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A new miniaturized liquid extraction cartridge equipped with a functional porous polytetrafluoroethylene membrane was developed for the determination of formaldehyde in gaseous samples. The functional polytetrafluoroethylene membrane allows gas to pass through while repelling both water‐based and organic‐based liquids. A derivatization reagent for formaldehyde, 2,4‐dinitrophenylhydrazine, was placed in the cartridge and gaseous samples are collected through the cartridge at 20 ml/min for 30 min. Formaldehyde in the gaseous sample is captured as the corresponding 2,4‐dinitrophenylhydrazine hydrazone, and an aliquot of the sample collection solution can be directly subjected to high‐performance liquid chromatographic analysis. The limit of quantification for the developed method was 5 ng/L formaldehyde in gas with a sampling volume of 600 ml. Proof‐of‐concept for formaldehyde determination in an aqueous sample was demonstrated using the developed cartridge in a purge‐and‐trap extraction setup. [ABSTRACT FROM AUTHOR]

Gaseous hydrogen selenide (H2Se) generated by the addition of sodium tetrahydroborate (NaBH4) into an acidic aqueous sample was collected using an aqueous ammonia solution. The selenium (Se) concentration was determined using graphite furnace atomic absorption spectrometry (AAS). Several experimental conditions, such as the type of the collection solution, volume of NaBH4 and hydrochloric acid, and collection time, were optimized. In addition, the effect of coexisting ions was quantitatively evaluated and eliminated. The limit of detection for Se in a standard water sample was 1.3 ng/mL. The additional recovery of spiked Se in tap water and river water samples ranged from 98 ± 2.4 to 100 ± 2.2%. The proposed method facilitates simple and sensitive analysis for Se in water samples without H2Se gas generator for AAS. [ABSTRACT FROM AUTHOR]

A novel partitioning collection device comprising a glass cartridge packed with poly(dimethylsiloxane)-coated macroporous silica particles was developed for the precise quantification of polycyclic aromatic hydrocarbons in air. The analyte collection and elution performances achieved using different amounts of poly(dimethylsiloxane) coating were quantitatively evaluated. The sample retention power increased with increasing the coating, and more than 250 L of air could be collected without analyte breakthrough at a sampling temperature of 35°C. During the air collection, the moisture in the air was not retained on the particles due to the hydrophobic surface of the sorbent. A complete and rapid elution of the collected analytes from the device was accomplished by the passage of only 10 mL of acetone with ultrasonication for 1 min. The proposed method was successfully applied for the determination of airborne polycyclic aromatic hydrocarbons in tunnel air. [ABSTRACT FROM AUTHOR]

• A new analytical method for soil VOCs using a needle extraction device was developed. • The analytes including low molecular weight VOCs like dichloromethane. • Greater recovery and sensitivity were obtained than the standard method. A rapid and quantitative analytical method for volatile chlorinated hydrocarbons and benzene, such as chloroethylene, dichloromethane, and carbon tetrachloride, in soil samples was developed using a needle-type extraction device packed with activated carbon-based adsorbents. The soil sample of 10 g was placed in a glass cartridge and fixed with quartz wool to make sure not to move during the extraction process. After the internal standard solution was spiked into the soil sample, the cartridge was sealed with a polytetrafluoroethylene adapter, and the needle extraction device was used to collect the headspace gas. Analytes were purged from the soil sample and collected on the adsorbent, while pure nitrogen gas was introduced to the soil sample during the sample collection. The sampling time was approximately 10 min for 100 mL of gas sampling. After the sampling process, the extraction needle was directly inserted into a heated injection port of gas chromatography equipped with flame ionization detector (GC-FID) or that hyphenated to mass spectrometry (GC–MS). The extracted VOCs were thermally desorbed and simultaneously introduced to a GC capillary column for subsequent separation and determination. The limit of detection and limit of quantification of all the examined analytes was less than 20 and 60 ng/10 g soil in GC-FID and less than 2.5 and 7.5 ng/10 g soil in the case of GC–MS. Linear calibration curves were obtained up to 10 μg/10 g soil for all the analytes. The relative standard deviations of the ratio of analyte peak area and internal standard peak area were less than 10%. The recovery and sensitivity of analytes confirmed in the proposed method were compared with that obtained with a standard method conventionally employed. [ABSTRACT FROM AUTHOR]

A novel sampling device based on the partition of target analytes to the extraction medium was developed for the determination of sesquiterpenes in air samples. The extraction medium was prepared by the chemical derivatization of a specially prepared macroporous silica, with a specific surface area of 2.0 m2/g. Taking advantage of the sample extraction, which was mainly based on the partition of sesquiterpenes between air and a C18-bonded phase, the extracted analytes were rapidly and quantitatively desorbed just by passing a small amount of desorption solvent for subsequent analysis by gas chromatography with mass spectrometry. Several experimental conditions, such as the sampling volume and temperature, were systematically evaluated. Under optimized conditions, desorption of the extracted analytes was completed within 1 min with a desorption efficiency of more than 99.9%, achieved using 5 mL of acetone for all the evaluated sesquiterpenes. The applicability of the developed device was confirmed by the determination of several sesquiterpenes from coniferous trees. Although further improvements of the device are required for collecting large volumes or high-temperature air samples, the potential of the developed sampling device was confirmed by determining traces of semivolatile organic compounds in air samples. [ABSTRACT FROM AUTHOR]

