B. Law

Forensic aspects of the metabolism and excretion of cannabinoids following oral ingestion of cannabis resin

Following oral ingestion of cannabis resin, δ9‐THC−11−oic acid and its O‐ester glucuronide were detected using RIA and combined hplc/RIA and shown to be major plasma metabolites of δ9‐THC. δ9‐THC−11−oic acid was not excreted in the urine in significant concentrations, the glucuronide conjugate being the major urinary metabolite detected. δ9‐THC metabolites were detected in blood for up to 5 days and in urine for up to 12 days following a single oral dose of δ9‐THC (20 mg). Estimates for the half life of δ9‐THC−11−oic acid and its glucuronide in plasma, and total metabolites in urine have been obtained. Interpretation of blood or urine total cannabinoid levels is most difficult, however, drug/metabolite ratios and metabolite/metabolite ratios may have potential for indicating recent cannabis use.

High-performance liquid chromatography retention data for 84 basic drugs of forensic interest on a silica column using an aqueous methanol eluent

High-performance liquid chromatography retention characteristics have been measured for 84 basic drugs of forensic interest using a silica column with a methanol-aqueous ammonium nitrate eluent. The drugs are from two classes of major interest, namely, the narcotic analgesics (including antagonists, metabolites and analogues) and drugs structurally and pharmacologically related to amphetamine.

High-performance liquid chromatography systems for the separation of benzodiazepines and their metabolites

The high-performance liquid chromatographic (HPLC) retention characteristics of 21 benzodiazepine drugs and some of their metabolites have been examined on both silica and ODS-silica packing materials. Four HPLC systems have been considered and retention data are presented for the drugs on these systems. The correlation of retention data on the systems is considered with reference to the problem of identifying unknown benzodiazepines.

Passive inhalation of cannabis smoke

Six volunteers each smoked simultaneously, in a small unventilated room (volume 27 950 litre), a cannabis cigarette containing 17·1 mg Δ9‐tetrahydrocannabinol (THC). A further four subjects – passive inhalers – remained in the room during smoking and afterwards for a total of 3 h. Blood and urine samples were taken from all ten subjects and analysed by radioimmunoassay for THC metabolites. The blood samples from the passive subjects taken up to 3 h after the start of exposure to cannabis smoke showed a complete absence of cannabinoids. In contrast, their urine samples taken up to 6 h after exposure showed significant concentrations of cannabinoid metabolites (≤6·8 ng ml−1). These data, taken with the results of other workers, show passive inhalation of cannabis smoke to be possible. These results have important implications for forensic toxicologists who are frequently called upon to interpret cannabinoid levels in body fluids.

A computer search system for the identification of drugs using a combination of thin-layer chromatographic, gas-liquid chromatographic and ultraviolet spectroscopic data

A computer-based retrieval system has been developed for the identification of drugs and poisons in forensic toxicology using thin-layer chromatographic, gas-liquid chromatographic and ultraviolet spectroscopic data. The data collection has been compiled from various published and unpublished sources and contains information for over 1600 compounds. The retrieval program uses the concept of discrepancy index to match experimental data for an unknown with the information in the data file. Additional features include a series of help routines for new users and the facility to retrieve information on specific compounds or groups of compounds in the data collection.

Development and evaluation of a radioimmunoassay for the analysis of body fluids to determine the presence of tricyclic antidepressant drugs.

A radioimmunoassay has been developed for the direct detection of tricyclic antidepressant drugs in blood and urine. It is based on a radioiodinated derivative of desipramine and this allows the use of relatively simple gamma-counting procedures. The assay can detect low concentrations (50–500 ng ml–1, depending on the drug) in very small amounts (50 µl) of blood and urine. It is reliable, cheap, rapid, simple to perform and biological samples can be assayed directly. The antiserum is available commercially and the radiolabelled desipramine is easy to prepare. The assay is group specific, is well suited to the task of screening large numbers of samples and is now in routine use in several forensic science laboratories.

Appraisal of narrow-bore (1 mm I.D.) high-performance liquid chromatography columns with view to the requirements of routine drug analysis

The potential advantages of using 1-mm bore high-performance liquid chromatography columns to replace conventional 4-5-mm bore columns for routine drug analysis have been considered in the light of various claims and counter-claims in the scientific literature. Experimental work has been conducted to measure the changes in mass sensitivity when using both UV and electrochemical detection. Further work has investigated the coupling of these narrow-bore columns in order to achieve high plate counts with particular reference to the influence of peak asymmetry. Finally the linking of the narrow-bore columns to a mass spectrometer with a moving-belt interface has been examined. All results are discussed with reference to the needs of the routine analyst.

Development and evaluation of a radioimmunoassay for the detection of amphetamine and related compounds in biological fluids

A radioimmunoassay has been developed for the detection of amphetamine and its analogues in blood and urine without any pre-treatment of the samples. It is based on a commercially available antiserum and a [125I] iodinated derivative of amphetamine.The assay can detect low levels of amphetamine (less than 10 ng ml–1) in very small samples (50 µl) of blood and urine. It is cheap (3 pence per test), rapid, simple to perform and is specific for compounds closely related to amphetamine.A high, positive correlation was obtained (r 0.93) when results of the analyses of urine samples from volunteers who had ingested amphetamine were compared with those produced by gas chromatography - mass spectrometry.The assay has proved very useful for the detection of amphetamine and closely related compounds in biological fluids.

An iodine-125 radioimmunoassay for the direct detection of benzodiazepines in blood and urine.

A radioimmunoassay (RIA) for the direct detection of benzodiazepines in blood and urine is described. It is based on a commercially available antiserum and an easily synthesised radio-iodinated derivative of clonazepam that allows the use of relatively simple gamma-counting procedures. The assay can detect low therapeutic levels of all of the benzodiazepines currently available in the UK in 50-µl samples of blood and urine (1–50 ng ml–1, depending on the drug); no prior sample preparation is required. It is inexpensive, rapid, simple to perform and is broadly specific for the benzodiazepine class of drugs. The assay offers a most suitable means of screening large numbers of samples of forensic interest for the presence of the benzodiazepines.

Direct radioimmunoassay for the detection of barbiturates in blood and urine

A radioimmunoassay has been developed for the detection of barbiturates in blood and urine without any pre-treatment of the sample. It is based on a radioiodinated derivative of 4-hydroxyphenobarbitone which allows use of relatively simple gamma-counting procedures.The assay can detect therapeutic levels of barbiturates in very small amounts (50 µl) of blood and urine samples. It is cheap, rapid, simple to perform and is broadly specific for the barbiturate class of drugs to the exclusion of related drugs. The assay is, therefore, very well suited to the task of screening large numbers of samples for the presence of barbiturates.