Use of rotating-coiled columns for sample preparation in the analysis of petropolluted soils

It is shown for the first time that rotating-coiled columns (RCC) can be used as sample preparation tools in the analysis of petropolluted soils. The use of RCC allows for the extraction of petroleum products from soils in the dynamic mode without using additional means of sample preparation. A test sample of soil is retained in an RCC as a stationary phase. Petroleum products are extracted from soil in 15–25 mL of an organic solvent (n-hexane, acetonitrile). Sample preparation lasts no more than 60 min. Examples are presented for the extraction of hydrocarbons, constituents of diesel fuel, and phthalates in the analysis of petropolluted soil samples taken from the territory of oil-extracting and oil-refining enterprises of the Krasnoyarsk region and the Khanty-Mansiisk autonomous area.     

Flow-injection extraction spectrophotometric method for the determination of lead and its combination with minicolumn preconcentration

An automatic flow-injection method was developed for the determination of lead in the range 50–2000 μg l^?1. The method is based on the extraction of lead with the crown ether dicyclohexyl-18-crown-6 into chloroform from an acidic medium, subsequent addition of dithizone as chromogenic reagent to the extract and measurement of absorbance. The sample throughput is 45 h^?1. A microcolumn containing Chelex-100 chelating resin is used for on-line preconcentration of lead, giving a detection limit of 5 μg l^?1 with a sample throughout of 36 h^?1. The method compares favourably with the dithizone and diethyldithiocarbamate methods with respect to selectivity. Application to standard alloys, soil leachates and sea water is demonstrated.     

Rapid determination of 1,1-dimethylhydrazine transformation products in soil by accelerated solvent extraction coupled with gas chromatography–tandem mass spectrometry

A method for the analytical extraction of mobile species of eightmain transformation products of 1,1-dimethylhydrazine (formaldehyde dimethylhydrazone, acetaldehyde dimethylhydrazone, 2-furaldehyde dimethylhydrazone, 1,1,4,4-tetramethyl-2-tetrazene, N,N-dimethylformamide, N-nitrosodimethylamine, 1-methyl-1H-1,2,4-triazole, and 1-formyl-2,2-dimethylhydrazine) from soils using subcritical acetonitrile at a pressure of 100 bar is proposed. The effects of temperature, number of extraction cycles, and the moisture content of soil samples on the recovery of analytes were studied. It was found that, for soils with high concentrations of lignin humic substances, efficient extraction can be attained with an addition of significant amounts of alkali to the soil (2.5 g/g). Under the optimum conditions, the recovery of analytes was higher than 70% at the extraction time no more than 30 min. A combination of the proposed sample preparation approach with analysis by gas chromatography–tandem mass spectrometry (GC-MS/MS) ensures the determination of the products of unsymmetrical dimethylhydrazine (UDMH) transformation in complex matrixes, such as soils with high concentrations of organic substance with detection limits from 1.8 to 15 µg kg^–1 using the direct injection of the extract into the chromatography system. The error of determination at a confidential probability of 0.95 was not worse than 15% even for analyte concentrations close to lower limit of quantitation (LLOQ) values. The method developed is a significant improvement compared to the highly efficient methods previously reported in literature differing from them with simple sample preparation, rapidity, low consumption of reagents, the possibility of simultaneous determination of eight compounds and 1–2 orders of higher sensitivity. It was successfully used for the analysis of real samples of peaty soil from the place of impact of the first step of a carrier rocket.     

Effect of sample preparation conditions on the determination of the total concentrations of unsymmetrical dimethylhydrazine in soils

It is shown that, for a correct determination of the total concentration of unsymmetrical dimethylhydrazine (UDMH) in soil, it is necessary to consider the simultaneous presence of active products of its transformation, capable of hydrolysis to the parent compound, such as formic acid 1,1-dimethylhydrazide (FADMH). A comparative study is performed of the methods known in the literature for sample preparation to select conditions for the quantitative extraction of UDMH bonded by various mechanisms to organic and mineral fractions of soil, as well as FADMH as one of the most common active transformation products. It is found that the distillation with a 40% NaOH solution with an addition of Na₂S enables the quantitative recovery of UDMH and FADMH from soils of all types and the determination of the maximum concentration of UDMH in the analysis of real samples of contaminated soils, which allows us to recommend this option to determine the total concentration of UDMH.     

