Application Finder

The coupling of highly efficient ion chromatography (IC) to multi-dimensional detectors such as a mass spectrometer (MS) or an inductively coupled plasma mass spectrometer (ICP/MS) significantly increases sensitivity while simultaneously reducing possible matrix interference to the absolute minimum. By means of IC/MS several oxyhalides such as bromate and perchlorate can be detected in the sub-ppb range. Additionally, organic acids can be precisely quantified through mass-based determination even in the presence of high salt matrices. By means of IC-ICP/MS different valence states of the potentially hazardous chromium, arsenic and selenium in the form of inorganic and organic species can be sensitively and unambiguously identified in one single run.

The Restriction of Hazardous Substances (RoHS) Directive 2002/95/EC stipulates maximum limits for the hazardous metals cadmium, lead and mercury as well as the hexavalent chromium and the brominated flame retardants in electrical and electronic products. To ensure compliance, reliable analysis methods are required.This poster deals with the wet-chemical determination of trace concentrations of the six RoHS-restricted substances in a wide variety of materials including metals, electrotechnical components, plastics and wires. After sample preparation according to IEC 62321, the metals lead, cadmium and mercury are best determined by anodic stripping voltammetry (ASV) and the flame retardants PBB and PBDE are quantified by direct-injection ion chromatography (IC) using spectrophotometric detection. Chromium(VI) can be determined either by adsorptive stripping voltammetry (AdSV) or IC. Both methods are very sensitive and meet prescribed RoHS limits.

UV/VIS detection is one of the most sensitive detection techniques in trace-level chromatography. Sometimes, however, spectrophotometric detection lacks sensitivity, selectivity or reproducibility and chemical derivatizations are required. By using Metrohm`s rugged and versatile flow-through reactor, single- or multi-step derivatizations can be done fully automatically, in either pre- or post-column mode at any temperature between 25…120 °C. The variable reactor geometry allows to adjust the reactor residence time of the reactants according to derivatization kinetics. The flexibility of the reactor is demonstrated by optimizing four widespread post-column techniques: the relatively slow ninhydrin reaction with amino acids and the fast derivatizations of silicate, bromate and chromate(VI).

This poster looks at the possibility to modify the existing EPA Method to meet California's rigorous public health goal (PHG) of 0.02 µg/L. After optimizing instrument settings and method parameters, a method detection limit (MDL) of 0.01 µg/L is obtained.

This poster demonstrates the feasibility of coupling a Metrohm IC system to a PerkinElmer NexION ICP-MS, operated under Empower 3 Software.Using a Metrosep Carb 2 column, the chromatographic separation of both species was achieved with a high resolution. Low background and high sensitivity allow determination in the low ng/L range.Optimal separation and full complexation of Cr(III) is already possible with EDTA concentrations from 40 μmol/L in low matrix solutions and may need to be increased depending on the sample matrix.Handling of the system was easy and user friendly. It was shown that speciation of Cr(III) and Cr(VI) can be carried out on this system utilizing a professional data system for acquisition, processing, and reporting.

In the following tables, the half-wave potentials or peak potentials of 90 metal ions are listed. The half-wave potentials (listed in volts) are measured at the dropping mercury electrode (DME) at 25 °C unless indicated otherwise.

Two methods are described for the determination of chromium: a biamperometric titration and a polarographic analysis.

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.

This Application Bulletin describes the voltammetric determination of the elements antimony, bismuth, and copper. The limit of detection for the three elements is 0.5 ... 1 µg/L.

This Bulletin describes potentiometric titration methods for checking sulfuric acid and chromic acid anodizing baths. In addition to the main components aluminum, sulfuric acid, and chromic acid, chloride, oxalic acid, and sulfate are determined.

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+.

Wine sometimes contains heavy metals which can be precipitated out by the addition of potassium ferrocyanide. Generally, these are quantities of iron ranging between 1 and 5 mg, and exceptionally up to 9 mg Fe/L. Zinc, copper, and lead – in descending order of content – may also be present. To estimate the quantity of potassium ferrocyanide necessary for the «décassage of the wine», only very complicated and relatively inaccurate methods have been described until now.This Bulletin permits accurate results to be obtained easily with a simple instrumentation. The results are available in a short time.

