2-STAGE MICROTRAP AS AN INJECTION DEVICE FOR CONTINUOUS ONLINE GAS-CHROMATOGRAPHIC MONITORING

A microtrap is a small diameter sorbent trap packed with adsorbent. In previous studies it has been used as a concentration cum injection de vice for on-line GC monitoring of trace level organics. The microtrap is prone to breakthrough as it contains a small quantity of adsorbent. A larger diameter trap with more adsorbent reduces breakthrough, but generates broad injection bands that reduce chromatographic resolution , in this paper, we present a two-stage microtrap system. The first, a large diameter retention trap is packed with more sorbent material to increase the breakthrough volume or time. The retention trap is desor bed and the analytes are refocused onto the smaller diameter microtrap referred to as the injection trap. A few seconds delay is provided an d then the injection microtrap is desorbed to generate a sharp band in jection for GC separation. (C) 1998 Elsevier Science B.V.