Applications

A convenient adsorptive cathodic stripping voltammetric (AdCSV) method has been developed for trace determination of uranium(VI) in drinking water samples using chloranilic acid (CAA). The presence of various matrix components (KNO3, Cl-, Cu2+, organics) can impair the determination of the uranium-CAA complex. The interferences can be mitigated, however, by appropriate selection of the voltammetric parameters. While problematic water samples still allow uranium determination in the lower µg/L range, in slightly polluted tap water samples uranium can be determined down to the ng/L range, comparable to the determination by current ICP-MS methods.

The presence of copper in fuel ethanol blends has gained considerable attention, since Cu2+ catalyzes oxidative reactions in gasoline leading to a deterioration of olefins and the formation of gum. Anodic stripping voltammetry (ASV), one of the most sensitive and accurate techniques for trace-metal analysis, has been demonstrated for the determination of Cu(II) in ethanol/gasoline blends without any sample pretreatment. Copper ions are first electrodeposited onto the surface of a hanging mercury drop electrode (HMDE) before the amalgamated copper is quantitatively stripped (anodically dissolved), a current-voltage curve being recorded.Experimental conditions such as deposition time and potential as well as the suitable electrolyte and reference electrode were determined in preliminary experiments. For synthetic samples spiked with Cu2+ (5…100 µg/L), recovery rates between 96 and 112% were obtained. The copper-spiked E85 sample provided a recovery of 100%. The relative standard deviations for Cu2+ concentrations of 5 µg/L and above were 8.0 and 5.5% respectively. Using a preconcentration time of 60 s at -0.7 V versus Ag/AgCl, a linear range of 0…500 µg/L with a detection limit of 2 µg/L was obtained.

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.

This poster presents an approach that couples a Particle-Into-Liquid-Sampler (PILS) to a dual-channel ion chromatograph (IC) for measurement of aerosol anions and cations and a voltammetric measuring stand (VA) to determine the heavy metals. Feasibility of the PILS-IC-VA online system was demonstrated by collecting aerosol samples in Herisau Switzerland, at defined time intervals; air pollution events were simulated by burning lead- and cadmium-coated sparklers.

Because of its toxicity, the World Health Organization recommends a maximum arsenic content in drinking water of 10 μg/L. Anodic stripping voltammetry with the scTRACE Gold offers a straightforward, highly affordable alternative to spectroscopic determination.

Lead is known to be highly toxic, and lead salts are easily resorbed by humans. Cases of chronic lead poisoning caused by lead metal used in the water piping system are well known. Therefore, the control of drinking water for lead content is of utmost importance. The Lead and Copper Rule (LCR) published by the USEPA (United States Environmental Protection Agency) states an action limit of 15 μg/L lead for drinking water. Using a portable voltammetric instrument, lead can be determined in these concentrations directly at the point of sampling.

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.

The determination of the lead content in engine fuels has gained considerable importance since the introduction of the catalytic converter technique. Even small contents of lead interfere with the effectiveness of the catalysts or may destroy them. On the other hand, there are still many vehicles on the roads which run on leaded fuel (addition of tetraalkyl lead). Here also the knowledge of the lead content is of interest.With reference to DIN 51769 and ASTM 0-1269 a simplified procedure for the determination of lead in petrochemical products is described. The products are digested with HCl and the lead compounds are converted to lead(II) chloride. After extraction with water, the inverse voltammetric Pb determination is carried out.

The quantitative determination of the alkaloid nicotine, which is an essential constituent of the tobacco plant, can be carried out by polarography. The quantification limit is less than 0.1 mg/L in the polarographic vessel.

Fructose (fruit sugar) is the only ketose that occurs naturally. It is found free in a mixture with dextrose (honey, sweet fruits, tomatoes) or bound as a component of cane sugar and various starch-like carbohydrates. As fructose tastes sweeter than dextrose, it finds great use as a sweetening agent.In 1932, the polarographic reducibility of sugar was described for the first time by Heyrovsky and Smoler. The following method can be used to determine the fructose content of fruit, fruit juice and honey quantitatively.

