Applications

This article describes a simple and sensitive method for chromium(VI) determination in children's toys. The solution to be analyzed is prepared in accordance with DIN EN 71. Not only VIS detection but also post-column derivatization using diphenylcarbizide are parts of this method. The procedure described here is suitable for the precise determination of hexavalent chromium in the single-digit ppt range and, in addition, fulfils without difficulty the limit value of 10 ppt prescribed by the EU directive 2009/48/EC.

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.

Haloacetic acids (HAAs) are commonly produced as disinfection byproducts (DBPs) from water treatment processes. Some HAAs are regulated by the authorities and have been classified as potentially carcinogenic. They have traditionally been analyzed by gas chromatography (GC), a technique that requires time-consuming sample extraction and derivatization, leading to higher costs per analysis. Ion chromatography hyphenated to mass spectrometry (e.g., single or triple quadrupole MS systems) is a powerful tool that can handle many challenging analytical tasks such as measuring μg/L levels of HAAs in potable water samples. This White Paper explains the benefits of using this hyphenated technique for the accurate measurement of HAAs in potable water.

This white paper presents IC-MS as powerful analysis technique. This multiparameter method determines various analytes such as inorganic cations and amines in one run.

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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.

A complete tap water analysis includes the determination of the pH value, the alkalinity and the total water hardness. Both the pH measurement and the pH titration by means of a standard pH electrode suffer from several drawbacks. First, the response time of several minutes is too long and, above all, the stirring rate significantly influences the measured pH value. Unlike these standard pH electrodes, the Aquatrode Plus with its special glass membrane guarantees rapid, correct and very precise pH measurements and pH titrations in solutions that have a low ionic strength or are weakly buffered. Total water hardness is ideally determined by a calcium ion-selective electrode (Ca ISE). In a complexometric titration, calcium and magnesium can be simultaneously determined up to a calcium/magnesium ratio of 10:1. Detection limits for both ions are in the range of 0.01 mmol/L.

This study compares air sampling data obtained by a filter-based method including off-line manual filter extraction followed by ion chromatographic analysis with those gained by an automated Particle-Into-Liquid-Sampler coupled to an ion chromatograph (PILS-IC).PILS-IC is a straightforward instrument for aerosol sampling that provides near real-time measurements for long-term unattended operation and is thus an indispensable tool to monitor rapid changes in aerosol particle ionic composition.

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.

Metal precipitation and cyanide recovery in the SART process (sulfidization, acidification, recycling, thickening) depend to a great extent on the sulfide concentration. Among the flow injection analysis methods coupled to wet-chemical analyzers, the combination of a gas diffusion cell with an ion chromatograph (IC) plus subsequent direct spectrophotometric detection has proven to be one of the most convenient methods of sulfide analysis.This paper deals with the determination of sulfide anions via the coupling of a gas diffusion cell to an IC with subsequent spectrophotometric detection.

On the basis of the experiments that have been performed, it is possible to determine the effectiveness of the ozonization of iodized X-ray contrast media using IC-ICP-MS via the amount of iodate formed. Whereas a 120-minute ozonization guarantees a practically quantitative decomposition of amidotrizoic acid to iodate, approximately 16% of the Iomeprol is still present under the same ozonization conditions. Given that only 14% is present in iodate form in the absence of iodide anions and given that additional, not yet identified peaks occur in the ion chromatogram, the presence of additional decomposition products containing iodine must be assumed. Nonetheless, it is not possible to detect the intact iodized X-ray contrast media with the selected ion chromatographic conditions. Furthermore, the possibility exists of identifying the peak of the unknown decomposition product of the Iomeprol using IC-ESI-TOF-MS.

This article describes the investigation using ion chromatography and subsequent inductively coupled plasma mass spectronomy (ICP/MS) to determine the extent to which the iron(III) flocculation carried out in the context of wastewater treatment releases toxic gadolinium(III) ions as the result of recomplexing.

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.

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 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 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.

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.

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.

This Bulletin describes fluoride determination in various matrices with the help of the ion-selective fluoride electrode (F-ISE). The F-ISE is comprised of a lanthanum fluoride crystal and exhibits a response in accordance with the Nernst equation across a wide range of fluoride concentrations.The first part of this Bulletin contains notes regarding the handling and care of the electrode and the actual fluoride determination itself. The second part demonstrates the direct determination of fluoride with the standard addition technique in table salt, toothpaste and mouthwash.

"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, using practical examples, indicates how the user can achieve optimum pH measurements. As this Bulletin is intended for actual practice, the fundamentals - which can be found in numerous books and publications - are treated only briefly.

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.

Coal contains a certain amount of fluorine, chlorine, and sulfur compounds. During combustion of the coal, these components release corrosive acids (e.g., fluorine compounds form hydrofluoric acid). Thermal power plants therefore request low-fluorine coal to avoid massive hydrofluoric acid production. In this application note, fluorine content in coal is determined by ion chromatography after pyrohydrolysis.

Naphtha is the first petroleum product during the distillation process of crude oil or coal tar. It is primarily used as a base material for the production of gasoline or as a solvent. Accidental spills occur regularly at many locations throughout the world, leading to soil contamination.Investigation of contaminated sites is usually performed using gas chromatography, for which the soil sample has to be frozen, grinded, and subsequently extracted prior to the analysis. Using Visible-Near Infrared Spectroscopy such sample preparation steps are not necessary at all, making this method a viable, fast, and simple to use alternative.

