromate (Cr(VI)) is considered toxic and potentially carcinogenic for which reason its concentrations should be as low as possible. This sample is prepared with C18 cartridges and injected applying Metrohm intelligent Preconcentration Technique (MiPCT). After each injection, the preconcentration column requires additional rinsing to eliminate matrix effects. For this purpose, no other instrument than an 800 Dosino is required. The system is optimized for sample volumes between 20 and 2000 µL. For most samples additional rinsing of the preconcentration column is not required.

Feedwater for steam generation in boiling water reactors (BWR) needs to be analyzed for corrosion products. Presence of transition metals, mainly nickel and iron, indicates corrosion problems. Traces of these ions are determined using Inline Preconcentration (MiPCT). After separation, post-column reaction with 4-(2-pyridylazo)resorcinol (PAR) allows VIS detection at 510 nm.

In industrial cooling water systems, copper and its alloys are widely used because of their superior heat transfer properties. These materials are, however, susceptible to corrosion. Azoles are commonly used to protect copper and its alloys from corrosion. These corrosion inhibitors are quantified by ion chromatography with UV/VIS detection.

Speciation analysis is an important tool in analytical chemistry giving information about the quantitative distribution of different oxidation states of one and the same metal ion. The speciation of iron(II) and iron(III) (Fe 2+/Fe 3+) is achieved by ion chromatographic separation of their anionic dipicolinic acid complexes. Afterwards, post-column reaction with 4-(2-)pyridylazo-resorcinol (PAR) allows VIS detection at 510 nm.

Potassium bromate is used as a flour improver. The determination of the carcinogen bromate in flour requires extraction and additional sample preparation. In this application, Inline Dialysis is used after sonication and centrifugation of the extraction mixture. Bromate is detected by conductivity following suppression and UV/VIS detection and post-column reaction.

The determination of iodate and iodide in used electroplating baths is a demanding task due to the high concentration of other ions. Iodate is used as a stabilizer for the bath and needs to be checked for proper electroplating. The use of a sodium chloride eluent, the Metrosep A Supp 5 - 250/4.0 column and direct UV/VIS detection permits the analysis of these samples without matrix interferences.

Complexing agents are used in fertilizers to bind trace nutrients such as cobalt, iron, manganese, etc. EN 13368-1 describes the determination of EDTA, HEDTA, and DTPA. As sample preparation, Fe3+ is added to build complexes with the three agents. The complexes are separated on an anion-exchange column and detected by UV/VIS after addition of perchloric acid.

The determination of transition metals by ion chromatography is possible with direct conductivity detection (see AN-C-137) as well as with UV/VIS detection after post-column reaction. Here, the cations are separated as anionic complexes and analyzed after post-column reaction with PAR with subsequent UV/VIS detection. Speciation determination of iron (separation of Fe(II) and Fe(III)) is possible with this procedure. For trace analysis, Metrohm Inline Preconcentration Technique (MiPCT) is applied.

Chromate (Cr(VI)) is regarded as being carcinogenic, mutagenic and damaging to DNA, which is why Cr(VI) concentrations are to be kept as low as possible. The EU Toy Safety Directive 2018/725 defines migration limit values for the release of chromate from toys. The "HCl migration solutions" are diluted with a buffer before 2,000 µL are injected via Metrohm intelligent Preconcentration Technique with Matrix Elimination (MiPCT-ME). Determination is performed with VIS detection following derivatization with diphenylcarbazide.

Hexavalent chromium (Cr(VI)) is regarded as being toxic and potentially carcinogenic. Its concentration in drinking water should therefore be kept as low as possible. The determination of Cr(VI) is performed using ion chromatography. The separation takes place on the Metrosep A Supp 10 - 250/2.0 separation column. The presence of Cr(VI) is determined photometrically following post-column reaction (PCR) with diphenylcarbazide.

Paracetamol is an effective antipyretic and analgesic. Its determination in tablets using reverse phase chromatography and UV detection is quick and easy with the sample preparation described in this Note. The 815 Robotic Soli Prep for LC does everything automatically: from dissolving the tablets, homogenizing and filtering, to 250-nL-Loop injection.

Ion chromatography trace analysis of anions in seawater is difficult, due to the high chloride concentrations. In contrast to chloride, nitrite, bromide and nitrate absorb UV radiation in the low wavelength range, thus enabling a UV detection of these three anions. This Application Note describes the separation on a column of the Metrosep Carb 2 - 100/4.0 type with a sodium chloride eluent. This minimizes the influence of the surplus chloride and enables low detection limits.

