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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.

Quantitation of the functionalization of a water-soluble polymer was achieved using a portable Raman spectrometer. The Raman spectrum provides strong, unique bands for both the initial and fully reacted polymer. This enables development of a simple, robust quantitative analysis of the percent polymer functionalization. This method is now routinely used in a manufacturing plant's quality control laboratory.

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.

Raman spectroscopy’s use for process analytics in the pharmaceutical and chemical industries continues to grow due to its nondestructive measurements, fast analysis times, and ability to do both qualitative and quantitative analysis. Spectral preprocessing algorithms are routinely applied to quantitative spectroscopic data in order to enhance spectral features while minimizing variability unrelated to the analyte in question. In this technical note we discuss the main preprocessing options pertinent to Raman spectroscopy with real applications examples, and to review the algorithms available in B&W Tek and Metrohm software so that the reader becomes comfortable applying them to build Raman quantitative models.

Hydroxyl is an important functional group and knowledge of its content is required in many intermediate and end-use products such as polyols, resins, lacquer raw materials and fats (petroleum industry). The test method to be described determines primary and secondary hydroxyl groups. The hydroxyl number is defined as the mg of KOH equivalent to the hydroxyl content of 1 g of sample.The most frequently described method for determining the hydroxyl number is the conversion with acetic anhydride in pyridine with subsequent titration of the acetic acid released: H3C-CO-O-CO-CH3 + R-OH -> R-O-CO-CH3 + CH3COOH. However, this method suffers from the following drawbacks: - The sample must be boiled under reflux for 1 h (long reaction time and laborious, expensive sample handling) - The method cannot be automated - Small hydroxyl numbers cannot be determined exactly - Pyridine has to be used, which is both toxic and foul-smellingBoth standards, ASTM E1899-08 and DIN 53240-2, offer alternative methods that do not require manual sample preparation and therefore can be fully automated: The method suggested in ASTM E1899-08 is based on the reaction of the hydroxyl groups attached to primary and secondary carbon atoms with excess toluene-4-sulfonyl-isocyanate (TSI) to form an acidic carbamate. The latter can then be titrated in a non-aqueous medium with the strong base tetrabutyl- ammonium hydroxide (TBAOH). The method suggested in DIN 53240-2 is based on the catalyzed acetylation of the hydroxyl group. After hydrolysis of the intermediate, the remaining acetic acid is titrated in a non-aqueous medium with alcoholic KOH solution. The present work demonstrates and discusses an easy way to determine the hydroxyl number according to ASTM E1899-08 or DIN 53240-2 with a fully automated titrimetric system for a great variety of industrial oil samples.

The presence of excessive water in plastics adversely affects the performance of polymeric goods which is why water determination is of crucial importance. This article describes the accurate and straightforward determination of the water content using the Karl Fischer Oven Method in ten different plastic types that are not amenable to direct Karl Fischer titration. The experiments revealed that besides the determination of the oven temperature, sample preparation is one of the most important steps of the analysis, especially in case of hygroscopic plastic samples.

The Combustion IC system presented allows the automated determination of organic halogen and sulfur compounds in all flammable samples. Both combustion digestion, which is automatically controlled with a flame sensor, and the professional Liquid Handling guarantee highest precision and trueness. This poster describes the determination of the halogen and sulfur content in a certified polymer standard, a coal reference material as well as in latex and vinyl gloves.

Carbonyl compounds (CC) occur in many products, such as bio-oils and fuels, cyclic and acyclic solvents, flavors and mineral oils. Carbonyl compounds can be responsible for the instability of these products during storage or processing. Especially pyrolysis bio-oils are known to cause issues during storage, handling and upgrading. This bulletin describes an aqueous and a non-aqueous analytical titration method for the determination of carbonyl compounds by potentiometric titration.

Indication of the titration endpoint of the weakly alkaline or weakly acidic terminal groups in non-aqueous solution is frequently not easy. An improvement is possible by using a suitable titrant (TBAH = tetrabutylammonium hydroxide for terminal carboxyl groups; perchloric acid for terminal amino groups).An improvement in the evaluation can also be achieved by choosing benzyl alcohol as the solvent.The choice of electrode combination and the measuring setup is also important. Differential potentiometry using the three-electrode technique results in a great improvement in titrations in poorly conducting solutions. Noisy signals are eliminated.

