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

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) and N-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)(2)Si](+), [M-TMS/(TBDMS)COO](+), [M-TBDMSOH](+), [M-TBDMSO](+), [M-TBDMSNH](+) and numerous others could be utilized for identification purposes.