Applikationer

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.

The determination of cyanide is very important not only in electroplating baths and when decontaminating wastewater but, due to its high toxicity, also in water samples in general. Concentrations of 0.05 mg/L CN- can already be lethal for fish.This Bulletin describes the determination of cyanide in samples of different concentrations by potentiometric titration.Chemical reactions:2 CN- + Ag+ → [Ag(CN)2]-[Ag(CN)2]- + Ag+ → 2 AgCN

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.

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 document explains how to measure Na ion concentration in diverse matrices with a sodium ion-selective electrode (Na-ISE) using direct measurement and standard addition.

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).

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.

Although the known photometric methods for the determination of ammonia/ammonium are accurate, they require a considerable amount of time (Nessler method 30 min, indophenol method 90 min reaction time). A further disadvantage of these methods is that only clear solutions can be measured. Opaque solutions must first be clarified by time-consuming procedures. These problems do not exist with the ion-selective ammonia electrode. Measurements can be easily performed in waste water, liquid fertilizer, and urine as well as in soil extracts. Especially for fresh water and waste water samples several standards, such as ISO 6778, EPA 350.2, EPA 305.3 and ASTM D1426, describe the analysis of ammonium by ion measurement. In this Application Bulletin, the determination according to these standards is described besides the determination of other samples as well as some general tips and tricks on how to handle the ammonia ion selective electrode. Determination of ammonia in ammonium salts, of the nitric acid content in nitrates, and of the nitrogen content of organic compounds with the ion-selective ammonia electrode is based on the principle that the ammonium ion is released as ammonia gas upon addition of excess caustic soda:NH4+ + OH- = NH3 + H2OThe outer membrane of the electrode allows the ammonia to diffuse through. The change in the pH value of the inner electrolyte solution is monitored by a combined glass electrode. If the substance to be measured is not present in the form of an ammonium salt, it must first be converted into one. Organic nitrogen compounds, especially amino compounds are digested according to Kjeldahl by heating with concentrated sulfuric acid. The carbon is oxidized to carbon dioxide in the process while the organic nitrogen is transformed quantitatively into ammonium sulfate.

Determination of sodium, ammonium, methylamine, guanidine (Gu), and aminoguanidine (Agu) in wastewater using cation chromatography with direct conductivity detection.

Determination of sodium, potassium, calcium, and magnesium in the water soluble fraction of a washing powder using cation chromatography with direct conductivity detection.

Determination of lithium, sodium, ammonium, potassium, manganese, calcium, magnesium, strontium, and barium in an offshore effluent using cation chromatography with direct conductivity detection.

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.

Wastewaters often contain high loads of sodium, making the determination of minor cations quite a challenge. In the present wastewater study, the determination of lithium, ammonium, zinc, strontium, and barium is requested. If the sodium concentration exceeds 2 g/L, this negatively influences the peak shape of closely eluting peaks. Applying a appropriate dilution factor to the sample enables the quantification of minor cations. Therefore zinc and barium can be properly quantified with a dilution ratio of 1:2, while lithium and ammonium require minimum dilution factors of at least 1:10 and 1:100, respectively.

AOF (adsorbable organic fluorine) is used to screen for per- and polyfluorinated alkyl substances in aqueous matrices via pyrohydrolytic combustion and ion chromatography.

Combustion ion chromatography (CIC) measures AOX (adsorbable organically bound halogens, i.e., AOCl, AOBr, AOI) and AOF as well as CIC AOX(Cl) according to DIN 38409-59 and ISO 18127.

Cation analysis by IC in wastewater is a proven method. Limiting factor is often the Na/NH4 separation. High sodium concentrations may make ammonium determination impossible due to peak overlapping. The use of sequential suppression and a Dose-in gradient improve the Na/NH4 separation and enables determination of low ammonium concentrations.

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

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

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

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

Cyanides are used in some industrial processes, but if not handled carefully, they could contaminate the wastewater. In an acidic or neutral environment, this contaminated wastewater can form highly toxic hydrogen cyanide gas. Furthermore, the cyanide salts could also poison the environment and enter the ground water system. Therefore, it is essential to monitor the content of cyanide in effluent water. Cyanides can be easily determined with a cyanide ion-selective electrode. This application note presents a method for cyanide analysis according to APHA Method 4500-CN and ASTM D2036.

