The use of cyclohexanone as a "derivatizing" reagent for the GC-MS detection of amphetamines and ephedrines in seizures and the urine.

A GC-MS method has been developed for the detection of amphetamine, methamphetamine, and the ephedrines, in seizures and the urine, based on on-GC condensation (derivatization) with cyclohexanone. The method is simple: the dried seizure material or the urine extract was mixed with cyclohexanone and injected into the GC-MS. The method was found to be superior to the methods based on acyl and trimethylsilyl (TMS) derivatization. Unlike for the acyl and TMS derivatives, the molecular and fragment ions of the cyclohexanone condensation products (cyclohexanone derivatives) were of substantial abundance, a useful property in unambiguous compound characterization. Furthermore, the high stability of the "derivatizing" reagent, cyclohexanone, compared with acyl and TMS derivatizing reagents, is a useful property in method development. The present method has proved selective and, tentatively, sensitive enough in the following areas (where methods based on acyl and TMS derivatization, as tested in this laboratory, have failed): (a) detection of amphetamine as a metabolite of methamphetamine; (b) detection of norpseudoephedrine as a metabolite of pseudoephedrine; (c) detection of amphetamine as an impurity of methamphetamine; (d) detection of cathine (norephedrine) as a constituent of Khat leaves; and (e) differentiation of Khat use from phenylpropanolamine use.

Investigation into some aspects of EMIT d.a.u., TLC, and GC-MS urinalysis of bromazepam.

Among the different 1,4-benzodiazepine urinary metabolites, those of bromazepam possess distinctive chemical features that may be used in their selective isolation and detection. The detection of bromazepam metabolites in urine was carried out using EMIT d.a.u., thin-layer chromatography (TLC), and gas chromatography-mass spectrometry (GC-MS). The positive EMIT d.a.u. benzodiazepine assay for bromazepam was found to be due to the 3-hydroxybromazepam (3HOB) metabolite. The detection by TLC and GC-MS was carried out after enzyme or acid hydrolysis of the glucuronide conjugates. Both the 2-amino-3-hydroxy5-bromobenzoylpyridine (AHBBP) metabolite and the acid hydrolysis product of 3-HOB, 2-amino-5-bromobenzoylpyridine (ABBP), were selectively detected by TLC. The bromazepam metabolites in urine could be both isolated and detected selectively by GC-MS in the presence of the metabolites of other 1,4-benzodiazepines that were sometimes used in combination with bromazepam. Both 3-HOB and AHBBP were detected by GC-MS only after trimethylsilyl (TMS) derivatization and not as the free compounds or the acetyl derivatives. Only ABBP was detected in three forms: ABBP, the TMS derivative, and the acetyl derivative. Evidence has been obtained from the enzyme hydrolysis and the TLC studies for the formation of the glucuronide conjugate of AHBBP at the 3-OH group rather than at the 2-NH2 group. All the results have been validated using reference 3-HOB and AHBBP.

A GC-MS method for the detection of toluene and ethylbenzene in volatile substance abuse.

The interference of some substances with the gas chromatography-flame ionization detection and gas chromatography-Fourier transform infrared detection of toluene and ethylbenzene in volatile substance abuse poses problems. A gas chromatography-mass spectrometry (GC-MS) method that will overcome such interference has been developed for the detection of toluene and/or ethylbenzene in the headspace of preparations and products containing these substances and in the headspace of blood samples in the cases of volatile substance abuse. The method is based on converting toluene to benzoic acid via the formation of benzotrichloride. The latter compound was obtained upon the reaction of toluene with chlorine gas under direct sunlight conditions. In the presence of water, benzotrichloride was converted to benzoic acid. Ethylbenzene was converted to benzoic acid and two phenylethanols via the formation of side chain chloro-substituted phenylethanes followed by reaction with water. The chloro-substituted phenylethanes were obtained by the reaction of ethylbenzene with chlorine under direct sunlight conditions. The benzoic acid resulting from toluene and/or ethylbenzene and the two phenylethanols resulting from ethylbenzene were detected by GC-MS as their trimethylsilyl (TMS) derivatives. For the method to be viable for the detection of volatile substance abuse, the chlorination reactions were effected in the gaseous state.

The GC/MS analysis of some commonly used non-steriodal anti-inflammatory drugs (NSAIDs) in pharmaceutical dosage forms and in urine.

All the commonly used non-steriodal anti-inflammatory drugs (NSAIDs), except mefenamic acid, when extracted from the pharmaceutical dosage forms or the urines of users, and derivatized by silylation and then analysed by GC/MS, gave the mono- or the di-trimethylsilyl derivatives (depending on the number of derivatized groups in the drug) as the sole products. Mefenamic acid gave a mixture of products. When extracted from pharmaceutical dosage froms or from the urines of users, and analysed by GC/MS without derivatization, some of the NSAIDs were separated and detected as the unchanged molecules as the sole products, while others were separated and detected in altered forms as sole products or mixtures, depending on: (a) the solvent in which the extract was dissolved for injection into GC/MS, (b) the chemical structure of the drug, and (c) specifically for diflunisal, the presence or absence of potential methylating and/or acetylating agents on the GC column and/or septum. The main thermally-induced reactions of the underivatized NSAIDs included (i) methyl ester formation at the COOH group when the extract was dissolved in methanol, (ii) decarboxylation (i.e., loss of CO2), (iii) dehydration (i.e., loss of H2O) when the chemical structure permitted, such as for diclofenac, and (iv) cleavage at a carbon-heterocyclic nitrogen bond when one is present in an NSAID. Heating the urine in approximately 2 M HCl at 100 degrees C for 30 min, has been found to be a satisfactory means for effecting hydrolysis of the NSAIDs glucuronide conjugates. No metabolites, resulting from aromatic-ring hydroxylation, have been detected in urine for any of the NSAIDs studied.