Features of the highway road network that generate or retain tyre wear particles.

The environmental accumulation of microplastics poses a formidable global challenge, with tyre wear particles (TWPs) emerging as major and potentially harmful contributors to this particulate pollution. A critical pathway for TWPs to aquatic environments is via road drainage. While drainage assets are employed worldwide, their effectiveness in retaining microplastics of highly variable densities (TWP ~ 1-2.5 g cm3) remains unknown. This study examines their ability to impede the transfer of TWPs from the UK Strategic Road Network (SRN) to aquatic ecosystems. Samples were collected from the influent, effluent and sediments of three retention ponds and three wetlands. The rate of TWP generation is known to vary in response to vehicle speed and direction. To ascertain the significance of this variability, we further compared the mass of TWPs in drainage from curved and straight sections of the SRN across eight drainage outfalls. Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) was used to quantify tyre wear using benzothiazole as a molecular marker for TWPs (with an internal standard benzothiazole-D4). Tyre wear was present in drainage from the SRN at concentrations of 2.86 ± 6 mg/L and was found within every sample analysed. Drainage from curved sections of the SRN contained on average a 40% greater TWP mass than straight sections but this was not significant. The presence of wetlands and retention ponds generally led to a reduction in TWP mass (74.9% ± 8.2). This effect was significant for retention ponds but not for wetlands; most probably due to variability among sites and sampling occasions. Similar drainage assets are used on a global scale; hence our results are of broad relevance to the management of TWP pollution.

Qualitative drug analysis of hair extracts by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

A technique using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC/TOFMS) is applied to a qualitative analysis of three sample extracts from hair suspected of containing various drug compounds. The samples were also subjected to a quantitative target analysis for codeine, morphine, 6-monoacetylmorphine (6-MAM), amphetamine, methamphetamine, methylenedioxyamphetamine (MDA), methylenedioxymethylamphetamine (MDMA), methadone, and benzylpiperazine (BZP) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). GCxGC/TOFMS provided a non-specific procedure that identified various drugs, metabolites, and impurities not included in the target analysis. They included cocaine, diazepam, and methaqualone (quaalude). Comprehensive GCxGC separation was achieved using twin-stage cryo-modulation to focus eluant from a DB-5 ms (5% phenyl) to a BPX50 (50% phenyl) GC column. The TOF mass spectrometer provided unit mass resolution in the mass range m/z 5-1000 and rapid spectral acquisition (< or = 500spectra/s). Clean mass spectra of the individual components were obtained using mass spectral deconvolution software. The 'unknown' components were identified by comparison with mass spectra stored in a library database.

The detection of various opiates and benzodiazepines by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

A technique using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOFMS) is applied to qualitative and quantitative drug testing. Human serum was 'spiked' with known quantities of benzodiazepines and a 'street heroin' mixture including some of the major metabolites and impurities. The sample components were extracted from the matrix by solid-phase extraction (SPE). Constituents containing polar hydroxyl and/or secondary amine groups were derivatised with N-methyl-N-(tert-butyldimethyl)trifluoroacetamide (MTBSTFA) to improve the chromatographic performance. An orthogonal separation of the matrix constituents was achieved by coupling a DB-5ms (5% phenyl) to a BPX50 (50% phenyl) GC column. The eluant was focused onto the second column by a twin-stage cryo-modulator. Rapid 6 s modulation times were achieved by transfer from a 30 m x 0.25 mm (length x internal diameter) to a 2 m x 0.1 mm column. TOFMS with rapid spectral acquisition (< or =500 spectra/s) was employed in the mass range m/z 40-650. A clean mass spectrum was obtained for each analyte using mass spectral deconvolution software. The sensitivity and repeatability of the method were evaluated by the preparation of calibration standards for two benzodiazepines, flunitrazepam and its major metabolite 7-aminoflunitrazepam (7-amino-FN), in the concentration range 5-1000 ng/mL. The limits of detection (LODs) and limits of quantitation (LOQs), calculated by repeat injections (x10) of the lowest standard, were 1.6 and 5.4 ng/mL (flunitrazepam); 2.5 and 8.5 ng/mL (7-amino-FN), respectively. There is scope to extend this protocol to screen a large number of drugs and metabolites stored in a library database.