GC–MS and GC–NPD Determination of Formaldehyde Dimethylhydrazone in Water Using SPME

Formaldehyde dimethylhydrazone (FADMH) is one of the important transformation products of residual rocket fuel 1,1-dimethylhydrazine (1,1-DMH). Thus, recent studies show that FADMH toxicity is comparable to that of undecomposed 1,1-DMH. In this study, a new method for quantification of FADMH in water based on solid phase microextraction (SPME) in combination with gas chromatography (GC) with mass spectrometric (MS) and nitrogen-phosphorus detection (NPD) is presented. Effects of SPME fiber coating type, extraction and desorption temperatures, extraction time, and pH on analyte recovery were studied. The optimized method used 65 micron polydimethylsiloxane/divinylbenzene fiber coating for 1 min headspace extractions at 30 °C. Preferred pH and desorption temperature from the SPME fiber are >8.5 and 200 °C, respectively. Detection limits were estimated to be 1.5 and 0.5 μg L−1 for MS and NPD, respectively. The method was applied to laboratory-scale experiments to quantify FADMH. Results indicate applicability for in situ sampling and analysis and possible first-time detection of free FADMH in water

Adsorption of Benzene, Toluene, Ethylbenzene and o-Xylene by Carbon-Based Adsorbents

This study explored the possibility of applying different carbon-based adsorbents for removal of benzene, toluene, ethylbenzene and o-xylene (BTEX) from indoor air in static and dynamic modes. To determine BTEX removal effectiveness, the approach based on solid-phase microextraction (SPME) in combination with gas chromatography – mass spectrometry (GC-MS) was used. In static mode, removal effectiveness of BTEX from indoor air using different carbon-based adsorbents (shungite, walnut shell, saxaul, apricot pits, activated charcoal, Tenax, carbon black) varied from 80% to 100%. Optimal preparation conditions for shungite-based adsorbent are no activation and addition of NaOH at 1:0.8 ratio. Shungite-based adsorbent was not able to remove BTEX from polluted indoor air at the flow rate 300 mL/min corresponding to the linear flow rate 25 cm/s, a minimum value for most commercial air purification systems. At the flow rate 75 mL/min (6.25 cm/s), a saturation time of shungite-based adsorbent made up 368 min for benzene and 437 min for toluene. At this flow rate, BTEX adsorption capacities of the shungitebased adsorbent were 0.3, 2.1, 0.2 and 0.3 µg/g, respectively. Compared to shungite, activated charcoal allowed the complete removal of BTEX at both flow rates in the whole studied time frame. Thus, shungite-based adsorbents are not recommended for BTEX removal from air because of much greater efficiencies of classic activated charcoal adsorbents. Applied methodology based on SPME-GC-MS allowed simple, fast and inexpensive collection of data and can be recommended as the analytical tool for developing new adsorbents and systems for air purification

Rapid Screening Method for the Total Petroleum Hydrocarbons in Water Samples by Solid-Phase Microextraction and GC-MS

Determination of total petroleum hydrocarbons (TPH) in water is an important tool for monitoring of contamination due to oil spills or leaking storage tanks. In this study, a screening method for the quantification of total petroleum hydrocarbons in water based on solid phase microextraction (SPME) in combination with gas chromatography – mass spectrometry (GC-MS) is presented. Extraction of hydrocarbons from water samples were conducted by SPME fiber coating placed into the headspace above water. Petroleum hydrocarbons were desorbed from the fiber coating in the injection port of gas chromatograph. The effect of the following parameters affecting the distribution of the analytes between three phases on the response of TPH were studied: SPME fiber coating type and dimensions, extraction temperature, extraction time and pH. The optimized method uses 100 μm polydimethylsiloxane fiber coating, extraction time 600 s, extraction temperature 80 °C, without addition of salt at basic pH. The developed method was successfully applied for detection of total petroleum hydrocarbons in water taken from Koschagyl oil fields and Koschagyl village

Percentage of articles and reviews by countries in sources discontinued by Scopus

This dataset is important for estimating the problems with academic policy and quality control in some countries, which result in an excessive (compared to other countries) percentage of publications in questionable journals not providing a proper peer review and/or violating research ethics. Such journals are regularly discontinued from Scopus

Percentage of articles and reviews by countries in sources discontinued by Scopus

This dataset is important for estimating the problems with academic policy and quality control in some countries, which result in an excessive (compared to other countries) percentage of publications in questionable journals not providing a proper peer review and/or violating research ethics. Such journals are regularly discontinued from Scopus

Percentage of articles and reviews by countries in sources discontinued by Scopus

This dataset is important for estimating the problems with academic policy and quality control in some countries, which result in an excessive (compared to other countries) percentage of publications in questionable journals not providing a proper peer review and/or violating research ethics. Such journals are regularly discontinued from Scopus

Percentage of articles and reviews by countries in sources discontinued by Scopus

This dataset is important for estimating the problems with academic policy and quality control in some countries, which result in an excessive (compared to other countries) percentage of publications in questionable journals not providing a proper peer review and/or violating research ethics. Such journals are regularly discontinued from Scopus