Cu2+, Co2+, Ni2+, Zn2+, and Fe2+/Fe3+ are determined simultaneously. Interference due to the presence of other metals is mentioned, and methods given to eliminate it. The threshold of determination is ρ = 20 µg/L for Co and Ni, and ρ = 50 µg/L each for Cu, Zn, and Fe.

This Application Bulletin describes methods for the polarographic and voltammetric determination of small quantities of chromium in water, effluent water and biological samples. Methods for the sample preparation for various matrices are given.

"A sensitive methods to determine manganese is described. It is primarily suitable for the investigation of ground, drinking and surface waters, in which the concentration of manganese is important. The method can naturally also be used for trace analysis in other matrices.Manganese is determined in an alkaline borate buffer by the anodic stripping voltammetry (ASV). Interference by intermetallic compounds is prevented by the addition of zinc ions in the sample. The limit of determination lies at b(Mn) = 2 µg/L."

The metals Cd, Co, Cu, Fe, Ni, Pb, and Zn are determined in the sub-ppb range (limit of detection 0.05 µg/L) by means of stripping voltammetry. The DP-ASV method is used for Cd, Cu, Pb, and Zn whereas Co, Ni, and Fe are determined by means of the DP-CSV method (dimethylglyoxime or catechol complexes).Use of the VA Processor and the sample changer allows automatic determination of the above metal ions in one solution. The method has been specially developed for trace analysis in the manufacture of semiconductor chips based on silicon. It can naturally also be employed successfully in environmental analysis.

This Bulletin gives a survey of standard methods from the field of water analysis. You will also find the analytical instruments required for the respective determinations and references to the corresponding Metrohm Application Bulletins and Application Notes. The following parameters are dealt with: electrical conductivity, pH value, fluoride, ammonium and Kjeldahl nitrogen, anions and cations by means of ion chromatography, heavy metals by means of voltammetry, chemical oxygen demand (COD), water hardness, free chlorine as well as a few other water constituents.

The method describes the determination of Cr traces in a range between 1 ... 250 μg/L. The method is based on the adsorption of a Cr(lll)-diphenylcarbazonate complex on the Ultra Trace graphite rotating disk electrode (RDE). Organic compounds present in samples (e.g. natural waters) have a strong interfering effect. So they have to be removed by e.g. UV digestion. The determination is made by adsorptive stripping voltammetry in the DC (direct current) measuring mode. Purging with nitrogen is not necessary. The determinations work well also in high salt concentration solutions.

This Application Bulletin describes two methods for the determination of iron at the Multi Mode Electrode.Method 1, the polarographic determination at the DME, is recommended for concentrations of β(Fe) > 200 μg/L. For this method the linear range is up to β(Fe) = 800 μg/L.For concentrations < 200 μg/LMethod 2, the voltammetric determination at the HMDE, is to be preferred. The detection limit for this method is β(Fe) = 2 μg/L, the limit of quantification is β(Fe) = 6 μg/L. The sensitivity of the method cannot be increased by deposition.Iron(II) and iron(III) have the same sensitivity for both methods.These methods have been elaborated for the determination of iron in water samples. For water samples with high calcium and magnesium concentrations such as, for example, seawater, a slightly modified electrolyte is used in order to prevent precipitation of the corresponding metal hydroxides. The methods can also be used for samples with organic loading (wastewater, beverages, biological fluids, pharmaceutical or crude oil products) after appropriate digestion.

This Application Bulletin describes the voltammetric determination of the elements iron, copper and vanadium. Fe as well as Cu and V can be determined as catechol complex at the HMDE by adsorptive stripping voltammetry (AdSV). Fe(II) and Fe(III) are determined as Fe(total) with the same sensitivity for both species in either phosphate buffer or PIPES electrolyte. Cu and V can be determined in PIPES buffer.The methods are primarily suitable for the investigation of ground, drinking and surface waters, in which the concentration of these metals is important. But the methods can naturally also be used for trace analysis in other matrices.The limit of detection for all three elements in PIPES buffer is 0.5 ... 1 µg/L, for iron in phosphate buffer it is approx. 5 µg/L.