This Application Bulletin gives an overview of the volumetric 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 E203.

This Application Bulletin describes a simple polarographic method to determine monomeric styrene in polymers. The limit of determination lies at 5 mg/L. Before the determination, styrene is converted to the electrochemically active pseudonitrosite using sodium nitrite.

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.

Maleic and fumaric acid can be reduced electrochemically to succinic acid. In acidic solutions a differentiation of the two acids is not possible since both are reduced at the same potential. On the other hand, separation at pH 7.8...8.0 is easily possible since fumaric acid is now more difficult to reduce at the lower proton concentration (as a result of cis-trans isomerism) than maleic acid.

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.

Polyurethanes are one of the most commonly used types of plastic. They are produced by the reaction of raw polyols with isocyanates. Depending on the starting material a wide variety of plastics can be obtained. The determination of the acid value, hydroxyl value, and isocyanate content plays an important part in the analysis of raw materials for plastics.The acid number of polyol raw material is usually used in quality control to ensure batch-to-batch uniformity. Additionally it is used as correction factor for calculating the true hydroxyl number. In this Application Bulletin the determination of the acid number according to ASTM D4662 and ASTM D7253 is described.One raw material for polyurethanes are polyols. Polyols contain multiple hydroxyl groups. Therefore, hydroxyl number of a raw material directly correlates to the amount of polyols present and it is thus an important quality control parameter. In this Application Bulletin the determination of the hydroxyl number according to ASTM E1899 and DIN 53240-3 is described.As polyols react stoichiometrically with isocyanates, the knowledge of the isocyanate content is an important quality parameter for the production of polyurethanes. In this document the determination according to EN ISO 14896 method A, ASTM D5155 method A and ASTM D2572 is described.

This Application Bulletin describes the determination of the thermostability of PVC in accordance with ISO 182 Part 3 using the dehydrochlorination method with the 895 Professional PVC Thermomat. The instrument permits fully automatic determination of the stability time. The test is suitable for monitoring the manufacture and processing of PVC products manufactured in the injection molding process, for their final clearance, characterization and for the comparison of PVC products and for testing the effectiveness of heat stabilizers.

Generally speaking, the gas extraction or oven method can be used for all samples which release their water when they are heated up. The oven method is indispensable in cases in which the direct volumetric or coulometric Karl Fischer titration is not possible, either because the sample contains disruptive components or because the consistency of the sample makes it very difficult or even impossible to transfer it into the titration vessel.The present Application Bulletin describes automatic water content determination with the aid of the oven technique and coulometric KF titration, using samples from the food, plastic, pharmaceutical and petrochemical industry.

The presented titration system can be used for the fully automated determination of the hydroxyl number (HN) according to ASTM E1899 and EN ISO 4629-2. The method allows, the determination of polyols and oxooils without boiling under reflux or other sample preparation and is therefore a big benefit for laboratories that have to cope with a high sample throughput.The standards EN 15168 and DIN 53240-3 relay on the same analysis method as in ASTM E1899.

This bulletin describes a procedure to determine the bromine index (BI) using coulometric titration. The bromine index is the fraction of reactive unsaturated compounds (mostly C=C double bonds) in hydrocarbons encountered in the petrochemical industry. The double bonds are split with the attachment addition of bromine.

The present Application Bulletin elucidates several applications for the polymer industry that can be carried out with the aid of NIR instruments. This Bulletin contains analyses of a wide range of parameters in a very large array of samples. The hydroxyl number is one of the best-known of the parameters that can be determined rapidly using near-infrared spectroscopy. The determination of the hydroxyl number in different areas and in different polyol types is also a part of this Bulletin. Each application describes the sample and the instrument that was originally used for the analysis, as well as the recommended instruments and the results.

Determination of sodium, ammonium, and potassium in polyethers using cation chromatography with direct conductivity detection.

Polyols are important raw materials in polyurethane production. Contamination in the raw materials have a great influence on reactions and impair the quality of the end product. Alkali metals are particularly strong catalysts for linear or branched reactions. A rapid and precise method for their simultaneous determination is ion chromatography following Inline Matrix Elimination.

1,3,5-trioxane is a heterocyclic compound formed by trimerization of formaldehyde. Trioxane is used for the production of polyformaldehyde plastics such as poly(oxymethylene) (POM) and solid fuels. Aqueous 1,3,5-trioxane solutions frequently contain trace triethylamine that requires quantification. This is performed on the Metrosep C 3 - 250/4.0 column with subsequent direct conductivity detection.

