Journal Published Online: 01 May 1999
Volume 44, Issue 3

Aqueous Phase Hexylchloroformate Derivatization and Solid Phase Microextraction: Determination of Benzoylecgonnine in Urine by Gas Chromatography-Quadrupole Ion Trap Mass Spectrometry



A derivatization/solid phase microextraction (SPME) method for the determination of benzoylecgonine in urine was developed. The derivatization is conducted directly in 1 mL of urine while sonicating for 3 min with 12 μL of hexyl chloroformate and 70 μL of a mixture containing acetonitrile:water:hexanol:2-dimethylaminopyridine (5:2:2:1 v/v), yielding benzoylecgonine hexyl ester (BHE) as the product. After the 3 min period, an aliquot of 250 μL is transferred to a vial for SPME. After the desired extraction time the 100 μm polydimethylsiloxane SPME fiber was transferred to the GC-MS for separation and analysis with a quadrupole ion trap mass spectrometer. The hexyl chloroformate derivatization and SPME procedures were optimized for compatibility and sensitivity. The method was found linear for 0.10 to 20.0 μg/mL (r2 = 0.999) of benzoylecgonine in urine using benzoylecgonine-d3 as an internal standard (1.5 μg/mL). Intra-day precisions were 8.8 and 6.8% RSD for 0.30 μg/mL and 17 μg/mL benzoylecgonine standards in urine (n = 6), respectively. Inter-day precision (n = 3) were ≤3.3% RSD, indicating good reproducibility. A detection limit of 0.03 μg/mL (S/N = 3) was achieved, thus making the SPME method a simplified alternative to SPE for GC-MS confirmation after EMIT tests for benzoylecgonine which have a cutoff of 0.30 μg/mL. Quantitative results by SPME and SPE of two clinical urine specimens known positive for cocaine by EMIT were in excellent agreement. Benzoylecgonine was detected by the derivatization/SPME method in 22 out of 22 other urine specimens known positive for cocaine.

Author Information

Hall, BJ
The University of Texas at Austin, Austin, TX
Parikh, AR
The University of Texas at Austin, Austin, TX
Brodbelt, JS
The University of Texas at Austin, Austin, TX
Pages: 8
Price: $25.00
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Stock #: JFS14504J
ISSN: 0022-1198
DOI: 10.1520/JFS14504J