ac5b02599_si_002.pdf (325.2 kB)
Quantitative Silylation Speciations of Primary Phenylalkyl Amines, Including Amphetamine and 3,4-Methylenedioxyamphetamine Prior to Their Analysis by GC/MS
journal contribution
posted on 2015-10-20, 00:00 authored by Borbála Molnár, Blanka Fodor, Imre Boldizsár, Ibolya Molnár-PerlA novel,
quantitative trimethylsilylation approach derivatizing
11 primary phenylalkyl amines (PPAAs), including amphetamine (A) and
3,4-methylenedioxyamphetamine (MDA), was noted. Triggering the fully
derivatized ditrimethylsilyl (diTMS) species with the N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA)
reagent, a new principle was recognized followed by GC/MS. In the
course of method optimization, the complementary impact of solvents
(acetonitrile, ACN; ethyl acetate, ETAC; pyridine, PYR) and catalysts
(trimethylchlorosilane, TMCS; trimethyliodosilane, TMIS) was studied:
the role of solvent and catalyst proved to be equally crucial. Optimum,
proportional, huge responses were obtained with the MSTFA/PYR = 2/1–9/1
(v/v) reagent applying catalysts; A and MDA needed the TMIS, while
the rest of PPAAs provided the diTMS products also with TMCS. Similar
to derivatives generated with hexamethyldisilazane and perfluorocarboxylic
acid (HMDS and PFCA) (Molnár
et al. Anal. Chem. 2015, 87, 848−852), the fully
silylated PPAAs offer several advantages. Both of our methods save
time and cost by allowing for direct injection of analytes into the
column; this is in stark contrast with the requirement to evaporate
acid anhydrides by nitrogen prior to their injection. Efficiences
of the novel catalyzed trimethylsilylation (MSTFA) and our recently
introduced (now, for A and MDA extended) acylation principle were
contrasted. Catalyzed trimethylsilylation led to diTMS derivatives
resulting in on average a 1.7 times larger response compared to the
corresponding acylated species. Catalyzed trimethylsilylation of PPAAs,
A, and MDA were characterized with retention, mass fragmentation,
and analytical performance properties (R2, LOQ values). The practical utility of ditrimethylsilyation was
shown by analyzing A in urine and mescaline (MSC) in cactus samples.