Four different crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were evaluated in an automated direct-immersion solid-phase microextraction method (automated DI-SPME) in combination with gas chromatography (GC). The crosslinked PIL coatings were based on vinyl-alkylimidazolium- (ViCnIm-) or vinylbenzyl-alkylimidazolium- (ViBzCnIm-) IL monomers, and di-(vinylimidazolium)dodecane ((ViIm)2C12-) or di-(vinylbenzylimidazolium)dodecane ((ViBzIm)2C12-) dicationic IL crosslinkers. In addition, a PIL-based hybrid coating containing multi-walled carbon nanotubes (MWCNTs) was also studied. The studied PIL coatings were covalently attached to derivatized nitinol wires and mounted onto the Supelco assembly to ensure automation when acting as SPME coatings. Their behavior was evaluated in the determination of a group of water pollutants, after proper optimization. A comparison was carried out with three common commercial SPME fibers. It was observed that those PILs containing a benzyl group in their structures, either in the IL monomer and crosslinker (PIL-1-1) or only in the crosslinker (PIL-0-1), were the most efficient sorbents for the selected analytes. The validation of the overall automated DI-SPME-GC-flame ionization detector (FID) method gave limits of detection down to 135 μg · L(-1) for p-cresol when using the PIL-1-1 and down to 270 μg · L(-1) when using the PIL-0-1; despite their coating thickness: ~2 and ~5 μm, respectively. Average relative recoveries with waters were of 85 ± 14 % and 87 ± 15 % for PIL-1-1 and PIL-0-1, respectively. Precision values as relative standard deviation were always lower than 4.9 and 7.6 % (spiked level between 10 and 750 μg · L(-1), as intra-day precision). Graphical Abstract Automated DI-SPME-GC-FID using crosslinked-PILs sorbent coatings for the determination of waterpollutants.
<p>Tenerife (2,034 km<sup>2</sup>) is the largest of the Canary Islands and the North South Rift Zone (NSRZ) is one of the three active volcanic rift-zones of the island. The NSRZ (325 km<sup>2</sup>) is characterized mainly by effusive activity of basaltic lavas forming spatter and cinder cones and comprises 139 monogenetic cones representing the most common eruptive activity occurred on the island during the last 1Ma. In order to provide a multidisciplinary approach to monitor potential volcanic activity changes at the NSRZ volcano, diffuse CO<sub>2</sub> emission surveys have been undertaken since 2002. This study shows the results of the last soil CO<sub>2</sub> efflux survey undertaken in summer 2019, with &#8275;600 soil gas sampling sites homogenously distributed in the study area. Soil CO<sub>2</sub> efflux measurements were performed at the surface environment by means of a portable non-dispersive infrared spectrophotometer (NDIR) LICOR Li820 following the accumulation chamber method. Soil CO<sub>2</sub> efflux values ranged from non-detectable (&#8275;0.5 g m<sup>-2</sup> d<sup>-1</sup>) up to 30 g m<sup>-2</sup> d<sup>-1</sup>, with an average value of 2.6 g m<sup>-2</sup> d<sup>-1</sup>. In order to distinguish the existence of different geochemical populations on the soil CO<sub>2</sub> efflux data, a Sinclair graphical analysis was done. The average value of background population was 2.1 g m<sup>-2</sup> d<sup>-1 </sup>and that of peak population was 18.5 g m<sup>-2</sup> d<sup>-1</sup>, representing the 97% and the 1% of the total data, respectively. To quantify the total CO<sub>2</sub> emission rate from the NSRZ volcano a sequential Gaussian simulation (sGs) was used as interpolation method. The diffuse CO<sub>2</sub> emission rate for the studied area was estimated in 2019 in 819 &#177; 18 t d<sup>-1</sup>, ranging from 466 to 819 t d<sup>-1</sup> between 2002 and 2019, with the highest value measured in 2015 (707 t d<sup>-1</sup>). The temporal evolution of diffuse CO<sub>2</sub> emission at the NSRZ shows a clear relationship with the volcano seismic activity in and around Tenerife Island, which started to taking place from the end of 2016. This study demonstrates the importance of studies of soil CO<sub>2</sub> efflux at the NSRZ volcano of Tenerife island as an effective volcanic monitoring tool, especially in areas where there is no visible degassing (fumaroles, etc.)</p>
<p>Carbon dioxide (CO<sub>2</sub>) is one of the first gases to escape from the magmatic environment due to its low solubility in basaltic magmas at low pressures. Monitoring of volcanic gases in Tenerife Island (2,304 km<sup>2</sup>) has been focused mainly on diffuse CO<sub>2</sub> degassing and other volatiles due to the absence of visible gas manifestations except fumaroles at the summit of Teide volcano. An inexpensive method to determine CO<sub>2</sub> fluxes based in the absorption of CO<sub>2</sub> through an alkaline medium followed by titration analysis has been used with the aim of contributing to the volcanic surveillance of Tenerife. During summer 2016, a network of 31 closed alkaline traps was deployed along the three volcanic rifts of Tenerife (NE, NW and NS) and at Ca&#241;adas Caldera. To do so, an aliquot of 50 mL of 0.1N KOH solution is placed inside the chamber at each station to absorb the CO<sub>2</sub> released from the soil. The solution is replaced in a weekly basis and the trapped CO<sub>2</sub> is later analyzed at the laboratory by titration. Values are expressed as weekly integrated CO<sub>2 </sub>efflux. We present herein the results of one year CO<sub>2 </sub>efflux estimated by closed alkaline traps. The CO<sub>2</sub> efflux values ranged from 1.0 to 14.5 g&#183;m<sup>-2</sup>&#183;d<sup>-1</sup>, with average values of 8.5 g&#183;m<sup>-2</sup>&#183;d<sup>-1</sup> for the NE rift-zone, 5.2 g&#183;m<sup>-2</sup>&#183;d<sup>-1 </sup>for Ca&#241;adas Caldera, 6.4 g&#183;m<sup>-2</sup>&#183;d<sup>-1</sup> for NW rift-zone and 6.1 g&#183;m<sup>-2</sup>&#183;d<sup>-1</sup> for NS rift-zone. The estimated CO<sub>2 </sub>efflux values were of the same order than the observed ones in 2016. Relatively high CO<sub>2</sub> efflux values were observed at the NE rift-zone, where maximum values were measured. The temporal evolution of CO<sub>2 </sub>efflux estimated by closed alkaline traps did not show significant variations during 2019. However, small seasonal variations are observed during the period 2016 &#8211; 2019. To investigate the origin of the soil CO<sub>2</sub>, soil gas samples were weekly sampled on the head space of the closed chambers. Chemical and isotopic composition of C in the CO<sub>2</sub> were analysed in the gas samples. The concentration of CO<sub>2</sub> on the head space of the closed chambers showed a range of 355-50,464 ppm, with an average value of 1,850 ppmV, while the isotopic composition expressed as d<sup>13</sup>C-CO<sub>2</sub> showed a range from -5.03 to -30.44 &#8240;, with an average value of -15.9 &#8240;. The heaviest values of d<sup>13</sup>C-CO<sub>2</sub> are in the NW rift-zone. The systematics of closed static chambers alkaline traps can be a simple and economical tool with volcanic surveillance purposes in system where visible volcanic gases manifestations are absence.</p>
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