Capillary gas chromatography oftert-butyldimethlysilylamino acids with PTV injection

Abstract

The programmable temperature vaporizing injector (PTV) has been used to study the effects of injection temperature and initial heating period on the FID response factors of TBDMS derivatives of 17 protein amino acids. The relative response factors were calculated for injection temperatures of 50°C, 90°C, 160°C, 220°C, and 260°C with different initial heating periods (1 s, 5 s, and 10 s) and the results compared with the values obtained for the calculated response factors obtained under classical split injection conditions (300°C, continuous). Except for expected peak broadening effects, the initial heating period does not seem to have significative effects on relative peak areas. The response to the derivatives of alanine, glycine, α-aminobutyric acid, valine, proline, methionine, cysteine, phenylalanine, asparagine, and arginine was only slightly affected by increasing the injection temperature whereas the response factors for the derivatives of serine, threonine, glutamic acid, lysine, histidine, tyrosine, and tryptophan were strongly dependent upon initial injection temperatures, decreasing rapidly at temperatures above 160°C. The cold split-splitless injection is clearly advantageous over the classical hot injection techniques for the analysis of this type of aminoacid derivative.