M. David Osselton

Collection of analytical data for benzodiazepines and benzophenones

Abstract On April 1st, 1986, amendments were made to Schedule 2 to the Misuse of Drugs Act 1971 such that 33 benzodiazepines became controlled as Class C drugs in the U.K. An analytical database has been prepared to aid the detection and identification of controlled benzodiazepines. Chromatographic properties have been measured including gas chromatography (GC) retention index values, high-performance liquid chromatography (HPLC) capacity factors and thin-layer chromatography (TLC) R F × 100 values. UV spectroscopic and mass spectrometric (MS) data have also been recorded. Analytical data (GC, TLC and MS) are also presented for benzophenones which were produced by acid hydrolysis of the parent benzodiazepines.

Detection of ketamine and its metabolites in urine by ultra high pressure liquid chromatography-tandem mass spectrometry

Current analytical methods used for screening drugs and their metabolites in biological samples from victims of drug-facilitated sexual assault (DFSA) or other vulnerable groups can lack sufficient sensitivity. The application of liquid chromatography, employing small particle sizes, with tandem mass spectrometry (MS/MS) is likely to offer the sensitivity required for detecting candidate drugs and/or their metabolites in urine, as demonstrated here for ketamine. Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) was performed following extraction of urine (4 mL) using mixed-mode (cation and C8) solid-phase cartridges. Only 20 microL of the 250 microL extract was injected, leaving sufficient volume for other assays important in DFSA cases. Three ion transitions were chosen for confirmatory purposes. As ketamine and norketamine (including their stable isotopes) are available as reference standards, the assay was additionally validated for quantification purposes to study elimination of the drug and primary metabolite following a small oral dose of ketamine (50 mg) in 6 volunteers. Dehydronorketamine, a secondary metabolite, was also analyzed qualitatively to determine whether monitoring could improve retrospective detection of administration. The detection limit for ketamine and norketamine was 0.03 ng/mL and 0.05 ng/mL, respectively, and these compounds could be confirmed in urine for up to 5 and 6 days, respectively. Dehydronorketamine was confirmed up to 10 days, providing a very broad window of detection.

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-ammonium nitrate eluent : Batch-to-batch reproducibility of the stationary phase

The effect of changing the brand and batches of the silica stationary phase used with a methanol-aqueous ammonium nitrate eluent for the high-performance liquid chromatographic separation of basic drugs has been studied. Considerable care had to be taken to obtain a reproducible eluent and the effect of small changes in the concentration of the ammonia solution were examined closely. Large differences in both the capacity factor and relative capacity factors were found for separations on columns packed with four different brands of silica. Significant differences were also observed with columns containing eighteen different batches of Spherisorb S5W, which had been manufactured over a period of several years.

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-ammonium nitrate solvent : Interlaboratory collaborative study

The reproducibility of the separation of basic drugs on silica columns has been tested in a collaborative study between nine laboratories. The results from the different laboratories were very similar. Various methods of recording the retention properties of the drugs were compared with reference to their reproducibility and ability to discriminate between different compounds. Relative retention times, relative capacity factors, and corrected capacity factors were much better than retention times and capacity factors, although all the methods suffered from large errors with weakly retained compounds. All the work was carried out using a single batch of silica to avoid variations due to the stationary phase.

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-ammonium nitrate eluent : The effect of the mobile phase and the operating conditions

The reproducibility of capacity factors and relative capacity factors are compared as methods for recording retentions for the high-performance liquid chromatography of basic drugs on a silica column with methanol-aqueous ammonium nitrate as the eluent. The effects of changing the column temperature and the ionic strength, pH and proportion of organic modifier in the eluent on the retentions and selectivity have been studied. The results suggest that the mobile phase and operating conditions must be closely defined in order to obtain results of adequate reproducibility to develop a data base of retention values for interlaboratory comparisons and/or for the identification of basic drugs.

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-high-pH buffer eluent : Effect of operating conditions on separations using an organic buffer

Abstract Basic drugs can be separated by high-performance liquid chromatography on silica using a methanol-aqueous pH-10 buffer eluent prepared from 3-(cyclohexylamino)-1-propanesulphonic acid and sodium 3-(cyclohexylamino)-2-hydroxyl-1-propanesulphonate. The buffer could be reproducibly prepared. The effects of small changes in the buffer and eluent composition and in the operating temperature on the relative retentions of the different groups of drugs were determined.

International collaborative study of the retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-ammonium nitrate eluent.

An international collaborative study between 10 laboratories has been carried out to study the reproducibility of the separation of basic drugs on silica columns. The laboratories used common solutions of drugs on both a common batch of packing material and different batches of the same brand of packing material. These were also compared with separations on other brands of packing material. Variations within-batch, within-brand and between brands have been compared. The retentions of the drugs were compared using retention times, capacity factors and relative capacity factors compared with an internal standard. The last method was found to give the most reproducible results. Considerable variations were found between the different brands of silica with a smaller variation between the batches of a single silica brand. However, unlike earlier studies, significant variations were found for separations on a single batch of silica which were partly attributed to differences in eluent preparation and column temperature.

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol—high-pH buffer eluent: Changes in selectivity with the age of the stationary phase

The long-term reproducibility of the separation of basic drugs by high-performance liquid chromatography using a silica column with a methanol-high-pH eluent was examined. The relative capacity factors of specific tertiary amines changed systematically compared with the other drugs on storage of the columns for 1 year. The changes were enhanced on storing the column in mobile phase and were accelerated by prolonged washing with water. A comparison of freshly packed columns suggested that similar changes also occurred with the dry silica on storage. These effects may be a contributor to previously observed batch-to-batch differences in the silica.

Analytical Forensic Toxicology

My brief for this paper is to provide an overview of forensic toxicology and to illustrate what it is about forensic toxicology that makes it unique. I would therefore like to outline the background in which the forensic toxicologist works, describe some of the sorts of problems which may be encountered and illustrate how modern advances in scientific methodology may be applied to assisting the forensic toxicologist fulfil his objectives.

Comparison of Drug Retention Indices Determined on Packed, Wide Bore Capillary and Narrow Bore Capillary Columns

The retention indices of 75 drugs and other compounds of toxicological significance have been measured on SE-30 equivalent, chemically bonded, fused silica capillary columns under isothermal conditions. The data have been assessed to determine the validity of using retention indices measured on packed columns for the identification of compounds eluting from narrow bore thin film or wide bore thick film capillary columns. The results indicate that the extensive retention index data bases published for SE-30 packed columns may be used for the preliminary identification of peaks eluting from capillary columns in toxicological screening. The study also indicates that retention index data bases generated on narrow bore capillary columns are applicable to wide bore thick film capillary columns.