Journal Published Online: 01 November 1994
Volume 39, Issue 6

Improved Gas Chromatography/Mass Spectrometry Analysis of Barbiturates in Urine Using Centrifuge-Based Solid-Phase Extraction, Methylation, with d -Pentobarbital as Internal Standard

CODEN: JFSCAS

Abstract

Effective solid-phase extraction, derivatization, and GC/MS procedures are developed for the simultaneous determinations of butalbital, amobarbital, pentobarbital, and secobarbital, using a deuterated pentobarbital (d5-pentobarbital) as the internal standard. Buffered (pH 7) urine samples were extracted with Bond Elute Certify II™ cartridge. Iodomethane/ tetramethylammonium hydroxide in dimethylsulfoxide was used for methylation, while a HP 5970 MSD equipped with a 13 m J & W DB-5 column (5% phenyl polysiloxane phase) and the Thru-Put Target® software package were used for GC/MS analysis and data processing. This protocol was found to be superior, in both chromatographic performance characteristics and quantitation results, over a liquid-liquid extraction procedure without derivatization using hexobarbital as the internal standard. Extraction recoveries observed from control samples containing four barbiturates range from 80% to 90%. Good one-point calibration data are obtained for all four barbiturates in the 50 to 3200 ng/mL range. Interestingly, the one-point calibration data for pentobarbital are inferior to the other three barbiturates—due to interference from the internal standard (d5-pentobarbital). The calibration data of pentobarbital are best described by a hyperbolic curve regression model. Precision data (% CV) for GC/MS analysis, over-all procedure, and day-to-day performance are approximately 2.0%, 6.0%, and 8.0%, respectively. With the use of a 2 mL sample size, the attainable detection limit is approximately 20 ng/mL.

Author Information

Liu, RH
University of Alabama at Birmingham, Birmingham, AL Environmental Health Research and Testing, Inc., Birmingham, AL
McKeehan, AM
Environmental Health Research and Testing, Inc., Birmingham, AL
Edwards, C
Environmental Health Research and Testing, Inc., Birmingham, AL
Foster, G
University of Alabama at Birmingham, Birmingham, AL Environmental Health Research and Testing, Inc., Birmingham, AL
Bensley, WD
University of Alabama at Birmingham, Birmingham, AL
Langner, JG
Environmental Health Research and Testing, Inc., Birmingham, AL
Walia, AS
Environmental Health Research and Testing, Inc., Birmingham, AL
Pages: 11
Price: $25.00
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Stock #: JFS13737J
ISSN: 0022-1198
DOI: 10.1520/JFS13737J