Simultaneous capillary electrophoresis determination of barbiturates from meconium

Meconium is the first stool passed by a new born and, as such, represents a record of the fetal environment during the last two trimesters of pregnancy. We have developed the first capillary electrophoresis (CE) method for the analysis of meconium. This method has the potential to help tremendously in the study of fetal drug exposure. Solid-phase extraction (SPE) was used to extract the drugs (pento-, mepho-, pheno-, seco-, and amobarbital) and the internal standard, hexobarbital, from meconium. The extraction efficiency was studied using C-18, C-8, Silica (Si), and polymeric cartridges for samples buffered at pHs 2.5, 7.0, and 9.0. The polymeric (Oasis HLB) SPE cartridge at pH 9.0 was selected because it gave clean extractions and high recoveries for most of the studied barbiturates. The CE system consisted of a 75 mum I.D. 77 cm length fused silica capillary and a UV detector set at 254 nm. The run buffer consisted of 150 mM tris buffer at pH 7.8 and the run voltage was 25 kV (at 25degreesC). Linear calibration curves show a coefficient of determination of more than 0.99 for all components. The method also showed high between run and within run precision and accuracy. The limit of quantification was 10 mug per gram of meconium. Some common drugs such as aspirin, acetaminophen, and caffeine may be taken in conjunction with barbiturates. The method completely resolved these compounds, along with several other potential interferences, from all the barbiturates in this analysis.