Application Finder

Specialty chemicals have to fulfill multiple quality requirements. One of these quality parameters, which can be found in almost all certificates of analysis and specifications, is the moisture content. The standard method for the determination of moisture content is Karl Fischer titration.This method requires reproducible sample preparation, chemicals, and waste disposal. Alternatively, near-infrared spectroscopy (NIR) can be used for the determination of moisture content. With this technique, samples can be analyzed without any preparation and without using any chemicals.

Control of NCO content in isocyanates is essential for polyurethane production. However, wet chemistry methods are slow, hazardous, and preparation intensive. Near-infrared spectroscopy (NIRS) offers a rapid, reagent-free alternative, determining NCO content in seconds without sample preparation. This makes NIRS a practical and environmentally compliant solution for routine quality control of isocyanate raw materials.

Packaging has become an indispensable part in the food manufacturing process. To improve the appearance and properties of the packaging, a wide variety of coatings and inks are used. Different additives enhance rheological properties, control the wetting dispersion, or in the case of wax increase abrasion resistance. The regulations of these coatings in food packaging applications are very strict in some countries, creating the need for close monitoring of the production process.A fast, reliable, and simple to use solution for quantifying rheological additives and wax in such coatings is Visible-Near Infrared Spectroscopy (Vis-NIRS). Both parameters are determined simultaneously by Vis-NIRS in less than a minute.

Moisture content is one of the most commonly measured properties of fertilizers. Globally, regulations for different fertilizers vary, but local legal limits ensure that the maximum amount of water must not be exceeded. Next to gravimetric methods, Karl Fischer titration is often used for accurate moisture determination.Compared to these methods, near-infrared spectroscopy (NIRS) offers unique advantages: it generates reliable results within seconds, and at the same time does not create chemical waste. This Application Note explains how NIRS can offer fast, reagent-free analysis of moisture content in various fertilizer products.

The quality control of diesel exhaust fluids (DEF) is key to ensure the optimal catalytic performance and prevent damage to the exhaust system in diesel vehicles. The standard method to determine urea content is measuring the refractive index (ISO 22241-2:2019). The issue is that although this method is fast, it is not as accurate as other methods (e.g., HPLC). This application note demonstrates that the DS2500 Liquid Analyzer provides a fast solution with high accuracy for the determination of urea in DEF. With no sample preparation or chemicals needed, visible near infrared (Vis-NIR) spectroscopy allows for the analysis of diesel exhaust fluids in less than a minute.

Near-infrared spectroscopy (NIRS) can determine water content in PGME (propylene glycol monomethyl ether) within seconds as shown in this Application Note.

Determination of glycolic acid and monochloroacetic acid in cocoamidopropyl betaine using ion-exclusion chromatography with direct conductometric detection.

Determination of L-lactide, citrate, and lactate in an acetone solution using ion-exclusion chromatography with direct conductivity detection.

Determination of citrate, ascorbate, and acetate in photographic developer solution using ion-exclusion chromatography with suppressed conductivity detection.

Arabinonic acid, glyceric acid, glycolic acid and formic acid can be determined in organic compounds using ion-exclusion chromatography with subsequent conductivity detection in accordance with inverse suppression. The Metrohm Suppressor Module in its lithium form is used for this purpose: This reduces background conductivity and ensures that the acids are present in their completely disassociated Li+ form. The suppressor is regenerated with lithium chloride.

This Application Note describes carbonate determination with ion chromatography in a 50% sodium hydroxide solution. Sodium hydroxide solutions form carbonates through the absorption of carbon dioxide from ambient air. The carbonate content of an NaOH solution is determined using ion-exclusion chromatography with subsequent conductivity detection following inverse suppression. The samples are diluted 1:20 prior to the analysis and – in order to prevent CO2 absorption – stored in closed sample vessels.

Monoethylene glycol (MEG) is used to remove water from natural gas before further processing. Due to high temperatures applied, glycol degradation to glycolic, formic, and acetic acid may occur. These reactions are unwanted as the emerging acids are corrosive. The determination of the organic acids is achieved by ion-exclusion chromatography with conductivity detection after inverse suppression.

Glycol solutions act as antifreeze agents and are often used as such in motor vehicles. Due to the toxicity of (mono)ethylene glycol (MEG), use is being increasingly expanded to the non-toxic propylene glycol. This Application Note presents the separation and quantification of the two glycols. Separation is performed on the Metrosep Carb 2 - 250/4.0 column. Due to the absence of chromophores and the low conductivity of the glycols, pulsed amperometric detection (PAD) is used to facilitate determination.Key words: ethanediol, propanediol

In this Process Application Note, the analysis of low concentrations of calcium and magnesium (0–20 µg/L) in brine is addressed. The presence of calcium and magnesium can shorten the performance and lifetime of the membranes used in the chlor-alkali industry for the production of chlorine. Accurate online monitoring of the hardness is needed in several stages of the process. Other parameters such as acidity, carbonate, hydroxide, silica, alumina, ammonia, iodate and chlorine can also be analyzed online.

Monitoring hydrogen peroxide content online in the HP-PO production process requires a rugged explosion-proof solution like the 2060 TI Ex Proof Process Analyzer.