The photometric determination of nitrate is limited by the fact that the respective methods (salicylic acid, brucine, 2,6-dimethyl phenol, Nesslers reagent after reduction of nitrate to ammonium) are subject to interferences. The direct potentiometric determination using an ion-selective nitrate electrode causes problems in the presence of fairly large amounts of chloride or organic compounds with carboxyl groups. The polarographic method, on the other hand, is not only more rapid, but also practically insensitive to chemical interference, thus ensuring more accurate results. The limit of quantification depends on the matrix of the sample and is approximately 1 mg/L.

This Bulletin is a supplement to Application Bulletin no. 36 (Half-wave potentials of inorganic substances) in the sense that the half-wave potentials of 100 different organic substances are listed. At the same time the supporting electrolytes used and the limits of determination are given.The various substances are listed in alphabetical order. The most important polarographically active functional groups are taken into consideration. This means that substances for related structures can also be determined polarographically in the same or similar supporting electrolytes, although they may not appear in the list.Unless otherwise stated, the half-wave potentials refer to a temperature of 20 °C, and the potentials are given in volts, measured with a sat. KCI-Ag/AgCl electrode assembly.The determination limits give the smallest concentrations which can be measured without risking serious errors in the results. In all cases, the limit of detection lies below the limit of determination.

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.

According to the described method, NTA and EDTA can be determined in mass concentrations of 0.05 mg/L up to 25 mg/L in polluted water and wastewater.At first NTA and EDTA are converted to the corresponding Bi complexes by addition of Bi3+ ions at a pH value of 2.0. As these Bi complexes have significantly different peak potentials, they can be determined simultaneously by DP polarography. The interfering anions nitrite, sulfite, and sulfide are removed from the sample by acidification and purging. Interfering cations are removed by cation exchange; any NTA or EDTA heavy metal complexes present in the sample are disintegrated during this procedure. To remove surfactants and other organic components interfering with the analysis, the sample solution is run through a column filled with non-polar adsorber resin.

This Application Bulletin describes the determination of mercury by anodic stripping voltammetry (ASV) at the rotating gold electrode. With a deposition time of 90 s, the calibration curve is linear from 0.4 to 15 μg/L; the limit of quantification is 0.4 μg/L.The method has primarily been drawn up for investigating water samples. After appropriate digestion, the determination of mercury is possible even in samples with a high load of organic substances (wastewater, food and semi-luxuries, biological fluids, pharmaceuticals).

Edible oils and fats contain natural tocopherols and, in some cases, also synthetic tocopherols added as antioxidants. The method described below allows the simple and rapid determination of the tocopherol content by voltammetry. The tocopherols are oxidized electrochemically at the glassy carbon electrode (GCE). The limit of quantitation is approximately 5 ppm (mg/kg) tocopherol.

In addition to its natural occurrence in fruit and vegetables, ascorbic acid (Vitamin C) is used as an antioxidant in foods and drinks. Ascorbic acid is furthermore also to be found in numerous drugs.Ascorbic acid and its salts and esters can be determined with titration or by using polarography, for which ascorbic acid is oxidized to form dehydroascorbic acid.Bi-voltammetric or photometric equivalence point indication can be used for titrimetric determination. It must be taken into account here that only bi-voltammetric indication is independent of the inherent color of the sample. Polarography is the most selective of the methods described, as other reducing or oxidizing substances are not recorded.

This Application Bulletin describes a polarographic method for the determination of cyanide that allows to determine free cyanide fast and accurately. The determination also succeeds in solutions containing sulfides, where other methods fail. Cyanide concentrations in the range b(CN–) = 0.01...10 mg/L cause no problems. Interference caused by anions and complexed cyanides has been investigated.

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.

Cadmium, lead, and copper can be determined simultaneously in oxalate buffer by anodic stripping voltammetry (ASV) after digestion with sulfuric acid and hydrogen peroxide. Tin present in the sample does not interfere with the determination of lead.For the voltammetric determination of tin please refer to Application Bulletin no. 176.