The determination of halogens and sulfur in waste products is important. The inline combination of the Mitsubishi Combustion Module with the Metrohm IC is a suitable method for this type of samples. The recovery rates are analyzed with a certified reference material, e.g., a low-density polyethylene (LDPE).Keyword: pyrohydrolysis

Latex gloves are used in clean room environments in order to prevent contaminations. The use of gloves that release corrosive halogenides or sulfate is forbidden in nuclear power plants. The total content of halogen and sulfur is determined by means of Combustion Ion Chromatography. An eluate test is carried out to check the elutable percentage of halogens and sulfate from gloves. Sample preparation is comprised of preconcentration and matrix elimination (MiPCT-ME), as described in AN-S-304.Keyword: pyrohydrolysis

Combustion Ion Chromatography combines pro-hydrolytic sample combustion and the absorption of emerging combustion gases in an oxidizing, aqueous solution that is then channeled to an ion chromatograph for the analysis of halogenides and sulfur (as sulfate). The combustion and analysis of the certified reference materials (ZRM) makes clear the reliability of Metrohm Combustion Ion Chromatography.Keyword: pyrohydrolysis

Polyisobutene (PIB) is an important raw material for a large range of products. Quality control requires the determination of the fluorine content. This task is easily done by Metrohm Combustion IC applying flame sensor technology and Inline Matrix Elimination.Keyword: pyrohydrolysis

The Restriction of Hazardous Substances Directive (RoHS) requires to reduce the halogen content in several organic materials used in electrical and electronic equipment. In this context, there is a huge interest for using halogen-free polymers. To check for halogens in polymers according to standard IEC 60754, Metrohm Combustion IC applying flame sensor technology and Inline Matrix Elimination is an indispensable method. The examined polymeric material contains halogens at a level of up to 1%.

Halobutyl rubber is frequently used in the production of pharmaceutical stoppers. It is ideal for this application due to its low permeability to gases and its chemical resistance. Chlorinated and brominated butyl rubber stoppers are analyzed for their halogen and sulfur content. Halogen and sulfur compounds are released by pyrohydrolysis and analyzed by subsequent ion chromatography (IC).

Polystyrol is brominated to increase flame retardation. The brominated polystyrene finally consists of 25 to 35% of bromine. The determination of bromine by combustion ion chromatography (CIC) requires a specially optimized absorption solution to trap all bromide. This work shows the optimization of the absorption solution for high-bromine samples.

Polymer materials that are used for building and decoration purposes need to be flame resistant. To reach the required level of resistance flame-retardants are added to the plain polymer. Flame-retardants are often haloorganic compounds. The use of such components and the respective concentration of introduced halogens can be determined by Combustion IC. The recovery over the full system is tested with acertified reference material (CRM).

Cellulose ester foils are produced using chlorinated solvents. The residual amount of the solvent used in production evaporates within a few days in ambient conditions. The residual solvent is determined by combustion IC, through the conversion of organically bound chlorine to chloride by pyrohydrolysis. The final product needs to be free of all chlorinated solvents. Therefore, critical contents of such compounds can be detected in quality control analysis. Application of MiPT in this study has enabled an automated and precise calibration out of a single standard.

Organic halides must be monitored in the environment. Combustion ion chromatography (CIC) is used for accurate halogen analysis in solids following EN 17813:2023.

A reference electrode has a stable and well-defined electrochemical potential (at constant temperature), against which the applied or measured potentials in an electrochemical cell are referred. A good reference electrode is therefore stable and non-polarizable. In other words, the potential of such an electrode will remain stable in the used environment and also upon the passage of a small current. This application note lists the most used reference electrodes, together with their range of use.

The TSC SW Closed and TSC Battery cells are compact systems designed for measurements on air or moisture-sensitive materials, such as those used in batteries. In this document, two testing procedures are explained. The first procedure is withpotentiostatic cyclic voltammetry (CV), while the second is via electrochemical impedance spectroscopy (EIS).

In the application note AN-EIS-004 on equivalent circuit models, an overview of the different circuit elements that are used to build an equivalent circuit model was given. After identifying a suitable model for the system under investigation, the next step in the data analysis is estimation of the model parameters. This is done by the non-linear regression of the model to the data. Most impedance systems come with a data-fitting program. In this application note, the way NOVA is uses to fit the data is shown.

