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Raman spectroscopy is used for material characterization by analyzing molecular or crystal symmetrical vibrations and rotations that are excited by a laser, and exhibit vibrations specific to the molecular bonds and crystal arrangements in the molecules. Raman technology is a valuable tool in distinguishing different polymorphs. Examples of portable Raman spectroscopy for identification of polymorphs and in monitoring the polymorphic transiton of citric acid and its hydrated form are presented.

This article demonstrates the utility of portable Raman spectroscopy as a versatile tool for process analytical technology (PAT) for raw material identification, in-situ monitoring of reactions in developing active pharmaceutical ingredients (APIs), and for real-time process monitoring. Raw material identification is done for verification of starting materials as required by PIC/S and cGMP, and can be readily done with handheld Raman. Portable Raman systems allow users to make measurements to bring process understanding and also provide proof of concept for the Raman measurements to be implemented in pilot plants or large-scale production sites. For known reactions which are repetitively performed or for continuous online process monitoring of reactions, Raman provides a convenient solution for process understanding and the basis for process control.

Although the process of building, validating and using a method is well-defined through software, the robustness of the method is dependent on proper practice of sampling, validation, and method maintenance. In this document, we will detail the recommended practices for using the multivariate method with NanoRam-1064. These practices are recommended for end users who are in the pharmaceutical environment, and can expand to other industries as well. This document aims to serve as a general reference for NanoRam-1064 users who would like to build an SOP for method development, validation and implementation.

This poster describes a method for automated and precise dosing of liquid samples into the Karl Fischer titration cell using Metrohm Dosino liquid handling technology. First, the titer was automatically determined with ultrapure water. The same dosing procedure proved valuable for the automated water determination in highly viscous water-glycol fluids and low-boiling organic solvents such as n-pentane. Lastly, the method copes with the labor-intensive and human error-prone suitability test stipulated in chapter 2.5.12 in the European Pharmacopoeia.

If chloride and bromide are present in approximately equal molar concentrations they can be titrated directly with silver nitrate solution after addition of barium acetate. If, however, the molar ratio n(Br-) : n(Cl-) changes from 1 : 1 to 1 : 5, 1 : 10, 5 : 1 or 10 : 1 then greater relative errors must be expected with this method. The Bulletin describes an additional titration method that allows bromide to be determined in the presence of a large excess of chloride. The determination of small chloride concentrations in the presence of a large excess of bromide is not possible by titration.

A potentiometric, nonaqueous method is described for analyzing nitrating acid using cyclohexylamine as titrant. Both sulfuric and nitric acid can be determined quantitatively.

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

Bromide is removed from the sample as BrCN by distillation. The BrCN is absorbed in sodium hydroxide solution and decomposed with concentrated sulfuric acid, then the released bromide ions are determined by potentiometric titration with silver nitrate solution. Iodide does not interfere with the determination.Iodide is oxidized to iodate by hypobromite. After destruction of the excess hypobromite, the potentiometric titration (of the iodine released from iodate) is carried out with sodium thiosulfate solution. Bromide does not interfere, even in great excess.The described methods allow the determination of bromide and iodide in the presence of a large excess of chloride (e.g., in brine, seawater, sodium chloride, etc.).

After acid digestion, the sample solution is neutralized with sodium hydroxide to form sodium dihydrogen phosphate. An excess of lanthanum nitrate is added and the released nitric acid is then titrated with sodium hydroxide solution.NaH2PO4 + La(NO3)3 → LaPO4 + 2 HNO3 + NaNO3This determination method is suitable for higher phosphate concentrations.

This Application Bulletin gives an overview of the coulometric water content determination according to Karl Fischer.Amongst others, it describes the handling of electrodes, samples, and water standards. The described procedures and parameters comply with the ASTM E1064.

This Bulletin describes three potentiometric, one photometric, one thermometric and one conductometric titration method for sulfate determination. The question of which indication method is the most suitable depends primarily on the sample matrix.Method 1: Precipitation as barium sulfate and back titration of the Ba2+ surplus with EGTA. Use of the ion-selective calcium electrode as indicator electrode.Method 2: As with Method 1, although with the electrode combination tungsten/platinum.Method 3: Precipitation titration in semi-aqueous solution with lead nitrate in accordance with the European Pharmacopoeia using the ion-selective lead electrode as indicator electrode.Method 4: Photometric titration with lead nitrate, dithizone indicator and the Optrode 610 nm, particularly suitable for low concentrations (up to 5 mg SO42- in the sample solution).Method 5: Thermometric precipitation titration with Ba2+ in aqueous solution, particularly suitable for fertilizers.Method 6: Conductometric titration with barium acetate in accordance with DIN 53127

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

Sulfate can be rapidly and easily titrated thermometrically using a standard solution of Ba2+ as titrant. In industry, the widespread procedure is applied to the determination of sulfate in wet-process phosphoric acid.