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.

In the past, selenium determinations have always been either unreliable or have required complicated methods. However, as selenium is on the one hand an essential trace element (vegetable and animal tissues contain about 10 μg/kg), while on the other hand it is very toxic (threshold value 0.1 mg/m3), it is very important to cover determinations in the micro range. Cathodic stripping voltammetry (CSV) enables selenium to be determined in mass concentrations down to ρ(Se(IV)) = 0.3 μg/L.

"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."

This Bulletin describes a simple polarographic method for the determination of quinine in drinks and tablets. Whereas in drinks quinine can be determined directly, in the case of tablets it must first be extracted. The limit of quantification is 0.2 mg/L or 4 μg/tablet.

Nitrite can be determined polarographically after its conversion to diphenylnitrosamine (C6H5)2NNO. Potassium thiocyanate is used as a catalyst in order for the conversion to proceed rapidly and quantitatively. The reaction takes place in acid solution at a pH value of approx. 1.5. The limit of quantification is 5 μg/L NO2-.

This Application Bulletin describes a voltammetric method for the determination of aluminum in water samples, dialysis solutions, sodium chloride solutions and digestion solutions (e.g. of lyophilisates). The method utilizes the complexation of the Al3+ ion by Calcon (Eriochrome blue black R). The formed complex can easily be reduced electrochemically at 60 °C. The limit of quantitation depends on the purity of the reagents used and is approx. 5 µg/L.

A method is described in this Bulletin that allows molybdenum to be determined in steel and other materials containing a high iron concentration. Mo(VI) is determined at the dropping mercury electrode by catalytic polarography. The determination limit is approx. 10 μg/L Mo(VI).

This Application Bulletin describes a simple polarographic method to determine monomeric styrene in polymers. The limit of determination lies at 5 mg/L. Before the determination, styrene is converted to the electrochemically active pseudonitrosite using sodium nitrite.

As the determination of the exact content of individual glycerides in fats and oils is difficult and time-consuming, several fat sum parameters or fat indices are used for the characterization and quality control of fats and oils. Fats and oils are not only essential for cooking, they are also an important ingredient in pharmaceuticals and personal care products, such as ointments and creams. Consequently, several norms and standards describe the determination of the most important quality control parameters. This Application Bulletin describes eight important analytical methods for the following fat parameters in edible oils and fats:Determination of water content in accordance with the Karl Fischer method; Oxidation stability in accordance with the Rancimat method; Iodine value; Peroxide value; Saponification value; Acid value, free fatty acids (FFA); Hydroxyl number; Traces of nickel using polarography; Special care is taken to avoid chlorinated solvents in these methods. Also, as many of the mentioned methods as possible are automated.

"Molybdenum is an essential trace element for plant growth. Since it occurs in natural waters only in trace amount, a very sensitive method of determination is needed. Using the following polarographic method, it is possible to determine 5·10-10 mol/L resp. 50 ng/L.The principle of the method is based on the reaction between the molybdate ion MoO42- and the complexing agent 8-hydroxy-7-iodo-quinoline-5-sulfonic acid (H2L) to form a MoO2L22- complex, which is adsorbed on the mercury electrode. The adsorbed Mo(VI) is reduced electrochemically to the Mo(V) complex. The hydrogen ions present in the solution oxidize Mo(V) again spontaneously to form the Mo(VI) complex, which is thus newly available for electrochemical reduction. This catalytic reaction is the reason for the high sensitivity of the method.Tungsten W(VI) exhibits practically the same electrochemical behavior as molybdenum, but is not described in detail in this Application Bulletin."

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.

