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Biomedical and Pharmaceutical Applications 281

(a)

(b)

FID Response NE NG ß-19-NT

(c)

28 29 30 31 32 33 34 35
(d) Time (min)

0 5 10 15 20 25 30 35
Time (min)
Figure 11.13 (a–c) Immunoaffinity extraction-SPE–GC-FID traces of (a) HPLC-grade
water (b) urine (c) urine spiked with -19-nortestostrone (0.5 g/l) or norethindrone and
norgestrel (both 4 g/l); (d) SPE–GC-FID trace of urine. Reprinted from Analytical
Chemistry, 63, A. Farjam et al., ‘Direct introduction of large-volume urine samples into an
on-line immunoaffinity sample pretreatment-capillary gas chromatography system,’ pp.
2481–2487, 1991, with permission from the American Chemical Society.

is exposed to the sample by suppressing the plunger. Sorption of the analytes on the
fibre takes place in either the sample by direct-immersion or the headspace (HS) of
the sample. After equilibrium or a well-defined time, the fibre is withdrawn in the
septum piercing needle and introduced into the analytical instrument where the