STRUCTURE ELUCIDATION OF 2,4-DINITROPHENYLHYDRAZONE DERIVATIVES OF CARBONYL-COMPOUNDS IN AMBIENT AIR BY HPLC MS AND MULTIPLE MS/MS USING ATMOSPHERIC CHEMICAL-IONIZATION IN THE NEGATIVE-ION MODE/

Ion trap multiple fragmentation mass spectrometry (MSn) combined with high-performance liquid chromatography (HPLC) has been used for the st ructure elucidation and identification of 2,4-dinitrophenylhydrazone d erivatives of carbonyl compounds' in ambient air samples, Atmospheric pressure chemical ionization in the negative ion mode was the most sui table detection method. Different measures are described to decrease t he MS background originating from the HPLC system. Low-picogram quanti ties were detectable in extracted mass chromatograms generated from fu ll-scan records. Fragment ions produced by MS/MS allowed identificatio n of substructures of the carbonyls. Detailed fragmentation paths were studied by MS3 to MS4 using reference compounds. A fragmentation sche me was established which enabled a structure confirmation and identifi cation with 1-10 ng by HPLC/MS/MS. The identification of a compound co eluting with n-pentanal-DNPH and of a dimerization byproduct are given as examples.