Determination of Amino Acid Composition of Two Carp Species by GC-MS

Abstract

An isotopic dilution gas chromatography-mass spectrometric (ID-GC/MS) technique was used to evaluate the effects in quantitative amino acids of fish plasma after Se addition in food in comparison with control. The stable isotope internal standard used was ¹⁵N-methionine. A trace DSQ ThermoFinnigan quadrupole mass spectrometer coupled with a trace gas chromatography was used. Amino acids were separated on a Rtx-5MS capillary column, 30 m × 0.25 mm, 0.25 μm film thickness, using a temperature program from 50 ºC, 1 min, 6 ºC/min at 100 ºC, 4 ºC/min at 200 ºC, 20 ºC/min at 300 ºC, (3 min). The transfer line temperature was 250 ºC, the injector temperature 200 ºC and ion source temperature 250 ºC; splitter: 10:1. The amino acids were purified on a Dowex 50W-W8 exchange resin and derivatized in a procedure following two steps to obtain trifluoroacetyl butyl esters. Concentrations of majority of free amino acids as methionine, glutamic acid, aspartic acid, lysine, phenylalanine, increased with Se supplementation.