In most electrolytes the peak potentials of lead and tin are so close together, that a voltammetric determination is impossible. Difficulties occur especially if one of the metals is present in excess.Method 1 describes the determination of Pb and Sn. Anodic stripping voltammetry (ASV) is used under addition of cetyltrimethylammonium bromide. This method is used when:• one is mainly interested in Pb• Pb is in excess• Sn/Pb ratio is not higher than 200:1According to method 1, Sn and Pb can be determined simultaneously if the difference in the concentrations is not too high and Cd is absent.Method 2 is applied when traces of Sn and Pb are found or interfering TI and/or Cd ions are present. This method also uses DPASV in an oxalate buffer with methylene blue addition.

Maleic and fumaric acid can be reduced electrochemically to succinic acid. In acidic solutions a differentiation of the two acids is not possible since both are reduced at the same potential. On the other hand, separation at pH 7.8...8.0 is easily possible since fumaric acid is now more difficult to reduce at the lower proton concentration (as a result of cis-trans isomerism) than maleic acid.

This Bulletin describes the voltammetric determination of aluminum in water samples down to a concentration of 1 μg/L. An aluminum complex is formed with alizarin red S (DASA) and enriched at the HMDE. The following determination employs differential pulse adsorptive stripping voltammetry (DP-AdSV). Disturbing Zn ions are eliminated by addition of CaEDTA.

4-Carboxybenzaldehyde, in the following referred to as 4-CBA, can be reduced directly at the dropping mercury electrode (DME) in an ammoniacal solution. After a very simple sample preparation it is now possible to determine the concentration of 4-CBA in terephthalic acid quickly and precisely by polarography down to the lower ppm range.

After the degradation of biological samples (e.g. milk, wool, etc.), it is often important to know the cystine/cysteine ratio. This Application Bulletin describes the simultaneous, polarographic determination of the two amino acids. The determination is performed in perchloric acid solution at the DME. Samples with a high protein content require that the determination is performed in an alkaline solution.

Thiourea forms highly insoluble compounds with mercury. The resulting anodic waves are used for the polarographic determination of thiourea. For the analysis of very small quantities (µg/L), cathodic stripping voltammetry (CSV) is used. Differential Pulse measuring mode is used in both cases.

Formaldehyde can be determined reductively at the DME. Depending on the sample composition it may be possible to determine the formaldehyde directly in the sample. If interferences occur then sample preparation may be necessary, e.g. absorption, extraction, or distillation.Two methods are described. In the first method formaldehyde is reduced directly in alkaline solution. Higher concentrations of alkaline or alkaline earth metals interfere. In such cases the second method can be applied. Formaldehyde is derivatized with hydrazine forming the hydrazone, which can be measured polarographically in acidic solution.

Sulfide and sulfite can be determined polarographically without any problems. For sulfide, polarography is performed in an alkaline solution, for sulfite in a slightly acidic primary solution. The method is suitable for the analysis of pharmaceuticals (infusion solutions), wastewater/flue gas water, photographic solutions, etc.

This Application Bulletin describes the stripping analysis of Ag at the rotating disk electrode (RDE) with glassy carbon tip (GC) or Ultra Trace graphite tip. In routine operation, the determination limit lies at approx. 10 μg/L Ag, with careful work 5 μg/L Ag can be obtained. After appropriate digestion, silver determination is also possible with samples containing a relatively high proportion of organic substances (e.g. wine, foodstuffs etc.). The method has been developed primarily for water samples (well, ground and wastewater, desilvering solutions of the photographic industry).

This Application Bulletins describes the determination of nicotinamide (vitamin PP), a vitamin of the B series. Instructions for the determination in solutions (e.g. fruit juice), vitamin capsules and multivitamin tablets are given. The linearity range of the determination is also specified. The limit of detection is approximately 50 μg/L nicotinamide.

This Application Bulletin describes the polarographic determination of folic acid, a vitamin of the B series, also known as vitamin B9 or vitamin BC. Instructions for the determination in solutions (e.g. fruit juice), vitamin capsules and multivitamin tablets are given. The linear range of the determination is also specified. The limit of detection is approx. 75 µg/L folic acid.

This Application Bulletins describes the polarographic determination of thiamine (vitamin B1). The procedure allows an analysis in monovitamin preparations. The linear range of the determination is also given. The limit of detection is approx. 50 µg/L thiamine.

