Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
39, Number 4, January 2001, pp. 129-136
Use
of a Statistically Designed Experimental Approach to Optimize the Propylketal
Derivatization of BarbituratesMark
M. Kushnir*,[1] and Francis M. Urry[2]
[1] ARUP Institute for Clinical and Experimental Pathology, Salt Lake City,
UT 84108 and
[2] Department of Pathology, University of Utah School of Medicine, Salt Lake
City, UT 84112
The derivatization
of barbiturates with dimethylformamide dipropylacetal and dimethylformamide
diisopropylacetal is studied with respect to the optimization of reaction recovery
and reliability. A second-order orthogonal experimental design is utilized in
order to obtain regression equations for the reaction recovery dependence on
the derivatization solution composition, incubation temperature, and time for
amobarbital, butalbital, pentobarbital, phenobarbital, and secobarbital. Regression
equations for the effect of incubation temperature and time on the derivative
recovery and the optimum conditions for derivatization recoveries are obtained.
Differences in the phenomena of the derivative formation are evaluated between
the two derivatizing reagents and the barbiturates. Based on the analysis of
the obtained equations, it is concluded that the dipropylketal derivative of
barbiturates is superior in comparison with diisopropylketal when considering
the milder conditions of the reaction, absence of sudden changes in the recovery
with a variation in the derivatization parameters, and reliability for the simultaneous
testing of the barbiturates. A method for the routine testing of the barbiturates
by gas chromatography–mass spectrometry in urine specimens is included.
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