Examination of Firearms Review: 2007 to 2010 - Interpol

microextraction (HF-LPME) [272].
Hollow fibre liquid-phase microextraction (HF-LPME) has an improved stability
and reliability over the SDME method, and may become the most widely used
LPME method [244]. It is an efficient technique for sample clean-up, with a
good extraction efficiency [273]. Its main disadvantage is that polar analytes
are difficult to extract, and the pH of the sample solution must be adjusted in
order to have total ionization of the analytes [267]. Recent studies using
HF-LPME included the determination of some antidepressant drugs
(imipramine, amitriptyline, and sertraline) in urine and plasma by HPLC [274],
progesterone in human serum by GC-MS [275], β-agonists and β-blockers
(clenbuterol, metoprolol, and propranolol) in urine, with derivatization by
N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) followed by GC-MS
[276], xenobiotics (DNP, DNOC, Dinoseb, and Dinoterb) in human plasma
using LC/ESI-MS [ 277 ], an anti-diabetic drug (pioglitazone) [ 278 ], and
antidepressants (amitriptyline, imipramine, and sertraline) [279] in biological
fluids by HPLC. An automated method was also developed for the
determination of flunitrazepam in plasma and urine samples using GC-MS/MS
[280].
3.2.2 Electrokinetic membrane extraction (EME)
In HF-LPME the driving force for the extraction of analytes is the passive
diffusion, and hence the extraction times typically range from 15 - 60 min
[267,281]. In electrokinetic membrane extraction, two electrodes, one in the
sample solution and the other in the acceptor solution, are placed such that
electrical field is the driving force for the extraction process; therefore, the
extraction time can be shortened to approximately 5 – 10 min [281,282].
Recent studies were reported using EME on basic drugs and acidic drugs
[283], basic drugs (pethidine, nortriptyline, tramadol, methadone, haloperidol,
and loperamide) from untreated human plasma and whole blood, with
recoveries at range 19 – 51% [284]. Basic drugs extraction using EME at low
voltage (9V) (obtainable by common batteries) was demonstrated by Kjeisen
et al. [285].
3.2.3 Solid-phase extractions (SPE)
Solid-phase extractions (SPE) are becoming a more popular extraction
method over the traditional LLE due to its lower solvent consumption, higher
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