GC-MS of amino acids as their trimethylsilyl/t-butyldimethylsilyl Derivatives: In model solutions III

Summary Fragmentation patterns of the essential amino acids (AAs) as their silyl derivatives have been obtained with the aid of ion trap detection (ITD). Three derivatizing reagents, hexamethyldisilazane+trifluoroacetic acid (HMDS+TFAA),bis-(trimethylsilyl)trifluoroacetamide (BSTFA) andN-methyl-N-(t-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) were used. Simple and multiple derivatives obtained with each reagent have been investigated, with regard to their sensitivity and selectivity. Our study performed in the concentration range of 5-2000 ng amino acids has shown that, contrary to literature data, thirteen of the twenty-two AAs investigated including the TBDMS derivatives give rise to more than one peak when eluted. As a result of ion/molecule interaction the very informative ions of high masses, (M]⁺, M+TMS/(TBDMS)]⁺, M+1]⁺) are formed with considerable intensities. The fragments M-CH₃]⁺, M-C₄H₉]⁺, M-(CH₃)₂Si]⁺, M-TMS/(TBDMS)COO]⁺, M-TBDMSOH]⁺, M-TBDMSO]⁺, M-TBDMSNH]⁺ and numerous others could be utilized for identification purposes. Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999