|SOFT - TIAFT 1998||Poster Session 4||Friday October 9, 1998|
DETERMINATION OF BUTALBITAL, SECOBARBITAL AND PHENOBARBITAL IN A DEPARTMENT OF DEFENSE DRUG TESTING LABORATORY BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY|
Delores M Ragsdale, Paula J Underwood, Gerald E Kananen, Edwin K Armitage
Forensic Toxicology Drug Testing Laboratory, Fort Meade, MD 20755, USA
|As part of a mission requirement to support Department of Defense (DoD) urine drugs of abuse testing policy, this laboratory established a procedure for the determination of butalbital, secobarbital and phenobarbital in urine at DoD specified cutoffs. The importance of this determination is in it providing technically and forensically supportable test results for these analytes. This procedure could also be applied to other forensic or clinical applications.
Established procedures using a SPE column extraction of the analyte with SIM analysis of an TMAH/DMSO derivative were modified to incorporate the use of butalbital-D5, secobarbital-D5, and phenobarbital-D5 internal standards. Selection of this deuterated internal standard combination was driven by availability and practical qualifying ion ratio characteristics.
Limits of detection were determined as 75 ng/ml for butalbital, 50 ng/mL for secobarbital and 25 ng/mL for phenobarbital. Cutoff precision was established with a CV of 1.42% for butalbital, 1.58% for secobarbital and 1.32% for phenobarbital. Linearity was determined over the range of lower limit of quantitation of 75 ng/mL to an upper limit of quantitation of 3000, 1000 and 4000 for butalbital, secobarbital and phenobarbital respectively. (Butalbital, y = 0.972x + 11.05, R = 0.9987, secobarbital, y = 1.036x + 4.67, R = 0.9991 and phenobarbital, y = 0.930x + 16.33, R = 0.9996). Linearity was also determined over the range of limit of detection to upper limit of quantitation (Butalbital, y = 1.022x +1.58, R = 0.9999, secobarbital, y = 1.043x - 3.72, R = 0.9996 and phenobarbital, y = 1.094x - 10.68, R = 0.9998).
The assay was verified through participation in an open proficiency program in which the laboratory has performed all barbiturate open proficiency specimens within acceptable limits. The laboratory control materials are 75 ng/mL low control, 200 ng/mL non-extracted, and 300 ng/mL high control and are listed as mean, one standard deviation, coefficient of variation (%) and n respectively . For butalbital 75 ng/mL ( 75.3, 1.43, 1.8%, 29) 200 ng/mL (214.3, 4.77, 2.2, 29) and 300 ng/mL ( 313.6, 7.0, 2.32, 29). For secobarbital 75 ng/mL ( 74.2, 1.58, 2.1%, 29) 200 ng/mL (218.9, 5.9, 2.1, 29) and 300 ng/mL ( 314.7, 6.9, 2.2, 29). For phenobarbital 75 ng/mL ( 71.7, 1.84, 2.6%, 30) 200 ng/mL (208.4, 7.8, 2.6, 30) and 300 ng/mL ( 312.6, 9.0, 2.9, 30).