Chromatographic behavior of bupivacaine and five of its major metabolites in human plasma, utilizing solid-phase extraction and capillary gas chromatography.
Bupivacaine and its five known metabolites were determined in underivatized form using capillary gas chromatography. Gas chromatography with mass spectrometry (GC-MS) and nitrogen-phosphorus detection was used for the determination of bupivacaine and its metabolites. A comparison between seven commercially available columns of differing polarity and from different manufacturers was made. Peak symmetries and retention factors varied significantly between the columns. The nonpolar columns (dimethylpolylsiloxane), Ultra1 and CP-Sil, gave good peak symmetries and an analysis time of 9 min with complete baseline separation for all of the analytes studied. The stability of the substances at different injector temperatures, 200-350 degrees C, was studied. The limit of detection was 0.13-0.16 pmol using GC-MS in positive chemical ionization mode. Different conditions for the extraction of analytes from plasma samples using solid-phase extraction (SPE) were investigated. Different sorbents (C(2), C(8), C(18), and ENV+, divinyl-polystyrene) were tested. The ENV+ phase gave recoveries of between 82-120% for all the analytes studied. Several attempts at varying the washing and elution steps in order to obtain a high recovery and clean extract were investigated.
Onnerud
Hans
H
ABB Power Technologies AB, SE-771 80 Ludvika, Sweden.
Bassiouny
Fatma
F
Abdel-Rehim
Mohamed
M
D002045:Bupivacaine / Q000031:analogs & derivatives / Q000097:blood; D004355:Drug Stability; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D016014:Linear Models; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000379:methods*; D013696:Temperature
D002045:Bupivacaine