Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS) as an Alternative to Gas Chromatography/Mass Spectrometry (GC/MS) for the Analysis of Cyclohexanone and Cyclohexanol in Plasma

Self-poisoning with professional agricultural pesticide products is responsible for about 20% of global suicide, with most cases occurring in South Asia and China. Treatment of severe poisoning involves long-term intensive clinical care and is often unsuccessful. Solvent co-formulants (such as cyclohexanone) also contribute to mortality themselves or via more toxic metabolic products (such as cyclohexanol). Faster detection of co-formulants could aid earlier identification of pesticide poisoning and faster intervention, reducing mortality. Conventional analysis of volatiles in blood uses headspace (HS)-GC/MS. This paper evaluates SIFT-MS, a direct MS technique that provides higher sample throughput than GC/MS, as a potential tool for cyclohexanone and cyclohexanol analysis in plasma. Both instruments were calibrated using a conventional approach prior to analysis of each porcine plasma sample on both instruments. Comparative data were evaluated using Bland-Altman plots, demonstrating that the techniques were in good agreement. Compared with GC/MS, SIFT-MS provides fourfold higher sample throughput and shows great promise as an alternative analytical tool.

622 Potential Application of Electrocardiographs (ECG) to Diagnose Breech Presentations of Fetuses

Breech presentation, i.e. the abnormal lie of a foetus longitudinally with the buttocks closest to the mother’s cervix, is a common issue affecting up to 5% of women during delivery resulting in poor outcomes such as traumatic labour, infection and increased neonatal mortality.

Currently, abdominal palpation is the screening method of choice for breech presentation; however, 15,000 breech presentations remain undiagnosed across England annually. While routine ultrasonography has been suggested, its cost-effectiveness and scalability remain concerning, especially in low/middle-income countries.

Various algorithms have been applied to maternal trans-abdominal ECGs to obtain foetal ECGs, but current applications only allow heart rates, congenital heart defects, hypoxia, and foetal distress to be identified. The use of ECG is proposed to determine foetal position as breech foetuses tend to display QRS complexes in a similar pattern to the maternal trace, whereas cephalic foetuses would demonstrate inverted QRS complexes.

ECGs are cost-effective, safe and do not require highly skilled technicians to operate, which makes it an ideal starting platform for the development of a device with high sensitivity and reasonable diagnostic speeds to identify breech foetuses. Future considerations include the use of artificial intelligence to increase diagnostic accuracy and development of a patient-facing mobile application.

Comparison of passive-dosed and solvent spiked exposures of pro-carcinogen, benzo[a]pyrene, to human lymphoblastoid cell line, MCL-5

Genotoxicity testing methods in vitro provide a means to predict the DNA damaging effects of chemicals on human cells. This is hindered in the case of hydrophobic test compounds, however, which will partition to in vitro components such as plastic-ware and medium proteins, in preference to the aqueous phase of the exposure medium. This affects the freely available test chemical concentration, and as this freely dissolved aqueous concentration is that bioavailable to cells, it is important to define and maintain this exposure. Passive dosing promises to have an advantage over traditional 'solvent spiking' exposure methods and involves the establishment and maintenance of known chemical concentrations in the in vitro medium, and therefore aqueous phase. Passive dosing was applied in a novel format to expose the MCL-5 human lymphoblastoid cell line to the pro-carcinogen, benzo[a]pyrene (B[a]P) and was compared to solvent (dimethyl sulphoxide) spiked B[a]P exposures over 48 h. Passive dosing induced greater changes, at lower concentrations, to micronucleus frequency, p21 mRNA expression, cell cycle abnormalities, and cell and nuclear morphology. This was attributed to a maintained, definable, free chemical concentration using passive dosing and the presence or absence of solvent, and highlights the influence of exposure choice on genotoxic outcomes.

Measurement of cyclic volatile methylsiloxanes in the aquatic environment using low-density polyethylene passive sampling devices using an in-field calibration study--challenges and guidance

Cyclic volatile methylsiloxanes (cVMS) are used in personal care products and are hydrophobic, volatile and persistent. Their environmental water concentrations are low and are difficult to detect using conventional sampling methods. This study shows the potential of passive sampling for cVMS. We used low-density polyethylene (LDPE) samplers and in-field calibration methods for octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5). (13)C-D4 and (13)C-D5, methyltris(trimethylsiloxy)silane (MT), tetrakis(trimethylsiloxy)silane (TK), and five deuterated polycyclic aromatic hydrocarbons (PAHs) were used as performance reference compounds (PRCs). Samplers were calibrated (7-d) using effluent at a treatment plant, with uptake of cVMS and losses of the PRCs measured at 12 time-points. Concentrations of D4 (53ngL(-1)) and D5 (1838ngL(-1)) were stable in the effluent. Uptake of D4 and loss of (13)C-D4 were isotropic and equilibrium was approached by 7-d. Two estimates of sampler uptake rate (Rs) were 2.1Ld(-1) and 2.5Ld(-1). The estimated log LDPE/water partition coefficient was 4.4. The uptake of D5 was slower (Rs=0.32Ld(-1)) and equilibrium was not reached. Offloading of (13)C-D5, MT and TK were slow, and isotropic behaviour was not demonstrated for D5. Offloading of PAHs followed the predicted pattern for LDPE. Uptake of cVMS appeared to be under membrane control, due to low diffusion coefficients in LDPE. Samplers can monitor time-weighted average concentrations of D4 for less than a week, and D5 for longer periods. LDPE samplers allow cVMS to be determined at lower concentrations than by spot sampling methods.

Simulated use and wash-off release of decamethylcyclopentasiloxane used in anti-perspirants

The cyclic volatile methylsiloxane, decamethylcyclopentasiloxane (D5) is used in a large variety of personal care products. Based on the physical-chemical properties of D5, it is likely that losses due to volatilisation may strongly influence the levels entering the aquatic environment. The aim of this study was to quantify the amount of D5 in waste wash water, after typical application and use in a range of deodorant and anti-perspirant (AP) products. Results implied significant losses after a 24h period (>99.9%), and suggest that the use of D5 in leave-on products, such as deodorants/AP is not likely to contribute a significant down-the-drain emission source. An illustrative example is presented, based on data reporting the use of D5 in a range of personal care products (both wash-off and leave-on), which suggests that the contribution of D5 used in wash-off products to the aquatic environment may be considerably more significant. Limitations associated with our understanding of the actual D5 inclusion levels in the products, the market share of the products containing D5, and the variability of consumer habits, are identified as data gaps that need to be addressed in order to better refine down-the-drain emission estimates.