The Benfield Process is a well known procedure to remove H2S and CO2 from petroleum and industrial gases. Vanadium pentoxide is added as a corrosion inhibitor and is most effective in a certain V(IV)/V(V) ratio. Therefore, speciation and determination of V(IV) and V(V) is important. This speciation is easily achieved on A Metrosep A Supp 5 - 50/4.0 column with EDTA as an eluent and UV/VIS detection at 282 nm.

In gold mining, there is a tendency to switch from cyanide leaching to the much less toxic thiosulfate leaching process. Thiosulfate leaching is a sensitive process that requires more optimization of the components of the leach reaction to maximize gold recovery and reagent loss. Sulfite, thiosulfate, thiocyanate, and tetrathionate are separated on a Metrosep A Supp 5 - 250/4.0 column. Perchlorate is choosen as an eluent as most of the metal perchlorates are soluble in water. This avoids metal precipitation in the IC System.

Nitrite in tobacco facilitates the release of tobacco-specific nitrosamines. Most of these nitrosamines are carcinogenic. Therefore, the determination of nitrite in tobacco is required. This application describes the determination of nitrite and nitrate in acetic acid extracts of tobacco. The ion chromatographic separation is followed by UV/VIS detection after sequential suppression.

Aluminum (as gel or salt) is used in vaccines as an adjuvant. This helps to get a stronger immune response. The amount of aluminum in vaccines is regulated e.g., by USP. According to USP maximum amounts of Al3+ in a vaccine dose lay between 0.85 and 1.25 mg. This work describes the determination of aluminum as the 8-hydroxyquinoline complex by ion chromatography with UV/VIS detection.

Manufacturers and laboratories must use validated methods to determine the zinc content in skin care products and pharmaceutical supplements to meet strict quality standards set by the United States Pharmacopeia and National Formulary (USP-NF). USP-NF has updated the zinc monograph (General Chapter <591>, Zinc Determination) and replaced the existing identification procedure of titration with ion chromatography (IC). The analysis involves separating Zn using a Metrosep A Supp 10 column followed by post-column reaction using 4-(2-pyridylazo)resorcinol and detection at 530 nm.

Hexavalent chromium (chromate) in soil needs to be minimized as it acts cancerogenic. Chromate may be introduced to soil by applying fertilizers containing Cr(VI). Most of this chromate is reduced to Cr(III) by oxidizing organic matter. The remaining chromate is determined according to EN ISO 15192 by alkaline digestion followed by ion chromatography with post-column reaction with 1,5-diphenylcarbazide and subsequent visible detection at 538 nm. Procedure B of EN 16318 applies the alkaline digestion and the same analytical procedure to fertilizers.

Scale formation is a critical issue in cooling systems leading to system damage, which generates enormous operational losses. One important component of scale forming is silica. Amorphous silica and metal silicates especially tend to build up scale. Therefore, it is crucial to know the silica concentration in cooling agents. By ion chromatography with UV/VIS detection and PCR, it is possible to determine both free and total silicate content. Sample dilution in ultrapure water and direct injection delivers the free silicate concentration. The total silicate content is determined after hydrolysis of amorphous silica by sample dilution in alkaline eluent, and injection after a reaction time (e.g. 4 hours) prior to the analysis.

Chromate and dichromate are the two oxoanions of chromium. In both, chromium is present in its hexavalent form (Cr(VI)). In aqueous solutions, chromate exists under alkaline and dichromate under acidic conditions. Hexavalent chromium is highly toxic and carcinogenic. It is therefore restricted in manufactured goods as well as in the environment and requires thorough monitoring. DIN 38405-52 describes the determination of Cr(VI) in water, wastewater, and sludge by photometric methods. In Appendix C, chapter C.6 the use of ion chromatography is described. This AN shows the application of the method to drinking water samples.

Nitrite and nitrate salts are used as preservatives for meat and meat products. Nitrate salts (labeled E 251 or E 252) have a low toxicity but long-term exposure is of concern, as the lower gut reduces them to nitrite, a precursor of nitrosamines (classified as carcinogenic). Nitrite itself is classified as probably carcinogenic to humans. The European Food Safety Authority (EFSA) lists the MPL (maximum permitted levels) after the manufacturing process for nitrite (labeled E 249 or E 250) as between 50–180 mg/kg, and for nitrate between 150–300 mg/kg, depending on the product. The European Commission (Regulation (EC) No 1333/2008) limits nitrate and nitrite salts in processed meat to less than 150 mg/kg. Ion chromatography with UV detection offers a robust and universal method for quality control of nitrite and nitrate in different meat matrices. Additional sample preparation techniques like Inline Ultrafiltration help to save time and costs as well as overcome analysis issues with difficult sample matrices.