Dynamic fractionation of trace metals in soil and sediment samples using rotating coiled column extraction and sequential injection microcolumn extraction: A comparative study

Dynamic fractionation has been recognized as an appealing alternative to conventional equilibrium-based sequential extraction procedures (SEPs) for partitioning of trace elements (TE) in environmental solid samples. This paper reports the first attempt for harmonization of flow-through dynamic fractionation using two novel methods, the so-called sequential injection microcolumn (SIMC) extraction and rotating coiled column (RCC) extraction. In SIMC extraction, a column packed with the solid sample is clustered in a sequential injection system, while in RCC, the particulate matter is retained under the action of centrifugal forces. In both methods, the leachants are continuously pumped through the solid substrates by the use of either peristaltic or syringe pumps.A five-step SEP was selected for partitioning of Cu, Pb and Zn in water soluble/exchangeable, acid-soluble, easily reducible, easily oxidizable and moderately reducible fractions from 0.2 to 0.5 g samples at an extractant flow rate of 1.0 mL min⁻¹ prior to leachate analysis by inductively coupled plasma-atomic emission spectrometry.Similarities and discrepancies between both dynamic approaches were ascertained by fractionation of TE in certified reference materials, namely, SRM 2711 Montana Soil and GBW 07311 sediment, and two real soil samples as well. Notwithstanding the different extraction conditions set by both methods, similar trends of metal distribution were in generally found. The most critical parameters for reliable assessment of mobilisable pools of TE in worse-case scenarios are the size-distribution of sample particles, the density of particles, the content of organic matter and the concentration of major elements. For reference materials and a soil rich in organic matter, the extraction in RCC results in slightly higher recoveries of environmentally relevant fractions of TE, whereas SIMC leaching is more effective for calcareous soils.     

On-line coupling of miniaturized solid-phase extraction and microcolumn liquid-phase separations

On-line coupling of miniaturized solid-phase extraction methods and microcolumn separation techniques are reviewed. A conventional solid-phase micro-extraction device and fiber-in-tube solid-phase extraction was employed as the sample preparation method. In the fiber-in-tube technique, a novel fibrous polymeric material was introduced as the extraction medium for the microscale sample preparation step which could be directly coupled with microcolumn liquid-phase separation systems, such as microcolumn liquid chromatography, capillary electrophoresis, and capillary electrochromatography. The applications of these hyphenated systems, consisting of the sample preparation and separation processes, are also reviewed.     

In-Valve Sample Preparation Cartridge Designed for Microcolumn Liquid Chromatography

Miniaturized sample preparation technique for complex sample matrices has been developed with a polymer-coated fibrous extraction medium. By using extraction cartridge packed longitudinally with polymer-coated fiber into a short PEEK capillary, the extraction efficiency was significantly improved. The extraction cartridge was installed in an injection valve as a sample loop and the on-line coupling with microcolumn liquid chromatography (micro-LC) was demonstrated. This on-line coupled sample preparation/separation system showed a good validity for the analysis of phthalates and tricyclic antidepressant drugs in typical water samples. The lowest limits of quantification for several phthalates and tricyclic antidepressants (TCA) drugs were less than 1 ng mL^?1. The effect of polymeric coating on the filament surface on the extraction power was also investigated.     