Phosphate can be rapidly and easily titrated thermometrically using a standard solution of Mg2+ as titrant. The phosphate-containing solution is basified and buffered with NH3/NH4Cl solution before titration. The formation of insoluble MgNH4PO4 is exothermic. The method is a titrimetric adaptation of a classical gravimetric procedure. This bulletin deals with the determination of phosphate in phosphoric acid and granular fertilizers such as MAP (monoammonium phosphate), DAP (diammonium phosphate) and TSP (triple superphosphate). Results are reported as percentage of P and P2O5.

The present Application Bulletin contains NIR applications and feasibility studies for NIRSystems devices in the chemical industry. Qualitative and quantitative analyses of a wide variety of samples are part of this bulletin. Each application describes the instrument that was originally used for the analysis, as well as the system recommended for the analysis and the results that were achieved thereby.

MATi 4 (Metrohm Automated Titration) is a configured system for automated water content determination in liquid samples using coulometric Karl Fischer titration. The maximum sample volume is 5 mL. Up to 160 samples are filled in glass vials and sealed with lids. This ensures that the water content in the samples remains constant. The samples are aspirated and transferred into the coulometric cell through a needle. The tiamo™ software controls the system.

This method is applicable to all samples containing glycerin in the absence of other triols or other compounds that react with periodate to produce acidic products. Glycerin may be determined in the presence of glycols. A periodate solution reacts slowly with diols and triols in acidic aqueous media at room temperature. A quantitative amount of formic acid is generated from the reaction with glycerin (a triol). The reaction with diols produces neutral aldehydes. The amount of formic acid generated by this reaction is determined by titration against sodium hydroxide.

Determination of calcium and magnesium in high-purity sodium chloride using cation chromatography with direct conductivity detection.

Determination of sodium, potassium, iron(II), magnesium, and calcium in an extract of monoethylene glycol using cation chromatography with direct conductivity detection.

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

Determination of calcium and magnesium in a dolomite sample using cation chromatography with direct conductivity detection.

Determination of trimethylamine in hydrogen peroxide (31 %) using cation chromatography with direct conductivity detection after inline matrix elimination, inline preconcentration, and inline calibration.

Determination of magnesium, manganese, and zinc in a zinc sulfate solution using cation chromatography with direct conductivity detection.

Determination of strontium and barium in monoethylene glycol using cation chromatography with direct conductivity detection.

Determination of sodium, potassium, iron(II), magnesium and calcium in antifreeze (monoethylene glycol) using cation chromatography with direct conductivity detection. Ascorbic acid reduces iron(III) to iron(II). In this way total iron is determined as iron(II).

Determination of lithium, sodium, ammonium, potassium, calcium, magnesium, and strontium in brine using cation chromatography with direct conductivity detection.

Determination of magnesium, cadmium, and iron in phosphoric acid using cation chromatography with direct conductivity detection.

As a rule, brine samples are diluted extremely in order to avoid overloading the column. Manual dilution is very error-prone, which is why this application relies on injection with a 0.25 µL internal loop, thus saving an additional dilution step. Sodium, potassium, magnesium and calcium in brine are determined on a Metrosep C 6 - 150/4.0 column with subsequent direct conductivity detection.

Microbore ion chromatography offers better sensitivity, shorter retention times, and consumes less eluent, increasing sample throughput and reducing running costs.

Cyclohexane is an important organic solvent. Recycled cyclohexane must be tested for trace substances, e.g., chloride and sulfate. Metrohm Combustion Ion Chromatography with flame sensor and Inline Matrix Elimination is the method of choice.Keyword: pyrohydrolysis

Determination of the sulfate content of wet process phosphoric acid.

Determination of the sulfate content of brines.

Determination of acetic anhydride in the presence of acetic acid in acylation mixtures.

Determination of sulfate and total acids in a nitrating mixture.

Determination of sodium, potassium, and silica values in sodium and potassium silicates.

Determination of bicarbonate and carbonate in a mixture by sequential thermometric titrations.

Determination of phosphoric and nitric acids in liquors from the Nitrophos fertilizer manufacturing process.

Dissolution of urea in glacial acetic acid, and titration with standard 0.1 mol/L trifluoromethanesulfonic acid in acetic acid using isobutyl vinyl ether as a thermometric endpoint indicator.

A sample of concentrated mineral acid is dissolved in anhydrous acetonitrile, and the water content titrated with a solution of TEOF in acetonitrile. The TEOF reacts exothermically with water in the presence of a strong acid (acting as a catalyst).

Hypochlorite ions react with bromide ions to form hypobromite ions, which in turn rapidly oxidize ammonium ions to nitrogen. Hypobromite reacts more rapidly with ammonium than hypochlorite, and is formed in situ (Vogel, 1961). The titration is carried out with in a solution containing bromide and bicarbonate.

This Application Note supplements AN-H-003 with the treatment of the standard addition of sulfate as sulfuric acid. This technique may be contemplated when either sulfate levels are too low for a satisfactory direct titration, or when the sample matrix hinders endpoint detection, leading to poor precision and accuracy.

