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Published:
Journal of Analytical Toxicology,
ISSN 0146-4760,
Volume 26, Number 6, September 2002,
pp. 325-332
A General Screening Method for Acidic, Neutral, and Basic
Drugs in Whole Blood using the Oasis MCX® Column
J. Yawney[1], S. Treacy[2], K.W. Hindmarsh[3], and F.J.
Burczynski[1],[4]
[1]Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, Canada;
[2]Royal Canadian Mounted Police Toxicology Laboratory, Winnipeg, Manitoba,
Canada;
[3]Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada; and
[4]Department of Pharmacology and Therapeutics, Faculty of Medicine, University
of Manitoba, Winnipeg, Manitoba, Canada
Solid-phase extraction (SPE)
is becoming a commonly used extraction technique. Most existing SPE methods
extract a single drug from a relatively clean biological matrix (e.g., plasma,
serum, or urine) using a silica-based column. These methods, however, are generally
not satisfactory for forensic applications because the majority of biological
samples are not as clean (e.g., whole blood, bile, tissues). Silica-based columns
also may have reproducibility and stability problems. Polymer-based columns
have been developed to overcome some of these limitations. In this study, sequential
extraction of acidic, neutral, and basic drugs from whole blood using a polymer-based
column, Oasis MCX, was undertaken. The extraction procedure developed involved
a conditioning step using methanol followed by water; a three-step wash sequence
using water, 0.1M hydrochloric acid, then water/methanol (95:5); and two elution
steps. One elution step was for acidic and neutral drugs utilizing acetone/chloroform
(1:1), and a second used ethyl acetate/ammonium hydroxide (98:2) for basic drugs.
Of the drugs tested, 75% were extractable from whole blood and detectable at
therapeutic concentrations. Good recoveries and clean extracts were achieved
for the basic drugs; however, the extracts were not as clean for acidic drugs.
Unfortunately, the Oasis MCX procedure was not suitable for extracting all drugs
(e.g., benzodiazepines). Reproduction
of editorial content of this journal is prohibited without publisher’s
permission.
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