Page 281 - Multidimensional Chromatography

276 Multidimensional Chromatography

1
(a)

3-4
6
5
2

30 40 50
Time (min)

(c)
(b)

0.82 2.25

25.75
25.67 17.33
14.66 17.20 26.77 2.66 26.86
12.88 2.04 2.55 11.91 16.37 26.09

Figure 11.10 (a) Micro-SEC–UV trace of Sustanon, where peak 2-5 were transferred to the
GC unit. Peak identification is as follows: 1, benzylalcohol; 2, testosterone propionate; 3,
testosterone isocaproate; 4, testosterone phenylpropionate; 5, testosterone decanoate; 6, oil
matrix; (b) GC analysis of the transfer (4 l) from the micro SEC system; (c) Direct GC anal-
ysis of a standard solution of the steroid esters. Reprinted from Proceedings of the 10th
Symposium on Capillary Chromatography, M. Ghys et al., ‘On-line micro size-exclusion
chromatography–capillary gas chromatography,’ 1989, with permission from Wiley-VCH.

Presently, the on-line coupling of NPLC and GC via heart-cutting is an estab-
lished procedure which has been used successfully for several bioanalytical applica-
tions. Obviously, direct analysis of aqueous samples is not possible by NPLC, and
therefore, a solvent switch by a sample pretreatment step (e.g. liquid–liquid
extraction or SPE) is always required when biological samples are analysed by
NPLC–GC.