Weak, organic bases that are soluble in nonaqueous solvents (including nonpolar solvents) are determined in glacial acetic acid using titration with strong acids, e. g., anhydrous perchloric acid or trifluoromethanesulfonic acid. The endpoint of such titrations can be determined thermometrically, insofar as a suitable thermometric endpoint indicator exists. The exceptional suitability of isobutyl vinyl ether (IBVE) as indicator has been demonstrated.

Hydrogen peroxide solutions can be determined through thermometric endpoint titration (TET) using iodometry. Iodide is oxidized to become iodine, which is then titrated with a standard thiosulfate solution in an exothermic reaction.

This Application Note covers the formation of calcium carbonate from solution.

The water content of potassium chlorate is determined according to Karl Fischer using the oven method (300 °C).

In this application note, Karl Fischer titration is used to determine the water content of urea.

The water content of ethylene dichloride is determined according to Karl Fischer. As the sample may contain free chlorine, which interferes with the determination, separate KF reagents have to be used.

The water content of lime is determined according to Karl Fischer using the oven method (150 °C).

Determination of the water content of liquid ammonia according to Karl Fischer after absorption of the water in ethylene glycol.

The water content of aniline is determined according to Karl Fischer in buffered solvent.

The water content in methylcyclohexane is determined by coulometric Karl Fischer titration.

The water content in Ca carbonate is determined by volumetric Karl Fischer titration.

Determination of NO3- and ClO4- in the presence of a large excess of HCl using anion chromatography with direct conductivity detection (using time program for full scale change after 18 min).

Determination of acetate, formate, chloride, bromide, and sulfate in toluene using anion chromatography with direct conductivity detection.

Determination of traces of iodide in HCl (25%) using anion chromatography with amperometric detection at a silver electrode.

Determination of traces of carbonate in urea using anion chromatography with direct conductivity detection.

Determination of traces of bromide and iodide using anion chromatography with amperometric detection at the silver electrode.

Determination of traces of bromide in HCl (32%) using anion chromatography with amperometric detection at the silver electrode.

Determination of traces of iodide in acetic acid using anion chromatography with amperometric detection at the carbon paste electrode.

This Application Note describes a fast, nondestructive, and reliable method for the determination of the chemical composition of alcohol mixtures exemplified by ethanol/isopropanol mixtures. With visible near infrared spectroscopy (VIS-NIRS), results are available in real-time, thus making NIRS highly suited for fast quality control.

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.

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

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.

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.

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.

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.

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.

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

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, 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 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 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 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 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 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 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 in concentrated nitric acid using anion chromatography with conductivity detection and 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 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, 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 chloride, nitrate, and sulfate in 85% H3PO4 using two-dimensional 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.

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.

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.

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

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

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

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.

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.

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. 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.

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.

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.

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 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.

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.

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

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

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

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.

The concentration of Fe(total) is determined in monoethylene glycol by adsorptive stripping voltammetry with 2,3-dihydroxy-naphthalene as complexing agent. The detection limit of the method is approx. 0.1 µg/L with respect to the content in the measuring vessel. If no bromate is added to the supporting electrolyte the sensitivity of the method is about 10 times lower. All reagents have to be added in the order as listed below. Fe(II) and Fe(III) give signals with the same sensitivity. All reagents typically contain iron impurities, especially the 2,3-dihydroxy-naphthalene. Therefore a subtraction of the reagent blank is recommended.

It is crucial to monitor iodide in NaCl brine to prevent membrane fouling during chlor-alkali electrolysis. Stripping voltammetry offers precise iodide analysis.

This polarographic method uses the Multi-Mode Electrode Pro for simultaneous detection of carbonyl impurities in alcohols, ensuring high product quality and stability.

Quality control is impacted by multiple challenges, which can have an influence on the functioning of the QC lab. The present White Paper provides approaches, how to simplify the daily quality control using near-infrared spectroscopy combined with a dedicated smart software like Vision Air.

Analyzer systems monitoring product quality can offer substantial advantages when organized in a client-server network compared to the more traditional local installation. This white paper presents different client-server setups and their benefits. Security aspects that need to be considered are discussed based on the example of the client-server Vis-NIR (visible near-infrared) spectroscopy software Vision Air, widely used for quality control in the chemical, polymer, pharmaceutical, and petrochemical industry.

This White Paper explores the critical role of advanced online and inline process analysis in brine chlorine operations, emphasizing their advantages over traditional methods.

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.

Underestimation of quality control (QC) processes is one of the major factors leading to internal and external product failure, which have been reported to cause a loss of turnover between 10–30%. As a result, many different norms are put in place to support manufacturers with their QC process. However, time to result and the associated costs for chemicals can be quite excessive, leading many companies to implement near-infrared spectroscopy (NIRS) in their QC process. This paper illustrates the potential of NIRS and displays cost saving potentials up to 90%.

With Hydranal™ NEXTGEN FA reagents, the water content in ketones can be determined quickly and reliably. Compared to other existing KF reagents for ketones on the market, the side reactions are measurably better suppressed.

OMNIS Client/Server boosts business performance with scalable server management, cutting costs by reducing hardware, energy use, and maintenance across locations.