Investigation into the determination of trimethylarsine in natural gas and its partitioning into gas and condensate phases using (cryotrapping)/gas chromatography coupled to inductively coupled plasma mass spectrometry and liquid/solid sorption techniques

Speciation of trialkylated arsenic compunds in natural gas, pressurized and stable condensate samples from the same gas well was performed using (Cryotrapping) Gas Chromatography-Inductively Coupled Plasma Mass Spectrometry. The major species in all phases investigated was found to be trimethylarsine with a highest concentration of 17.8 ng/L (As) in the gas phase and 33.2 μg/L (As) in the stable condensate phase. The highest amount of trimethylarsine (121 μg/L (As)) was found in the pressurized condensate, along with trace amounts of non-identified higher alkylated arsines. Volatile arsenic species in natural gas and its related products cause concern with regards to environment, safety, occupational health and gas processing. Therefore, interest lies in a fast and simple field method for the determination of volatile arsenicals. Here, we use simple liquid and solid sorption techniques, namely absorption in silver nitrate solution and adsorption on silver nitrate impregnated silica gel tubes followed by total arsenic determination as a promising tool for field monitoring of volatile arsenicals in natural gas and gas condensates. Preliminary results obtained for the sorption-based methods show that around 70% of the arsenic is determined with these methods in comparison to volatile arsenic determination using GC-ICP-MS. Furthermore, an inter-laboratory- and inter-method comparison was performed using silver nitrate impregnated silica tubes on 14 different gas samples with concentrations varying from below 1 to 1000 μg As/m³ natural gas. The results obtained from the two laboratories differ in a range of 10 to 60%, but agree within the order of magnitude, which is satisfactory for our purposes.     

Using Surfactant System to Wash a Polluted Soil by Petroleum Derivatives in Egyptian Abu Madi Fields in Terms of Emulsification

The exploration and production activities of the natural gas in Abu Madi region (in middle delta) progressed in the last decade. The condensate hydrocarbon and formation water are bi‐products produced during the natural gas industry. The accompanied water contains 10–15% condensate (gasoline). This water with gasoline was drained into the Shehab El‐Din drain. The farmers were used this water to irrigate their fields. Great areas of the fields were out of order of planting as the result of gasoline pollution. This work concentrates on washing the polluted soil using locally prepared surfactant (LABSA‐Na) in the washing process. The soil sample was picked up from the Abu Madi field and was divided into pots (four pots for each treatment). The experiment was designed on the basis of polluting the soil by gasoline (condensate) from 1 to 10%. The washing process was carried out in presence of 0.1, 0.3, and 0.5% surfactant solutions. The control and blank sample were taken in consideration. The washed and the latent oil percentages were determined using the spectrophotometric method. After polluting and washing the soil, the pots were fertilized and planted by Zea Mays. The pots were irrigated twice a week. The length of plants was followed up. The obtained results cleared that, the efficiency of washing process increases with increasing of the pollutant percentage and also with increasing of surfactant concentration. The maximum washed oil (gasoline) was obtained at 10% gasoline and 0.5% surfactant concentration. The length of plants after 21 days of planting were; 0 (no planting), 24, 34, 39, 54, and 57 cm against polluted soil and planted (control) washed soil by water only; washed soil by 0.1%; washed soil by 0.3%; washed soil by 0.5% and no polluted soil (blank) respectively. These data revealed that, removing the hydrocarbon from the soil by washing using surfactants is the most effective method as the result of solubilization and emulsification of the hydrocarbon by surfactant which make it more removable.     

Chromatographic determination of total hydrocarbons in ethanolamine employed in sweetening process of natural gas

Summary A rapid and easy gas chromatographic method is proposed for the determination of condensate content in monoethanolamine employed in the sweetening process of natural gas in the petroleum industry. This method covers a wide range of heavy hydrocarbons (condensate) content by using a short conventational column. A comparative study has been carried out and the advantages of the gas chromatographic technique have been demonstrated.     

Classification of gasoline by octane number and light gas condensate fractions by origin with using dielectric or gas-chromatographic data and chemometrics tools

The approach for classification of gasoline by octane number and light gas condensate fractions by origin with using dielectric permeability data has been proposed and compared with classification of same samples on the basis of gas-chromatographic data. The precision of dielectric permeability measurements was investigated by using ANOVA. The relative standard deviation of dielectric permeability was in the range from 0.3 to 0.5% for the range of dielectric permeability from 1.8 to 4.4. The application of exploratory chemometrics tools (cluster analysis and principal component analysis) allow to explicitly differentiate the gasoline and light gas condensate fractions into groups of samples related to specific octane number or origin. The neural networks allow to perfectly classifying the gasoline and light gas condensate fractions.     

