Applications of deactivated GC columns for analysis of nitrogen-containing chemicals related to the chemical weapons convention.

Nitrogen-containing chemicals are one of the important families of compounds relevant to the purposes of the Chemical Weapons Convention (CWC). Several applications, using various injection modes, of new deactivated columns specially designed for basic compounds are presented. These columns prove remarkably well-suited to the gas chromatographic (GC) analysis of the chemicals of interest, even to underivatized amino-alcohols, whose analysis on conventional GC columns is often difficult and hindered by poor resolution and high detection limits. Such a deactivated phase can even replace the typical GC phases used for CWC verification purposes.

Investigation of compound-independent calibration and partial molecular formula determination by gas chromatography-atomic-emission detection for characterisation of organophosphorus and organosulfur agents related to the chemical weapons convention.

Atomic-emission detection (AED) is a technique particularly-well suited to screening complex samples for multiple compounds containing heteroatoms such as phosphorus, sulfur, or nitrogen, which are especially relevant in verification of chemical disarmament. Among other GC detectors, AED has unique characteristics such as compound-independent calibration and possible raw-formula determination. Because contradictory results have been reported on these points, we set up a study with the objectives not only of applying these techniques to chemical weapons convention-related chemicals but of determining under which conditions they would yield satisfactory results. The extensive data collected in this study are evidence that the response of the detector, particularly for the phosphorus line, is very dependent on the molecular mass and concentration of the chemicals analysed whereas molecular structure seems to have less effect on the AED signal. Most interestingly, compound-independent calibration and subsequent partial molecular formula determination usually seem satisfactory when the reference compounds used to calibrate the system have GC retention times and molecular masses close to those of the unknown analytes (whose molecular mass may be determined by GC-CI-MS). We therefore suggest the use of a reference set of compounds covering a large chromatographic window, which enables the selection, within this set, of the most appropriate reference compound for calibration and for determination of the raw formula of an unknown analyte. For optimal performance, the use of a new discharge tube is also recommended.

Optimisation of sorbent trapping and thermal desorption-gas chromatography-mass spectrometric conditions for sampling and analysis of hydrogen cyanide in air.

Among the chemicals belonging to the schedules of the Chemical Weapons Convention (CWC), sampling and analysis of highly volatile compounds such as hydrogen cyanide (HCN) require special consideration. The latter is present in numerous old chemical weapons that are stockpiled awaiting destruction in Northeastern France: thus, sampling on stockpile area and subsequent verification of HCN levels is compulsory to ensure safety of workers on these areas. The ability of several commercial sorbents to trap hydrogen cyanide at various concentration levels and in various humidity conditions, was evaluated. Furthermore, thermal desorption of the corresponding samples, followed by analysis by gas chromatography-mass spectrometry was also optimised. Carbosieve S-III, a molecular sieve possessing a very high specific area, proved the most efficient sorbent for HCN sampling in all conditions tested. Conversely, the presented results show that Tenax, albeit generally considered as the reference sorbent for air monitoring and analysis of CWC-related chemicals, is not suitable for HCN trapping.