Determination of Fe, Pb, Cd, and Cu in Co(Ac)2 solution using the MME.

Determination of Cr, Mn, and Ti in a PTA solution containing HCl.

Determination of Ni, Co, and Fe in a PTA solution containing HCl.

Determination of Zn, Cd, Pb, Cu, and Cr in triglyceride.

Determination of Cd, Pb, and Sb in acetic acid.

Determination of Cd, Pb, and Cu in brine and NaOH.

Simultaneous determination of Zn, Cd, Pb, Cu, Fe, Ni, and Co in 50% NaOH.

Determination of Ni, Sb, Cd, Tl, and Cu in a neutral, highly concentrated zinc solution from the plating industry.

Determination of Ni, Fe, and Cu in a silver plating bath.

Determination of Cr and Se in a silver plating bath.

Determination of Sn and Pb in an organo plating bath.

Lead is commonly used as stabilizer in electroless nickel plating processes. The regular and precise determination of the electrochemically active Pb(II) concentration is essential to keep the plating process running optimally under stable conditions. Differential pulse anodic stripping voltammetry can be used to determine the active lead content after dilution. The voltammetric determination has been established as a straightforward, sensitive, selective, and interference-free method for this application.

Simultaneous determination of Sb and Bi in an alkaline ZnO solution.

Determination of Al in alkaline ZnO solution with Eriochrome Blue Black R at 60 °C.

Determination of Cu and Cr in an etching bath. Due to the high concentrations of Mn and Ni, Cu is determined as the EDTA complex and Mn as DTPA complex.

Determination of Fe and Zn in a nickel sulfate bath containing surfactants after UV digestion.

Determination of Cu in a nickel sulfate bath containing surfactants after UV digestion.

Determination of Zn, Cd, Pb, Ni, and Co in hydrochloric acid (37.8%).

Determination of Zn, Cd, Pb, Ni, and Co in Javelle water.

Determination of Zn, Cd, Pb, Ni, and Co in FeCl3 solution of 40%.

Determination of coumarin and tartrazine in vodka.

Determination of Zn, Cd, Pb, Cu, Ni, Co, and Fe in freeze-dried hops after a wet digestion.

Determination of Zn, Pb, Cu, and Fe in sugar after wet digestion.

Determination of Zn, Cd, Pb, and Cu in chili sauce after digestion UV.

Determination of Hg in chili sauce after UV digestion.

Determination of aluminum with Eriochrome Blue Black R at 60 °C in albumin lyophilizate after a wet digestion.

Determination of Zn, Cd, Pb, and Cu in whiskey after UV digestion.

Determination of Cd, Pb, Cu, Ni, and Co in soybean oil after extraction by boiling with HCl under reflux.

Determination of zinc in a herbal pharmaceutical drug against cancer of the prostate.

Voltammetric determination of boron in plasma using Beryllon III as a ligand [L. Thunus (1996), Anal. Chim. Acta 318: 303–308].

Uranium can be determined in drinking water by adsorptive stripping voltammetry (AdSV) at the hanging mercury drop electrode (HMDE). Chloranilic acid is used as complexing agent.

Determination (after digestion) of zinc, cadmium, lead, copper, nickel, and cobalt in fabrication powder of vitamin tablets.

Determination of manganese, iron, and molybdenum (after digestion) in fabrication powder of vitamin tablets.

Determination of clothiapine in a pharmaceutical standard.

Determination of cadmium and lead in herbicide powder containing 37% copper after digestion.

Determination of artemisinin and artesunate in a standard.

The concentration of Pd in pharmaceutical products is determined by polarography after wet digestion.

Determination of ß-propiolactone in vaccine.

Determination of ascorbic acid (vitamin C) in vitamin capsules after sample digestion.

Thiomersal (also called thimerosal) is a mercury containing organic molecule that has been widely used as preservative for vaccines and eye drops. It is very effective, even in very low concentrations, against a wide range of microorganisms and viruses. To reduce the risk for consumers the maximum concentration of mercury in the products is limited by the authorities. Polarography or voltammetry can be used to accurately determine the concentration of thiomersal in vaccines or other cosmetic and pharmaceutical solutions (such as eye drops). The method is simple to perform, specific, and free of interferences.

