Applications

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.

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.

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

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

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.

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.

Acrylic dispersion paints are made of pigment suspended in acrylic polymer emulsions, which also include other organic material such as plasticizers, defoamers, or stabilizers. Acrylic dispersion paints are water-soluble but become resistant to water when dry. Due to the fact that once dry, acrylic dispersion paints can no longer be used, they should be stored air-tight at room temperature. For research purposes, it is of interest to assess the dissolved oxygen (DO) concentration in such samples as it is assumed that the DO amount can be related to the storage life. This Application Note describes a fast and accurate determination of dissolved oxygen by using an optical sensor.

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

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.

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.

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.

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.

To prevent styrene from polymerization at ambient temperature, tertiary-butylcatechol (TBC) must be added as a stabilizer during storage and transport. TBC concentration levels in styrene need to be maintained between 10 - 15 mg/L. With optimum storage conditions, the process analyzers from Metrohm Applikon for photometric analyses ensure that the TBC concentration in styrene does not fall below this value. The method is based on ASTM D4590.

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

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 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.

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 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.

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

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