Extraction of alkyl methylphosphonic acids from aqueous samples using a conventional polymeric solid-phase extraction sorbent and a molecularly imprinted polymer.

The analysis of alkyl methylphosphonic acids (AMPAs) constitutes an important subject for verifying the compliance to the Chemical Weapons Convention (CWC). Indeed, alkyl methylphosphonic acids are the degradation products of V and G nerve agents such as VX, sarin or soman. Lowering the limits of detection of analytical methods for complex aqueous matrices implies the introduction of concentration and clean-up steps in the whole analytical process. Therefore a molecular imprinted polymer (MIP) has been previously developed for the selective extraction and the concentration of the alkyl methylphosphonic acids. Unfortunately, the selective retention process on this MIP has involved the development of hydrogen bonds and so does not allow the direct percolation of aqueous samples. A change of solvent is then necessary and can be performed using solid-phase extraction (SPE) with conventional non selective hydrophobic sorbents. Two polymeric sorbents, Oasis HLB and HR-P resins, were selected for their high specific surface area. The extraction recoveries obtained on both sorbents were compared and the Oasis HLB sorbent was further selected and used for the percolation of acidified aqueous samples. An optimised SPE procedure was then applied to concentrate an aqueous soil extract spiked with isobutyl methylphosphonic acid (iBMPA) and cyclopentyl methylphosphonic acid (cPMPA) that was further cleaned-up by passing through the MIP. The resulting LC-MS full scan chromatograms highlight the clean-up effect of the SPE-MIP association by the removal of the matrix substances and the preservation of 95% of the compounds of interest.

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.

Selective extraction of organophosphorus nerve agent degradation products by molecularly imprinted solid-phase extraction.

The analysis of alkyl alkylphosphonic acids, the degradation products of V and G nerve agents as VX, Sarin or Soman, is an important task for the verification of compliance to the Chemical Weapons Convention. The detection of these contaminants at low concentration levels is often difficult in complex matrices due to the amount of interfering substances. Molecularly imprinted solid-phase extraction technique should allow a selective extraction of these compounds from complex samples, and thus make their detection easier. Two molecularly imprinted polymers (MIPs) prepared with methacrylic acid (MAA) as monomer and pinacolyl methylphosphonic acid (PMPA) as template molecule were synthesised and tested. The first polymer, MIP A, was prepared with ethylene glycol dimethacrylate (EGDMA) in dichloromethane. The second polymer, MIP B, was synthesised using trimethylolpropane trimethacrylate (TRIM) in acetonitrile. To evaluate the selectivity provided by these MIPs, the retention of the ethyl methylphosphonic acid (EMPA) target molecule was studied in parallel on a non-imprinted polymer (NIP). While MIP A does not show any difference compared to NIP A, a good selectivity was obtained for MIP B. After the optimisation of the extraction process, 60% of EMPA can be removed from the NIP B without affecting the retention on the MIP B. A recovery of extraction of 93% was then obtained on the MIP B. Its capacity was then measured and corresponds to 97 microg of EMPA per gram of MIP. Finally, the selectivity of MIP B was clearly demonstrated by applying it to the clean-up of a soil extract spiked with EMPA.

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.