Determination of cysteine and cystine in an infusion solution.

Determination of 1-methyl-nicotinamide hydrochloride in a standard using Na2CO3 as electrolyte.

Determination of cysteine and cystine in caseinate after sample preparation with NaOH.

Accurate determination of Fe(II) and Fe(III) in water is crucial for many industries. Cathodic sweeping voltammetry (CSV) offers a robust, cost-effective solution.

4-Carboxybenzaldehyde can be reduced directly on the DME in a solution containing ammonium.

Polarographic determination of cyanide in gases resulting from the incineration of plastic insulation materials after sample preparation.

Determination of styrene monomers in polystyrene. Free styrene is converted to a polarographically active pseudonitrosite.

Determination of W(VI) in the organic phase after digestion

Cd and Pb can be determined in seawater samples in the ng/L concentration range by anodic stripping voltammetry on a mercury film electrode (MFE).

Nickel and cobalt can be determined in seawater by adsorptive stripping voltammetry (AdSV) at the HMDE.

Iodide contamination in glacial acetic acid poses risks for downstream processes. Cathodic stripping voltammetry (CSV) at the HMDE offers reliable iodide measurement.

Rhodium and platinum can be determined in water samples after UV digestion and complexation by adsorptive stripping voltammetry (AdSV) at the HMDE.

NTA and EDTA can be determined as their bismuth complexes at the DME.

Ascorbic acid (vitamin C) can be determined in fruit and vegetable juices at the DME without sample preparation.

Riboflavin (vitamin B2) can be determined in vitamin preparations at the DME.

Nicotinamide (vitamin B3, vitamin PP) can be determined in vitamin preparations at the DME.

Cobalt can be determined in the presence of high concentrations of gold at the DME using 5-sulfosalicylic acid as supporting electrolyte and DMG as complexing agent.

Nickel can be determined in concentrated zinc solutions by adsorptive stripping voltammetry (AdSV) at the HMDE using ammonia buffer as supporting electrolyte and dimethylglyoxime (DMG) as complexing agent. The determination of cobalt does not work under these conditions as the very high Zn2+ concentration interferes with the Co signal. Therefore, an alternative complexing agent has to be used: α-benzil dioxime in ammonia buffer under addition of sodium nitrite.

The concentration of total Sb in zinc plant electrolytes is determined by anodic stripping voltammetry (ASV) in 5 mol/L HCl. If 0.6 mol/L HCl is used, only the concentration of antimony(III) is determined selectively. The interference of an excess of Cu is suppressed by the selective oxidation of Cu. Nevertheless, the concentration of Cu in the sample limits the amount of sample that can be used for the determination.

Germanium can be determined by adsorptive stripping voltammetry (AdSV) at the HMDE using acetate buffer as supporting electrolyte and catechol as complexing agent.

Germanium can be determined by adsorptive stripping voltammetry (AdSV) at the HMDE using acetate buffer as supporting electrolyte and catechol as complexing agent.

Copper, iron, and vanadium can be determined in salt samples in the µg/kg concentration range by adsorptive stripping voltammetry (AdSV) at the HMDE. No sample preparation is necessary.

Cr(III) forms an electrochemically active complex with diethylenetriaminepentaacetic acid (DTPA), so does Cr(VI) after in situ reduction on the surface of the HMDE. Depending on the sample preparation procedure and the waiting time after the addition of the complexing agent, the different chromium species can be differentiated:Total active chromium [total concentration of Cr(VI) and free Cr(III)]:The measurement is carried out immediately after the addition of DTPA.; Cr(VI): Between the addition of DTPA and the start of the analysis a minimum waiting time of 30 min is necessary. During this waiting time the Cr(III)-DTPA complex becomes electrochemically inactive.; Cr(III): The difference between the total active Cr and Cr(VI).; Totalchromium: Determination of total active Cr after UV digestion.;

Zinc, cadmium, lead, and copper can be determined in wastewater samples after UV digestion by anodic stripping voltammetry (ASV) according to DIN 38406 part 16.

Total chromium can be determined in wastewater samples. UV digestion is necessary to remove interfering organic matter before the analysis. Complete oxidation of Cr(III) to Cr(VI) is guaranteed by an additional UV irradiation step at pH > 4.