Gas chromatographic analysis of petroleum associated condensate oil with simultaneous determination of some characteristic physical parameters

A method is developed for the analysis of associated condensate by capillary gas chromatography (GC) with simultaneous determination of its major physical characteristic parameters. The method aims at the qualitative and quantitative determination of C(2)-C(36) alkanes, methylcyclopentane, cyclohexane, methylcyclohexane, benzene, toluene, ethylbenzene, xylenes, and 1,2,4-trimethylbenzene. This composition is according to the petroleum companies demand. The method is used for the simultaneous determination of the condensate average molecular weight, density, carbon-to-hydrogen ratio, and boiling range. The data obtained by the method has a good agreement with those obtained by other methods. The literature methods cited later used a simulated distillation method to obtain the hydrocarbon distribution spectrum of the given condensate sample. The obtained results revealed that the GC capillary method used is most rapid and accurate for achieving the demanded analytical report.     

Determination of individual sulfur-containing compounds in liquid hydrocarbon raw materials and their processing products by gas chromatography

The publications dedicated to the determination of individual sulfur-containing compounds in liquid hydrocarbon raw materials and their processing products by gas chromatography are summarized. In the analysis of petroleum raw materials, the preliminary separation of sulfur-containing compounds and a hydrocarbon matrix is usually performed. In the analysis of liquid oil refining products and gas condensate, the direct determination of individual sulfur-containing compounds can be frequently conducted. The use of currently available sulfur-selective chemiluminescence and atomic emission detectors in combination with nonpolar or slightly polar capillary columns and also two-dimensional chromatography is the most promising.     

Determination of arsenic in surface waters of the Ob river basin

A simple voltammetric procedure for determining arsenic is conidered. It was tested in natural water and in substances suspended in river ecosystems of the Ob river basin. The results of analysis using the voltammetric procedure were verified by atomic absorption spectrometry after atomizing arsenic hydride in a fused-silica cell and by statistical methods employing standard criteria. Specific features of the electrochemical determination of arsenic and its spatial distribution in the Upper and Central Ob and in the Novosibirsk water storage basin were considered.     

汽油中苯的测定

采用高分辨毛细管气相色谱对汽油中的苯进行测定。在汽油样品组分中选定一组分为内标,测定样品后再用内加法添加苯,再次测定,并以两次测定的峰面积数据计算苯量。本文在汽油辛烷值的测定基础上,发展了一种新的汽油中苯量的测定方法：采用国产色谱仪,带内标的内加法即可对汽油中的苯量进行准确测定．在不同标号的汽油测定实验中,相对标准偏差不超过3％。与国标方法相比,该方法简便快速,对仪器设备要求低,提高了分析效率,降低了分析成本,便于推广。     

Arsenic Speciation in Water by High-Performance Liquid Chromatography with Electrothermal Atomic Absorption Detection

A procedure was developed for determining arsenite, arsenate, monomethylarsonate, and dimethylarsinite ions in natural waters in concentrations 0.05–0.07 mg/L. The procedure involved separation by high-performance liquid chromatography and off-line determination by electrothermal atomic absorption spectrometry. The procedure was used to study arsenic transformations in the aquatic ecosystem of a tailing pit of an ore-dressing industrial plant.     

水介质对有机硫化物形成影响的模拟实验

利用高压釜反应装置在高温高压下开展了汽油-硫酸镁化学还原反应含水和无水体系的模拟实验,通过气相色谱仪、微库仑仪、毛细管气相色谱/脉冲火焰光度检测器、红外光谱仪及X射线衍射仪对气、油、固三相产物分别进行了分析并对动力学进行了解析,表明主要生成氧化镁、硫、焦炭、硫化氢、二氧化碳以及硫醇、硫醚和噻吩类等有机硫化物;随反应温度升高,反应体系中无机硫转化为有机硫的趋势增强,并主要生成热稳定性高的噻吩硫。 动力学解析表明,含水和无水条件硫酸镁转化反应的活化能分别为68.9和78.5 kJ/mol,证明水存在有利于无机硫向有机硫转化。     

Determination of Low Interfacial Tension with a Laser Light Scattering Technique and a Comparative Analysis with Drop Shape Methods

A comparative analysis of laser light scattering and drop shape techniques for measuring low interfacial tension is provided with particular reference to the gas condensate systems in petroleum reservoirs. Measurements of interfacial tensions for two real reservoir gas condensate samples were undertaken at elevated pressure and temperature reservoir conditions with the laser light scattering technique. The purposes of this study are (a) to clarify some existing confusion on the usefulness of three major interfacial tension measurement methods, pendant drop, spinning drop, and laser light scattering; and (b) to show the applicability of the laser light scattering technique to real reservoir gas condensate interfaces at low interfacial tensions. The laser light scattering technique has appeared to be the most suitable approach for the determination of low gas condensate interfacial tensions at reservoir conditions in terms of precision and operation. Copyright 2001 Academic Press.     

