Determination of 1-methyl-1H-1,2,4-triazole in soils contaminated by rocket fuel using solid-phase microextraction, isotope dilution and gas chromatography–mass spectrometry

Environmental monitoring of Central Kazakhstan territories where heavy space booster rockets land requires fast, efficient, and inexpensive analytical methods. The goal of this study was to develop a method for quantitation of the most stable transformation product of rocket fuel, i.e., highly toxic unsymmetrical dimethylhydrazine – 1-methyl-1H-1,2,4-triazole (MTA) in soils using solid-phase microextraction (SPME) in combination with gas chromatography–mass spectrometry. Quantitation of organic compounds in soil samples by SPME is complicated by a matrix effect. Thus, an isotope dilution method was chosen using deuterated analyte (1-(trideuteromethyl)-1H-1,2,4-triazole; MTA-d3) for matrix effect control. The work included study of the matrix effect, optimization of a sample equilibration stage (time and temperature) after spiking MTA-d3 and validation of the developed method. Soils of different type and water content showed an order of magnitude difference in SPME effectiveness of the analyte. Isotope dilution minimized matrix effects. However, proper equilibration of MTA-d3 in soil was required. Complete MTA-d3 equilibration at temperatures below 40 °C was not observed. Increase of temperature to 60 °C and 80 °C enhanced equilibration reaching theoretical MTA/MTA-d3 response ratios after 13 and 3 h, respectively. Recoveries of MTA depended on concentrations of spiked MTA-d3 during method validation. Lowest spiked MTA-d3 concentration (0.24 mg kg−1) provided best MTA recoveries (91–121%). Addition of excess water to soil sample prior to SPME increased equilibration rate, but it also decreased method sensitivity. Method detection limit depended on soil type, water content, and was always below 1 mg kg−1. The newly developed method is fully automated, and requires much lower time, labor and financial resources compared to known methods

Effects of Moisture Content and Solvent Additive on Headspace Solid-Phase Microextraction of Total Petroleum Hydrocarbons from Soil

Present paper describes optimization of the method of quantitative determination of total petroleum hydrocarbons in soil samples using headspace solid - phase microextraction (SPME) in combination with gas chromatography - mass spectrometry (GC-MS). Effects of moisture content and solvent additives were studied. It was established that an increase of the moisture content in soil leads to an increase of the response of petroleum hydrocarbons reaching its maximum at 15-20% depending on the soil type and concentration of total petroleum hydrocarbons followed by its gradual decrease. For the same concentration of petroleum hydrocarbons, an increase of moisture content in soil from 0 to 20% may lead to a 15x increase of total petroleum hydrocarbons response by solid - phase microextraction. Determination of total petroleum hydrocarbons in soils by SPME -GC-MS without moisture control of samples may lead to large errors, especially at low concentrations. It was established that addition of the solvent to a soil-water mixture allows dissolution of an oil film on the water surface and provides better extraction of hydrocarbons from soil to water phase. To avoid effect of moisture content on the extraction efficiency and more precise analysis of the real samples, addition of the excess distilled water must be done. Addition of the polar organic solvent to a soil-water mixture (10% isopropanol) allows dissolution of an oil film on the water surface and provides linear dependence of extraction efficiency vs total petroleum hydrocarbons content in soil. Testing of the optimized method on model soil samples provided quantitative data, results being in 30-120% range from the real values

Mechanism of the thermochemical transformation of wheat grain’s processing waste during heat treatment

The thermal destruction of wheat grain’s processing wastes from Almaty and South Kazakhstan regions was studieв. The structure of the products obtained depending on the temperature of the carbonization process was formed, and the basic physico chemical characteristics of the obtained carbon material based on the WGPW were studied using thermogravimetric analysis, differential scanning calorimetry, IR spectroscopy and EPR spectroscopy. The analysis of the elemental composition of the obtained samples of the sorption material showed that the carbon content in the composition of the obtained carbon material is 75.08 - 76.12%, which in turn can cause a sufficiently high degree of sorption capacity of this material, as well as its mechanical strength. The obtained carbon materials based on OIP were modified with ammonium nitrate (NH4NO3) to improve its physico-chemical characteristics, such as specific surface area, porosity and adsorption capacity by iodine. It is shown that structural transformations of the processing waste of wheat grain (bran) in the process of heat treatment irrespective of temperature (in the studied interval) proceed through the stage of formation of free radicals. The concentration of free radicals formed in this process, as well as the composition of the graphite-like component of the products obtained, are determined by the temperature indices of the process

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

Экстракция скандия расплавом ди-2-этилгексилфосфорной кислоты в легкоплавких разбавителях

