Application Finder

This Application Note describes the photometric determination of sulfate in aqueous solutions using the Optrode (520 nm). Sulfate is precipitated with an excess of barium chloride solution. Excess barium is subsequently titrated with EDTA.

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.

This Application Note describes the photometric determination of sulfate using the Optrode (610 nm). Sulfate is titrated with a lead nitrate solution; dithizone is used as indicator.

The automated system MATi 13 determines the permanganate index in all kind of water samples according to EN ISO 8467. The high degree of automation (e.g., automated sample addition, automated titer and blank value determination) minimizes errors and guarantees robust and reproducible results.

This Application Note describes an automated system with which the chloride content in various water samples can be determined. The high degree of automation (e.g., automated addition of acid and titer determination) reduces errors to a minimum and ensures outstanding reproducibility.

This Application Note describes automatic sulfate determination using a combined ion-selective calcium electrode. Sulfate is precipitated with an excess of barium chloride solution. Excess barium is subsequently back-titrated with a standard EGTA solution.

Water hardness is often determined photometrically using two different indicators and while performing the determination at two different pH values. Additionally, the determination itself is subjective, as the color change is determined by the analyst and not by an analytical device.This application note introduces a more robust option to easily assess calcium, magnesium, and total hardness in water by using the Cu-ISE and two different titrants. Sample preparation is identical for both analyses and can therefore be automated without any issues.

Alkalinity is well-suited as a means of describing the capacity of a body of water to neutralize acid contaminations. It is therefore an important indicator for estimating the influence of contaminations on the ecological system.

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

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

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.

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

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.

Mannitol content determination is an important aspect of quality control in the pharmaceutical and food industries. Selective oxidative cleavage can be used to quantify the amount of 1,2-diol groups in the analyte. Determining the 1,2-diol content by iodometric titration can be fully automated for the most accurate results using an automated titrator and the dPt Titrode from Metrohm.

Titration is an accurate and precise method that can be used to determine the pyrophosphate content in aqueous products. The OMNIS Titrator equipped with a dUnitrode delivers reliable determinations.

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

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

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

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

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

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

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

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

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

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

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

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.

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

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

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

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

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

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.

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.

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

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.

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.

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 Cu in seawater is determined by anodic stripping voltammetry (ASV) in acetate buffer on a mercury film electrode (MFE). Gallium is added to overcome zinc interferences.