ABSTRACT
II. EXPERIMENTAL A. Instrumentation A commercial gas chromatograph equipped with any kind of detector is required to apply the RF -GC technique, provided that it is slightly modified to include a T -shaped cell inside the chromatographic oven, and a four-port gas valve inside or outside of the oven. In principle, the whole experimental arrangement is not substantially different from those given and already described [1b,2b,4). For the applications mentioned at the end of the Introduction, which are the object of the present review, the exact arrangements are those given in Fig. 1 of Ref. 11 and Fig. 1 of Ref. 13. For the sake of convenience, they are both repeated here in Figs. 1 and 2. The only difference between these two figures is that the diffusion column (20-80 em x 3-5 rom inner diameter), connected perpendicularly to the sampling column (11.5 m x 3-5 mm inner diameter) at about its midpoint, in Fig. 1, it has the walls of the tube covered with a thin layer of adsorbent ( <0.5 rom thick), forming a so-called denuder tube, whereas in Fig. 2, a small length L 2 (4-9 em) near the closed end of the diffusion column is filled with particles of the adsorbent, forming a solid bed, similar to a catalytic bed. No solid or liquid material is put inside the
den:ucler coating
The carrier gas (helium, argon, nitrogen, artificial air, etc.) flows, via the valve only through the sampling column, at low flow rates (e.g., 20 cm3/min). No carrier gas flows through the denuder or the diffusion column and the solid bed, although these devices are filled wtih a stagnant column of the gas.