В настоящее время распространение экстракционных методов при использовании легкоплавких реагентов объясняется рядом свойственных им преимуществ, таких как высокие кинетические характеристики процесса, легкость разделения двух фаз, большая селективность многих экстрагентов, возможность сравнительно полной их регенерации. Для экстракции скандия в технологических целях применяют нейтральные и катионообменные экстрагенты. Ряд экстракционных реагентов легко плавится при повышении температуры, и такие расплавы можно использовать для экстракции. Эффективность экстракционного извлечения металлов катионообменными реагентами зависит от многих факторов. Исследована экстракция скандия расплавом смесей ди-2-этилгексилфосфорной кислоты – высшие карбоновые кислоты – парафин и  рассмотрено влияние кислотности водной фазы, концентрации скандия в водной и экстрагента в органической фазах, соотношения объемов органической и водной фаз на экстракцию металла. Установлено, что экстракция скандия протекает по катионообменному механизму. Скандий количественно извлекается (>99,0%) из кислых растворов. Оптимальная концентрация ди-2-этилгексилфосфорной кислоты составляет 0,250 М в экстрагенте, количественное извлечение скандия наблюдается в интервале его концентраций 10-3 – 10-6 М и при соотношении объемов органической и водной фаз 1:5 – 1:20

Generation of Hydrogen and Oxygen from Water by Solar Energy Conversion

Photosynthesis is considered to be one of the promising areas of cheap and environmentally friendly energy. Photosynthesis involves the process of water oxidation with the formation of molecular oxygen and hydrogen as byproducts. The aim of the present article is to review the energy (light) phase of photosynthesis based on the published X-ray studies of photosystems I and II (PS-I and PS-II). Using modern ideas about semiconductors and biological semiconductor structures, the mechanisms of H+, O2↑, e− generation from water are described. At the initial stage, PS II produces hydrogen peroxide from water as a result of the photoenzymatic reaction, which is oxidized in the active center of PS-II on the Mn4CaO5 cluster to form O2↑, H+, e−. Mn4+ is reduced to Mn2+ and then oxidized to Mn4+ with the transfer of reducing the equivalents of PS-I. The electrons formed are transported to PS-I (P 700), where the electrochemical reaction of water decomposition takes place in a two-electrode electrolysis system with the formation of gaseous oxygen and hydrogen. The proposed functioning mechanisms of PS-I and PS-II can be used in the development of environmentally friendly technologies for the production of molecular hydrogen

Generation of Hydrogen and Oxygen from Water by Solar Energy Conversion

Photosynthesis is considered to be one of the promising areas of cheap and environmentally friendly energy. Photosynthesis involves the process of water oxidation with the formation of molecular oxygen and hydrogen as byproducts. The aim of the present article is to review the energy (light) phase of photosynthesis based on the published X-ray studies of photosystems I and II (PS-I and PS-II). Using modern ideas about semiconductors and biological semiconductor structures, the mechanisms of H+, O2↑, e− generation from water are described. At the initial stage, PS II produces hydrogen peroxide from water as a result of the photoenzymatic reaction, which is oxidized in the active center of PS-II on the Mn4CaO5 cluster to form O2↑, H+, e−. Mn4+ is reduced to Mn2+ and then oxidized to Mn4+ with the transfer of reducing the equivalents of PS-I. The electrons formed are transported to PS-I (P 700), where the electrochemical reaction of water decomposition takes place in a two-electrode electrolysis system with the formation of gaseous oxygen and hydrogen. The proposed functioning mechanisms of PS-I and PS-II can be used in the development of environmentally friendly technologies for the production of molecular hydrogen

Effects of Moisture Content and Solvent Additive on Headspace Solid-Phase Microextraction of Total Petroleum Hydrocarbons from Soil

Present paper describes optimization of the method of quantitative determination of total petroleum hydrocarbons in soil samples using headspace solid - phase microextraction (SPME) in combination with gas chromatography - mass spectrometry (GC-MS). Effects of moisture content and solvent additives were studied. It was established that an increase of the moisture content in soil leads to an increase of the response of petroleum hydrocarbons reaching its maximum at 15-20% depending on the soil type and concentration of total petroleum hydrocarbons followed by its gradual decrease. For the same concentration of petroleum hydrocarbons, an increase of moisture content in soil from 0 to 20% may lead to a 15x increase of total petroleum hydrocarbons response by solid - phase microextraction. Determination of total petroleum hydrocarbons in soils by SPME -GC-MS without moisture control of samples may lead to large errors, especially at low concentrations. It was established that addition of the solvent to a soil-water mixture allows dissolution of an oil film on the water surface and provides better extraction of hydrocarbons from soil to water phase. To avoid effect of moisture content on the extraction efficiency and more precise analysis of the real samples, addition of the excess distilled water must be done. Addition of the polar organic solvent to a soil-water mixture (10% isopropanol) allows dissolution of an oil film on the water surface and provides linear dependence of extraction efficiency vs total petroleum hydrocarbons content in soil. Testing of the optimized method on model soil samples provided quantitative data, results being in 30-120% range from the real values.This article is published as Alimzhanova, M. B., B. N. Kenessov, M. K. Nauryzbayev, and J. A. Koziel. "Effects of moisture content and solvent additive on headspace solid-phase microextraction of total petroleum hydrocarbons from soil." Eurasian Chemico-Technological Journal 14, no. 4 (2012): 331-335. Posted with permission.</p

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.This article is from Chromatographia 73 (2011): 123–128, doi:10.1007/s10337-010-1820-6. Posted with permission.</p