In this application note, the advantage of recording the raw time domain data for each individual frequency during an electrochemical impedance measurement is described.

The water content of plastic chips is determined according to Karl Fischer. Because of the low water content of the sample, the oven method (200 °C) and coulometric titration have to be used.

The water content of organic peroxides is determined according to Karl Fischer using two-component reagents. To prevent any unwanted side reactions, the determinations are carried out at -20 °C.

The presence of water in expandable polystyrene (EPS) can have a negative impact on the thermal insulation properties, as it increases thermal conductivity. If EPS is exposed to a high moisture environment, additional water may be absorbed, which can further affect thermal insulation.Direct analysis of the moisture content by Karl Fischer titration requires the water to be extracted from the EPS, which involves several time-consuming steps. Therefore, determination of the water content with an oven system is preferred. As EPS expands when heated, the use of sample boats, as required by ASTM D6869, is not possible, as the EPS will contaminate the oven system. This Application Note describes the determination of water content in EPS using an oven system with closed sample vials. A determination takes about 7 to 14 min depending on the water content of the sample and the sample size.

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

The water content of 2-methyl-1,3-butadiene and 2,5-norbornadiene is determined according to Karl Fischer using a special solvent mixture to prevent unwanted side reactions.

The water content of piperidine and piperazine is determined according to Karl Fischer using a buffered solvent mixture.

The water content of melamine is determined according to Karl Fischer in a buffered solvent mixture at 50 °C.

The water content of beta-caprolactam is determined according to Karl Fischer.

The water content of vinyl chloride is determined according to Karl Fischer.

The water content, also called moisture content, of plastics is an important quality parameter, as it affects the properties and processability of some plastics. A high water content can lead to degradation of the plastic by hydrolysis or cause surface imperfections. Additionally, it can affect the physical properties of some plastics.For this analysis, the oven technique is used, as volatile compounds present in plastics will interfere, if the water content is directly determined by coulometric Karl Fischer titration. The water content determination in polycarbonate pellets, performed with the 885 Compact Oven Sample Changer and 899 Coulometer, is described in this Application Note.

The water content determination by volumetric Karl Fischer titration is one of the most important analyses worldwide. Using an OMNIS system consisting of an OMNIS Titrator and an OMNIS Sample Robot, the fully automatic analysis of water content is possible in various products and matrices. The OMNIS Sample Robot is capable of running several different titrations in parallel. In this Application Note, we present the results of a volumetric Karl Fischer titration run in parallel to an aqueous acid-base titration on the same system. The water content is not influenced by the parallel running aqueous titration, allowing the combination of potentiometric titrations and Karl Fischer titrations on the same automated system.

Karl Fischer reagents contain buffer substances (usually imidazole) since the reaction constant is dependent on the pH value. A constant pH therefore ensures the most repeatable results. In 2015, imidazole was classified by European Union the as a CMR (carcinogenic, mutagenic or toxic) substance and the statement H360D was added, stating possible harm to fertility or a fetus. Meanwhile, other reagents free of imidazole are available for purchase. This Application Note summarizes test measurements with 34433 HYDRANAL™ NEXTGEN Coulomat AG-FI.

This Application Note describes the determination of copolymer levels in polyethylene (PE) and polyvinylacetate (PVA) pellets using NIRS. The determination of the composition of the polymer blends takes less than 30 seconds and requires no sample preparation. The second derivative spectra are analyzed by means of the linear least-squares regression method.

This Application Note shows that NIR spectroscopy is an excellent tool for determining low concentrations of additives in finished polypropylene pellets. This is demonstrated by monitoring the UV stabilizer Tinuvin 770 and the antioxidant Irganox 225. The application of multiple linear regression (MLR) models minimizes interferences that originate from different coating thicknesses and interferences in the polymer pellets.

This Application Note demonstrates how NIR spectroscopy can be used to determine the content of coatings on nylon fibers, quickly and without requiring either sample preparation or the use of reagents. In order to suppress the effects arising from scattering on the surface coatings, one forms the second derivative spectra; the linear least-squares regression method is used to calculate the calibration function.

