APPLICATION OF MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY TO FORENSIC ANALYSIS OF BARBITURATES IN BIOLOGICAL-FLUIDS

Micellar electrokinetic capillary chromatography (MECC) is a form of c apillary zone electrophoresis. Addition of a surfactant produces micel les in an aqueous/organic buffer. Separation of drugs is obtained via differences in the electrophoretic mobilities of the analytes within t he capillary, resulting from their electrophoretic velocity and the el ectroosmotic flow of the buffer in a given electric field. The migrati on order is determined by the differential partitioning of the drugs b etween the micelles and the aqueous/organic phase. Barbiturates were e xtracted from various biological fluids at pH 4.5 with TOXI-TUBES B. M ECC analyses were performed using a Waters Quanta 4000 Capillary Elect rophoretic System with a 745 Data Module with a 75 mu X 60 cm capillar y and an aqueous/organic buffer of 85% 10 mM berate, 10 mM phosphate, 100 mM sodium dodecyl sulfate and 15% acetonitrile at a pH of 8.5 with a voltage of 20 kV using ultraviolet absorption detection at 214 nm. Migration times were: phenobarbital, 7.78 min.; butalbital, 8.01 min.; butabarbital, 8.23 min.; mephobarbital (internal standard), 8.88 min. ; amobarbital, 9.41 min.; pentobarbital, 10.03 min. and secobarbital, 10.79 min. Correlation coefficients (r) between peak areas and concent ration ranges of 3 to 60 mu g/mL were from 0.964 to 0.999. Coefficient s of variation (CV) ranged from 2.6 to 8.6% between days and 2.3 to 9. 8% within day. Application of this methodology to four forensic cases of butalbital intoxication detected concentrations of 0.7 to 12.7 mu g /mL in blood; 0.8 to 1.9 mu g/mL in vitreous humor and 1.5 to 7.6 mu g /mL in urine. MECC is applicable to forensic analysis of barbiturates extracted from biological fluids.