Rapid Evaluation of the Bioremediation of Fuel Oil in Soil by Gas Chromatography–Laser Ionization Time-of-Flight Mass Spectrometry

Gas chromatography–laser ionization time-of-flight mass spectrometry (GC-LI-TOFMS) was applied to the analysis of fuel oil in soil and soil treated by bioremediation. To demonstrate rapid and selective measurement, only filtered samples after extraction of fuel oil from soil were prepared. The required time for preparing three sample solutions from an oil-contaminated soil sample was only ca. 30?min. The degree of the decrease in the fuel oil in a soil sample by vaporization was confirmed by GC-LI-TOFMS, and after 7 days, the five peak areas arising from the constituents in fuel oil were decreased to between 39 and 79% of their original values. Next, the effect of bioremediation was confirmed by the addition of microbes (Rhodococcus sp. and Acinetobacter sp.). As a result, after 7 days, the five peak areas were decreased to between 61 and 81% of the values of the first decreases, after allowing for the effect of vaporization. This method showed sufficient selectivity, robustness, and rapidity for the measurement of oil-contaminated soil treated by bioremediation, which is essential for the evaluation of real environmental remediation.     

On-line coupling of flow injection sequential extraction to hydride generation atomic fluorescence spectrometry for fractionation of arsenic in soils

A new flow injection on-line sequential extraction procedure coupled with hydride generation atomic fluorescence spectrometry (HG-AFS) was developed for rapid and automatic fractionation of arsenic in soils. The developed methodology involved a three-step sequential extraction procedure with deionized water, KOH solution, and HCl solution. 25 mg of the soil sample packed into a microcolumn (4 mm i.d. × 3 cm long) was dynamically extracted by continuously pumping each individual extractant through the column. The extracted arsenic solution was merged with 4% (m/v) K₂S₂O₈ solution for on-line oxidation of all arsenic species into As^V. The total extracted arsenic was on-line detected by HG-AFS, and quantitated using an on-line standard addition calibration strategy. The total time for the three-step sequential extraction and on-line detection lasted only 10 min. The developed methodology offers several advantages over conventional batch sequential extraction protocols, including minimization of readsorption/redistribution problem, improvement of accuracy, high speed, less amounts of sample/reagents required, less risk of contamination and analyte loss. The developed methodology was successfully applied to the fractionation of arsenic in certified soil reference materials.     

Determination of 1,1-Dimethylhydrazine and its Transformation Products in Soil by Zwitterionic Hydrophilic Interaction Liquid Chromatography/Tandem Mass Spectrometry

1,1-Dimethylhydrazine is widely used as a fuel by some classes of carrier rockets. Being an extremely toxic and reactive substance, it gives a number of hazardous transformation products and poses a serious threat to the ecological state of the launch sites and territories used for landing of spent rocket parts. On the basis of studies of the retention of analytes on the sulfobetaine zwitterionic stationary phase, the HILIC–ESI-MS/MS method for simultaneous and rapid determination of unsymmetrical dimethylhydrazine and six major products of its transformation (methylhydrazine, N-nitrosodimethylamine, N,N-dimethylformamide, 1-methyl-1,2,4-1H-triazole, 1,1,4,4-tetramethyl-2-tetrazene, 1,1-dimethylguanidine) was developed. The achieved detection limits for the analytes were 0.02–7 μg L^?1 and, for most compounds, they are significantly lower compared to the existing IC–MS/MS method. Direct combination of HILIC–MS/MS with preliminary pressurized extraction with acetonitrile allowed analysis of peat bog soils contaminated with rocket fuel within 40 min, including all sample preparation steps. The developed method was successfully tested on a sample of real soil from the falling place of the spent carrier rocket stage.     

Photometric determination of trace selenium in aqueous media

A new procedure is developed for the photometric determination of trace selenium in aqueous solutions. The selection of 2-(p-nitrophenyl)-3,5-diphenyltetrazolium chloride as a reagent for selenium is justified. The proposed sample preparation procedure involves gas extraction of selenium as hydrogen selenide followed by its liquid-adsorption extraction from the gas phase to an aqueous reagent solution with the formation of a water-insoluble formazan. Formazan formed upon the absorption of hydrogen selenide is extracted with isoamyl alcohol. The concentration of selenium is determined from the absorbance of the formazan extract in the isoamyl alcohol. The procedure allows the determination of 10–120 μg/L selenium.     