Determination of the diethylene glycol content, isophthalic acid content, intrinsic viscosity (ASTM D4603), and the acid number (AN) of polyethylene terephthalate (PET) is a lengthy and challenging process due to the sample’s limited solubility and the need to use different analytical methods. This application note demonstrates that the DS2500 Solid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a cost-efficient and fast solution for a simultaneous determination of these parameters in PET. Vis-NIR spectroscopy allows for the analysis of PET in less than one minute without sample preparation or using any chemical reagents.

This Application Note shows that near-infrared spectroscopy with its exceptionally short analysis times significantly accelerates quality monitoring of polymer granulates and raw materials. Polyethylene (PE) und polypropylene (PP) can be identified in parallel. PE density is also determined in the same measurement.

Toxic and corrosive chemicals such as p-toluenesulfonyl isocyanate (TSI) and tetrabutylammonium hydroxide are used for the Hydroxyl Number analysis of polyols by titration according to ASTM D4274-16. This application note demonstrates how the XDS RapidLiquid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a cost-efficient and fast solution for the determination of the hydroxyl (OH) number of polyols. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows for the analysis of polyols in less than a minute.

Functional group and viscosity analysis (ASTM D789) of polyamides can be a lengthy and challenging process due to the sample’s limited solubility. This application note demonstrates that the DS2500 Solid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a cost-efficient and fast solution for a simultaneous determination of the intrinsic viscosity as well as the amine, carboxylic, and moisture content in polyamides. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows for the analysis of polyamides in less than a minute.

This Application Note demonstrates the feasibility of Vis-NIRS for the simultaneous determination of multiple chemical and physical parameters in epoxy resins. Vis-NIRS is a fast alternative to conventional lab methods: it accelerates raw material inspection, process monitoring, and final product control.

Determination of isocyanates (ASTM D7252) is a challenging procedure due to the reactivity of these organic species with atmospheric moisture, as well as their toxicity. Furthermore, HPLC analysis typically used for this kind of analysis involves sample preparation steps and chemicals, with each measurement taking up to 20 minutes to complete. This application note demonstrates that the XDS RapidLiquid Analyzer operating in the visible and near infrared spectral region (Vis-NIR) provides a chemical-free and fast solution (under one minute) for determination of isocyanate content.

Polyvinyl alcohol (PVA) is a linear polymer, used in a variety of medical products (e.g. eye drops). Here, the degree of alcoholysis is an important index for the water solubility, viscosity, and adhesion of the product. The degree of alcoholysis is defined as the percentage of hydroxyl functional groups compared to the total functional groups accessible in the molecule. Conventional alcoholysis determination can take up to six hours per sample. Compared to the primary method, analysis with near-infrared spectroscopy (NIRS) only takes one minute. The following application note describes the determination of the degree of alcoholysis by NIRS.

Caprolactam is an important polymer used for the production of Nylon 6, which is the base material for industrial fibers. Due to its commercial significance, many different synthesis methods have been developed over the years. Caprolactam is hygroscopic and water soluble, therefore it is important to have a reliable analysis technique for water determination. Analyzing the water content by conventional methods requires each sample to be weighed, dissolved, heated, and titrated. Compared to the primary method, near-infrared spectroscopy (NIRS) offers unique advantages: it generates reliable results within seconds, but it does not need any sample preparation nor does it create chemical waste.

Determination of the density of polyethylene (PE) (ASTM D792) is normally a challenging procedure due to reproducibility difficulties. Measurement via FT-IR can be problematic when larger sample sizes must be analyzed due to sample inhomogeneity. This application note demonstrates that the DS2500 Solid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a reliable and fast solution for determination of the density of PE. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows the analysis of larger, inhomogeneous sample sizes of PE in less than a minute.

Polypropylene (PP) is a general purpose resin widely used in industries such as electronic manufacturing and construction, as well as in packaging materials. PP resins must be melted first in order to be formed into the intended shape, and therefore flow properties are important characteristics which affect the production process. The standard procedure to analyze melt flow rate (MFR) requires a significant amount of work with packing the sample, preheating, and cleaning. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows the analysis of MFR in less than a minute.

Identification of individual polymers with FT-IR spectroscopy can be a challenge due to sample inhomogeneity especially when larger sample sizes need to be analyzed. This application note demonstrates that the DS2500 Solid Analyzer operating in the visible and near infrared spectral region (Vis-NIR) provides a reliable and fast solution for the identification of high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP). With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows the identification of larger inhomogeneous sample amounts in less than a minute.