Iron is an essential element in the human diet and is found in many natural and treated waters. Therefore, the World Health Organization (WHO) does not issue a health-based guideline value for iron. Higher concentrations of iron in surface waters can indicate the presence of industrial effluents or outflow from other operations and sources of pollution. Because of this, precise, rapid, and accurate iron determination at low concentrations in environmental and industrial samples is of great importance. This can be achieved with the method described in this Application Bulletin.

Determination of sodium, potassium, iron(II), magnesium, and calcium in an extract of monoethylene glycol using cation chromatography with direct conductivity detection.

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

Determination of traces of zinc and iron(II) in the presence of lithium, sodium, ammonium, potassium, calcium, and magnesium in boiler water using cation chromatography with direct conductivity detection.

Determination of copper, zinc, iron(II), and manganese in red wine using cation chromatography with UV/VIS detection after post-column reaction with PAR.

Determination of sodium, potassium, iron(II), magnesium and calcium in antifreeze (monoethylene glycol) using cation chromatography with direct conductivity detection. Ascorbic acid reduces iron(III) to iron(II). In this way total iron is determined as iron(II).

Determination of magnesium, cadmium, and iron in phosphoric acid using cation chromatography with direct conductivity detection.

Advances in polymeric membranes and screen-printed technologies have enabled miniaturized, portable potentiometric sensors ideal for point-of-care analysis.

Determination of ferrous ions in heat exchanger and vessel acid wash solutions, for measuring the effectiveness of acid inhibitors used in the solutions. Depending on the condition of the sample, the lower practical limit for the determination will vary from approximately 20-100mg/Kg Fe2+. Samples with high silicic acid contents require relatively large amounts of dilution water to render them mobile, and this limits the aliquot size and hence the amount of Fe2+ which can be analyzed.

Determination of chromium in leather waste solutions in the range between 1000 and 30,000 ppm.

Standardization of 0.1 mol/L ammonium ferrous sulfate solution for use in thermometric titration of Cr(VI) solutions.

Thermometric complexometric titration of metals is often performed with tetrasodium EDTA. This Application Note explains the standardization of tetrasodium EDTA titrant with copper.

Standardization of copper back-titrant using standard tetrasodium EDTA titrant in the determination of metals.

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

Determination of Fe3+ and Cu2+ in copper refining solutions by thermometric titration. It was found that the conventional approach of masking Fe3+ to permit the iodometric determination of Cu2+ is not possible in some copper refining solutions.

A measured amount of acidic hydrometallurgical leach liquor is further acidified with sulfuric acid, prior to being titrated with standard potassium dichromate solution to an exothermic endpoint. Thus, 1 mol K2Cr207 ≡ 6 mol Fe2+.

A measured amount of acidic hydrometallurgical leach liquor is pH modified with a small amount of glacial acetic acid, and the Fe(III) content reduced to Fe(II) with iodide ion. The liberated iodine is titrated with standard thiosulfate solution to an exothermic endpoint. Thus, 1 mol Fe3+= 1 mol S2O32-.

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.

This Application Note looks at the determination of ferrous ion in acidic solutions from approximately 0.25 g/L by thermometric titration with ceric titrant. The exothermic oxidation reaction shows a sharp endpoint that is detected using the Thermoprobe as a sensitive temperature 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.

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.

Hexavalent chromium, also referred to as chromate or Cr(VI), is considered toxic and potentially carcinogenic, which is why its concentrations in drinking water should be kept as low as possible. Determination of Cr(VI) is performed by combining ion chromatography with ICP/MS. Separation takes place on the Metrosep A Supp 1 Guard/4.6.

Chromate (Cr(VI)) is considered toxic and potentially carcinogenic, which is why its concentrations in children's toys should be kept as low as possible. The EU directive 2009/48/EC defines limit values for the migration of chromate from children's toys. The hydrochloric-acid-containing migration solution is diluted with a buffer. 2000 μL of this solution are injected automatically using intelligent preconcentration technology and matrix elimination. Detection takes place via ICP/MS.

