Page 436 - Multidimensional Chromatography

428 Multidimensional Chromatography

Slack et al. have provided an example one of of the many types of forensic and
related analyses that can be performed by using SFE–GC (46). These authors ana-
lyzed several explosives from water using on-line SFE–GC and describe several of
the method development considerations. The SFE stage is essentially a non-selective
elution of the components of interest from the matrix as a group. This is followed by
selective elution using capillary gas chromatography. Figure 15.14 shows one of the
typical method development problems, i.e. the temperature of the trap between the
first (SFE) and second (GC) dimensions. Analyses of several explosives, using dif-
ferent trapping temperatures, are shown. It is seen that as the temperature of the trap
is decreased, the response for the earlier eluting compounds is increased, while little

2,4-DNT

Figure 15.14 Separation of explosives extracted from water by using SPE–SFE–GC at sev-
eral SFE trapping temperatures. peak identification is as follows: NG, nitroglycerin; 2,6-DNT,
2,6-dinitrotoluene; 2,4-DNT, 2,4-dinitrotoluene; TNT, trinitrotoluene; IS, 1,3-trichloroben-
zene. Adapted Journal of High Resolution Chromatography, 16, G. C. Slack et al., ‘Coupled
solid phase extraction supercritical fluid extraction–on-line gas chromatography of explosives
from water’, pp. 473-478, 1993, with permission from Wiley-VCH.