Solid-phase microextraction–gas chromatographic determination of volatile monoaromatic hydrocarbons in soil

Benzene, toluene, ethylbenzene, three isomers of xylene, and cumene have been isolated and enriched from soil samples by a combination of water extraction at room and elevated temperature and headspace–solid-phase microextraction before their gas chromatographic–mass spectrometric (GC–MS) determination. The conditions used for all stages of sample preparation and chromatographic analysis were optimized. Analytes sampled on a polydimethylsiloxane-coated solid-phase microextraction fiber were thermally desorbed in the split/splitless injector of a gas chromatograph (GC) coupled with a mass spectrometer (MS). The desorption temperature was optimized. The GC separation was performed in a capillary column. Detection limits were found to be of the order of ca. 1 ng g^–1. Relative recoveries of the analytes from soils were found to be highly dependent on soil organic-matter content and on compound identity; they ranged from ca 92 to 96% for sandy soil (extraction at room temperature) and from ca 27 to 55% for peaty soil (extraction at elevated temperature). A few real-world soil samples were analyzed; the individual monoaromatic hydrocarbon content ranged from below detection limits to 6.4 ng g^–1 for benzene and 8.1 for the total of p- + m-xylene.     

Analysis of Explosives in Soil Using Solid Phase Microextraction and Gas Chromatography

Abstract

Current methods for the analysis of explosives in soils utilize time consuming sample preparation workups and extractions. The method detection limits for EPA Method 8330 for most analytes is substantially higher than the typical explosive concentrations encountered in soils near unexploded ordnance items, landmines, or other hidden explosive devices. It is desirable to develop new analytical techniques to analyze soil with low concentrations of explosives to support the development of explosive sensors. This report describes efforts to adapt headspace solid phase extraction and gas chromatography/mass spectrometry to provide a convenient and sensitive analysis method for explosives in soil.     

A Review of the Extraction of Herbicide Residues from Aged Saskatchewan Field Soils

Abstract

Polar solvents based on aqueous methanol and aqueous acetonitrile are good extractants of herbicides from Saskatchewan field soils that had received treatments of the individual chemicals 6 to 17 months previously. The addition of small amounts of acetic acid or ammonium hydroxide to aqueous acetonitrile resulted in greater recovery of most herbicides. In general, 50 ml of the extraction solvent were added to 20 g of soil and the soils were then initially extracted for 1-hr on a wrist-action shaker and then allowed to stand overnight before being shaken for a further 1-hr period.     

The determination of petroleum hydrocarbons in soil using a miniaturized extraction method and gas chromatography

A gas chromatographic (GC) method for the determination of petroleum hydrocarbons (PH) in the boiling range from 175°C to 525°C (C₁₀?C₄₀ alkane) in soil was evaluated. The extraction was carried out using minimal amounts of acetone and heptane, prior to a clean up with silica gel. The extraction procedure was tested by means of standard solutions of petroleum products and soil samples. The clean up procedure did not have any significant effect on the amounts of petroleum hydrocarbons present and hydrocarbons of natural origin were removed effectively. The recovery of the extraction and clean up procedure for petroleum products in soil was greater than 90%. The standard deviation for the repeatability was estimated to be less than 10% based on multiple analyses of homogenized soil samples. The detection limit for soil was determined to be 10 mg/kg dry matter. Comparing the GC method with the widely used infrared spectrometry (IR) method in combination with a Soxhlet-extraction using Freon-113, the results obtained are equivalent.     

Determination of lead in petroleum and petroleum products by atomic absorption spectrometry with a carbon rod atomizer

The use of a carbon rod atomizer for the analysis of lead in petroleum and petroleum products is described. Variables affecting sensitivity studied include: type of lead salt and type of solvent for standard and sample preparation, hydrogen diffusion flame, choice of analytical wavelength and interferences. For the 217.00-nm line, a sensitivity of 1·10^-11 g (absolute) and for the 283.31-nm line, a detection limit of 2·10^-12 g (absolute) are reported. Results of analysis of gasoline, used bunker heating oil, used jet engine lubricating oil, and crude oil for lead content are presented. An organic-to-aqueous solvent extraction system for lead is described.     