Even in low concentration, sulfide ions cause odor and corrosion problems in ground water and waste water. They can release hydrogen sulfide in acidified water, which is toxic in even minuscule amounts. This Application Note describes the determination of sulfide concentration in water via direct measurement with the Ag/S-ISE in accordance with ASTM D4658.

Bromide is ubiquitous in sea water, where it is present in concentrations of around 65 mg/L. By contrast, the maximum bromide concentration in drinking and ground water is usually less than 0.5 mg/L. A higher bromide content may indicate a contamination of the water caused by fertilizer, road salt or industrial waste water. This Application Note describes the determination of the bromide content in water via direct measurement with a Br ion-selective electrode in accordance with ASTM D1246.

Increased fluoride concentrations in water may cause tooth damage, growth disorders, and bone deformation. According to the World Health Organization (WHO), concentrations above 1.5 mg/L are critical.One possible source of fluoride is landfills. Rain washes out harmful substances from landfills which can enter the groundwater. The leachate from landfills should thus be monitored for the fluoride concentration.Ion measurement is a fast and inexpensive method to determine the fluoride content in water samples compared to other methods such as ion chromatography. This Application Note describes a reproducible and accurate measurement of the fluoride content using the fluoride ion-selective electrode with an OMNIS system.

Groundwater contains many minerals, but can be contaminated by sodium-rich leachate from landfills. Accurate Na determination in water is possible following AOAC 976.25 using the Na-ISE.

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.

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

The new DIN draft standard 38407-53 outlines TFA analysis in water using direct injection LC-MS/MS, enabling quantification from 0.1–3.0 μg/L as shown in this Application Note.

Determination of fluoride, chloride, nitrite, nitrate, and sulfate in an effluent sample using anion chromatography with direct conductometric detetction.

Determination of iodide in wastewater (dye industry) using anion chromatography with amperometric detection at the silver electrode and dialysis for sample preparation.

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

Determination of chloride and sulfate in effluent after Metrohm Inline Dialysis using anion chromatography with direct conductivity detection.

Determination of sulfide in an effluent sample using anion chromatography with amperometric detection.

The determination of cyanide and sulfide in the trace range requires an alkali eluent and amperometric detection. This Application Note describes a new column/eluent combination for optimized separation. The combination consists of the Metrosep A Supp 10 - 100/2.0 Microbore Column and a sodium hydroxide eluent that contains traces of EDTA for the complexation of the transition metals. This yields a better peak shape and detection limits below 0.05 µg/L.

Sulfide and cyanide are toxic anions. Their trace determination in any kind of water samples, especially in wastewater, is requied for safety reasons. However, metal traces present in the eluent can mask target anions due to complexation. The addition of a stronger complexing agent to the eluent mask these metal cations enabling interference free determaination. This application is mainly used for the analysis of cyanide and/or sulfide in water. However, it also fulfills the requirements of ASTM D2036 for the determination of total, amenable, weak acid dissociable cyanides. The determination of cyanide and sulfide require an alkaline eluent and amperometric detection. This Application Note describes a new column/eluent combination for optimized separation. The combination consists of the Metrosep A Supp 10 - 100/4.0 column and a sodium hydroxide eluent containing a trace of EDTA for transition metal complexation. This yields in better peak shape and detection limits below 0.1 μg/L.

Ion chromatographic determination of sulfide in wastewater is performed using amperometric detection and an alkali eluent to ensure the stability of the sulfide. Measurements are performed in single-potential or direct current (DC) amperometric mode. It is the best-known and most sensitive amperometric measuring method and also provides, in addition to a high selectivity, a large selection of working electrodes.Sulfide determination is performed on a Metrosep A Supp 10 - 100/4.0 type column; a silver electrode is used as the working electrode.

