Chemical Warfare Agent Degradation Product Detection in Foods using a Combination of LC-ICP-MS and LC-ESI-MS

摘要

As the threat of terrorist attacks looms over the US, scientific methods must be developed to assess the nature and extent of a terrorist act. One route of attack entailing great concern is contamination of the food supply. In order to assess whether food has been exposed to toxins or poisons, methods must be developed. Whenever possible, methods developed for counterterrorism should be rapid, simple, robust and easily transferable to other laboratories. They should have broad applicability to a wide variety of matrices and have adequate sensitivity to detect and identify specific toxins, poisons or degradation products of the toxins or poisons. Such methods for the detection of phosphorous containing chemical warfare agent degradation products (CWADPs) are explained here. Organophosphorous CWADPs are similar in structures to inorganic phosphate, differing mainly in alkyl chain length. Their pK_(A) values are also very similar to inorganic phosphate, with pK_(A) values typically pK_(A1) approx 2. Previous work utilizing HPLC-ICP-MS experienced problems as inorganic phosphate coeluted with EMPA (a specific degradation product of VX). As ICP-MS is selective for phosphorus it renders no structural data, thus when coelution occurs, false identifications are possible. The methods presented here address the overlap in retention times of inorganic phosphate (which is present in virtually all real world samples) and analytes of interest in attempt to resolve the two. Using HPLC, they can be separated by their anionic/hydrophobic properties. Two separation methods are presented which utilize the PRP-X100 (Hamilton) column with the ~(31)P specific detection capabilities of ICP-MS. One of the two methods employs a buffer system which is compatible with ESI-MS allowing for additional structural confirmation that can not be provided by the ICP-MS.