Determination of the vinyl content of silicone rubber is a lengthy and challenging process. First, the vinyl groups must be converted to ethylene by reacting with an acid, followed by the determination of the produced ethylene with gas chromatography (GC).This application note demonstrates that Vis-NIR (visible near-infrared) spectroscopy provides a cost-efficient and fast solution for the determination of vinyl content in silicone rubbers. With the DS2500 Solid Analyzer it is possible to obtain results in less than a minute without sample preparation or any chemical reagents.

PVC (polyvinyl chloride) foils with a PVDC (polyvinylidene chloride) coating are often used for high performance packaging films like pharmaceutical blister packs or in food packaging. In multi-layer blister films, the PVC serves as the thermoformable backbone structure, whereas the PVDC coating acts as a barrier against moisture and oxygen. The Water Vapor Transmission Rate (WVTR) and Oxygen Transmission Rate (OTR) are influenced by the composition and the thickness of the coating. A fast way to monitor PVDC coating thickness is with near-infrared spectroscopy. Results are provided in a few seconds, indicating when adjustments in the polymer production process are necessary.

To monitor the quality of PVC (polyvinyl chloride), it is important to measure the molecular weight during the production process, as this parameter has a significant influence on chemical and mechanical stability as well as fire retardant properties. The standard method to determine PVC molecular weight, defined here as the average weight of the molecules that make up the polymer, is by size exclusion chromatography (SEC). This analytical method is time-intensive and requires trained personnel to perform. Determining the molecular weight of PVC is easier with near-infrared spectroscopy (NIRS). NIRS provides results in just a few seconds and can quickly indicate when adjustments to the production process are necessary.are necessary.

The standard test method for ash content analysis is thermogravimetric analysis (TGA). Although TGA is easy to perform, it is time-intensive and requires the use of nitrogen gas. In contrast to the primary method, near-infrared spectroscopy (NIRS) is a fast analytical technique which can measure multiple parameters including ash content in polymers within one minute.

This Application Note shows the feasibility of NIR spectroscopy for the analysis of density in polyethylene granulates. Compared to the standard method, NIRS analysis shows a lower prediction error when air bubbles are present in PE pellets.

The synthetic rubber known as Bromobutyl (BIIR) has many of the attributes of butyl rubber, but has better adhesion to other rubbers and metals, resulting in substantially faster cure rates. The simultaneous quantification of the bromine content, Mooney viscosity, volatile content, calcium stearate content, and functional bromide in BIIR can be easily performed with near-infrared spectroscopy (NIRS) without the use of chemicals.

Near-infrared (NIR) spectroscopy is able to determine the intrinsic viscosity of rPET in less than one minute without any sample preparation. This Application Note demonstrates that the Metrohm DS2500 Solid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) offers users an easier way to perform this analysis without the use of toxic chemicals.

Near-infrared spectroscopy streamlines ethylene tetrafluoroethylene production by offering rapid, chemical-free analysis of melt flow rate and moisture content.

Polypropylene and polyethylene can pose recycling challenges. With near-infrared spectroscopy (NIRS), users receive polyolefin composition results in seconds.

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.

Permanganate absorption number (PAN) analysis per ISO 8660 ensures caprolactam purity, a precursor of Nylon 6. This application describes real-time, continuous PAN monitoring.

Polyurethanes are a class of synthetic polymers formed by reacting liquid di/polyisocyanates and polyols with a catalyst and various additives in a reactor. Polymer properties are modified with stepwise additions of these chemicals at different points in time depending on whether the process has reached an equilibrium. NCO functional groups from unreacted isocyanates must be quenched at the end for a finished product, and this parameter must be known to determine the proper chemical mixing ratio. A fast, non-destructive real-time measurement of %NCO can be obtained by using NIR spectroscopy with a probe seated directly in the reactor.

This Process Application Note presents a way to closely monitor multiple parameters simultaneously during the dioctyl terephthalate production process with near-infrared spectroscopy.

The thermostability of polyvinyl chloride (PVC) was determined using the dehydrochlorination procedure at 180 °C. Comparison of the thermostability of pure PVC polymer, blended PVC (blended with stabilizer, plasticizer, filler) and blended PVC after processing.

Determination of the thermostability of polyvinyl chloride (PVC) using the dehydrochlorination procedure at 200 °C.

