Automated extraction and LC-MS-MS analysis of 11-nor-9-carboxy-tetrahydrocannabinol isomers and prevalence in authentic urine specimens.

11-Nor-9-carboxy-Δ9-tetrahydrocannabinol (Δ9-THCCOOH) is the most frequently detected illicit drug metabolite in the military drug testing program. An increasing number of specimens containing unresolved Δ8-THCCOOH prompted the addition of this analyte to the Department of Defense drug testing panel. A method was developed and validated for the quantitative confirmation of the carboxylated metabolites of Δ8- and Δ9-THC in urine samples utilizing automated pipette tip dispersive solid-phase extraction and analysis by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Analytes were separated isocratically over an 8.5-min runtime and detected on an MS-MS equipped with an electrospray ionization source operated in negative mode. A single point calibrator (15 ng/mL) forced through zero demonstrated linearity from 3 to 1,000 ng/mL. Intra- and inter-day precision were ≤9.1%, and bias was within ±14.1% for Δ8-THCCOOH and Δ9-THCCOOH. No interferences were found after challenging the method with different over-the-counter drugs, prescription pharmaceuticals, drugs of abuse and several cannabinoids and cannabinoid metabolites, including Δ10-THCCOOH. Urine specimens presumptively positive by immunoassay (n = 2,939; 50 ng/mL Δ9-THCCOOH cutoff) were confirmed with this analytical method. Δ8-THCCOOH and Δ9-THCCOOH were present together above the 15 ng/mL cutoff in 33% of specimens. However, nearly one-third of the specimens analyzed were positive for Δ8-THCCOOH only. This manuscript describes the first validated automated extraction and confirmation method for Δ8- and Δ9-THCCOOH in urine that provides adequate analyte separation in urine specimens with extreme isomer abundance ratios.

Modified Method for Detection of Benzoylecgonine in Human Urine by GC-MS: Derivatization Using Pentafluoropropanol/Acetic Anhydride.

An existing GC-MS method for detecting benzoylecgonine (BZE) in urine was modified by changing derivatizing reagents. This method modification presents a cost-effective alternative derivatization procedure for the detection of BZE in urine by GC-MS. The combination of pentafluoropropanol and acetic anhydride was found to produce the same reaction product for BZE as pentafluoropropanol with pentafluoropropionic anhydride, while reducing reagent cost. With no anhydride present, derivatization of BZE by pentafluoropropanol did not occur.

Phentermine interference and high L-methamphetamine concentration problems in GC-EI-MS SIM Analyses of R-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride-derivatized amphetamines and methamphetamines†.

In order to achieve chromatographic separation, urine samples shown to be initially positive for amphetamines and methamphetamines in US Department of Defense immunoassays are derivatized with R-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride (R-(-)-MTPA) prior to gas chromatography-electron impact-mass spectrometry (GC-EI-MS) analysis. Phentermine, a member of the phenethylamine class of drugs and a common appetite suppressant, interferes with GC-EI-MS assays of R-(-)-MTPA-derivatized d-amphetamine, degrading the chromatography of the internal standard and analyte ions and skewing concentration calculations. Additionally, when specimens with high concentrations of l-methamphetamine are derivatized with R-(-)-MTPA, signal peaks have the potential to be misidentified by integration software as d-methamphetamine. We have found that replacing R-(-) MTPA with (S)-(+)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride reduces phentermine interference problems related to internal standard chromatography, reduces the possibility of concentrated l-methamphetamine peaks being misidentified by integration software, improves resolution of d-methamphetamine in the presence of high l-methamphetamine concentrations, and is a cost-neutral change that can be applied to current amphetamines GC-EI-MS methods without the need for method modification.