Photometric Determination of Trace Arsenic in Aqueous Media

A new procedure has been proposed for the photometric determination of arsenic as its compounds with tetrazolium salts. The choice of 5(1,3-benzadioxole-5-yl)-2-(4-iodophenyl)-3-phenyl-2H-tetrazolium chloride as a reagent for arsenic has been substantiated. The developed scenario of sample preparation involves the gas extraction of arsenic as arsine from the reaction mixture and its absorption isolation from the gas phase into a reagent solution in a 10 : 3 : 12 water–butanol-1–dimethyl sulfoxide mixture. The procedure provides the determination of from 1 to 120 g/L arsenic.     

Determination of arsenic and arsenic compounds in natural gas samples

Organic arsenic compounds (trialkylarsines) present in natural gas were extracted by 10 cm³ of concentrated nitric acid from 1 dm³ of gas kept at ambient pressure and temperature. The flask containing the gas and the acid was shaken for 1 h on a platform shaker set at the highest speed. The resulting solution was mixed with concentrated sulfuric acid and heated to convert all arsenic compounds to arsenate. Total arsenic was determined in the mineralized solutions by hydride generation. The arsenic concentrations in natural gas samples from a number of wells in several gas fields were in the range 0.01–63 μ As dm^?3. Replicate determinations of arsenic in a gas sample with an arsenic concentration of 5.9 μ dm^?3 had a relative standard deviation of 1.7%. Because of the high blank values, the lowest arsenic concentration that could be reliably determined was 5 ng As dm^?3 gas. Analysis of nonmineralized extracts by hydride generation identified trimethylarsine as the major arsenic compound in natural gas. Low-temperature gas chromatography-mass spectrometry showed more directly than the hydride generation technique, that trimethylarsine accounts for 55–80% of the total arsenic in several gas samples. Dimethylethylarsine, methyldiethylarsine, and triethylarsine were also identified, in concentrations decreasing with increasing molecular mass of the arsines.     

Simultaneous determination of methyl tert.-butyl ether and its degradation products,other gasoline oxygenates and benzene,toluene, ethylbenzene and xylenes in Catalonian groundwater by purge-and-trap-gas chromatography-mass spectrometry

In Catalonia (northeast Spain), a monitoring program was carried out to determine methyl tert.-butyl ether (MTBE), its main degradation products, tert.-butyl alcohol (TBA), tert.-butyl formate (TBF), and other gasoline additives, the oxygenate dialkyl ethers ethyl tert.-butyl ether, tert.-amyl methyl ether and diisopropyl ether and the aromatic compounds benzene, toluene, ethylbenzene and xylene (BTEX) in 21 groundwater wells that were located near different gasoline point sources (a gasoline spill and underground storage tank leakage). Purge-and-trap coupled to gas chromatography-mass spectrometry was optimised for the simultaneous determination of the above mentioned compounds and enabled to detect concentrations at ng/l or sub-microg/l concentrations. Special attention was given to the determination of polar MTBE degradation products, TBA and TBF, since not much data on method performance and environmental levels are given on these compounds in groundwater. All samples analysed contained MTBE at levels between 0.3 and 70 microg/l. Seven contaminated hot spots were identified with levels up to US Environmental Protection Agency drinking water advisory (20-40 microg/l) and a maximum concentration of 670 microg/l (doubling the Danish suggested toxicity level of 350 microg/l). Samples with high levels of MTBE contained 0.1-60 microg/l of TBA, indicating (but not proving) in situ degradation of parent compound. In all cases, BTEX was at low concentrations or not detected showing less solubility and persistence than MTBE. This fact confirms the suitability of MTBE as a tracer or indicator of long-term gasoline contamination than the historically used BTEX.     