The thermal stability of raw or processed PVC provides information about the quality of the plastic. Higher stability times can be correlated with longer lifespans. With the 895 Thermomat, the dehydrochlorination rate at elevated temperatures can be determined within a short time. Additionally, quality deviations in the purchased raw material as well as in the end products can be detected. The 895 Thermomat has been optimized for this application regarding three important points: safety, handling, and time-savings. The measurement is based on the standard EN ISO 182-3.

This application highlights Metrohm’s XTR® technology to identify colored polymers by extracting the Raman signal from spectra with strong background fluorescence.

Handheld Raman spectroscopy enables rapid polymer masterbatch analysis, while Metrohm’s XTR® algorithm mitigates fluorescence interference for accurate additive identification.

Raman spectroscopy can easily monitor polymerization by tracking monomer consumption and polymer formation, providing a valuable tool for polymer manufacturers.

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.

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

Determination of fluoride, glycolate, chloride, and oxalate in a latex dispersion using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of fluoride, chloride, nitrite, nitrate, benzoate, and sulfate in PVC film 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, sulfite, sulfate, oxalate, and thiosulfate in lignin using anion chromatography with conductivity detection after chemical suppression.

Determination of phosphate and sulfate in a liquid polymer sample using anion chromatography with conductivity detection after chemical suppression.

Aromatic dicarboxylic acids, e.g., terephthalate, isophthalate and 5-sulfoisophthalate, are important monomers in the manufacture of polyesters and alkyd resins. The monomer ratio of the dicarboxylic acids has an enormous influence on polymerization. The separation of the late-eluting components is completed within 15 minutes if a short Metrosep A Supp 15 - 50/4.0 type column is used together with high eluent concentrations and flow rates.

Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most promising ICPs due to its high conductivity, electrochemical stability, catalytic properties, high insolubility in almost all common solvents and interesting electrochromic properties (transparent in the doped state and colored in the neutral state). In this Application Note, PEDOT film is evaluated by spectroelectrochemical techniques.

The carboxyl end groups (CEG) in polymers, such as polyethylene terephthalate (PET), are a measure of the number of unreacted carboxylic acid groups at each end of a polymer chain. The number of CEGs may influence the hydrolysis resistance of geosynthetics, such as geogrids and geotextiles. The lower the CEG value the higher is the hydrolysis resistance of geosynthetics, which in turn increases their stability.This Application Note describes the photometric titration of carboxyl end groups in PET pellets using the Metrohm Optrode. The acidic end groups of the polymer are titrated with an ethanolic KOH solution using bromophenol blue as indicator.

The epoxy content of epoxy resins has a strong influence on the reactivity of the resins as well as on the properties of the coating obtained from the resin curing process. The epoxy content is thus an important quality control parameter for manufacturers as well as consumers. This analysis is based on the reaction of hydrogen bromide with the epoxy groups of the sample. Hydrogen bromide in turn is produced by the reaction of tetraethylammonium bromide (TEABr) with standardized perchloric acid. The standards EN ISO 3001 and ASTM D1652 describe the determination of the epoxy content expressed as epoxy equivalent weight (EEW) by titration. The use of a Titrando and Solvotrode easyClean instead of manual titration greatly increases the reproducibility and repeatability of the determination.

The basicity and the CPR (controlled polymerization rate) are very important parameters for the quality of polyols used in polyurethane production. The knowledge of these values is crucial to prevent gelation during handling in the production. In this Application Note their determination by automated, potentiometric titration according to ISO 14899 is described.

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 partial acid number (also partial acid value) describes the quantity of potassium hydroxide that is required for neutralizing all carboxyl-terminated groups and free acids plus half the anhydride groups in an unsaturated polyesterresin (UPR). This Application Note describes the determination of the partial acid value by automatic, potentiometric titration according to EN ISO 2114 using KOH in ethanol as titrant.

The total acid number (TAN) indicates the amount of potassium hydroxide required for neutralizing all carboxyl-terminated groups and free acids plus the free anhydride groups in an unsaturated polyester resin (UPR). In this Application Note the TAN determination using automated, potentiometric titration according to EN ISO 2114 using KOH in ethanol as titrant is described.

The hydroxyl number indicates the amount of potassium hydroxide in milligrams required to neutralize the acetic acid taken up on acetylation of 1 g of an unsaturated polyester resin (UPR) containing free hydroxyl groups. In this Application Note the determination of the hydroxyl number by automated, potentiometric titration according to EN ISO 2554 using KOH in methanol as titrant is described.