As a rule, soil contains small percentages of chromium that originate chiefly from rock weathering processes, although anthropogenic sources also exist. The speciation analysis of trivalent – Cr(III) – and hexavalent chromium – Cr(VI) – is important, because the former is a trace element and the latter is highly toxic. The two chromium species are separated as Cr(III)-EDTA-complex and chromate on the Metrosep A Supp 4 - 250/4.0 column. Mass spectrometric isotope dilution analysis (SIDMS) is used for quantification.

Speciation analysis of iron is important, given that its oxidation level has a great influence on environmental response, not only with respect to its absorption by organisms but also to the transport and the storage of the element. Iron(II) and Iron(III) are separated on the Metrosep A Supp 10 S-Guard/4.0 column. IC-ICP/MS with isotope dilution is used for quantification.

Differentiation between Cr(III) and Cr(VI) is possible following ISO 24384 guidelines by combining ion chromatography with inductively coupled plasma mass spectrometry.

Determination of chromate using anion chromatography with post-column reaction and UV/VIS detection.

This Process Application Note is dedicated to the online analysis of zinc, iron and sulfuric acid in several stages of the zinc production process. Additionally, traces of germanium, antimony, as well as several transition metals (e.g., Ni, Co, Cu, Cd) can be precisely determined (<50 µg/L) in the purification filtrates and reactor trains.

Pickling baths are used in the galvanic industry to clean steel surfaces and prevent corrosion through passivation. Maintaining specific Fe2+/Fe3+ and free acid/total acid ratios is vital to ensure the baths' optimal performance, which directly impacts the final product quality and reduces production costs by minimizing reagent consumption. This application presents a method to regularly monitor the acid and iron composition in pickling baths online by using a process analyzer from Metrohm Process Analytics.

Chromium is extracted from chromite ore and is an important part in the production of stainless steel. Chromium is mainly divalent, trivalent and hexavalent in its compounds. In contrast to chromium(III), which is an important trace element and one that is only sparingly soluble in water, hexavalent chromium is extremely toxic and very water-soluble. Cr(VI) is furthermore an important raw material for industry. It must be determined rapidly and precisely in the lower µg/L range in wastewater. Metrohm Applikon offers an array of process analyzers for the analysis of wastewater streams which determine chromium precisely and reproducibly using photometry.

Corrosion in the water-steam circuit of power plants leads to shorter lifetimes of most metal components and potentially dangerous situations. Flow Accelerated Corrosion (FAC) is a specific case, leading to thinned pipes and elevated Fe concentrations in the circuit. Additionally, metal transport issues such as with Cu from copper heat exchangers can lead to deposition on the high pressure turbine blades, decreasing their efficiency. Current methods can monitor but not prevent these issues, and analysis times are extremely long (up to three weeks). In combination with the power plant’s Distributed Control System (DCS), online monitoring of Fe and Cu with the 2060 Process Analyzer from Metrohm Process Analytics ensures that corrosion can be controlled before it affects the power plant efficiency, ultimately decreasing downtime and lowering maintenance costs. Results are offered within 20 minutes, allowing fast adjustments to the water-steam circuit to protect company assets.

A setup that allows online sampling is crucial for immediate and contamination-free analysis of power plant water samples. This application recommends a setup that facilitates simultaneous anion/cation determinations. Automated inline sample preparation combines variable preconcentration (MiPCT) and calibration with a single multi-ion standard. AN-Q-004 displays the respective cation results.

Determination of chloride, sulfate, chromate, methanesulfonic acid (MSA), methanedisulfonic acid (MDSA), and ethanedisulfonic acid (EDSA) in a chromium plating bath using anion chromatography with conductivity detection after chemical suppression.

Determination of nitrate, phosphate, sulfate, and chromate in a cataphoretic paint bath using anion chromatography with conductivity detection after chemical suppression.

Determination of sulfate, molybdate, and chromate in a plating bath using anion chromatography with conductivity detection after chemical suppression.

Qualitative determination of chloride, phosphate, and sulfate as well as chlorite, nitrite, chlorate, bromide, and chromate in urine using anion chromatography with conductivity detection after chemical suppression.

Determination of chromate in cement using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, hypophosphite, chlorite, bromate, chloride, nitrite, bromide, chlorate, nitrate, phosphite, phosphate, sulfate, arsenate, iodide, chromate, and perchlorate using anion chromatography with conductivity detection after gradient elution and chemical suppression.