This Application Bulletin describes the polarographic determination of riboflavin (vitamin B2). The procedure allows an analysis in monovitamin preparations. The limit of determination is approx. 100 μg/L.

This Application Bulletin describes …

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.

This Application Bulletins describes the polarographic determination of pyridoxine (vitamin B6). The method given allows determination in monovitamin and in some multivitamin preparations. The linear range of the analysis is also specified. The limit of detection is approx. 100 µg/L pyridoxine · HCI.

This Bulletin describes the determination of arsenic by anodic stripping voltammetry (ASV) at the rotating gold electrode. A determination limit of 0.5 μg/L can be achieved with 10 mL sample solution. A differentiation between the As(III) concentration and the total arsenic concentration can be made by appropriate selection of the deposition potential. The analyses are performed with a special gold electrode whose active surface is located laterally; c(HCl) = 5 mol/L is used as supporting electrolyte. For the determination of the total arsenic content, As(III) and As(V) are reduced at -1200 mV by nascent hydrogen to As0, which is preconcentrated on the electrode surface. If the deposition is carried out at -200 mV then only As(III) is reduced; this allows the differentiation between total arsenic and As(III). During the subsequent voltammetric determination the preconcentrated As0 is again oxidized to As(III).

The standard method postulated by DIN 38406 Part 16 describes the determination of Zn, Cd, Pb, Cu, Tl, Ni, and Co in drinking, ground, surface and precipitation (e.g. rain) water. Because the presence of organic substances in the water samples can strongly interfere with the voltammetric determination, a pretreatment with UV digestion using hydrogen peroxide is necessary. This digestion ensures the elimination of all organic substances without introduction of blank values. These methods can, of course, also be applied for trace analysis in other materials, e.g. trace analysis in the production of semiconductor chips based on silicon. Zn, Cd, Pb, Cu, and Tl are determined on the HMDE by means of anodic stripping voltammetry (ASV), Ni and Co by means of adsorptive stripping voltammetry (AdSV).

This Application Bulletin describes the determination of cadmium and lead at a mercury film electrode (MFE) by anodic stripping voltammetry (ASV). The mercury film is plated ex situ on a glassy carbon electrode and can be used for up to one day. With a deposition time of 30 s, the limit of detection is ß(Cd2+) = 0.02 µg/L and ß(Pb2+) = 0.05 µg/L. The linear working range for both elements goes up to approx. 50 μg/L using the same deposition time.

The method described allows the determination of W(VI) traces in the range 0.2 to 50 µg/L (ppb). Traces of organic compounds present in the samples (e.g. natural waters) interfere. They have to be removed by UV digestion (e.g. 705 UV Digester). Interference by Fe(III) up to a concentration of 100 mg/L is eliminated by reduction to Fe(lI) with ascorbic acid. If the amount of Cu(II) in the sample exceeds the amount of W(VI) by a factor of 200 or more, the Cu ions have to be bound with thiourea. Moreover, the concentration of Cu(II) should not exceed 5 mg/L. The determination is made by adsorptive stripping analysis in the DP mode.

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.

Diazepam belongs to the 1,4-benzodiazepine group of compounds, which are used for medical purposes as tranquilizers and antidepressants. This Bulletin describes the determination of diazepam in tablets and body fluids (blood, serum, urine) by means of differential pulse polarography. If a Britton-Robinson buffer pH = 2.8 with a methanol volume fraction of 20% is used as the supporting electrolyte then a pronounced reduction peak is obtained at -0.73 V; this allows diazepam concentrations even below 0.05 µg/mL to be determined in blood. The necessary sample preparation steps are also dealt with in this Bulletin.

Cinchocaine (dibucaine) is used in the form of ointments or injection solutions as a local anaesthetic. Its base is soluble in diethyl ether; its hydrochloride, on the other hand, is insoluble in diethyl ether but easily soluble in water. This Bulletin describes the determination of cinchocaine in ointments, creams and injection solutions by means of differential pulse polarography. An acetate buffer pH = 4.8 is used as the supporting electrolyte. The limit of quantitation and the linear working range of the method are given. The necessary sample preparation steps are also dealt with in this Bulletin.

