Page 287 - Multidimensional Chromatography

282 Multidimensional Chromatography

Figure 11.14 Analysis of amphetamines by GC-NPD following HS-SPME extraction from
human hair: (a) Normal hair; (b) normal hair after addition of amphetamine (1.5 ng) and
methamphetamine (16.1 ng); (c) hair of an amphetamine abuser. Peak identification is as fol-
lows: 1, -phenethylamine (internal standard); 2, amphetamine; 3, methamphetamine; 4, N-
propyl- -phenethyamine (internal standard). Reprinted from Journal of Chronatography, B
707, I. Koide et al., ‘Determination of amphetamine and methamphetamine in human hair by
headspace solid-phase microextraction and gas chromatography with nitrogen-phosphorus
detection,’ pp. 99–104, copyright 1998, with permission from Elsevier Science.

analytes are either thermally desorbed into the GC unit or re-dissolved in a proper
solvent for LC. Coupling to the LC system requires an appropriate interface and
was first reported in 1995. The technique was commercialized in 1993 by Supelco.
The initial work was exclusively done with SPME–GC (135–137), due to the
direct and convenient sample introduction into the GC system, while the main
application area being environmental analysis. Recently, SPME is being increas-
ingly used in bioanalysis. Successful coupling with LC systems enables the analy-
sis of pharmaceuticals, proteins and surfactants that cannot be analysed by GC. Up
until now, only a few papers have described the use of direct-immersion SPME for
plasma analysis (138–141). For plasma and blood samples, the relevant drug parti-
tions between the fibre, sample and proteins. Models for the relationship between
the total amount of the drug present in the plasma and the amount of drug extracted
have been developed (138, 139). In this way, a good approximation of the
drug–protein binding can also be obtained. A few other typical bioanalytical exam-
ples will be discussed below.
In a recent report, HS-SPME was used for the extraction of amphetamines from
human hair (142). Human hair analysis is gaining interest in the analysis of drugs of
abuse, since it offers attractive features: easy and ‘unlimited’ sampling, and as the