Selective photometric determination of selenium in aqueous media

A procedure is developed for the photometric determination of selenium in aqueous media using 2-(p-nitrophenyl)-3,5-diphenyltetrazolium chloride. To selectively determine selenium, a two-stage scheme of sample preparation is chosen. It includes the gas extraction of selenium liberated as hydrogen selenide, its extraction from the gas phase to a solution of lead nitrate by liquid absorption and repeated extraction of hydrogen selenide, followed by its absorption with an aqueous reagent solution to form water-insoluble formazan. The formazan is extracted with chloroform. The concentration of selenium is determined from the absorbance of the chloroform extract of formazan. The procedure involves no special preconcentration operations and allows from 10 to 100 μg/L selenium to be determined.     

Fossil fuel applications of SFC and SFE: A review

The use of supercritical fluid technology for sample preparation and analysis in the petroleum industry will be described using various examples including: separation of petroleum fuels into hydrocarbon classes, determination of polynuclear aromatic hydrocarbon in soils and petroleum fuels, characterization of fuel-contaminated soil, assessment of fuel boiling point distribution, determination of polymer additives, and characterization of shale rock and drilling mud.     

Sulfur trace determination in petroleum products by isotope dilution ICP-MS using direct injection by thermal vaporization (TV-ICP-IDMS)

An accurate, sensitive, and fast method for direct determination of total sulfur in petroleum products after thermal vaporization of an isotope-diluted sample was developed by using ICP-MS. ³⁴S-labelled dibenzothiophene spike was used for the isotope dilution step. The isotope-diluted sample was injected into a thermal vaporizer which was directly connected by a heated transfer line to the plasma torch. Sample transport was achieved by using a helium gas flow, and the isotope ratio ³⁴S/³²S was determined within seconds after injection. No other sample preparation other than the simple and fast isotope dilution step, which enables accurate and sensitive determination of sulfur at high sample throughputs, is necessary. Thus, this technique fits all needs for routine analyses. Validation of the TV-ICP-IDMS method was carried out by analyzing the certified gas oil reference materials BCR672 and BCR107. Comparison of results for noncertified low- and high-boiling samples, obtained from an ICP-IDMS microwave-assisted digestion method, also resulted in very good agreement. The low detection limit of 40 ng/g and the large dynamic range of TV-ICP-IDMS fulfill all necessities to allow analysis of sulfur in different petroleum products, e.g., even at the low concentration level of ‘sulfur-free’ gasoline.     

Application of a Sequential Extraction Procedure to Calcareous Soil Samples: Preliminary Studies

Abstract

The localization of trace metals in soils is usually performed by sequential extraction procedures. Our purpose was to study the fractioning of copper in calcareous soils, in order to predict its mobility, using the extraction procedure proposed by Tessier et al. This preliminary study is devoted to the improvements of this method applied to calcareous soil samples.

First, it was necessary to assess the experimental conditions allowing the complete solubilisation of the different compartments involved in the extraction procedure with their appropriate reagent (acetic acid-sodium acetate and carbonates, iron hydroxide and hydroxylamine, organic matter and hydrogen peroxide, fluorhydric-perchloric acid and residual fraction). The complete solubilisation of each compartment was tested by measuring the residual phase.

Secondly, it was necessary to study the analytical protocol for the determination of copper with electrothermal atomic absorption; an improvement of this determination was particularly necessary for the reagent used for the exchangeable fraction (sodium acetate at pH = 8.5).

According to the experimental results, the quality (repeatability, concordance of the sum of fractions with the total content of copper determined with independent measurement) of the proposed protocol seems to be quite good.

Some results of the fractioning of copper in calcareous soil samples are given; these samples are characterised by a high value of copper in the residual fraction corresponding to a poor availability of this element.