NOVEL PRECONCENTRATION TECHNIQUE FOR ONLINE COUPLING TO HIGH-SPEED NARROW-BORE CAPILLARY GAS-CHROMATOGRAPHY - SAMPLE ENRICHMENT BY EQUILIBRIUM (AB)SORPTION - I - PRINCIPLES AND THEORETICAL ASPECTS

In recent years, there has been substantial progress in the field of h igh-speed narrow-bore capillary gas chromatography (GC) in general, an d in the development of (trans)portable gas chromatographs for fast an d accurate analysis in field applications in particular. Due to the li mited (concentration) sensitivity of instrumentation for high-speed (p ortable) GC, environmental applications of this technique frequently r equire a preconcentration step. The equilibrium (ab)sorption technique described in this article was found to be very promising for on-line coupling to high-speed narrow-bore capillary GC and field portable GC instruments. Enrichment factors up to at least 100 can be obtained rap idly without the use of complicated instrumentation. The new preconcen tration technique is shown to have clear advantages over enrichment ba sed on conventional adsorption, i.e. thermal desorption techniques. It can be carried out at ambient trapping temperatures, gives uniform de sorption profiles, reduces water effects, uses inert adsorption materi als and does not require a (cryogenic) refocusing step. Moreover, the new preconcentration method allows the enrichment factors to be predic ted from tabulated chromatographic data, thereby facilitating calibrat ion. (C) 1997 Elsevier Science B.V.