Direct thermal desorption gas chromatographic determination of toxicologically relevant concentrations of ethylene glycol in whole blood.

A simple and rapid method involving thermal desorption gas chromatography (TD-GC) with flame ionisation detection has been successfully developed for the determination of ethylene glycol in whole blood. No sample extraction or derivatization steps were required. The conditions required for the direct determination of ethylene glycol in whole blood were optimised and require only the addition of the internal standard, 1,2-butanediol, to the sample. A 1 µL aliquot of the sample was then introduced to the thermal desorption unit, dried, and thermally desorbed directly to the gas chromatograph. A calibration curve was constructed over the concentration range of 1.0 to 200 mM and was found to be linear over the range investigated with an R2 value of 0.9997. The theoretical limit of detection based on 3σ was calculated to be 50.2 µM (3.11 mg L-1). No issues with carryover were recorded. No interferences were recorded from endogenous blood components or a number of commonly occurring alcohols. The proposed method was evaluated by carrying out replicate ethylene glycol determinations on fortified whole blood samples at the levels of 12.5 mM, 20.0 mM, 31.2 mM, 100 mM and 200 mM comparable to commonly reported blood levels in intoxications. Mean recoveries of between 84.8% and 107% were obtained with coefficients of variation of between 1.7% and 5.8%. These data suggest that the method holds promise for applications in toxicology, where a rapid, reliable method to confirm ethylene glycol poisoning is required.

Determination of licit and illicit drugs and metabolites in human sweat by liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry screening method in sweat was developed for the simultaneous determination of three licit drugs (nicotine, paracetamol, and caffeine); four illicit drugs (cocaine, ketamine, 25I-NBOMe and methamphetamine) and two metabolites (benzoylecgonine and cotinine). Target drugs were liberated from sweat patches with pH 5 sodium acetate buffer and further purified by solid phase extraction (SPE) utilising Strata-X-Drug B cartridges. Optimal solvent constituents for SPE organic wash and elution were 70% v/v methanol in deionised water and 5% v/v ammonium hydroxide in methanol respectively. Chromatographic separation was achieved using a superficially porous particle C18 column with gradient elution, using (A) 0.1% formic acid in water and (B) acetonitrile as mobile phase constituents. Target drugs were identified using a combination of retention time, and the ion ratios for two precursor-product ion transitions for each analyte monitored in multiple reaction monitoring (MRM) mode. The method was linear for all target drugs from 1.0-150.0 ng mL-1 with corresponding limits of quantitation of 1.0 ng mL-1. Limits of detection were found to range from 0.1-0.6 ng per patch. The method was subsequently applied to the analysis of sweat samples from five male and four female participants aged 20-25 years. Sweat was collected from two areas (right forearm and left thigh) using protected layers of gauze. All eighteen patches tested positive for at least one target analyte. The results of this study not only show a multi-substance screening method was achieved but also that sweat patches can be used to indicate an individual's drug use. Therefore, they can provide an alternative non-invasive technique for forensic applications.

Extraction-Free, Direct Determination of Caffeine in Microliter Volumes of Beverages by Thermal Desorption-Gas Chromatography Mass Spectrometry.

An extraction-free method requiring microliter (µL) volumes has been developed for the determination of caffeine in beverages. Using a pyrolysis-gas chromatography mass spectrometry system, the conditions required for the direct thermal desorption-gas chromatography mass spectrometry (TD-GC/MS) determination of caffeine were optimised. A 5 µL aliquot was introduced to the thermal desorption unit, dried, and thermally desorbed to the GC/MS. The response was linear over the range 10 to 500 µg/mL (R 2 = 0.996). The theoretical limit of detection (3 σ) was 0.456 µg/mL. No interferences were recorded from endogenous beverage components or from commonly occurring drugs, such as nicotine, ibuprofen, and paracetamol. Replicate caffeine determinations on fortified latte style white coffee and Pepsi Max® gave mean recoveries of 93.4% (%CV = 4.1%) and 95.0% (%CV = 0.98%), respectively. Good agreement was also obtained with the stated values of caffeine for an energy drink and for Coca-Cola®. These data suggest that the method holds promise for the determination of caffeine in such samples.

Illicit drug contamination of the Bristol pound local currency.

