Applications

In modern days, a new breed of energetic (explosive) materials is emerging. Traditional aromatic nitrates are still in use, but there is dire need of analytical techniques for energetic materials in the chemical class of peroxides, azo etc. This presentation will demonstrate the use of a modern HPLC system with traditional detector (DAD) and also coupled with mass spectrometry for the analysis of abovementioned various classes of energetic materials.

The analytical challenge treated by the present work consists in detecting sub-ppb concentrations of low-molecular-weight amines in the presence of strongly retained cationic drugs by using ion chromatography (IC) with upstream inline coupled-column matrix elimination (CCME). In contrast to direct-injection IC, where the late elution of strongly retained drugs requires eluents with added acetonitrile, the CCME technique uses two preconcentration columns in series. In an «inverse matrix elimination step, cationic drug and target amines are trapped on a high-capacity and a very-high-capacity preconcentration column, respectively. During amine determination, a rinsing solution flushes the drug to waste. This significantly shortens the analysis time and improves sensitivity as well as selectivity. Besides the determination of monomethylamine in Nebivolol hydrochloride discussed here, the CCME technique is a promising tool for detecting further low-molecular-weight amines in a wide range of drugs.

By combining the information from electrochemical and spectroscopic techniques, UV/VIS spectroelectrochemistry (UV/VIS-SEC) allows a comprehensive analysis of electron-transfer processes and complex redox reactions. The anodic oxidation of a N-aryl-D2-pyrazoline derivative was investigated by combining cyclic voltammetry and UV/VIS spectroscopy. In-situ measured UV/VIS absorbance depicted the absorption changes that accompanied the anodic oxidation and could therewith prove the stability of the electrogenerated radical cation. UV/VIS-SEC provides a powerful tool for the in situ study of shorter-lived species, reaction mechanims, and kinetics in a wide variety of electrochemical active organic, inorganic, and biological molecules.

The quantitative determination of the alkaloid nicotine, which is an essential constituent of the tobacco plant, can be carried out by polarography. The quantification limit is less than 0.1 mg/L in the polarographic vessel.

This Bulletin is a supplement to Application Bulletin no. 36 (Half-wave potentials of inorganic substances) in the sense that the half-wave potentials of 100 different organic substances are listed. At the same time the supporting electrolytes used and the limits of determination are given.The various substances are listed in alphabetical order. The most important polarographically active functional groups are taken into consideration. This means that substances for related structures can also be determined polarographically in the same or similar supporting electrolytes, although they may not appear in the list.Unless otherwise stated, the half-wave potentials refer to a temperature of 20 °C, and the potentials are given in volts, measured with a sat. KCI-Ag/AgCl electrode assembly.The determination limits give the smallest concentrations which can be measured without risking serious errors in the results. In all cases, the limit of detection lies below the limit of determination.

The two potentiometric titration methods described here allow the determination of the content of commercial betaine solutions. Neither method is suitable for determining the betaine content of formulations. The possibilities and limits of both methods are described and distinctive features and possible sources of interference are mentioned. The Bulletin explains the most important theoretical principles and is intended to help users to develop their own product-specific titration methods.

Fast IC means short run times and a high sample throughput on columns with a relatively high flow rate and the standard eluent. Mono-, di- and tri-ethanolamine are separated with the Metrosep C 4 - 150/2.0 within 2.5 minutes.

Fast IC means short run times and a high sample throughput on columns with a relatively high flow rate and the standard eluent. Mono-, di- and trimethylamine are separated with the Metrosep C 4 - 150/2.0 within four minutes.

In natural gas production, the removal of contaminants, and in particular acidic gases such as H2S and CO2, is exceptionally important. These acidic gases are removed in the amine wash through chemical treatment with amines or alkanol amines. This application shows a convenient and precise analysis with the separation of various amines and standard cations on a column of the Metrosep C 6 - 250/4.0 type with subsequent direct conductivity detection.

N-methyldiethanolamine and piperazine are used in scrubber solutions, e.g., in the natural gas process. Testing this type of samples by ion chromatography requires a good resolution and the separation of amines from standard cations. The separation is achieved on a Metrosep C 4 - 150/4.0 column applying direct conductivity detection.