This Application Bulletin describes the determination of zinc at a mercury film electrode (MFE). Zinc can also be determined simultaneously with cadmium and lead. The determination of copper at the MFE is not possible. The mercury film is plated ex-situ on a glassy carbon electrode and can be used for half a day up to one day.Zinc can be determined at the mercury film electrode by anodic stripping voltammetry (ASV). The presence of copper, which is naturally present in many samples, affects the determination of zinc due to the formation of an intermetallic compound. As a result the determined concentrations of zinc are too low. The addition of gallium can eliminate the interference to a certain extent since the intermetallic complex of gallium and copper is more stable than the complex of zinc and copper.With a deposition time of 10 s, the limit of detection is β(Zn2+) = 0.15 μg/L. The linear working range goes up to approx. 300 μg/L.With the deposition time of 10 s the method is suitable for samples between 10 μg/L and 150 μg/L Zn content. For samples with lower concentrations the results are more reliable if the deposition time is increased to e.g. 30 s. Samples with higher concentrations have to be diluted.

This Application Bulletin describes the determination of titanium by adsorptive stripping voltammetry (AdSV) using mandelic acid as complexing agent. The method is suitable for the analysis of ground, drinking, sea, surface and cooling waters, in which the concentration of titanium is of importance. The methods can, of course, also be used for the trace analysis in other matrices.The limit of detection is approx. 0.5 µg/L.

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 determination of arsenic in water samples by anodic stripping voltammetry using the scTRACE Gold sensor. This method makes it possible to distinguish between As(total) and As(III). With a deposition time of 60 s, the limit of detection for As(total) is 0.9 µg/L, for As(III) it is 0.3 µg/L.

This Application Bulletin describes the determination of inorganic mercury in water samples by anodic stripping voltammetry using the scTRACE Gold sensor. With a deposition time of 90 s, calibration is linear up to a concentration of 30 µg/L; the limit of detection lies at 0.5 µg/L.

Copper is one of the few metals which is available in nature also in its metallic form. This and the fact that it is rather easy to smelt led to intense use of this metal already in the so-called Copper and Bronze Age. Nowadays, it is more important than ever, because of its good electrical conductivity and its other physical properties. For plants and animals, it is an essential trace element; for bacteria, in contrast, it is highly toxic.This Application Bulletin describes the determination of copper by anodic stripping voltammetry (ASV) using the scTRACE Gold electrode. With a deposition time of 30 s, the limit of detection is about 0.5 μg/L.

This Application Bulletin describes the methods for the determination of uranium by adsorptive stripping voltammetry (AdSV) according to DIN 38406 part 17. The method is suitable for the analysis of ground, drinking, sea, surface and cooling waters, in which the concentration of uranium is of importance. The methods can, of course, also be used for the trace analysis in other matrices.Uranium is determined as chloranilic acid complex. The limit of detection in samples with low chloride concentration is about 50 ng/L and in seawater about 1 µg/L. Matrices with high chloride content can only be analyzed after reduction of the chloride concentration by means of a sulfate-loaded ion exchanger.

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.

This Application Bulletin describes the determination of Sn(II) in presence of Sn(IV) by anodic stripping voltammetry (ASV). Using an electrolyte containing fluoride, Sn(IV) gives no signal, so that a speciation is possible. The limit of detection is 2.5 µg/L.

Lead is known to be highly toxic and lead salts are easily absorbed by creatures. By interfering with enzyme reactions,lead can affect all parts of the human body. It can cause severe damage to brain and kidneys and can cross the bloodbrain barrier. Cases of chronic lead poisoning caused by lead metal used in the water piping system are well known. Therefore, the control of drinking water for lead content is of utmost importance. In many countries (e.g., EU, USA), the limit for lead in drinking water is between 10 and 15 μg/L. These concentrations can reliably be determined with the method described in this Application Bulletin. The determination is carried out by anodic stripping voltammetry at a silver film applied to the scTRACE Gold electrode.