In the cumene process, phenol and acetone are produced from benzene and propylene. For a successful process control, it is crucial to monitor the sulfuric acid concentration, which impacts the acid-catalyzed cleavage of cumene hydroperoxide to yield phenol and acetone. This Process Application Note describes the online analysis of sulfuric acid using titration. In such hazardous environments, the analyzer can be ex-proof or located in an ex-proof shelter.

In the Solvay process, ammonium hydrogen carbonate and table salt are converted to sodium hydrogen carbonate and ammonium chloride. Heating the former yields sodium carbonate (soda), an important raw material for the soap and glass industries. Ammonia is an incipient and is regenerated almost completely through conversion of the ammonium chloride with lime milk (Ca(OH)2).A Metrohm process analyzer monitors the ammonia content in the saturated table salt solution after absorption tower, thus guaranteeing a good product yield in the carbonization tower. Additional parameters which can be determined with the analyzer in the Solvay process include: alkalinity, carbonate, chloride, calcium oxide and carbon dioxide.

The basic chemicals industry is responsible for producing thousands of raw materials at very large scales. The industries downstream rely upon a certain level of chemical purity to manufacture their own goods, as certain impurities can cause major issues in various processes. During the production of the basic chemicals NaOH and KOH, electrolysis of saturated brine solutions with membrane-cells yield the product which is further concentrated by evaporation. Impurities from the salts used in the brine will also be concentrated. Typically, this impurity analysis is performed offline with various hazardous chemicals with varying shelf-lives. The Process Ion Chromatograph is able to perform the measurement described in ASTM E1787-16 online, ensuring quality product without the need for time-consuming, hazardous laboratory experiments.

This Process Application Note presents a method to closely monitor low levels of moisture in propylene oxide safely and reliably by using a single explosion-proof inline process analyzer.

This Process Application Note describes a method to determine the strontium and barium concentration in brine as early detectors ofmembrane fouling via online process ion chromatography. Using this multiparameter analytical technique can help reduce the risk of premature membrane fouling and avoid unexpected maintenance and high utility costs with 24/7 automated analysis.

This Process Application Note presents a method to accurately monitor low levels of moisture in tetrahydrofuran (THF) in «real-time» safely, reliably, and optimally with a 2060 The NIR Analyzer from Metrohm Process Analytics. Due to the hazardous and hygroscopic nature of THF, a single explosion-proof inline process analyzer is the preferred solution for industries to reduce chemical treatment, improve product quality, and increase profits.

Boric acid is growing in demand for various industrial applications, but requires a more cost-efficient and environmentally friendly production process. This Application Note describes the performance of a Raman process analyzer (PTRam) when measuring low-concentration boric acid and sodium sulfate solutions (<100 mg/L) during boric acid production.

The combination of 940 Professional IC Vario, 942 Extension Module Vario LQH and 941 Eluent Preparation Module enables process monitoring with the aid of ion chromatography. Assigned the designation ProfIC Vario 12 Anion, this combination is the anion variant of Metrohm Process IC. Intelligent preconcentration technology with matrix elimination is used for sample preparation. The use of an ELGA PURELAB® Flex 6 guarantees the supply of ultrapure water of the highest quality, particularly in cases of high numbers of samples.

Substrates for surface-enhanced Raman spectroscopy (SERS) are typically fabricated with complex (micro/nano)structures of noble metals, enabling trace level detection of analytes. Due to the high costs and reactivity of these SERS substrates, they often have a limited shelf life. Development of new substrate materials which minimize these issues yet maintain the same performance standards is a constant concern.Screen-printed electrodes can be easily fabricated using different metallic materials with the well-established screen-printing method, leading to mass production of versatile, cost-effective, and disposable devices. In this Application Note, the feasibility of using readily-available screen-printed metal electrodes as suitable substrates for the fast and sensitive detection of different chemical species by in situ electrochemical SERS (EC-SERS) is shown.

Many electrochemical methods have been developed but are traditionally limited to aqueous media. Raman spectroelectrochemistry in organic solutions is an interesting alternative, but developing new EC-SERS procedures is still required. This Application Note demonstrates that the electrochemical activation of gold and silver electrodes enables the detection of dyes and pesticides in organic media.

EC-SERS enhances Raman sensitivity using electrochemically activated gold SPEs, enabling rapid, simplified pesticide detection without complex prep or instrumentation.

Operando Raman spectroelectrochemistry shows the potential-dependent structural evolution of Ni-based oxygen evolution catalysts, directly linking vibrational signatures to catalytic activity. Correlating these spectroscopic markers with electrochemical performance not only clarifies OER (oxygen evolution reaction) mechanisms but also guides the design of Ni-based catalysts for related oxidation reactions.

This Application Note describes the rapid and non-destructive identification of conventional organic solvents using hand-held Raman spectrometers. Measurements with the handheld Raman spectrometer Mira M-1 require no sample preparation and provide immediate and unambiguous results.

Solids used in road construction were analyzed with a hand-held Raman spectrometer. The materials examined are conventional pigments and resins, e.g., CaCO3, TiO2 and DEGALAN®. The measured spectra differ considerably from one another. In order to assess the main differences between the chemical structures, the peaks of the spectra were assigned to the functional groups that generated them.

This Application Note shows the rapid, non-destructive identification of isopropyl alcohol from two manufacturers using Raman spectroscopy following the creation of a suitable library. The measurements with the hand-held Raman spectrometer Mira M-1 require no sample preparation and provide immediate results that identify the samples unambiguously.

