Biomedical Engineering Reference
In-Depth Information
MS is a valuable alternative. They have successfully applied the method to clinical
and forensic serum samples of DUIDs cases and the results were in good correlation
to those obtained by offline SPE-GC-MS analysis.
A different application of SPE which needs 100-200 ml of sample has recently
been successfully applied to plasma. Micro SPE (mSPE) followed by HPLC-MS/
MS was used by Napoletano et al. [ 67 ] to determinate amphetamine, methamphet-
amine, MDA, MDE, MDMA, cocaine, BEG, mescaline, ketamine, PCP, psilocy-
bine in plasma. In this method 180 ml of plasma were submitted to slight PPT with
20 ml of methanol containing ISTD, 100 ml of supernatant were then collected and
passed through C18 tips, adapted to automatic pipettes. Validation results showed
mSPE allows to reduce matrix effect (£10 %) keeping satisfactory recoveries. m SPE
represent a simple, fast and reliable procedure with extremely reduced solvent con-
sumption; it will be discussed in more detail below in its other applications.
10.2
Oral Fluid as Alternative Matrix
Mandel in 1990 wrote that “Saliva lacks the drama of blood, the sincerity of sweat
and the emotional appeal of tears” [ 36 ]; however, the development of analytical
procedures for the determination of illicit drugs in OF has dramatically increased
over the last decade.
Sample collection is the first issue to study when developing analytical method:
it is very important to uniform and control the sampling methods [ 105- 107 ] . There
are different procedures reported in literature: spitting in a tube [ 93, 108 ] or differ-
ent sample collection devices [ 109- 111 ] .
10.2.1
PPT
A simple PPT was developed for plasma and OFs: recoveries of analytes from OF
are often higher when compared to plasma, but sonication before precipitation has
been proven necessary to help the analytes to release the protein binding, also in OF.
Developing a multiclass method with PPT has proved to be simpler in respect to
other extractive procedures, so it has been possible to obtain recoveries averaging
100 % and minimized matrix effects by the use of a deuterated ISTDs for each class
of substances [ 93 ] .
More recently Wang et al. have proposed analytical methods involving the use of
UHPLC-MS/MS to determine four opiates and metabolites, five amphetamines,
flunitrazepam and its two metabolites, cocaine and its four metabolites in OF.
Samples were collected by spitting in a tube, then the fluids were diluted with twice
the amount of distilled and deionized water and vortexed for 30 s. Liquid chroma-
tography was performed with a gradient elution and the total run time was 7.5 min.
The authors compared ESI, APCI, and APPI. The ion suppression ranged from
45 to 89 % and from 74 to 96 % on APCI and APPI, respectively. The authors
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