Use of Solid-Phase Extraction in Determination of Chemical Warfare Agents

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Abstract
This paper gives a comprehensive evaluation of the solid-phase extraction technique for isolation of chemical warfare agents and related compounds from aqueous solutions. Several factors which may affect the amounts recovered by this method were investigated. These included sorbent type, amount of sorbent, pretreatment of the sorbent, type of eluting solvent, amount of eluting solvent and washing procedures. In addition, the degradation of compounds retained on the sorbent has been evaluated at different temperatures. Among several non-polar sorbents, octadecylsilane (C18) was found to give the highest yields. The amounts recovered depended on the sample volume and the amount of sorbent used. The sorbent may be washed with water after application of the samples in order to remove polar impurities. Methanol and acetone were most effective in eluting the compounds from the C18 sorbent, but isopropanol, dichloromethane, chloroform and diethylether could also be used. In order to prevent degradation of unstable compounds during storage and transport, the cartridges should be kept as cool as possible, and preferably in a freezer or a box filled with dry ice. This is especially important if the time between application and elution is more than 24 h.