Identification of unknown materials in the field can be a complicated affair, especially in critical situations, where speed, safety, and ease-of-operation are essential. Mira DS, Metrohm Raman’s handheld Raman analyzer, and the intelligent Universal Attachment (iUA) give the user automated Content ID capabilities. Content ID achieves through container identification of unknown materials quickly, easily, and safely.

This application note presents the Orbital Raster Scan (ORS) technology from Metrohm Raman to overcome low resolution, poor sensitivity, and sample degradation while still interrogating a large sample area.

Signal-to-noise ratio, spectrograph design, resolution of MIRA handheld Raman analyzers.

TacticID-1064 ST is a handheld Raman device that can identify materials through paper, plastic, glass, and multilayer packaging, reducing exposure risks and eliminating the need to open containers.

Metrohm’s MIRA XTR handheld Raman spectrometer enables fast, reagent-free identification of phosphate species, enabling continuous monitoring of dynamic systems.

Raman spectroscopy with PLS modeling enables rapid, accurate, nondestructive quantification of the total phosphate content in solution with minimal sample preparation.

Mercaptans in fuels are corrosive and regulated at trace levels. SERS enhances Raman signals to enable their accurate detection and quantification below standard LODs.

Compared to potentiometric titration, Raman spectroscopy is a rapid, accurate, and reliable secondary method for estimating the amine value (AV) of epoxy hardeners.

Raman spectroscopy is a fast alternative method to detect phosphate and sulfate species in solution for optimized phosphorus fertilizer production and improved product quality.

Low frequency Raman spectroscopy extends conventional Raman analysis by capturing vibrational modes down to 65 cm-1, enabling deeper insights into molecular structure, protein characterization, polymorph identification, and phase changes.

Determination of hypophosphite, formate, phosphate, adipate, p-nitrobenzoate, and sebacate in ethylene glycol using anion chromatography with conductivity detection after chemical suppression.

Determination of phosphate and tetrafluoroborate in 2% HF using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, sulfite, and sulfate in a surfactant solution using anion chromatography with conductivity detection after chemical suppression.

Determination of phosphate and sulfate in a cleaning solution 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 traces of chloride in a technical product using anion chromatography with conductivity detection after chemical suppression.

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

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

Determination of chloride, sulfate, maleate, oxalate, and fumarate in ink using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of phosphate and phosphite in poly(phosphonic acid) using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of glycolate, acetate, and chloride in monochloroacetic acid (MCA) using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, chloride, nitrate, phosphate, and sulfate in boric acid with sample preconcentration 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 chloride, chlorate, and sulfate in soda lye (NaOH 50%) after inline neutralization using anion chromatography with conductivity detection after chemical suppression.

Determination of acetate, chloride, nitrate, and sulfate in aluminum oxide using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, phosphate, phosphite, and sulfate in a dye solution using anion chromatography with conductivity detection after chemical suppression.

Determination of acetate and dichloroacetate in chloroacetic acid using anion chromatography with conductivity detection after chemical suppression.

Determination of bromide and sulfate in brine (300 g/L NaCl) using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, chloride, nitrite, bromide, nitrate, phosphate, sulfite, sulfate, and thiosulfate in colored liquors using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride and sulfate in potassium tetraborate (KB4O7 * 4 H2O) using anion chromatography with conductivity detection after chemical suppression.

Determination of sulfate in methansulfonic acid (70%) using anion chromatography with conductivity detection after chemical suppression.

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

Determination of NTA, HEDP, and ATMP using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, bromide, nitrate, phosphate, and sulfate in 20% NaOH after inline neutralization by cation exchange on the 793 IC Sample Prep Module using anion chromatography with conductivity detection after chemical suppression.

Determination of chlorate, nitrate, and perchlorate in firecracker powder using anion chromatography with conductivity detection after chemical suppression.

Determination of adipic acid and phthalic acid in an alkaline ester digestion solution using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride in adipic acid using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride and sulfate in hypophosphoric acid using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, nitrite, nitrate, phosphate, sulfate, trimeta-, and pyrophosphate in tripolyphosphate using anion chromatography with a high pressure gradient and conductivity detection after chemical suppression.

Determination of o-phosphate, pyrophosphate, and trimetaphosphate in sodium tripolyphosphate using anion chromatography with conductivity detection and chemical suppression.

Determination of bromoacetate, methanesulfonate, chloride, phosphate, and sulfate in an acidic cleaning solution using anion chromatography with conductivity detection and chemical suppression.

Determination of chloride in concentrated nitric acid using anion chromatography with conductivity detection and chemical suppression.

Determination of hexafluorophosphate in an ionic liquid BMIHFP (1-butyl-3-methylimidazolium hexafluorophosphate, >97%) using anion chromatography with conductivity detection after chemical suppression.

Determination of sulfate, phosphate, citrate, pyrophosphate, trimetaphosphate, and tripolyphosphate in a washing powder using anion chromatography with conductivity detection after chemical suppression.

Determination of traces of chloride in a quaternary ammonium hydroxide using anion chromatography with conductivity detection after chemical suppression and inline cation exchange to remove the matrix cations.

Determination of fluoride, chloride, and sulfate in an absorption solution containing H2O2 using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride and bromide in an absorption solution after Wickbold digestion using anion chromatographywith conductivity detection after chemical suppression.

