Applications

UV/VIS detection is one of the most sensitive detection techniques in trace-level chromatography. Sometimes, however, spectrophotometric detection lacks sensitivity, selectivity or reproducibility and chemical derivatizations are required. By using Metrohm`s rugged and versatile flow-through reactor, single- or multi-step derivatizations can be done fully automatically, in either pre- or post-column mode at any temperature between 25…120 °C. The variable reactor geometry allows to adjust the reactor residence time of the reactants according to derivatization kinetics. The flexibility of the reactor is demonstrated by optimizing four widespread post-column techniques: the relatively slow ninhydrin reaction with amino acids and the fast derivatizations of silicate, bromate and chromate(VI).

The present Application Bulletin describes applications that use near-infrared spectroscopy. Each application describes the used and alternatively deployable spectrometer as well as analysis conditions and results and, where available, information on feasibility studies.

In textiles, the water-repelling effect may be introduced by different treatments, such as the application of fluorochemicals. These compounds, especially perfluoroorganic substances, are extremely persistent in the environment and are therefore listed as emergent contaminants. Combustion IC with pyrohydrolysis and subsequent ion chromatographic determination is applied to analyze the fluorine content in fabrics.

Determination of chromium in leather waste solutions in the range between 1000 and 30,000 ppm.

Determination of chlorite by direct thermometric titration with standard sodium thiosulfate solution. The procedurewas applied originally to the determination of chlorite in hide treatment solutions.

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.

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 how the OMNIS NIR Analyzer Solid quickly determines the cotton content in various textile products within just 30 seconds.

Spectroelectrochemistry is a multi-response technique that provides both electrochemical and spectroscopic information about a chemical system in a single experiment, i.e., it offers information from two different points of view. Spectroelectrochemistry focused on the UV/VIS region is one of the most important combinations because this allows us to obtain not only valuable qualitative information, but also outstanding quantitative results. In this application note, the degradation kinetics for 4-nitrophenol, a known pollutant, were determined using SPELEC.

Determination of chromium(VI) (chromate) in leather extract using anion chromatography with UV/VIS detection after post-column reaction (PCR) and inline dialysis for sample preparation.

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.

The coupling of ion chromatography and inductively coupled plasma mass spectrometry (ICP/MS) leads to a high-performance measurement system that masters several particularly challenging analyses. It enables for example reliable determination of element compositions, oxidation states and chemical bonds. This information is used, for example, for assessing the toxicity of medications, environmental and water samples as well as foods and beverages.