Polyurethane (PU) is a class of very important polymers due to its flexibility and insulating properties. It is used in various industries such as the automobile industry, in building construction, as well as in the production of synthetic fibers. PU is mostly produced via a chemical reaction between polyisocyanates and polyols.The isocyanate (NCO) content in the raw material is crucial to control its properties. This Application Note shows an easy and straightforward way to determine the NCO content in polyurethane raw materials using a fully automated titration system from Metrohm.

The quantity of hydrolyzable chloride in epoxy resins has an influence on their reactivity and on the properties of the epoxy coating obtained.Rapid and accurate determination is possible with an OMNIS system using potentiometric titration with the dAg ring electrode and silver nitrate as the titrant.

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.

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.

The determination of PBBE (tetrabromobisphenol A - TBBPA, octabromodiphenyl ether - OCTA and decabromodiphenyl ether - DECA) in a polymer sample was carried out with the Nucleosil EC - 250 mm column; for this purpose a methanol and phosphate buffer was used as an eluent and subjected to UV detection in accordance with the IEC 62321 method for RoHS testing.

The determination of chromium(VI) polymers using anion exchange chromatography with UV/VIS detection after post-column reaction with diphenylcarbazide as per IEC 62321 method for RoHS testing.

Determination of Cr, Mn, and Ti in a PTA solution containing HCl.

Determination of Ni, Co, and Fe in a PTA solution containing HCl.

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

Polarographic determination of cyanide in gases resulting from the incineration of plastic insulation materials after sample preparation.

Determination of styrene monomers in polystyrene. Free styrene is converted to a polarographically active pseudonitrosite.

Ti is determined in polyethylene terephthalate (PET) after digestion in sulfuric acid and hydrogen peroxide. Adsorptive stripping voltammetry (AdSV) with mandelic acid as complexing agent is used for this application.

Co is determined in polyethylene terephthalate (PET) after digestion in sulfuric acid and hydrogen peroxide. The application is carried out with adsorptive stripping voltammetry (AdSV) in ammonia buffer with dimethylglyoxime (DMG) as complexing agent.

Sb is determined in polyethylene terephthalate (PET) after digestion in sulfuric acid and hydrogen peroxide. The application is carried out with anodic stripping voltammetry (ASV) in hydrochloric acid.

Raman spectroscopy is a quick nondestructive method for the direct identification of plastics. It can also be used for the analysis of flame retardants, lubricants and other additives. Coupled with chemometric software, quantitative and advanced qualitative analyses can be performed.

Small, fast high-performance Raman spectrometers are now readily available. Three real-life Raman quantitative and semi-quantitative analysis applications are discussed. These applications showcase the versatility of Raman spectroscopy and the potential impact that it can make in various industries such as security, pharmaceutical, and plastics and polymers.

Enhance quality control in material and chemical production with NIRS. Fast, cost-effective, and no sample prep needed. Learn more in our eBook.

This e-book explains how Raman and near-infrared (NIR) spectroscopy enable rapid, nondestructive polymer analysis, ensuring high quality while reducing costs and waste.

The automated combination of pyrolysis and subsequent ion chromatography (Combustion IC) permits the parallel detection of halogens and sulfur in all flammable solid and liquid matrices. The method is captivating, not only because of its outstanding precision and trueness, but also because of the high sample throughput.

Chromate is allergenic, carcinogenic and extremely toxic. It is therefore subject to strict monitoring. It is present in different concentrations in drinking water, toys, textiles, leather and many other materials. Metrohm has developed various methods for ion chromatographic determination of chromium(VI) which, thanks to Inline Sample Preparation, are suitable for a variety of matrices and concentration ranges – from ng/L to mg/L.

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

Chemical manufacturing such as polyurethane production is characterized by a cost intensive production process combined with a negative ecological impact. These adverse effects can be significantly improved by using vibrational spectroscopy. This analytical technique can assist the operator of the plant to reduce costs and minimize the impact onthe environment as is demonstrated in the present white paper.

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%.

This White Paper discusses the concept and benefits of NIR spectroscopy and outlines several real-life laboratory application examples with the use of OMNIS NIRS, the cutting-edge NIR spectrometer from Metrohm.

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