Low level detection of chemical agent simulants in meat and milk by ion trap mass spectrometry

Analytical methods for the detection of two chemical warfare agent simulants, diisopropyl methylphosphonate and chloroethylethylsulfide, in beef tissue and milk have been demonstrated to be effective to levels as low as 50–100 parts-per-billion. These methods are based upon thermal desorption into an ion trap mass spectrometer. Selective detection of the target compounds is achieved by isobutane chemical ionization in combination with collision-induced dissociation, which yields characteristic fragment ions. Rapid sample clean-up steps were also devised to reduce interferences from the sample matrix. The low detection limits achieved with this method suggest that it may be possible to take small tissue samples from livestock by needle biopsy, without requiring animal sacrifice for the analysis. In addition, because the new methods may be performed more quickly than conventional methods requiring substantial sample preparation and analysis time, more samples could be analyzed.