Michael Schaffer

A comparison of enzyme immunoassay and gas chromatography/mass spectrometry in forensic toxicology.

A series of 137 urine samples were analyzed for drugs of abuse by enzyme immunoassay (EMIT) and by gas chromatography/mass spectrometry (GC/MS). Agreement between these methods was excellent and ranged from 93.4% for benzodiazepines to 98.5% for propoxyphene. EMIT false negative were traced to the presence of elevated endogenous lysozyme or other interfering materials. In the case of moderate amounts of lysozyme the use of a blank would lead to correct results. Disagreement in the identification of nine benzodiazepine samples was found to be due to a low recovery of benzodiazepine metabolites from urine. Recovery could be improved by incubation of the urine sample with the enzyme beta-glucuronidase.

A Purinethol (6-mercaptopurine) fatality in a case of prescription negligence: a gas chromatographic determination of 6-mercaptopurine.

A 64-year-old white female was given Purinethol (6-mercaptopurine) in place of propylthiouracil. A gas chromatographic method for the determination of 6-mercaptopurine in blood and other biological tissues has been developed. Samples were extracted with chloroform/isopropanol (4:1) at pH 7.0 and back-extracted into 0.5N sodium hydroxide (NaOH). The NaOH fraction was neutralized and buffered at pH 7.0 and extracted with chloroform/isopropanol (4:1). Quantitation was made by gas chromatography following methylation of the drug with trimethylanilinum hydroxide on an OV-101 or OV-225 column, using an internal standard. 6-Mercaptopurine was identified in all tissues by gas chromatography/mass spectrometry. The derivatized drug was identified by its electron impact mass spectrum as a dimethylated compound that has a molecular ion at m/e 180, which is also the base peak. The highest concentration of Purinethol was found in blood (110 mg/L). Concentrations in other tissues have been given. This is probably the first reported death by Purinethol.

Carboxy-THC in Washed Hair: Still the Reliable Indicator of Marijuana Ingestion

The presence of the metabolite 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (C-THC) in hair is generally accepted as the definitive proof of delta-9-tetrahydrocannabinol (THC) ingestion. During hair analysis, the removal of any potential C-THC external contamination that could result from marijuana smoke or close personal contact via a wash procedure is critical. Here, we performed a series of experiments to demonstrate that C-THC is the reliable indicator of marijuana ingestion when paired with the correct washing procedure to remove potential external contamination.

Spontaneous Live Birth with a Maternal History of Intravenous Use of Pentazocine and Tripelennamine (T's and Blues)

A 24-year-old black female presented a live birth of six-months gestation. The 700-g neonate survived for 11 h. After toxicology revealed the presence of pentazocine and tripelennamine (Ts and Blues), the mother admitted to using this combination intravenously 9 h previous to admission. Concentrations of pentazocine and tripelennamine were simultaneously determined by gas-liquid chromatography (GLC) combined with nitrogen selective detection. Analyses were performed on a 3% OV-101 column, with the added internal standard, dexbrompheniramine. Both pentazocine and tripelennamine were qualitatively confirmed by their electron impact mass spectra. Concentrations of pentazocine and tripelennamine in various fluids and tissues were determined.

Hair Analysis in Drugs-of-Abuse Testing

Compounds trapped in hair during growth collect and remain in the mature hair strand. Defined lengths of the hair strand can be analyzed to provide information on ingestion of a substance during the window of time corresponding to the growth period of the segment of hair analyzed. Both screening (immunoassay) and confirmation (liquid chromatography-tandem mass spectrometry, gas chromatography-mass spectrometry, gass chromatography-tandem mass spectrometry) methods for drugs in hair require methods of liquefaction and/or extraction of the solid hair fiber. Extensive washing of hair samples to remove external contamination and/or drugs from sweat prior to analysis is integral to a meaningful hair result, particularly to distinguish use from contamination and to utilize the hair’s ability to reflect dose. Some results of drugs-of-abuse analysis in washed hair of proven drug users ranged (in ng/10 mg hair) from the cut-offs to 2270 (cocaine), 559 (morphine), 79 (methamphetamine), and 150 (phencyclidine). The metabolite of cannabis use, carboxy-tetrahydrocannabinol, was present in users’ hair samples in amounts up to 76 pg/10 mg hair. Hair analysis for drugs of abuse is most widely used for pre-employment and workplace testing, but has also shown utility in criminal justice settings, for diagnostic and monitoring purposes in rehabilitation programs, in determining prenatal drug exposure, and other arenas.

Nail Analysis for Drugs: A Role in Workplace Testing?

Analysis of nail clippings may be a useful back-up for hair analysis when hair is unavailable. One aspect of using nails or hair is the ability to analyze whether drug present is from ingestion or from contamination. A common method of three 15-s rinses in methanol failed to remove drug from nails that had been soaked in either 5 or 50 μg/mL cocaine, methamphetamine or morphine for 1 h. While methanol rinsing did not remove contaminating drug, washing the nails soaked with 5 and 50 μg/mL of these drugs with an extended wash, a method developed for hair analysis and consisting of a 15-min isopropanol wash, and three 30-min and two 60-min phosphate buffer-0.1% albumin washes, when applied to nails did remove most of the contaminating drug. The drug left in the nails after extended washing could be interpreted as contamination by applying a wash criterion that is routinely applied in hair analysis. Successful decontamination of the soaked contaminated nail model was followed by applying this extended wash method to presumptive positive nail samples identified in workplace testing. While the extended buffer wash and wash criterion distinguish contamination from ingestion with hair, we failed to demonstrate that the method effectively differentiates contamination from ingestion with nails.