Water of the water-steam cycle of boiling water reactors (BWR) needs to be free of corrosive anions. Analyzing these trace anions allows the parallel determination of chromate, which is a potential corrosion product. Automated sample preparation includes variable Inline Preconcentration (MiPCT) and automatic calibration with a single multi-ion calibration standard.

The development of a novel reflection cell for conventional electrodes facilitates the performance of spectroelectrochemical measurements. This device allows researchers to work in aqueous solutions as well as in organic media due to its chemical resistance.

Determination of Cr(VI) and Cr(III) in chromium baths by iodometric potentiometric titration with thiosulfate using the combined Pt electrode.

Determination of the iron content of iron powder by potentiometric titration with potassium dichromate using the Pt-Titrode.

Simultaneous determination of titanium and iron by potentiometric titration with potassium dichromate using a platinum electrode. Before determination, Ti4+ and Fe3+ are reduced with Cr2+.

Determination of iron and nickel in binary mixtures by potentiometric titration with EDTA at different pH values using the Cu-ISE.

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.

This Application Note describes the fully automated complexometric determination of total iron in cement with a copper ion-selective electrode.

The total iron content in iron ore plays a central economic role for mining companies. The higher the iron content in the ore, the more profitable the mining operation. Therefore, a fast and accurate analysis is important to determine the most profitable areas to work.The iron ore is dissolved in hydrochloric acid at 80 °C. Afterwards, the iron is quickly and accurately determined by potentiometric titration using the Pt-ring electrode and potassium dichromate as titrant.

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

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.

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.

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.

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.

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.

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.

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.

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.

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

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

Determination of Cr and Se in a silver plating bath.

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

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.

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.;

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.

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

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.

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.

Iron can be determined in ethanol by adsorptive stripping voltammetry (AdSV) at the HMDE. PIPES buffer is used as supporting electrolyte and catechol as complexing agent at a pH value of 7.0.

The concentration of Fe(total) is determined in wastewater after UV digestion. The method is suitable for iron concentrations down to the low μg/L range. Stripping voltammetry is not applicable for this method. Fe(II) and Fe(III) generate signals with identical sensitivity.

The concentration of Fe(total) is determined in deionized water. The method is suitable for iron concentrations down to the mid µg/L range. Electrochemical deposition is not applicable for this method. A subtraction of the reagent blank is recommended. Fe(II) and Fe(III) give signals with the same sensitivity.

The concentration of Fe(total) is determined in monoethylene glycol by adsorptive stripping voltammetry with 2,3-dihydroxy-naphthalene as complexing agent. The detection limit of the method is approx. 0.1 µg/L with respect to the content in the measuring vessel. If no bromate is added to the supporting electrolyte the sensitivity of the method is about 10 times lower. All reagents have to be added in the order as listed below. Fe(II) and Fe(III) give signals with the same sensitivity. All reagents typically contain iron impurities, especially the 2,3-dihydroxy-naphthalene. Therefore a subtraction of the reagent blank is recommended.

The concentration of Fe(III) is determined by adsorptive stripping voltammetry with solochrome violet RS as complexing agent. All reagents have to be added in the order as listed below. Fe(II) does not show any signal. All reagents typically contain iron impurities. Therefore a subtraction of the reagent blank is recommended.

The concentration of Fe is determined in water samples by adsorptive stripping voltammetry with 1-nitroso-2-naphthol as complexing agent. All reagents have to be added in the order as listed below. All reagents typically contain iron impurities. Therefore a subtraction of the reagent blank is recommended. Fe(II) and Fe(III) show different sensitivities. Therefore the sample should only contain one of the iron species. Ascorbic acid (Vitamin C) can be added to the measuring solution and to the Fe(III) standard solution if both Fe(II) and Fe(III) are present in the sample to determine the concentration of total iron. A final concentration of ascorbic acid of 0.002 mol/L is suitable.

