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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 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.

Raman analysis of fentanyl-soaked paper, SERS detection range for fentanyl on paper, and real-world example of fentanyl identification.

The concentration of Al is determined by adsorptive stripping voltammetry at the HMDE. The method is suitable for Al in concentrations in the range of 0.1 ppb to approx. 40 ppb Al3+. Pb2+ ions do not interfere up to a concentration ratio Pb:Al = 10:1. Due to the slow complex formation of Al with solochrome violet RS the measuring solution was heated to 40 °C for 10 min prior to the determination. For standard addition a solution of Al with solochrome violet RS complex was used. All reagents have to be added in the order as listed below.