An analytical method for the analysis of trihalomethanes in ambient air using solid-phase microextraction gas chromatography-mass spectrometry: An application to indoor swimming pool complexes.

A simple method for the collection and analysis of the four brominated and chlorinated trihalomethanes (THMs) in air samples is described. Ambient air samples were collected in pre-prepared glass vials, with THM analysis performed using solid-phase microextraction gas chromatography-mass spectrometry, where the need for chemical reagents is minimized. Analytical parameters, including oven temperature program, solvent volume, incubation time, vial agitation, extraction time and temperature, as well as desorption time and temperature, were evaluated to ensure optimal method performance. The developed method allows for point-in-time quantification (compared to an average concentration measured over extended periods of time), with detection limits between 0.7 to 2.6 µg/m3 . Excellent linearity (r2  > 0.99), repeatability (3% to 11% RSD), and reproducibility (3% to 16% RSD) were demonstrated over a concentration range from 2 to 5000 µg/m3 . The method was validated for the analysis of THMs in indoor swimming pool air and was used to investigate the occurrence of THMs in the air above 15 indoor swimming pools. This is the first study to report the occurrence of THMs in swimming pool air in Australia, and concentrations higher than those previously reported in other countries were measured.

Simultaneous analysis of haloacetonitriles, haloacetamides and halonitromethanes in chlorinated waters by gas chromatography-mass spectrometry.

Nitrogenous classes of disinfection by-products (DBPs), such as haloacetamides (HAAms), haloacetonitriles (HANs) and halonitromethanes (HNMs), while generally present at lower concentrations in disinfected waters than carbonaceous DBPs, such as trihalomethanes or haloacetic acids, have been shown to be more detrimental to human health. While several methods have been shown to be suitable for the analysis of some nitrogenous DBPs (N-DBPs) in disinfected waters, many are unable to quantify HAAms, the most detrimental to health of these three N-DBP classes. Here, we report the first method for the simultaneous analysis of twenty-five N-DBPs (nine HANs, nine HNMs and seven HAAms) in disinfected waters using liquid-liquid extraction followed by gas chromatography-mass spectrometry. The use of a programmable temperature vaporiser injector minimises degradation of the thermally labile HNMs, while avoiding the concomitant decreases in HANs and HAAms which occur when using lower injector temperatures. Extraction parameters, including sample pH, solvent volume, salt addition and sample pre-concentration, were investigated to determine the optimal conditions across all target N-DBPs. Good detection limits were achieved for all analytes (0.8-1.7 µg L-1) and both laboratory and instrumental runtimes were significantly reduced compared to previous methods. The method was validated for the analysis of N-DBPs in drinking, swimming pool and spa waters, and concentrations of up to 41 µg L-1 of some N-DBPs were measured in some pools.

Modulation of breathing by phasic pulmonary stretch receptor feedback in an amphibian, Bufo marinus.

This study examined the role of phasic pulmonary stretch receptor (PSR) feedback in ventilatory control, breath clustering and breath timing in decerebrate, paralysed and artificially-ventilated cane toads (Bufo marinus) under conditions designed to minimise tonic PSR feedback. Fictive breathing was recorded as trigeminal motor output to the buccal musculature. Artificial tidal ventilation, with hypercarbic gas mixtures, was either continuous or activated by the fictive breaths and was manipulated to provide differing amounts/patterns of phasic PSR feedback. The results demonstrate that increased amounts of phasic PSR feedback increase overall breathing frequency. Within multi-breath episodes there was an increase in the instantaneous breathing frequency during the later stages of the episode. The temporal relationship between a fictive breath and lung inflation influenced the duration of the pause between fictive breaths. The data indicate that phasic PSR feedback stimulates breathing by enhancing the occurrence of breathing episodes in this species but does not appear to modify the instantaneous breathing frequency during an episode.