Iron sucrose injection is a dark brown liquid which contains sucrose and iron(III) hydroxide in an aqueous solution, commonly used for the treatment of iron deficiency anemia. As a medical product, iron sucrose is subject to strict controls. Among other tests, the U.S. Pharmacopeia (USP) requires to monitor the limit of Fe(II) in the iron sucrose injection solution by polarography. The benefit of polarography is that Fe(II) and Fe(III) show signals at different potentials, and therefore an easier determination of Fe(II) without a previous separation of the two oxidation states is possible. The 884 Professional VA together with the viva software allows a straightforward determination of the Fe(II) content of iron sucrose injection solution following the requirements of the USP. The Fe(II) content is automatically calculated and stored in a database together with all relevant determination and calculation parameters.

The concentration of Fe(total) is determined polarographically in a chromium electroplating bath. The method is suitable for iron in concentrations in the ppm range. Fe(II) and Fe(III) show signals with the same sensitivity.

The concentration of Fe is determined polarographically in phosphoric acid. The method is suitable for iron in concentrations in the ppm range. Fe(II) and Fe(III) show signals with the same sensitivity

The concentration of Fe is determined by adsorptive stripping voltammetry at the HMDE with 1-nitroso-2-naphthol (1N2N) as complexing agent.

The concentration of Fe(total) is determined by polarography in oxalate buffer pH 2. This method is suitable for iron concentrations in the mg/L range.

The concentration of Fe(total) is determined by polarography in an alkaline electrolyte containing triethanolamine (TEA) and KBrO3. All reagents typically contain iron impurities. Therefore a subtraction of the reagent blank is recommended.

The concentration of Fe(total) is determined by polarography in alkaline electrolyte containing triethanolamine (TEA) and KBrO3. All reagents typically contain Fe impurities. Therefore a subtraction of the reagent blank is recommended.

The iron concentration in boiler feed water has to be monitored to ensure reliable and safe operation of the water-steam circuit. Various guidelines set limits for the maximum iron content.The concentration of total iron in boiler feed water can be determined with high sensitivity using adsorptive stripping voltammetry (AdSV) using 2,3- dihydroxynaphthalene (DHN) as complexing agent. Voltammetry is a viable, less sophisticated alternative to atomic absorption spectroscopy (AAS) or inductive couple plasma (ICP) for the determination of iron with only a moderate investment in hardware required and low running costs.

The concentration of Cr(VI) in cement is determined in tartrate electrolyte after acid extraction of the sample.

The EU directive on «Restriction of Hazardous Substances» (RoHS) requires the testing of four regulated heavy metals (Pb, Hg, Cd, Cr(VI)) in electrotechnical products. After sample preparation according to IEC 62321 the determination of chromium(VI) in electronic components can be carried out by polarography in ammonia buffer pH 9.6.

The EU directive on «Restriction of Hazardous Substances» (RoHS) requires the testing of four regulated heavy metals (Pb, Hg, Cd, Cr(VI)) in electrotechnical products. After sample preparation according to IEC 62321 the determination of chromium(VI) in polymer materials can be carried out by polarography in ammonia buffer pH 9.6.

The EU directive on «Restriction of Hazardous Substances» (RoHS) requires the testing of four regulated heavy metals (Pb, Hg, Cd, Cr(VI)) in electrotechnical products. After sample preparation according to IEC 62321 the determination of chromium(VI) in chromate coating on metallic materials can be carried out by adsorptive stripping voltammetry (AdSV) using DTPA (diethylenetriamine pentaacetic acid) as complexing agent.

Iron is an essential element in human nutrition. It can be present in drinking water as a result of water treatment or from corrosion in the water piping system. There is no guideline value for iron in the World Health Organization’s «Guidelines for Drinking-water Quality» because typical levels usually found in drinking water are of no concern. However, there are national limit values in various countries. The European Union has set a guideline indicator value for iron of 200 μg/L. Voltammetry is a viable, less sophisticated alternative to atomic absorption spectroscopy (AAS) for the determination of iron in drinking water. While AAS (and competing methods) can only be performed in a laboratory, anodic stripping voltammetric determinations can be done used conventionally in the laboratory or alternatively in the field using the with 946 Portable VA Analyzer. The determination is carried out with adsorptive stripping voltammetry (AdSV) using 2,3-dihydroxynaphthalene (DHN) on the scTRACE Gold electrode.

