Two-stage microtrap as an injection device for continuous on-line gas chromatographic monitoring

A microtrap is a small diameter sorbent trap packed with adsorbent. In previous studies it has been used as a concentration cure injection device 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 desorbed and the analytes are refocused onto the smaller diameter microtrap referred to as the injection trap. A few seconds delay is provided and then the injection microtrap is desorbed to generate a sharp band injection for GC separation.