The concentration of elemental sulfur in gasoline is determined by polarography in acetate containing toluene/methanol electrolyte. The determination is linear up to 2 mg/L with respect to the concentration of elemental sulfur in the measuring vessel. Organic sulfur compounds are not detected with this method. The method is not suitable for diesel fuel, because diesel is not completely soluble in the electrolyte used. The gas wash bottle (6.2405.030) for inert gas supply has to be filled with supporting electrolyte.

Cd, Pb, and Cu can be determined in one run in acetate buffer by anodic stripping voltammetry (ASV).

Nickel and cobalt can be determined in drinking water in one run by adsorptive stripping voltammetry (AdSV). Dimethylglyoxime (DMG) is used as complexing agent at a pH value of 9.3.

Mercury can be determined in wastewater by anodic stripping voltammetry (ASV) on a gold rotating disk electrode (Au RDE). After the addition of hydrochloric acid and hydrogen peroxide, digestion is done by UV irradiation.

Manganese in drinking water is determined by anodic stripping voltammetry (ASV) at the HMDE. The measurement is performed in an alkaline solution and zinc solution is added to prevent interference from intermetallic compounds.

For the determination of nickel in white wine, UV digestion is required to mineralize the sample. The determination is done by adsorptive stripping voltammetry (AdSV) at the HMDE in ammonia buffer with dimethylglyoxime (DMG).

Zinc, cadmium, lead, and copper can be determined in red wine after UV digestion by anodic stripping voltammetry (ASV).

For the determination of heavy metals in wine, UV digestion is required to mineralize the sample. The determination of platinum and rhodium is carried out with adsorptive stripping voltammetry (AdSV) at the HMDE.

Quinine can be determined by polarography at the DME using Britton-Robinson buffer at pH = 7.0 as supporting electrolyte.

Platinum in urine can be determined by adsorptive stripping voltammetry (AdSV) after UV digestion of the sample.

Cr(VI) is determined with the complexant DTPA at pH 6.2 by adsorptive stripping voltammetry (AdSV) at the HMDE.

Mo is determined by polarography at the SMDE in nitric acid solution.

Cadmium, lead, and copper are determined by anodic stripping voltammetry (ASV) at the HMDE using aqueous nitric acid as supporting electrolyte.

Ni and Co are determined in triphosphate by adsorptive stripping voltammetry (AdSV) in ammonia buffer at pH 9.5 with addition of dimethylglyoxime (DMG).

Anodic stripping voltammetry (ASV) at the HMDE is used to determine manganese in triphosphate. The sample is first digested and then measured in an alkaline solution.

Cr(VI) is determined at the HMDE in an electrolyte containing ethylenediamine and acetate. Because Cr(III) is electrochemically inactive, all Cr has to be oxidised prior to analysis.

Formaldehyde is determined polarographically at the DME in alkaline solution.

Thallium and cadmium can be determined by anodic stripping voltammetry (ASV) at the HMDE (Tl) and polarography at the DME (Cd), respectively using aqueous hydrochloric acid as supporting electrolyte. Since Cd is present in high excess and would therefore interfere with the determination of thallium, a post electrolysis procedure is applied to remove the co-deposited metal from the mercury drop.

Determination of nickel and cobalt in wastewater samples through adsorptive Stripping Voltammetry (AdSV). The wastewater samples first undergo a UV digestion in accordance with DIN 38406 Part 16.

Tin can be determined in wastewater by anodic stripping voltammetry (ASV) in oxalate buffer after addition of methylene blue. Samples with organic substances have to undergo UV digestion before analysis. Samples with higher concentrations of metals can be diluted before digestion.

Thallium in wastewater is determined in acetate buffer in presence of EDTA by anodic stripping voltammetry (ASV). Samples with organic substances have to undergo UV digestion before analysis.

Selenium is determined by cathodic stripping voltammetry (CSV) at the hanging mercury drop electrode (HMDE). Se(IV) is deposited on the surface of the mercury drop in sulfuric acid electrolyte under addition of copper ions as Cu xSe y.Wastewater samples containing organic contaminants have to be digested by UV irradiation before analysis. In addition, the sample has to undergo a second irradiation step at pH 7−9 to reduce Se(VI) to Se(IV), since only Se(IV) is electrochemically active.

Cr(VI) is determined by polarography at the SMDE in acetate solution containing ethylene diamine to mask interfering copper ions.Only Cr(VI) is electrochemically active. It is for that reason that all chromium compounds must be present before the analysis as CR(VI), which is guaranteed by UV radiation with a pH > 4.