Cyanide in wastewater is an important parameter to measure for health requirements. Free, weakly complexed, and strongly complexed cyanide can be differentiated. Direct measurement in the wastewater is not feasible due to the matrix itself. Therefore, total cyanide is determined after acidification of the sample, which releases all cyanide from complexes, and subsequent distillation and absorption of cyanide in an alkaline solution. Amperometric detection is applied using a gold working electrode. This electrode is advantageous over the silver electrode due to less contamination issues and better long-term stability.

This Process Application Note details the simultaneous online analysis of H2S and NH3 in sour water which was previously treated in the sour water stripper (SWS). The method includes automatic cleaning and calibration. Fast and accurate results are continuously supplied for process control.

Gold leaching by cyanidation requires precise monitoring of cyanide and gold. Online process analyzers perform such measurements, improving safety and compliance.

This Process Application Note deals with online measurements of ammonia, nitrite, and nitrate in wastewater treatment plants. These nitrogen compounds are analyzed simultaneously using a drift-free colorimetric measurement in a multi-parameter 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.

Phosphorus removal is essential in waste water treatment plants to ensure the environmental balance is not upset by discharged effluent. In the treatment facility it is important to know the bioavailable o-phosphate phosphorus (o-PO4-P) concentration in the influent stream either to feed bacteria or to calculate the amount of reagents needed for chemical treatment. For environmental compliance monitoring purposes, treated effluent is monitored for TP – the sum of all insoluble and dissolved phosphates present. With the Metrohm Process Analytics 2035 TP Analyzer (complete with integrated compact digestion cuvette photometer module), you can keep track of both o-PO4-P and TP according to DIN EN ISO 6878:2004-09 around the clock.

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

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

Determination of nitrite and nitrate in wastewater using anion chromatography with conductivity detection after chemical suppression.

Determination of sulfate in wastewater after nitric acid combustion using anion chromatography with conductivity detection after chemical suppression.

Determination of NTA, EDTA, and DTPA in surface water and wastewater using ion pair chromatography with UV-detection after post-column reaction with the MSM.

Determination of bromide, nitrate, and phosphate in wastewater using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of bromide and phosphate in waste dump drainage water in the presence of very high concentrations of other ions and organic substances using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of chloride, bromide, and sulfate in photographic process wastewater using anion chromatography with conductivity detection after chemical suppression.

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, sulfite, phosphate, and sulfate in wastewater using anion chromatography with conductivity detection after chemical suppression.

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

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

Determination of total phosphate in wastewater after digestion with peroxodisulfate using anion chromatography with conductivity detection after chemical suppression.

Determination of nitrite, nitrate, sulfite, and sulfate in wastewater containing high levels of chloride using anion chromatography with conductivity detection after chemical suppression and after inline chloride removal.

Determination of traces of fluoride, acetate, formate, chloride, and sulfate in an ion exchanger eluate containing 2 g/L nitrate using anion chromatography with a step gradient and conductivity detection after chemical suppression.

Determination of fluoride, acetate, formate, chloride, nitrite, nitrate, phosphate, and sulfate in wastewater containing N-methylpyrrolidone using anion chromatography with conductivity detection after chemical suppression and inline matrix elimination.

Determination of fluoride, chloride, nitrite, bromide, nitrate, phosphate, and sulfate in water from an agricultural irrigation system using anion chromatography with conductivity detection after chemical suppression.

Determination of thiooctanoate in wastewater using anion chromatography with conductivity detection after chemical suppression.

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

The determination of low nitrite concentrations in the presence of excess sodium chloride is demanding due to the small retention time difference of these two anions. Dual detection – conductivity and UV/VIS – is a powerful method for determining nitrite traces in a 20 g/L sodium matrix. The UV/VIS chromatogram displays no chloride interferences. The determination of ammonium traces in the presence of excess sodium is described in AN-C-145.

Inline Ultrafiltration is a proven sample preparation technique for samples that are slightly or massively contaminated with particles, algae or bacteria. Filtration and injection are coupled and fully automatic. As a rule, 100 or more samples can be filtered through a single membrane. Service life is extended – even with highly contaminated tannery effluent – to more than 300 injections because the filter membrane is rinsed again once more after the analysis with the aid of the Dosino backflush.