The presence of iron in drinking water can lead to an unpleasant taste, stains, or even growth of «iron bacteria» that can clog plumbing and cause an offensive odor. Over a longer period, the formation of insoluble iron deposits is problematic in many industrial and agricultural applications. To avoid these problems, the U.S. Environmental Protection Agency (EPA) defines the Secondary Maximum Contaminant Level (SMCL) for water treatment and processing plants as 0.3 mg/L Fe in drinking water.The voltammetric determination of the iron triethanolamine complex on the non-toxic Bi drop electrode allows both the detection at very low levels (limit of detection of 0.005 mg/L) and measurements in a wide range of concentrations up to 0.5 mg/L.

The guideline value for chromium in the World Health Organization’s (WHO) «Guidelines for Drinking-water Quality» is 50 µg/L. It should be noted here that chromium concentrations are often expressed as total chromium and not as chromium(III) or (VI). Chromium(VI) is responsible for changes in genetic material, and is found in significantly lower concentrations than Cr(III). Therefore an extremely sensitive method is required to monitor Cr(VI) in drinking water.The powerful adsorptive stripping voltammetry (AdSV) technique on the ex-situ mercury film modified glassy carbon electrode using DTPA as complexing agent can be used to determine such low concentrations.

The guideline value for total chromium in the World Health Organization’s (WHO) «Guidelines for Drinking-water Quality» is 50 µg/L. Chromium(VI) is more toxic than its trivalent form (Cr(III)) and is also less abundant. Therefore a robust and sensitive method is required to monitor its concentration in drinking water. The mercury film modified scTRACE Gold can be used to monitor chromium(VI), offering easy handling and a high grade of stability.

Lithium iron phosphate batteries offer users safety and durability. Polarographic speciation evaluates Fe(II) and Fe(III) in cathode material, useful for several tests.

This article describes the coupling of ion chromatography with mass spectrometry (IC-MS) and plasma mass spectrometry (IC-ICP/MS) for the trace analysis of potentially hazardous compounds in the environment.

Chromate is allergenic, carcinogenic and extremely toxic. It is therefore subject to strict monitoring. It is present in different concentrations in drinking water, toys, textiles, leather and many other materials. Metrohm has developed various methods for ion chromatographic determination of chromium(VI) which, thanks to Inline Sample Preparation, are suitable for a variety of matrices and concentration ranges – from ng/L to mg/L.

The coupling of ion chromatography and inductively coupled plasma mass spectrometry (ICP/MS) leads to a high-performance measurement system that masters several particularly challenging analyses. It enables for example reliable determination of element compositions, oxidation states and chemical bonds. This information is used, for example, for assessing the toxicity of medications, environmental and water samples as well as foods and beverages.

The analytical challenges of environmental analysis increase in difficulty from year to year. As well as analysis of particularly toxic types of metals such as chromium(VI), highly diverse and partially persistent organic fluorine compounds (e.g., trifluoroacetic acid) are presently in focus. The analysis of toxic oxohalides such as bromate and perchlorate is also a current subject of investigation.

Free white paper describes the effective use of electrochemical techniques to measure corrosion and the effectiveness of inhibitors.

It is widely accepted that prolonged exposure to hexavalent chromium compounds can have dire health effects. This has led to increased regulation of chromium-containing products and greater demand for technologies that can positively identify hexavalent chromium in potential matrices. These include paints, dyes, and primers, which can pose a problem for interrogation with Raman, as strongly colored materials often exhibit fluorescence when stimulated at 785 nm. Fluorescence can obscure the Raman signal and prevent positive identification. MIRA XTR DS provides all the functionality of handheld material ID with a new capability that selectively eXTRacts the Raman signal from fluorescent materials. Fluorescence rejection at 785 nm provides higher sensitivity and resolution than 1064 nm systems, as well as a much wider scope of applications amenable to Raman spectroscopy. MIRA XTR DS offers a comprehensive and versatile material ID test solution for field operations.

This White Paper presents four different «green» sensors: the scTRACE Gold, screen-printed electrodes, the glassy carbon electrode, and the Bi drop electrode from Metrohm that can be used to determine low concentrations of heavy metals in different sample matrices, such as boiler feed water, drinking water, and sea water.