Very volatile organic compounds (VVOCs), such as methanol, acetaldehyde, ethanol, acetone, acetonitrile, and dichloromethane, were extracted from water samples using a needle-type extraction device based on purge and trap analysis. The extracted analytes could then be determined by gas chromatography–mass spectrometry. By introducing carbon molecular sieves as the extraction medium, aqueous VVOCs could be successfully extracted using the extraction needle. The limit of quantification for methanol, acetaldehyde, ethanol, acetone, acetonitrile, and dichloromethane were 75, 75, 7.5, 0.5, 10 and 0.5 μg/L, respectively. This newly developed method was also successfully applied to the determination of VVOCs in commercial samples, such as fruit juice. [ABSTRACT FROM AUTHOR]

A novel miniaturized sample extraction capillary was developed to provide a simple and sensitive method for analyzing gaseous formaldehyde (FA) using conventional high-performance liquid chromatography (HPLC). The extraction capillary was prepared by packing silica gel particles in a stainless steel capillary with a 1.6-mm o.d. Before the gaseous samples were collected, the silica gel particles were impregnated with a derivatizing reagent 2,4-dinitrophenylhydrazine (DNPH) by passing a solution of DNPH through the extraction capillary. FA was derivatized to form the corresponding hydrazone during the active sampling of a gaseous sample, and the derivative was sorbed by the silica gel. The capillary was then directly connected to a six-port valve, and desorption from the capillary and injection into the HPLC were achieved simultaneously by passing a solvent through the capillary. The run-to-run and device-to-device variabilities, as relative standard deviations, were both less than 6.9 %. The limit of detection for FA was 2.5 ng/L using a sampling volume of 100 mL, and a sample collection time of 2 min. Acetaldehyde and acetone in a gaseous sample could also be simultaneously extracted and determined using this method. The applicability of the developed method for determining FA in real indoor air samples was confirmed by comparing the results obtained using the proposed method and a conventional sample preparation method. The developed method enables the rapid and simple sample preparation of gaseous FA and gives a good level of sensitivity. [ABSTRACT FROM AUTHOR]

Resistivities of single-crystalline as well as poly-crystalline samples of CeOBiS 2 without fluorine doping were measured at temperatures down to 0.13 K, and were compared with those of poly-crystalline LaOBiS 2 and PrOBiS 2 . Both poly-crystalline and single-crystalline CeOBiS 2 exhibited zero resistivity below 1.2 K while poly-crystalline LaOBiS 2 and PrOBiS 2 did not show zero resistivity down to 0.13 K. Superconducting transition temperature of CeOBiS 2 was reduced by increasing the applied current density. The superconductivity of CeOBiS 2 without chemical doping is likely triggered by the carriers induced by the valence fluctuation between Ce 3+ and Ce 4+ . [ABSTRACT FROM AUTHOR]

“F-free” CeOBiS 2 single crystals have successfully grown, thoroughly eliminating a concern about F-contamination by using a high-purity CsCl flux. The obtained crystals have a plate-like shape with a size of 1.0–3.0 mm in the well-developed plane. Single crystal X-ray structural analysis clearly revealed that the CeOBiS 2 crystallizes with a space group P 4/ nmm (with lattice parameters of a = 4.0189 (6) Å, c = 13.573 (2) Å). The bond valence sum estimation and X-ray photoelectron spectroscopy analysis showed that the chemical state of Ce was in the mixed valence of Ce 3+ and Ce 4+ . The single crystals show superconductivity with zero resistivity at ∼1.3 K. This is the first conclusive evidence of superconductivity driven by Ce valence fluctuation in surely non-doped CeOBiS 2 . The superconducting transition temperature was enhanced up to ∼3.8 K by applying hydrostatic pressure. [ABSTRACT FROM AUTHOR]

• Miniaturized sample preparation with braid-type extraction medium was developed. • The extraction capillary was prepared using the braid with a metal wire inside. • Applying low voltages to the metal wire, a heat-assisted desorption was made. A novel miniaturized sample preparation device with braid-type extraction medium was successfully developed. Introducing a set of bundles of fine synthetic filaments as the materials of the braid-type extraction medium and also the application of an appropriate tension during the braiding process, the outer diameter of the resulting braid has been controlled. Optimization of the tension enables an easy preparation of a group of braids that can be well-compatible to various internal diameters of capillaries to be packed. The extraction conditions were systematically optimized, and the efficient extraction was confirmed under the optimized conditions. All the parameters affects the desorption efficiency were also optimized, where typical extraction efficiency was more than 90% for the extraction of phenanthrene (1.0 μg/mL) in water. The extracted analyte was desorbed sufficiently by employing a sequential pumping process of two organic solvents. During the preparation of the braid, a different type of fibrous materials could be inserted to the opening at the center of the braid. Taking advantage of this feature of the braid, a stainless steel wire was inserted into the center of the braid. By applying low voltages to the stainless steel wire, a heat-assisted desorption of the extracted analyte was also studied. Experimentally complete desorption (higher than 99.0%) was obtained with the voltage application of 2 V. The lowest limit of quantification (LOQ) and the lowest limit of detection (LOD) for phenanthrene were 0.048 and 0.014 μg/mL, respectively. [ABSTRACT FROM AUTHOR]