Heavy metals, particularly cadmium and lead, are known to be highly toxic to humans. Therefore, controlling the cadmium and lead content in drinking water is of utmost importance. In many countries, the limit in drinking water for cadmium is between 3–5 µg/L, and for lead it is between 5–15 µg/L. These trace concentrations can reliably be determined with the method described in this Application Bulletin. The determination is carried out by anodic stripping voltammetry (ASV) using the non-toxic Bi drop electrode in a slightly acidic electrolyte.

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.

Cobalt is an essential element for humans because it is a component of vitamin B12. While small overdoses of cobalt compounds are only slightly toxic to humans, larger doses from 25–30 mg per day may lead to skin, lung, and stomach diseases, as well as liver, heart, and kidney damage, and even cancerous growths. The same is valid for nickel, which can lead to inflammation at higher concentrations. Drinking a large amount of water containing nickel can cause discomfort and nausea. In the EU the legislation specifies 0.02 mg/L as the limit value for the nickel concentration in drinking water. This concentration can be reliably determined with the method described in this Application Bulletin.

A reference electrode has a stable and well-defined electrochemical potential (at constant temperature), against which the applied or measured potentials in an electrochemical cell are referred. A good reference electrode is therefore stable and non-polarizable. In other words, the potential of such an electrode will remain stable in the used environment and also upon the passage of a small current. This application note lists the most used reference electrodes, together with their range of use.

The determination of heavy metal ions in a solution is one of the most successful application of electrochemistry. In this application note, anodic stripping voltammetry is used to measure the presence of two analytes, in a sample of tap water.

The study of the electrochemical behavior of platinum in acidic media is of crucial importance in fundamental electrochemistry and electrocatalysis. Most electrocatalytic processes occurring at Pt electrodes are highly sensitive to the structure of the platinum surface. Cyclic voltammetry (CV) is a widely used rapid measurement technique that provides both a qualitative and quantitative fingerprint of platinum surfaces. A comparison of results given by linear and staircase CVs is presented in this Application Note.

Capacitors are electronic components necessary for the success of the electronics industry. They have also become essential components of both electric and hybrid vehicles. Electrochemical tests, such as potentiostatic cyclic voltammetry, are used to check the performance of capacitors. VIONIC powered by INTELLO can perform both staircase and linear cyclic voltammetries (CV). This Application Note gives a comparison between the linear and the staircase potentiostatic cyclic voltammetries and highlights the necessity of using the linear CV to best study the performance of capacitors.

Many different configurations are made possible when using two-, three-, or four-electrode cell setups in research. Depending on the experimental requirements, one setup may be preferred over another. Therefore, the proper electrode arrangements for these three situations are defined in this Application Note. As an example, the potential at the counter electrode is measured during the platinum oxidation in acidic media, with the second sense (S2) of VIONIC powered by INTELLO. Since dissolved Pt in solution could bias the results, it is important to be able to monitor the potential of the counter electrode.

This Application Note highlights the use of Metrohm Hyphenated EC-Raman Solutions to monitor the reversible oxidation of ferrocyanide at a gold electrode.

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

Incineration flue gas requires treatment such as wet scrubbing. The 2060 VA Process Analyzer monitors heavy metals in the scrubbing water, ensuring compliance.

This Application Note demonstrates square wave voltammetry for sensitive, reproducible quantification of paracetamol using a screen-printed electrode and INTELLO.

This Application Note presents DPV as a sensitive, selective method for detecting heavy metals in water, detailing setup, parameters, and advantages over other techniques.

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.

Germanium is determined by adsorptive stripping voltammetry (AdSV) at the HMDE using aqueous sulfuric acid as supporting electrolyte and pyrocatechol violet as complexing agent. It is possible to determine 20 µg/L Ge in a sample containing 150 g/L Zn, 3 g/L Cd and 1 mg/L Pb.

