Silylation reagents for GC
Features

	Usually the term silylation in GC stands for replacement of active hydrogen atoms by a trimethylsilyl group (TMS derivative). Sometimes, however, trialkylsilyl groups or dimethylalkylsilyl groups with longer alkyl chains are used for derivatisation. The trialkylsilyl group increases volatility and enhances thermal stability of the sample.
	Silylation can be catalysed either acidic by addition of TMCS or basic by addition of pyridine or TSIM (e. g. for sterically hindered functionalities like tert. alcohols).
	Reactivity of silylation reagents (acc. to M. Donike): TMS amides (e. g. BSA, MSTFA) > TMS amine = TSIM > Enol-O-TMS ether > S-TMS ether > O-TMS ether > TMS-O-TMS
	Stability of the TMS derivatives: O-TMS ether > S-TMS ether > Enol-O-TMS ether > TMS amine > TMS amide

Summary of available silylation reagents

Compound	Code
N,O-bis-trimethylsilyl-acetamide	BSA
N,O-bis-trimethylsilyl-trifluoroacetamide	BSTFA
N-methyl-N-trimethylsilyl-trifluoroacetamide	MSTFA
N-methyl-N-trimethylsilyl-heptafluorobutyramide	MSHFBA
N-methyl-N-tert-butyldimethylsilyl-trifluoroacetamide	MBDSTFA
Dimethyldichlorosilane	DMCS
Hexamethyldisilazane	HMDS
Trimethylchlorosilane	TMCS
N-Trimethylsilyl-imidazole	TSIM
Mixtures of silylation reagents with or without pyridine	SILYL-Mixtures