A NOVEL FOCUSING INJECTION TECHNIQUE FOR CHEMILUMINESCENT DETECTION OF VOLATILE SULFUR-COMPOUNDS SEPARATED BY HRGC

A one meter stainless steel capillary column coated with a 20 mu m fil m of polydimethylsiloxane was used to replace the Teflon gas sampling loop of a HRGC - flameless SCD system. This column trap was equilibrat ed with the gaseous sample and then purged with carrier gas while bein g sequentially, resistively heated in ten 10 cm sections. The sequenti al heating of the 10 cm sections was timed such that the velocity of t he moving heated zone was approximately the same as the velocity of th e carrier gas. The thick stationary phase film served to retard the fr ont end of the injection band while the ballistic heating accelerated the back end. The net result was focusing of the injection, which gave rise to a narrower injection profile than that obtained with the orig inal Teflon loop.