, N,O-bis(trimethylsily)trifluoroacetamide; El, electron ionization; FBS, foetal bovine serum; GC-MS, gas chromatography-mass spectrometry; NCI, National Cancer Institute; SRB, sulforhodamine B; TCA, trichloroacetic acid; TMCS, chlorotrimethylsilane; TMSi, trimethylsilyl.
4] Nonstandard abbreviations: MAMP, methamphetamine; AMP, amphetamine; MDMA, 3,4-methylenedioxymethamphetamine; MDA, 3,4-methylenedioxyamphetamine; LOQ, limit of quantification; SAMHSA, Substance Abuse and Mental Health Services Administration; BSTFA
, N,O-bis(trimethylsilyl)trifluoroacetamide; MTBSTFA, N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide; TBDMCS, tert-butyldimethylchlorosilane; SPE, solid-phase extraction.
Seven calibration standards, ranging from 15 to 1,000 ng/[micro]L, were prepared in acetonitrile and derivatized using BSTFA
under the same conditions as samples before GC-MS analysis.
These were then derivatized with a few drops of BSTFA
, with 1% TMCS.
Derivatization prior to GC/MS analysis was performed with 250 [micro]l of BSTFA
, vigorous vortexing and incubation at 70 [degrees]C for 20 min.
(20 [micro]L containing 1% TMCS) was added, and the mixture heated for 15 min at 80[degrees]C.
To avoid BPA contamination occurring from leaching of parent BPA from the derivatization reagent, bis(trimethylsilyl)trifluoroacetamide (BSTFA
; Sulpeco, Deisenhofen, Germany), into the human samples, the vials with the dry samples were placed in 5-mL screw cap septum glass reaction vials (so-called external derivatization) containing 100 [micro]L BSTFA
, instead of directly adding BSTFA
to the dry samples (internal derivatization).
One mg of dry extract was reacted with 50 [micro]l pyridine + 100 [micro]l BSTFA
including 1% TMCS in a sealed glass tube for 30 min at 100 [degrees]C to prepare samples for gas chromatography.
A 20-[micro]L aliquot of BSTFA
+ 1% TMCS was added, vials were crimp-capped, and samples were heated at 80[degrees]C for 45 min.
+ 1% TMCS (20 [micro]L) was added to each vial, and extracts were crimp-capped and heated at 80[degrees]C for 45 min.
Fatty acids were converted into their nonionic forms with HCl, reextracted in hexane, dried, and then derivatized to TMS esters with BSTFA
+ 5% trimethylsilane for 30 min at 70 [degrees]C.
The residue was trimethylsilylated with 60 [micro]L of BSTFA
+ TMCS and 60 [micro]L of pyridine at 90[degrees]C for 30 min.