Examination of Firearms Review: 2007 to 2010 - Interpol

Reverse phase liquid chromatography (RPLC) has been widely used in
bioanalysis, but very polar compounds may be weakly retained. With the use
of a hydrophilic stationary phase and low-aqueous/ high-organic mobile phase,
hydrophilic interaction chromatography (HILIC) has been demonstrated to be a
powerful technique for the retention of polar analytes [247]. HILIC also proved
to improve MS sensitivity, allow higher flow rates, and reduce matrix effects
[248]. Because of its advantages over RPLC, there is an increased interest in
using HILIC in bio-analytical applications for drugs and their metabolites, which
are often polar in nature [244,249]. For example, cocaine and its metabolites,
especially ecgonine methyl ester, in hair samples [250], omeprazole and
lansoprazole in plasma [251], metoclopramide in plasma [252], estrogen
conjugates in urine [253], and acetylcholine, choline, and butyrobetaine in liver
tissues [254]. Analysis of polar analytes, such as the endogenous metabolite
trigonelline and the polar antibiotics amoxicillin in urine, using HILIC coupled to
NMR and MS, was also reported [255]. Analysis of EtG, could also be
performed by HILIC-MS/MS instead of GC; the latter requires derivatisation
[256].
Although HILIC gives good separations of polar compounds, neutral and
non-polar analytes generally show little retention [257]. To broaden the elution
window, pharmaceutical compounds were analysed using serial coupling of
reversed-phase and hydrophilic interaction liquid chromatography
(RPLC/HILIC) [258]. In addition, the use of low-aqueous/ high-organic mobile
phases in HILIC makes it possible for the eluent from SPE or liquid-liquid
extraction (LLE) to be directly injected to the HILIC column without
reconstitution, enabling high throughput and automated extractions
[247,251,255].
3.1.3 Capillary electrophoresis
The current application of capillary electrophoresis (CE) in forensic toxicology
has been reviewed with special focus on those areas where this technique has
shown real advantages over chromatographic methods, such as chiral drugs,
proteins, and alcohol biomarkers analyses [259].
The utilization of dynamic doubly coated capillaries for a fast separation of
methadone and its two major metabolites,
2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and
2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP), was investigated. Complete
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