Determination of nitrate and sulfate in a fertilizer after acid digestion using anion chromatography with conductivity detection after chemical suppression.

Determination of traces of perchlorate in a sample with a high salt load using anion chromatography with conductivity detection after chemical suppression.

Determination of nitrate and phosphate in a liquid fertilizer using anion chromatography with conductivity detection after chemical suppression.

Determination of traces of fluoride and sulfate in 35% hydrochloric acid (HCl) using anion chromatography with conductivity detection after chemical suppression and sample preparation by inline neutralization.

Determination of chlorate and sulfate in a brine solution (1.5% NaCl) using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, sulfite, sulfate, and thiosulfate in metam potassium (potassium N-methyldithiocarbamate) using anion chromatography with conductivity detection after chemical suppression.

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

Determination of oxalate, thiosulfate, and thiocyanate in an amine solution using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride, chlorate, and sulfate in soda lye (50% sodium hydroxide) using anion chromatography with conductivity detection after sequential suppression and Metrohm Inline Neutralization.

Determination of sulfate in methanedisulfonic acid using anion chromatography with conductivity detection after sequential 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.

Determination of formate, chloride, nitrate, phosphate, and sulfate in 20% TMAOH using anion chromatography with conductivity detection after sequential suppression and inline matrix neutralization.

Determination of chloride, nitrate, and sulfate in 85% H3PO4 using two-dimensional anion chromatography with conductivity detection after sequential suppression.

Determination of molybdate in 2.5% NaCl using anion chromatography with conductivity detection after chemical suppression and inline matrix elimination by molybdate preconcentration after the first separation and subsequent reinjection.

Determination of chloride, nitrate, and sulfate in cobalt acetate solution using anion chromatography with conductivity detection after sequential suppression using Metrohm Inline Dilution.

Determination of fosetyl-aluminum in a formulation using anion chromatography with conductivity detection after sequential suppression.

Determination of fluoride, chloride, and nitrate in concentrated sulfuric acid (96…98%) using anion chromatography with conductivity detection after sequential suppression.

Determination of fluoride, chloride, phosphate, and sulfate in sodium tetraborate using anion chromatography with conductivity detection after sequential suppression. Inline acidification is applied to convert tetraborate into boric acid which is not retained on the preconcentration column. Inline calibration minimizes the anion contamination.

Determination of phosphate, HEDP (etidronic acid), and pyrophosphate in a biocide sample using anion chromatography with conductivity detection after sequential suppression.

The high-capacity suppressor MSM-HC allows to run analyses with high eluent concentrations, e.g., sodium hydroxide eluents. The determination of anions in washing powder is a typical example where the high pH of NaOH is required for the separation of polyphosphates.

Ionic liquids, also denominated as «designer solvents», are organic salts that are liquid at low temperatures. They are powerful solvents, conduct the electric current, and are therefore used in many applications. Anions, in particular halogenides, are common byproducts in the manufacturing of ionic liquids. Therefore, their concentration has to be controlled.

Metrohm Inline Neutralization is a well-established sample preparation technique for anion determinations in hydroxide solutions. The intelligent Partial Loop Injection Technique (MiPT) allows to calibrate the system with one single standard solution and to adjust the injection volume according to the anion concentrations in the sample. This method has been successfully applied to anion analysis in potassium hydroxide (50 and 85%) and in potassium carbonate solutions (83%).

Hydrogen peroxide is used as a cleaning, oxidizing and bleaching agent. Depending on its purity, it may contain inorganic anions as well as organic acid anions, such as oxalate, phthalate, and dipicolinic acid. Dipicolinic acid is a complexing agent that binds transition metal cations and is sometimes added to increase the stability of hydrogen peroxide.

The separation of short-chain organic acids from fluoride and chloride requires diluted eluents. These weak eluents, however, induce long retention times for divalent anions. Adding a stronger eluent later in the separation sequence by use of a Dose-in Gradient makes these anions elute more rapidly. Furthermore, the Dose-in Gradient offers the advantage of low equipment and technical expense.

Electronic-grade nitric acid may not contain more than the slightest traces of anion contaminations (in the mg/L range). The ion chromatography determination of these kinds of anion traces requires not only a high-capacity column but also an eluent that allows the nitrate to be eluted by the column, although only after all of the other ions of interest have been eluted. This separation is achieved on a column of the Metrosep A Supp 16 - 250/4.0 type with the aid of a strong carbonate/hydrogen carbonate eluent.

Glycolate and lactate have to be determined in a dual phase varnish remover. Analyzed is only the upper aqueous phase. The separation is achieved on a Metrosep A Supp 16 - 250/4.0 column. The eluent composition is adapted to get a sufficient separation of glycolate and lactate without interference by formate and acetate. Conductivity detection after sequential suppression is applied.

Pyrophosphate is used as a stabilizer in aqueous hydrogen peroxide solution. “Reagent grade” solutions may contain pyrophosphate in the higher mg/L range, while “electronic grade” hydrogen peroxide should be free of this stabilizer. Here the determination of pyrophosphate in a high purity H2O2 solution (30%) is performed applying Inline Preconcentration with Matrix Elimination (MiPCT-ME) and a Dose-in Gradient.