The Simultaneous Arsenic,Antimony, and Selenium Determination in Water Samples by Batch Hydride Generation Atomic Absorption Spectrometry

The purpose of this paper is to present a procedure for the simultaneous determination of metalloids: arsenic, antimony, and selenium. Hydride generation was provided in a reaction vessel connected with the atomic absorption spectrometer (AAS) in a fast sequential mode. Two different types of water samples were used while developing the application: seawater and groundwater. The methodology of liquid samples analysis was developed with detection limits of 0.05, 0.03, and 0.06 ng · mL^?1 for arsenic, antimony, and selenium, respectively, in 10 mL samples. This methodology was used to determine arsenic, antimony, and selenium in natural water samples.     

Selective determination of trace arsenic and antimony species in natural waters by gas chromatography with a photoionization detector

Traces amounts of arsenic and antimony in water samples were determined by gas chromatography with a photoionization detector after liquidnitrogen cold trapping of their hydrides. The sample solution was treated with sodium hydroborate (NaBH₄) under weak-acid conditions for arsenic(III) and antimony(III) determination, and under strong-acid conditions for arsenic(III+V) and antimony(III+V) determination. Large amounts of carbon dioxide (CO₂) and water vapor obscured determination of arsine and stibine. Better separation from interference could be achieved by removing CO₂ and water vapor in two tubes containing sodium hydroxide pellets and calcium chloride, respectively. The detection limits of this method were 1.8 ng dm^?3 for arsenic and 9.4 ng dm^?3 for antimony in the case of 100-cm³ sample volumes. Therefore, it is suitable for determination of trace arsenic and antimony in natural waters.     

Effect of Petroleum Condensate/Gasoline Mixture on Automotive Engines

Twelve combustible mixtures of condensate/gasoline were evaluated with the aim to delimit the extent at which the adulteration of premium motor spirit (PMS) with condensate samples becomes hazardous to spark-ignited gasoline engines. Results of the quality-assurance tests (low RON (research octane number) rating and low volatility corroborated by <0.45 kg/cm² RVP (Reid vapor pressure) and high boiling-point (IBP (initial boiling point), FPB (final boiling point), and TR (total recovery)) ranges of atmospheric distillation) show that 16–100% (v/v) of condensate in the adulterated blends are undesirable for automotive engines. Such fuels may cause rough idling, detonation (pinging), and eventual knock of the spark-ignited engine. Continued availability of petroleum products in developing countries like Nigeria might discourage the uncanny practice of ‘black marketers’ who perpetrate the distribution of the ‘killer products’. This might also boost the already impeded consumer trust on petroleum products.     

Determination of Arsenic in Beverages and Foods by Hydride Generation Atomic Absorption Spectroscopy

Abstract

The determination of the arsenic content of foods and beverages by a technique involving a magnesium nitrate aided dry ashing step followed by an arsine generation atomic absorption finish is described. Recoveries of various arsenic species added prior to ashing was excellent. Total arsenic concentrations found in samples of beverages ranged from less than 10 to 265 ppb and in foods from 20 to 9290 ppb. The sensitivity of the technique is approximately ten-fold better than obtainable with commercially available hydride generation atomic absorption units.     

Determination of aldehydes and ketones in natural gas combustion in the ppb range by high-performance liquid chromatography

Summary The reported identification and determination of trace compounds in flue products of natural gas burning equipment is based on DNPH precolumn derivatization and followed by HPLC separation. The optimized HPLC analysis has been applied to the determination of trace amounts of aldehydes and ketones in polluted air such as lab and ambient air as well as natural gas and oil combustion products in a hospital. The results obtained in a hospital show that the oil fuel combustion process emits a considerable amount of toxic acrolein, whereas the emission of acetone is predominant in natural gas combustion.

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Bestimmung von Aldehyden und Ketonen bei der Erdgasverbrennung im ppb-Bereich mittels HPLC

     

Determination of the composition of a high-boiling condensate from natural gas by capillary gas chromatography and mass spectrometry

Summary A condensate from natural gas containing nearly 50% of the fraction boiling in the range from 180–320 C was analysed by capillary gas chromatography and by mass spectrometry with the aim to determine its composition and to evaluate suitability as a gasoline component.

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Bestimmung der Zusammensetzung eines hochsiedenden Kondensats aus Erdgas mit Hilfe der Capillar-Gas-Chromatographie und der Massenspektrometrie

Zusammenfassung Ein Kondensat aus Erdgas, das fast 50% der im Bereich 180–320 C siedenden Fraktion erhielt, wurde mit Hilfe der Capillar-GC und der MS analysiert. Die Zusammensetzung des Kondensats sollte im Hinblick auf seine Eignung als Benzinzusatz aufgeklÄrt werden.