Detection of pesticides from liquid matrices by ion mobility spectrometry

The detection of different pesticide compounds from liquid matrices was ach ieved by aspiration ion mobility spectrometry. This technique is based on i on mobility which is proportional to the molecular weight and charge. The i on mobility spectrometer is able to measure mobility changes of product ion s as well as mobility changes of reactant ions. In the ion mobility spectro meter used, it is possible to measure positive and negative ion clusters at the same lime in six different electrodes. Each measuring electrode detect s a different portion of the ion mobility distribution formed within the ce ll's radioactive source. The pattern recognition used is based on differenc es in the gas phase profiles of the different compounds. The results of thi s study reveal that the ion mobility spectrometer MGD-1 can also be used to measure pesticides even from liquid matrices. On the basis of projection c alculation, the responses for 2-propanol (= background) and pesticide compo unds were easily separated from each other. The greatest responses for pest icides were seen in the 2nd positive channel. Correspondingly, only minor b ackground signals were measured in the Ist and 2nd positive channels. The d etection limits of pesticides were at ng or mu g levels. The sensitivity of detection of the ion mobility spectrometer for different pesticides decrea sed in the order: diazinon, aldicarb, dimethoate and parathion. In comparis on with the traditional ion mobility spectrometric technique, the main adva ntages of this aspiration technique are its fast response, high sensitivity , real time vapor monitoring, straightforward maintenance and low cost. In addition, the cell tolerates high chemical concentrations and still recover s quickly. (C)2000 Elsevier Science B.V. All rights reserved.