Ultrapure chemicals are required in the semiconductor industry. Ionic impurities may lead to compromised products. This application describes the determination of anionic impurities in semiconductor grade 28% ammonium hydroxide solution. To avoid matrix disturbances, Inline Neutralization and Inline Preconcentration with Matrix Elimination needs to be applied.

Within the scope of the modernization of USP, chloride and sulfate are determined as impurities in potassium hydrogen carbonate (bicarbonate). USP41 monograph for potassium bicarbonate does not check for chloride and sulfate. Applying ion chromatography with conductivity detection after sequential suppression allows quantifying these impurities.

Sulfamic acid is a reasonably strong acid, used in descaling agents and for cleaning of dairy and brewing equipment. Here, a chemical solution is analyzed for sulfamate, chloride, nitrite, nitrate, and sulfate. As the solution can also contain hydramine, sufficient separation from the ions of interest is required.

The semiconductor industry requires high-purity or even ultrahigh-purity chemicals for the production of electronic components. The purity of the chemicals is crucial for the quality and efficient production of the parts. Here, hydrogen peroxide and ammonium hydroxide are analyzed applying traditional sample preparation methods like digestion and evaporation with subsequent reconstitution with ultrapure water. The received samples are injected applying intelligent Preconcentration Technique (MiPCT).

Analysis of sodium hydrogen carbonate (also known as sodium bicarbonate) for anionic contaminants is critical due the large amount of CO2 formed during suppression. Even applying sequential suppression does not completely remove the interferences due to the carbonate peak. The introduction of Inline Neutralization applying the Sample Preparation Module (SPM) with subsequent CO2 removal with the MCS (Metrohm CO2 Suppressor) prior to the injection solves the problem. After this pretreatment, the sequentially suppressed sample is analyzed without issues.

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

Determination of sulfate in brine by indirect potentiometric titration with EGTA using platinum and tungsten electrodes.

Determination of the cationic surfactant «cetrimide» in an antiseptic disinfectant by potentiometric titration with sodium dodecyl sulfate using the «Ionic Surfactant» electrode.

This application note shows a reliable way to determine the content of non-ionic surfactants in liquid cleaning solutions by potentiometric titration.

Determination of nonionic surfactants in compact washing powders by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

Peroxides are often used for disinfection and water treatment purposes due to their antiseptic properties. Lower concentrations between 0.3–3% are used in households, while higher concentrations can be used for sterilization purposes. Additionally, peroxides are utilized as oxidizing and bleaching agents. Peroxides, perborates, and percarbonates can easily be determined by titration. This application note presents two titration methods for peroxide analysis: ASTM D2180 for concentrated hydrogen peroxide solutions, and a second method for trace determination of hydrogen peroxide, suitable for concentrations as low as 0.4 mg/L.

Determination of perborate, percarbonate, or persulfate in washing powder by iodometric potentiometric titration using the Pt-Titrode.

Determination of Na2O and SiO2 in water glass by potentiometric titration with HCl using the Sb electrode.

Determination of the nitrogen content of nitrocellulose by potentiometric titration with Fe(II) using a combined Pt electrode.

Determination of free alkali in sodium hypochlorite by potentiometric titration with hydrochloric acid using a combined glass electrode.

Citric acid and oxalic acid are present in many products, such as foods or chemical solvents (e.g., decontamination solutions). Both acids are reducing agents and citric acid is additionally a powerful antioxidant. Due to their mutual impact (buffer effect), a content calculation is only possible with correction factors for each acid. A fast and accurate determination by potentiometric titration using the dEcotrode plus and sodium hydroxide as titrant can be realized in this Application Note.

Determination of the soap content of soap noodles by potentiometric titration with TEGO®trant A100 using the «Ionic Surfactant» electrode.

Determination of soaps and anionic surfactants in washing powder by potentiometric two-phase titration with TEGO®trant A100 using the «Surfactrode Resistant» electrode.

Determination of cationic surfactants in a household cleaner by potentiometric two-phase titration with sodium dodecylsulfate using the «Surfactrode Resistant» electrode.

This application note describes the determination of nonylphenol ethoxylate by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

Due to its price and wide availability, the anionic surfactant sodium lauryl sulfate (SLS; SDS) can be found in many detergents as an emulsifier or as a fat solvent e.g., in cleaning or cosmetic products. To avoid causing severe dry skin and hair, and thus skin irritation, regulations in many countries have restricted the sodium lauryl sulfate concentration in ready-to-use products to a range between 0.05–2.5% SLS. To control the concentration of SLS in different products, a titration is carried out with TEGO® trant A100 and the Optrode. The evaluation is done automatically by means of a software, leading to reliable and reproducible results.

Determination of lauryl ether sulfate (LAES) by potentiometric/turbidimetric titration with TEGO®trant A100 using the 610 nm Spectrode.

Determination of traces of calcium in brine by photometric titration with 1,2-diaminocyclohexanetetraacetic acid using the 610 nm Spectrode.

Determination of nitrite in aqueous solutions by potentiometric back-titration of the added permanganate excess with ammonium iron(II) sulfate using the Pt-Titrode.

Tallow amine ethoxylates are toxic to aquatic life, and therefore their use is restricted. This Application Note explains an approach to determine these non-ionic surfactants potentiometrically.

This application note shows how coconut oil ethoxylates can be determined via potentiometric titration.

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.

