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Biomedical subjects

P A Martel

Publications and source records attributed to P A Martel.

7 recordsLinked to original sources
PubMed1990

Industrial employee drug screening: a blind study of laboratory performance using commercially prepared controls.

Reference laboratories are an integral component of any industrial employee drug screening program. We evaluated the performance and accuracy of the reference laboratories used by Rockwell International, a large industrial employer with an active drug screening program. A total of 829 commercially prepared control samples containing drugs of abuse, over-the-counter drugs, and analytes found in the normal employee population were disguised as routine submissions to reference laboratories used by nine Rockwell facilities. Analyses of results included compilation of false-positive and false-negative errors per drug per laboratory and a correlation of errors with preliminary and confirmation methods. Error rates of 2% false-positive results and 20% false-negative results were found for all laboratories. The errors were not limited to any one technique nor to any particular drug. The error rates observed suggest the need for routine blind testing programs and increased interaction between industry and laboratories.

Animals↗
PubMed1989

A rapid sample-preparation technique for thin-layer chromatographic analysis for 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in human urine.

In this rapid TLC method of analysis for the urinary cannabinoid metabolite, 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), hydrolyzed urine specimens are aspirated through a porous, alkyl-silica extraction layer located along the lower edge of a biphasic thin-layer chromatogram; THC-COOH is simultaneously extracted from the sample and concentrated on the TLC plate for subsequent migration and detection. The method, evaluated in a blind study, identified all samples containing THC-COOH greater than or equal to 20 micrograms/L. The technique increases samples throughput, sensitivity, and specificity as compared with conventional TLC methods and is applicable to a wide variety of compounds.

Chromatography, Thin Layer↗
PubMed1987

Laboratory detection of cannabinoids.

Cannabis, or marijuana, has been known and used as a drug for many thousands of years. Recent interest in drug abuse and detection has spurred the development of several methodologies for cannabinoid detection. These methods include immunoassays and chromatography. Laboratories routinely performing cannabinoid testing use two or more methodologies; the accepted method is to screen with one methodology and confirm by a second. These methodologies vary widely in sensitivity, specificity, and time required for analysis. Although therapeutic applications of cannabis constituents often produce undesirable side effects, two cannabinoids, delta 9-THC and nabilone, have been approved for use as antiemetics in chemotherapy. Further investigations of cannabinoid pharmacology and structure-activity relationships may result in the development of promising new therapeutic agents.

Cannabinoids↗
PubMedDate not supplied

Evaluation of a multiple-variable thin-layer and reversed-phase thin-layer chromatographic scheme for identification of basic and neutral drugs in an emergency toxicology setting.

An analytical scheme composed of one normal-phase thin-layer chromatographic (TLC) method, one reversed-phase thin-layer chromatographic (RPTLC) method, and sequential analyte detection through four stages of color reactions is described. Eighty-one basic or neutral drugs were analyzed with this scheme and seventy-four were uniquely characterized with 95% confidence. Six of the remaining seven formed three unresolved pairs. The scheme was evaluated by mean list length analysis and shown to offer analyte resolution similar to that of a scheme of TLC and gas chromatography (GC) with nonspecific detection. Nine out of ten unknowns from the field of eighty-one drugs were uniquely identified with 95% confidence by the TLC/RPTLC scheme. The tenth unknown was not completely resolved from its isomer, but was statistically the more probable candidate.

Chromatography, Thin Layer↗
PubMedDate not supplied

Drug population in one thousand geographically distributed urine specimens.

Hundreds of drugs and other substances are excreted in urine. In a comprehensive drug screen, it is impossible to identify every detectable substance. In order to delineate the most commonly detected drugs, approximately 1000 urine specimens from geographically distributed clinical laboratories were analyzed for drug substances. Twenty-nine (29) clinical laboratories submitted up to 76 consecutive urine specimens found to be positive for substances other than nicotine and caffeine. Specimens were analyzed by thin layer chromatography and special procedures for salicylates, benzoylecgonine, PCP, benzodiazepines, and cannabinoid metabolites. Every specimen was also tested for opiates, PCP, and cannabinoid metabolites by an enzyme immunoassay procedure. The total number of drugs detected in 1000 specimens was 3014, an average of three drugs per specimen; and 110 different drugs were identified. Of these, 50 drugs accounted for 95% of the total detected; 21% of the specimens contained cannabinoid metabolites, and 4% of the specimens contained cocaine and/or benzoylecgonine. Most of the specimens were routine, and only 4% originated from comatose patients.

Humans↗