Studies of pesticides by collision-induced dissociation, postsource-decay,matrix-assisted laser desorption/ionization time of flight mass spectrometry

The use of collision-induced dissociation, postsource decay (CID-PSD) matri x-assisted laser desorption/ionization (MALDI) mass spectrometry for the an alysis of small organic molecules is demonstrated. Three pesticides: paraqu at, diquat, and difenzoquat were chosen for this study. The matrices 2,5-di hydroxybenzoic acid (DHB), alpha -cyano-4-hydroxycinnamic acid (alpha -CHCA ), and sinapinic acid (SA) were selected to investigate the effect of the m atrix on the CID-PSD MALDI spectra of these molecules. alpha -CHCA and DHB were found to be appropriate matrices for the pesticides studied. Spectra f or a given pesticide obtained from different matrices were compared with ea ch other, and the differences between them are discussed. A comparison of C ID-PSD MALDI with fast-atom bombardment MS/MS spectra is presented; the agr eement of pesticide fragmentation patterns between the two methods indicate s that CID-PSD MALDI MS is a reliable and efficient technique for structura l elucidation of small molecules. (J Am Soc Mass Spectrom 2001, 12, 590-598 ) (C) 2001 American Society for Mass Spectrometry.