Titrants are normally bought ready to use. However, it is necessary to determine the accurate concentration of your titrant solution on a regular basis using a primary standard. To correct the mentioned variation, a so-called «titer factor» is applied. The titer can be easily and quickly assessed by using the Metrohm brand of autotitrators. Predefined calculation formulas implemented in Metrohm titrators or software, respectively, as well as the automatic storage of the titer factor, makes standardization a simple task.

This Application Note presents a modified time-saving method to determine iodine value (IV) in edible oils based on several standards (EN ISO 3961, ASTM D5554, etc.).

Inorganic sulfate is determined in secondary alklysulfonate (raw material) in accordance with DIN EN 14880 with the use of the Pb ISE.

Acrylic acid dimerizes spontaneously. Determining the dimer content is, therefore, a key part of the quality control for acrylic acid. One quality control parameter for the dimerization is the acid number. This Application Note describes its determination by automated, potentiometric titration.

Citrate is used in detergents as a water softener for the prevention of lime deposits. The citrate or citric acid content is therefore an important parameter for the quality control of detergents that can be determined conveniently and precisely using titration with copper sulfate.

Nitrilotriacetate (NTA) is a complexing agent that is used in detergents as a water softener. NTA forms complexes with metal ions such as Ca2+, Cu2+ and Fe3+ and thus prevents the formation of lime and its deposits. The NTA content is therefore an important parameter for the quality of detergents and is determined using back titration of an excess of copper nitrate.

The iodine adsorption number (IAN) of carbon black is related to the surface area and can therefore be used for the characterization of carbon black. The presence of volatiles, surface porosity, or extractables will influence the iodine adsorption number. In this Application Note, the fully automated determination of the iodine adsorption number including sample preparation is described.

The hydroxyl number is an important sum parameter for quantifying the presence of hydroxyl groups in a chemical substance. As a key quality parameter, it is regularly determined in various polymers like resins, paints, polyesterols, fats, and solvents. Unlike other standards, EN 4629-2 works pyridine-free and without refluxing at elevated temperatures for a longer time. The determination is based on the catalytic acetylation of the hydroxyl group. It is performed at room temperature, requires only a small sample volumen, and can be fully automated.This Application Note describes the potentiometric determination of the hydroxyl number in 1-octanol and polyethylene glycol according to EN 4629-2. Using the OMNIS DIS-Cover technique, all sample preparation steps can be fully automated. Furthermore, the use of an OMNIS Sample Robot allows parallel analysis of multiple samples. The average time per analysis for one sample is thus reduced from approximately 49 min to 25 min., considerably increasing productivity in the laboratory.

The hydroxyl number is an important sum parameter for quantifying the presence of hydroxyl groups in a chemical substance. As a key quality parameter, it is regularly determined in various polymers like resins, paints, polyesterols, fats and solvents. Unlinke other standards, ASTM E1899 works pyridine-free and without refluxing at elevated temperatures for a longer time. It is performed at room temperature, requires only a small sample size, is applicable to extremely low hydroxyl numbers (<1 mg KOH/g sample) and can be performed fully automatically. This Application Note describes the potentiometric determination of the hydroxyl number in 1-octanol and polyethylene glycol according to ASTM E1899, EN 15168 and DIN 53240-3. Using the OMNIS DIS-Cover technique all sample preparation steps can be fully automated. Moreover, the use of an OMNIS Sample Robot allows parallel analysis of multiple samples. The average time per analysis for one sample is thus reduced from approximately 24 min to 12 min., increasing productivity in the laboratory considerably.

Fully automated determination of the total acid number and total base number in engine oils according to ASTM D664 and ASTM D2896 is possible with the OMNIS Titrator.

Quaternary ammonium salts are the active ingredients in fabric softener and require accurate determination to assess the cost and the performance of the fabric softener. This Application Note describes the determination of diamidoamine-based quaternary ammonium salts by potentiometric titration.

Quaternary ammonium salts are the active ingredients in fabric softener and require accurate determination to assess the cost and the performance of the fabric softener. This Application Note describes the determination of dialkyl dimethyl quaternary ammonium salts by back titration.

Compounds with carbonyl groups can be prone to oxidation for which reason their stability often decreases during storage or processing. The method presented here is suitable for the determination of aldehydes and ketones sparingly soluble in water.Samples are dissolved in deionized water. After a reaction with the hydroxylamine hydrochloride at 50 °C, carbonyl groups are quickly and accurately determined by potentiometric titration using the dUnitrode and sodium hydroxide as titrant.

Carbonyl compounds occur in many products such as bio-oils and fuels, solvents, flavors, and mineral oils. Carbonyl compounds are often prone to oxidation and thus their content has an influence on stability during storage or processing. Especially for pyrolysis bio-oils, stability issues are observed during storage, handling, and upgrading.Oils are dissolved in isopropanol. After a reaction with the hydroxylamine hydrochloride at 50 °C, a fast and accurate determination by potentiometric titration using the dSolvotrode and tetra-n-butylammonium hydroxide as titrant is performed.

Kjeldahl method is used to determine the nitrogen content in organic and inorganic samples. Kjeldahl consists of three steps: digestion, distillation, and titration. During the catalytic digestion step, organic nitrogen is converted into ammonium. Sodium hydroxide is added just before the distillation step for converting ammonium into ammonia. Through steam distillation the latter is transferred into the receiver vessel containing an absorbing agent (e.g., boric acid). Finally, the separated ammonia is titrated against sulfuric acid. Protein content in samples can also be determined from the nitrogen content obtained by Kjeldahl setup. USP describes the titration method to determine nitrogen content in organic products using Kjeldahl nitrogen setup. This Application Note illustrates nitrogen determination in heparin sodium.

