Trace analysis of amino acids in Permian/Triassic boundary sediments by electron capture gas chromatography

Liu De-ming, Cao Chang-qun and Yang Qun

pp. 35-50, in English, with Chinese abstract

Abstract:

A new method for trace analysis of 21 amino acids, involving conversion of amino acids into corresponding amino acid derivatives by reaction with n-propanol and PFP anhydride, is presented. The amino acids with α-aminoisobutyric acid and isovaline as their N(O)-PFP n-propyl esters were separated by fused-silica capillary gas chromatography, and the determination was achieved by using split injection and electron capture detection of flame ionization. By using N(O)-PFP amino acid n-propyl esters, the electron-capture detection response was 300-600 times more sensitive than flame-ionization detection response. The electron-capture detection limits were in the low picogram range. This method was applied to trace determination of amino acids from Permian/Triassic (P/T) boundary sediments at Meishan in Zhejiang Province.

Chromatographic results show that no α- aminoisobutyric acid (AIB) and racemic isovaline (Iva) are present in the P/T boundary layers. The absence of AIB and Iva does not suggest an extraterrestrial cause related with the end-Permian mass extinction as proposed by some researchers.

In addition, also resolved on Chirasil-Val were N(O)-perfluoroacyl alkyl ester derivatives of some DL-amino acids. A better resolution could be obtained with N(O)-pentafluoropropionyl isopropyl and n-propyl esters. Coupled with electron capture detection, the N(O)-pentafluoropropionyl derivatives may be applied to molecular palaobiological studies.

Keywords: Amino acids, molecular palaeobiology, Permian/Triassic boundary sediments, electron capture detection, gas chromatography