Traces of organic acids can be determined only with difficulty in the presence of high concentrations of standard anions, because their small peaks generally disappear under the larger peaks of the standard anions. A simple dose-in-gradient improves the separation: acetate and formate are baseline-separated from fluoride. Furthermore, oxalate elutes considerably less than sulfate. The separation takes place on a column of the Metrosep A Supp 7 - 250/4.0 type with subsequent conductivity detection following sequential suppression.

The Eco IC is an entry-level instrument that is particularly suitable for routine operations and water analysis. It is equipped with a conductivity detector and can be used both with and without chemical suppression. This Application Note describes the determination of anion content with the Metrosep A Supp 17 - 250/4.0 column. This column model is particularly suitable for water analysis at room temperature.

The microbore Metrosep A Supp 4 - 250/2.0 column is particularly suitable for the analysis of anions in critical samples. A waste water sample is being analyzed in the current application. The sample requires only one filtration prior to injection on the Metrosep A Supp 4 - 250/2.0. The anions are quantified with the application of conductivity detection following sequential suppression.

Kjeldahl nitrogen is a typical titration application that follows digestion and ammonia distillation. The ASTM Standard D8001 now offers an alternative applying persulfate digestion followed by IC determination. No distillation is required. In addition, the method enables the determination of total nitrogen and total phosphorus. We show the results of control samples containing organic substances. As these substances are dissolved in ultrapure water, the nitrogen concentration found corresponds to Total Nitrogen and Kjeldahl Nitrogen.

EN ISO 10304-1 is one of the most important standards for the determination of the seven standard anions in water samples. Many other standards refer to EN ISO 10304-01 if anion determination by IC is required. This standard asks for a membrane filtration for samples to avoid bacteria and solids, if required. This application shows the determination of anions according EN ISO 10304-1 applying Inline Ultrafiltration. This setup avoids tedious manual sample filtration and handles any samples fully automatically.

This Application Note presents a potentiometric titration method for trace H2S analysis in water on an OMNIS system using silver nitrate and an Ag Titrode.

ASTM D8192 describes the photometric titration of the total hardness, calcium hardness, and magnesium hardness in water with an optical sensor for objective endpoint indication, increasing precision and reliability. The method is suitable for both colored and colorless samples such as groundwater, surface water, wastewater, and drinking water. Using a fully automated OMNIS system equipped with an Optrode ensures that the sample preparation and analysis are repeatable.

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

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

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

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

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

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

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

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

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.

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.

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

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.

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.

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.

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.

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 Metrohm White Paper presents the important role of electrochemistry in the environmental sciences. The applications have to do with basic research for the fuel cell that yields energy from wastewater, the electrical clean-up of contaminated soil and electrochemical CO2 reduction of greenhouse gases for isolating chemical raw materials.

Brad Meadows is Vice President and Lab Director at the US company BSK Labs, which runs a number of environmental laboratories and service centers. Brad is an analytical chemist and has been working in the management of analysis laboratories for 15 years. He shared his experiences with Metrohm ion chromatography with us in the form of some concrete facts and figures.

Propylene oxide (PO) is a major industrial product used in assorted industrial applications, mainly for the production of polyols (the building blocks for polyurethane plastics). Several production methods exist, with and without co-products. This white paper lays out opportunities to optimize PO production for safer and more efficient processes, higher quality products, and substantial time savings by using online process analysis instead of laboratory measurements.

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

Learn about PFAS, their impact on water quality, EU Directive 2020/2184, and the benefits of AOF measurement using combustion ion chromatography (CIC).

The ASTM D8192 standard allows analysts to determine water hardness in different water matrices by complexometry with automated photometric endpoint recognition, increasing the reproducibility and the precision of the results.

This White Paper gives an overview of the energy-intensive nitrification process that converts ammonia into less harmful nitrogen compounds at wastewater treatment plants (WWTPs). It displays the results from a field test at a WWTP, showcasing the positive influence of single-method process analyzers on the efficiency of the nitrification process.