Anionic surfactants represent, by volume, the most important group of surfactants used in cleaning products. The potentiometric two-phase titration is a universal method for the accurate and fast determination of them. Using the Surfactrode Refill, the anionic surfactants are determined by potentiometric titration with hyamine as titrant.

The presence of acidic components in volatile solvents could be a result of contamination, decomposition during storage, distribution or manufacture. An increased acid content in solvents could lead to a variety of problems like shorter storage stability or chemical corrosion. Using the Optrode for indication, the acidity is determined by photometric titration with sodium hydroxide as titrant and phenolphthalein as indicator. If the volatile solvent is water soluble, it is dissolved in deionized water, if not, it is dissolved in carbon-dioxide free ethanol.

The bromine index is an important parameter for the determination of aliphatic C=C double bonds in petroleum hydrocarbons. For the titration, a solvent mixture of glacial acetic acid, methanol, and dichloromethane is usually used.In this Application Note, the chlorinated solvent in the solvent mixture was replaced with toluene, resulting in a more environmentally beneficial method in comparison to ASTM D2710 and IP 299.

The bromine index is an important quality control parameter for the determination of aliphatic C=C double bonds in aromatic hydrocarbons and is thus a measure for the presence of aliphatic unsaturation in these materials. In situ generated bromine reacts with the aliphatic double bonds. When the titration is finished an excess of free bromine causes a sudden change in the measured potential thus indicating the equivalence point.

The FOS/TAC value, sometimes referred to as VFA/TA, is a meaningful parameter for assessing both the current condition and the development of anaerobic digestion processes in a digester of a biogas plant. Knowledge of this value can help decrease the risk of acidification problems, which can result in a costly crash of the entire digestion process. Therefore, an accurate and reliable determination of the FOS/TAC value is important for both efficient and cost-effective production operations. This value is determined by an acid-base titration. Using the Eco Titrator from Metrohm equipped with an Ecotrode plus electrode, a reproducible and accurate determination of the FOS/TAC value is possible.

Lithium salts (e.g., lithium carbonate and lithium hydroxide) are used in myriad applications. Lithium hydroxide is used for the production of lithium stearate, an important engine lubricant. In addition, it is utilized as an air purifier due to its ability to bind carbon dioxide. While the majority of lithium carbonate is used for aluminum production, it is also used for the glass and ceramic industry. It lowers the melting point of these materials, lowering the associated electricity costs and making it cheaper to produce them.For all of these applications, it is important to know the quality of the pure lithium salts used in the various production processes. This Application Note presents an easy method for the assay of lithium hydroxide and lithium carbonate on an automated OMNIS system.

Lithium nitrate is an oxidizing agent used in the manufacture of red-colored fireworks and flares. In addition, the lithium nitrate trihydrate compound absorbs heat well and can be used for thermal energy storage. Since lithium nitrate is a hygroscopic substance, its purity must first be verified before it is used for synthesis or other applications. The purity assay is done by a fully automated precipitation titration between lithium and fluoride in an ethanolic solution. The benefit of titration is that the lithium nitrate does not need to be diluted after dissolving in ethanol as with other techniques such as ICP-MS.

Sodium hypochlorite and sodium chloride can be effectively use as disinfectant for water and surfaces. The World Health Organization (WHO) recommends, depending on the application, concentrations in disinfectants of 1000 mg/L to 5000 mg/L NaOCl and up to 200 g/L NaCl.This Application Note demonstrates a reliable method to determine the hypochlorite and sodium chloride content in disinfectants by two subsequent argentometric titrations in the range recommended by the WHO.

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

Electroplating processes are used in several different industry sectors to protect the surface quality of various products against corrosion or abrasion and significantly improve their working life. It is essential to check the bath composition on a regular basis to ensure that the process is operating correctly. Typical examples of electroplating baths include alkaline degreasing baths or acidic or alkaline baths containing metals e.g. copper, nickel, or chromium, or components like chloride and cyanide. It is crucial that the chosen analysis technique fulfills high safety standards for these kinds of analyses and produces reliable results. The OMNIS Sample Robot system automatically pipettes and analyzes aggressive electroplating bath samples on different workstations, increasing the safety in the lab. This provides more reliable results in comparison to manual titration and is more time efficient as different parameters can be analyzed in parallel.

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.

Boehm titration is a quantitative analysis of functional groups on the surface of carbon materials based on their reactions with basic solutions of NaHCO3 (pKa = 6.4), Na2CO3 (pKa = 10.3), and NaOH (pKa = 15.7). This is a cost-efficient method that gives absolute values with high precision of the accessible, mainly oxygen-containing functional groups on the surface. Originally, Boehm titration was developed for carbon materials like conductive carbon black (CCB), activated carbon, porous carbon, and graphite. Modern carbon-based materials like graphene, graphene oxide (GO), or carbon nanotubes can also be analyzed this way.

This Application Note presents a complementary method that allows a consecutive determination after the sample preparation (digestion) of both metal ions in one beaker with an optical sensor and xylenol orange as an indicator.

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.