The determination of low ammonium concentrations besides excess sodium is demanding due to the small retention time difference of these two cations. This Application Note shows direct conductivity detection as an ideal means to detect ammonium in a wastewater sample containing 400 mg/L sodium. AN-S-313 shows the analysis of nitrite traces.

Determination of magnesium, strontium, and barium in produced water using cation chromatography with direct conductivity detection.

Determination of sodium, potassium, DMEA (dimethylethanolamine), calcium, choline, and magnesium in a saline solution using cation chromatography with direct conductivity detection.

Fluoride content in drinking water can be determined quickly and conveniently with the help of potentiometric titration and the ion-selective fluoride electrode (F-ISE). The F-ISE is calibrated with suitable standard solutions before the measurement.

Nitrogen is essential for plant growth. In soil, it can be present in the form of nitrate, ammonium, or urea. Knowing the nitrogen content of soil and in which form it is present helps selecting the right kind of fertilizer to stimulate plant growth.This Application Note shows a fast and reliable way to determine the ammonium concentration in soil by using standard addition.

Determination of chloride in water by direct potentiometry using the Cl-ISE.

Nitrate is naturally present in the environment. However, excessive concentrations of nitrate in surface and ground water are problematic as such concentrations have a negative effect on the water quality. Usually, excessive levels of nitrate area direct result of extensive usage of fertilizers in agriculture. Nitrate is easily washed from soils and can end up in surface or ground water. As the nitrate content is regulated in many countries, a quick and inexpensive assessment of its concentration is required to monitor the water quality.The nitrate concentration can easily be obtained by direct measurement using a nitrate ion selective electrode. First, a calibration is performed, afterwards, the samples are measured in less than a minute.This is a fast, inexpensive and reliable method to determine the nitrate content in various water samples.

Oxygen diffuses into water sources from the air via aeration, however several factors can reduce the dissolved oxygen (DO) content in water. First, as water warms up, oxygen is released into the atmosphere. Secondly, oxygen is consumed by bacteria and other microorganisms which feed on organic material. Finally, plants can also consume oxygen in certain situations.Human-induced alterations can have a negative influence on surface water when DO values fall below crucial limits for maintaining the life supporting capacity of freshwater ecosystems. Therefore, monitoring the DO content in surface water by an optical sensor to assess its quality is important.

Determination of sulfide in wastewater by direct potentiometry with the Ag/S ion-selective electrode.

Determination of chloride, nitrate, phosphate and sulfate in plant leaf extracts using anion chromatography with direct conductometric detection.

Determination of borate in a borate effluent using anion chromatography with direct conductivity detection.

Determination of sodium dodecylsulfate (SDS, sodium laurylsulfate) using anion chromatography with direct conductivity detection.

Determination of iodide and thiosulfate in photographic process wastewater using anion chromatography with amperometric detection at the carbon paste electrode after chemical suppression.

Determination of fluoride, chloride, nitrate, phosphate, and sulfate on a short column or the ions mentioned plus bromate and nitrite on a long column in water samples applying intelligent column-switching using anion chromatography with conductivity detection after sequential suppression.

Determination of acetate, chloride, nitrite, bromide, nitrate, phosphate, sulfate, oxalate, fumarate, and molybdate using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, chloride, nitrate, phosphate, and sulfate in surface water using anion chromatography with conductivity detection after chemical suppression; nitrite with electrochemical detection (conductivity and ELCD detectors in series).

Determination of chloride and sulfate in dust using anion chromatography with conductivity detection after chemical suppression.Sample:dust sampleSample preparation:0.1 g of dust dissolved in 100 mL c(HNO3) = 0.02 mol/L 0.45 µm filtration

Determination of perchlorate in water containing 3 g/L of total dissolved solids (TDS) using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, acetate, propionate, formate, butyrate, chloride, nitrite, bromide, nitrate, benzoate, phosphate, sulfate, malonate, and oxalate in an industrial process water using anion chromatography with conductivity detection after sequential suppression.

VoltIC pro I is the perfect combination of voltammetry and ion chromatography for the fully automated analysis of anions, cations, and heavy metals (e.g., Zn, Cd, Pb, Cu): comprehensive water analysis on a single system.

Fast IC means short run times and a high sample throughput. This is attained using short columns and strong eluents. Drinking water (including fluoride) is analyzed on the Metrosep A Supp 5 - 100/4.0 under the same conditions as in AN-S-322.

In ion chromatography with suppressed conductivity detection, calibration curves quite often are not really linear. Especially, if a calibration has to cover a large concentration range, results will be more accurate when multiple calibration curves for different concentration ranges are applied. The MagIC Net software allows to apply multiple calibration curves within one single determination. This means that for every ion the optimal calibration is applied, improving the accuracy of the results. This method is applied to rainwater samples.

Determination of acetate, propionate, formate, and chloride in water using anion chromatography with conductivity detection after chemical suppression.

Perchlorate in water is mainly due to anthropogenic sources such as fertilizers, fireworks, rocket fuel, etc. Trace analysis of perchlorate in water samples is a critical task. The high content of standard anions leads to large peaks that interfere with the very small perchlorate peak. In the heart-cut technique, the perchlorate fraction – widely freed of interfering anions – is re-injected onto the column thus providing a sharp peak.

Determination of chloride, nitrate, phosphate, and sulfate in wastewater using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, chloride, bromide, nitrate, sulfate, and iodide in rock leachant using anion chromatography with conductivity detection after chemical suppression.