Thiourea is determined by cathodic stripping voltammetry (CSV) at the HMDE in ammonia buffer at pH 8.9. Chloride in the sample does not interfere with this determination.

Ti is determined in polyethylene terephthalate (PET) after digestion in sulfuric acid and hydrogen peroxide. Adsorptive stripping voltammetry (AdSV) with mandelic acid as complexing agent is used for this application.

Co is determined in polyethylene terephthalate (PET) after digestion in sulfuric acid and hydrogen peroxide. The application is carried out with adsorptive stripping voltammetry (AdSV) in ammonia buffer with dimethylglyoxime (DMG) as complexing agent.

Sb is determined in polyethylene terephthalate (PET) after digestion in sulfuric acid and hydrogen peroxide. The application is carried out with anodic stripping voltammetry (ASV) in hydrochloric acid.

Zn and Pb are determined by anodic stripping voltammetry (ASV) in acetate buffer at pH 4.6.

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.

Gold can be determined by anodic stripping voltammetry (ASV) in the µg/l range at the Ultra Trace Graphite electrode. The solution should not contain halide ions.

The concentration of nickel in ethylene glycol can be determined by adsorptive stripping voltammetry (AdSV) after the organic matrix is destroyed by UV digestion.

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 Al is determined by adsorptive stripping voltammetry at the HMDE. The method is suitable for Al in concentrations in the range of 0.1 ppb to approx. 40 ppb Al3+. Pb2+ ions do not interfere up to a concentration ratio Pb:Al = 10:1. Due to the slow complex formation of Al with solochrome violet RS the measuring solution was heated to 40 °C for 10 min prior to the determination. For standard addition a solution of Al with solochrome violet RS complex was used. All reagents have to be added in the order as listed below.

The concentration of Ni and Co is determined by adsorptive stripping voltammetry at the HMDE with dimethylglyoxime (DMG) as complexing agent.

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 Sb(total) in an acid Cu bath is determined by anodic stripping voltammetry using hydrochloric acid as electrolyte. Due to the excess of Cu the deposition potential has to be chosen only 50 mV more negative than the Sb signal

The concentration of Ni in a Ni plating bath is determined by polarography in ammonia buffer pH 9.6.

The concentration of Co in a sulfamate Ni plating bath is determined by adsorptive stripping voltammetry (AdSV) inammonia buffer pH 9.6 with dimethylglyoxime (DMG) as complexing agent. All reagents have to be added in the order listed below. Special care has to be taken that the measuring solution is mixed well before the complexing agent is added. In case of precipitations of Ni-DMG further dilution of the sample is necessary.

The concentration of Cu in a Ni plating bath is determined by polarography in chloride-containing acetate buffer at pH 4.7.

The concentration of Sb(III) and Sb(total) in an electroless nickel bath is determined by anodic stripping voltammetry (ASV). In c(HCl) = 0.6 mol/L only Sb(III) shows a signal. In w(HCl) = 10% the Sb(total) content is determined.

The concentration of Tl in a cyanidic Au bath is determined by anodic stripping voltammety (ASV) without further addition of electrolyte.

NTA in a cyanidic gold bath is determined as Bi-NTA complex by polarography. For standard addition a Bi-NTA standard solution is used.

The concentration of In in a Sn bath is determined in a HCl / Urotropin® containing electrolyte by anodic stripping voltammetry (ASV). The determination is linear up to approx. 0.5 mg/L with respect to the concentration of In in the measuring vessel. The standard addition solution is also prepared with HCl and Urotropin®.

The concentration of Bi in a Sn bath is determined in a HCl / Urotropin® containing electrolyte by anodic stripping voltammetry (ASV). A reaction time of at least 25 min is required before the determination is started. The standard addition solution is also prepared with HCl and Urotropin®.

The concentration of Pd in an activator bath is determined by polarography in ammonium chloride electrolyte.

The concentration of Cu in a cyanidic Cu bath is determined by polarography.

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.