This Application Note compares the OMNIS Titrator and 888 Titrando for determinations of nitric acid, phosphoric acid, and acetic acid in an aluminum etching bath, as well as the determination of tetramethylammonium hydroxide (TMAH). Identical analysis parameters were used, showing that OMNIS delivers results on par or even better than with other established titration systems.

The pH value in carbon black, an essential additive in modern lithium-ion batteries, is accurately and reliably analyzed in this Application Note by using the 913 pH Meter equipped with a Unitrode easyClean according to ASTM D1512 as well as ISO 787-9 and GB/T 1717-1986.

Hydrochloric acid is a strong, inorganic mineral acid with great significance in the chemical industry. The potentiometric titration of hydrochloric acid with sodium hydroxide is one of the most important and also most frequent analyses performed in the laboratory. In this Application Note, an acid-base titration is presented where the concentration of HCl is determined with NaOH using a pH electrode with an integrated Pt1000 temperature senor for the most accurate results

Phosphoric acid is a triprotic inorganic acid used for many purposes: as a raw material for the production of phosphate fertilizers, detergents, as an electrolyte in phosphoric acid fuel cells, rust removers, and for the passivation of iron and zinc to protect against corrosion. This Application Note presents an acid-base titration where the concentration of phosphoric acid is determined over all three of its dissociable protons by titrating it with sodium hydroxide.

The amine value is an important parameter and quality indicator to determine in chemical processes and pharmaceuticals. This Application Note presents the nonaqueous perchloric acid titration of triethanolamine.

The OMNIS Titrator equipped with a Pt Titrode accurately and reliably determines titer concentration even in diluted titrants as shown in this Application Note.

Accurate, reliable determination of ionic surfactants with the Epton two-phase titration method can be achieved using an OMNIS system as shown in this study.

The standardization of the cationic surfactant TEGOtrant is performed using potentiometric titration as well as near-infrared spectroscopy (NIRS) in this application.

The acid value of fatty acid methyl esters (FAME) like biodiesel can be determined according to EN 14104 using photometric titration with OMNIS and the Optrode.

Purity of rare earth elements (REEs) can be determined by absolute complexometric titration with xylenol orange (ISO 23597). This approach achieves around 100% recovery, eliminates the need for calibration, and offers higher accuracy and reproducibility than techniques such as AAS (atomic absorption spectroscopy). Photometric titration with the Optrode M2 offers adjustable wavelength detection, providing a fast, precise, and cost-effective alternative to other conventional methods.

Rare earth elements (REEs) are critical materials whose deposit viability and processing streams require accurate mass-fraction determination during ore dissolution and purification. This Application Note describes a rapid potentiometric back-titration using a copper ion-selective electrode (Cu-ISE) that enables selective quantification and partial separation of REEs in complex matrices with near-quantitative recovery. As an absolute, flexible, and cost-effective method with ICP-compatible sample preparation, back-titration is well suited both as a reference technique and for rapid on-site analysis.

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

Determination of traces of fluoride, bromide, nitrate, phosphate, and sulfate using anion chromatography with conductivity detection after chemical suppression and subsequent UV/VIS detection.

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

Determination of bromide in calcium chloride using anion chromatography with UV/VIS detection.

Determination of aluminum in phosphoric acid using cation chromatography with UV detection after post-column reaction with catechol violet.

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.

Dye samples are analyzed for trace chromate. Chromate (Cr(VI)) is considered toxic and potentially carcinogenic for which reason its concentrations should be as low as possible. This sample is prepared with C18 cartridges and injected applying Metrohm intelligent Preconcentration Technique (MiPCT). After each injection, the preconcentration column requires additional rinsing to eliminate matrix effects. For this purpose, no other instrument than an 800 Dosino is required. The system is optimized for sample volumes between 20 and 2000 µL. For most samples additional rinsing of the preconcentration column is not required.

Complexing agents are used in fertilizers to bind trace nutrients such as cobalt, iron, manganese, etc. EN 13368-1 describes the determination of EDTA, HEDTA, and DTPA. As sample preparation, Fe3+ is added to build complexes with the three agents. The complexes are separated on an anion-exchange column and detected by UV/VIS after addition of perchloric acid.

Chromate (Cr(VI)) is regarded as being carcinogenic, mutagenic and damaging to DNA, which is why Cr(VI) concentrations are to be kept as low as possible. The EU Toy Safety Directive 2018/725 defines migration limit values for the release of chromate from toys. The "HCl migration solutions" are diluted with a buffer before 2,000 µL are injected via Metrohm intelligent Preconcentration Technique with Matrix Elimination (MiPCT-ME). Determination is performed with VIS detection following derivatization with diphenylcarbazide.

Hexavalent chromium (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.

Determination of Fe, Pb, Cd, and Cu in Co(Ac)2 solution using the MME.

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 Zn, Cd, Pb, Ni, and Co in hydrochloric acid (37.8%).

Determination of Zn, Cd, Pb, Ni, and Co in Javelle water.

Determination of cadmium and lead in herbicide powder containing 37% copper after digestion.

4-Carboxybenzaldehyde can be reduced directly on the DME in a solution containing ammonium.

Determination of W(VI) in the organic phase after digestion

Iodide contamination in glacial acetic acid poses risks for downstream processes. Cathodic stripping voltammetry (CSV) at the HMDE offers reliable iodide measurement.

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(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.

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.

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.