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 sim ulants, 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 therm al desorption into an ion trap mass spectrometer. Selective detection of the target compounds is achieved by isobutane chemical ionization i n combination with collision-induced dissociation, which yields charac teristic fragment ions. Rapid sample clean-up steps were also devised to reduce interferences from the sample matrix. The low detection limi ts achieved with this method suggest that it may be possible to take s mall tissue samples from livestock by needle biopsy, without requiring animal sacrifice for the analysis. In addition, because the new metho ds may be performed more quickly than conventional methods requiring s ubstantial sample preparation and analysis time, more samples could be analyzed.