Reports have shown the prevalence of the contamination of banknotes with a number of different drugs. These studies have focused on investigating drug contamination levels on currency which is either nationally or even international distributed. To present there has been no studies undertaken on banknotes circulating in well-defined and limited geographic areas. In this present study we have investigated the presence of drug contamination on the Local Currency, circulating in a known geographic area in and around the city of Bristol, UK; the Bristol Pound (£B). The effect of sample size was investigated and a post-hoc statistical power analysis undertaken. Following liquid extraction with the aid of sonication, levels of cocaine, benzoylecgonine, MDMA, ketamine and methamphetamine were determined by liquid chromatography triple quadrupole mass spectrometry. Seven samples of each denomination in circulation were investigated. The calculated median values per note were 2030ng cocaine, 91.9ng benzoylecgonine, 0.779ng methamphetamine, 62.8ng MDMA and 3440ng ketamine. This study focuses on our preliminary studies and to our knowledge this is the first investigation focused on the drug contamination of a Local Currency.

Novel Blood Biomarkers that Correlate with Cognitive Performance and Hippocampal Volumetry: Potential for Early Diagnosis of Alzheimer's Disease.

BACKGROUND: Differential diagnosis of people presenting with mild cognitive impairment (MCI) that will progress to Alzheimer's disease (AD) remains clinically challenging. Current criteria used to define AD include a series of neuropsychological assessments together with relevant imaging analysis such as magnetic resonance imaging (MRI). The clinical sensitivity and specificity of these assessments would be improved by the concomitant use of novel serum biomarkers. The branched chain aminotransferase proteins (BCAT) are potential candidates as they are significantly elevated in AD brain, correlate with Braak Stage, and may have a role in AD pathology. OBJECTIVE: In this hypothesis-driven project, we aimed to establish if serum BCAT and its metabolites are significantly altered in AD participants and assess their role as markers of disease pathology. METHODS: Serum amino acids were measured using a triple quadrupole mass spectrometer for tandem mass spectroscopy together with BCAT levels using western blot analysis, coupled with neuropsychological assessments and MRI. RESULTS: We present data supporting a substantive mutually correlated system between BCAT and glutamate, neuropsychological tests, and MRI for the diagnosis of AD. These three domains, individually, and in combination, show good utility in discriminating between groups. Our model indicates that BCAT and glutamate accurately distinguish between control and AD participants and in combination with the neuropsychological assessment, MoCA, improved the overall sensitivity to 1.00 and specificity to 0.978. CONCLUSION: These findings indicate that BCAT and glutamate have potential to improve the clinical utility and predictive power of existing methods of AD assessment and hold promise as early indicators of disease pathology.

A simple and rapid method for the determination of nicotine in third-hand smoke by liquid chromatography and its application for the assessment of contaminated outdoor communal areas.

This is the first report on the determination of nicotine in third-hand smoke (THS) in outdoor communal areas. The term THS can be defined as the contamination of surfaces by second-hand smoke. This can remain for extended periods of time and undergo further chemical reactions to produce further pollutants which can be re-suspended in dust or re-emitted into the gas phase. As THS is a rather complex mixture, studies have focused on using nicotine as a marker of THS, as it is the most abundant organic compound emitted during smoking. In this present study, the extraction of dust-wipe samples and the subsequent chromatographic conditions required for the separation of nicotine by hydrophilic interaction liquid chromatography were optimized. The optimum chromatographic conditions were identified as a 150 mm x 4.6 mm, 5 µm Zorbax Carbohydrate Analysis column with a mobile phase consisting of 90 % acetonitrile, 10 % water at a flow rate of 1.0 mL/min with UV detection at 259 nm. Further investigations were made on samples collected from surfaces of public entrance ways. Under these conditions, a linear range for nicotine of 0.05 to 24 µg/mL (1.0-480 ng on column) was obtained, with a detection limit of 1.0 ng on column based on a signal-to-noise ratio of three. Acetone, naphthalene, phenol, musk ketone, and palmitic acid were found not to interfere. Communal entrance ways were found to be contaminated with THS nicotine levels of between 5.09 µg/m(2) and 309 µg/m(2) comparable to that found in other previous studies of indoor environments. Copyright © 2015 John Wiley & Sons, Ltd.