Compounds In Soil Samples Research Articles

A study on source identification of contaminated soil with total petroleum hydrocarbons (aromatic and aliphatic) in the Ahvaz oil field.

The oil industry in Khuzestan province (Southwest Iran) is one of the main reasons contributing to the pollution of the environment in this area. TPH, including both aromatic and aliphatic compounds, are important parameters in creating pollution. The present study aimed to investigate the source of soil contamination by TPH in the Ahvaz oil field in 2022. The soil samples were collected from four oil centers (an oil exploitation unit, an oil desalination unit, an oil rig, and a pump oil center). An area outside the oil field was determined as a control area. Ten samples with three replicates were taken from each area according to the standard methods. Aromatic and aliphatic compounds were measured by HPLC and GC methods. The positive matrix factorization (PMF) model and isomeric ratios were used to determine the source apportionment of aromatic compounds in soil samples. The effects range low and effects range median indices were also used to assess the level of ecological risk of petroleum compounds in the soil samples. The results showed that Benzo.b.fluoranthene had the highest concentration with an average of 5667.7 ug/kg in soil samples in the Ahvaz oil field. The highest average was found in samples from the pump oil center area at 7329.48 ug/kg, while the lowest was found in control samples at 1919.4 ug/kg-1. The highest level of aliphatic components was also found in the pump oil center, with a total of 3649 (mg. Kg-1). The results of source apportionment of petroleum compounds in soil samples showed that oil activities accounted for 51.5% of the measured PAHs in soil. 38.3% of other measured compounds had anthropogenic origins, and only 10.1% of these compounds were of biotic origin. The results of the isomeric ratios also indicated the local petroleum and pyrogenic origin of PAH compounds, which is consistent with the PMF results. The analysis of ecological risk indices resulting from the release of PAHs in the environment showed that, except for fluoranthene, other PAHs in the oil exploitation unit area were above the effects range median level (ERM) and at high risk. The results of the study showed that soil pollution by total petroleum hydrocarbons (TPH), both aromatic and aliphatic, is at a high level, and is mainly caused by human activities, particularly oil activities.

Investigation of 29 Antimicrobial Compounds in Soil Using Newly Developed UHPLC-MS/MS Method.

While the prudent and reasonable use of veterinary antimicrobial agents in food-producing animals is necessary, researchers over the decades have shown that these antimicrobial agents can spread into the environment through livestock manure and wastewater. The analysis of the occurrence of antimicrobial compounds in soil samples is of a great importance to determine potential impacts on human and animal health and the environment. In this study, an affordable, rugged and simple analytical method has been developed for the determination of twenty-nine antimicrobial compounds from five different classes (tetracyclines, fluoro(quinolones), macrolides, sulfonamides and diaminopirimidines). Liquid-liquid extraction (LLE) with extract filtration combined with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was the best strategy for the simultaneous determination of all analytes. The developed method was validated according to the Commission Implementing Regulation (EU) 2021/808. The limit of detections (LODs) ranged from 0.5 to 2.0 µg/kg, while the limit of quantitation (LOQ) was established at 1.0 to 20.0 µg/kg. The developed method was successfully applied for the determination of antimicrobial residues in one hundred and eighteen soil samples obtained from four European countries (Austria, Czech Republic, Estonia and Portugal). Doxycycline in the concentration levels of 9.07 µg/kg-20.6 µg/kg was detected in eight of the analysed samples. Samples were collected from areas where natural fertilizers (swine or cow manure) were applied. Our method can be efficiently used to monitor anti-microbial compounds in soil samples.

Hollow-Fiber Liquid-Phase Microextraction (HF-LPME) Coupled On-Line to Liquid Chromatography for the Determination of the Herbicides 2,4-Dichlorophenoxyacetic Acid and 2-Methyl-4-chlorophenoxyacetic Acid and Their Main Metabolites in Soil Samples

The use of hollow-fiber liquid-phase microextraction (HF-LPME) is very promising for the clean-up, enrichment, and analysis of chlorophenoxyacetic acid herbicides and their metabolites from environmental and biological samples. An on-line methodology coupling HF-LPME (using a hydrophobic polypropylene hollow fiber of 57 cm length, 0.3 mm i.d., 0.2 μm pore size, and 75% porosity) and HPLC-UV has been developed for the analysis of these compounds in soil samples taken from environments treated with these herbicides. Di-hexyl ether was found to be the best solvent for the enrichment of the target herbicides. The use of supported liquid membranes has shown a high and efficient clean-up of the dissolved organic matter present in soil extracts. The enrichment factors achieved with the on-line methodology have allowed us to reach the detection limits of 0.1–0.3 µg·kg−1 soil, by analyzing 20 mL of alkaline extract as a donor solution and using 1 mL of stripping solution, which has permitted us to detect and follow the presence of these compounds in soil samples until nine days after the application of the herbicide. The on-line method has been applied in a preliminary study to assess the mobility of the chlorophenoxyacetic acid herbicides through soils. It has also been found that degradation of these compounds in soil is relatively fast and some metabolites were detected in soils just one day after the application of the herbicide. The high enrichment factors obtained with the HF-LPME procedure allow for the obtainment of low detection limits, which permits the use of a simple HPLC detector, such as UV, which simplifies and reduces the cost of analyses.

Nanostructured polyaniline SPME fiber coating for chemical warfare agents analysis

Nanostructured polyaniline (PANI) was electrochemically obtained as a fiber coating of solid-phase microextraction (SPME) and then used in the analysis of selected organoarsenic and organophosphorus compounds in soil samples. Also, comparative studies of the obtained PANI fibers with seven commercially available fibers for varying miscellaneous polarity, and various absorption and/or adsorption natures, were carried out. Quantitative analysis of environmental samples was performed using a gas chromatograph coupled with a tandem mass spectrometer. During the analysis of organophosphorus compounds, the PANI fiber showed at least 20% greater sorption efficiency than any commercially available fiber, whereas, in the case of organoarsenic compounds, the sorption efficiency of the PANI fiber increased with the expansion in the number of phenyl rings in the molecule. The PANI coating material was characterised by N2 adsorption–desorption, scanning electron microscopy, infrared spectroscopy and thermogravimetric analysis. SEM imaging confirmed a nanostructured form of PANI. The repeatability for one fiber (n = 7), expressed as the relative standard deviation ranges from 3.2% to 4.4% depending on the kind of tested chemical compound. The reproducibility (calculated as relative standard deviation of the 9 prepared fibers) was not greater than 7.2% Under the optimized conditions, the proposed method was linear over approximately 4 orders for organophosphorus compounds (0.02–100 ng g−1) and 5 orders for organoarsenic compounds (0.12–5000 ng g−1) of magnitude for the tested compounds, with linear determination coefficients (R2) greater than 0.972, and the limit of detection for the home-made PANI fiber was relatively low (0.006–0.45 ng g−1). In comparison with all commercially available SPME fibers, the new PANI fiber was more selective for the tested aromatic and organophosphorus compounds and easily as well as inexpensively prepared. The resulting stationary phase allowed for quantitative analysis of selected organophosphorus and organoarsenic compounds from the group of warfare agents.

Modified dispersive solid-phase extraction and cleanup followed by GC-MS/MS analysis to quantify ultraviolet filters and synthetic musk compounds in soil samples.

A simple method for the analysis of 13 synthetic musk compounds and six ultraviolet filters in soil samples was developed using a modified dispersive solid-phase methodology known as "Quick, Easy, Cheap, Effective, Rugged and Safe," followed by gas chromatography-triple quadrupole mass spectrometry. The methodology was validated by assessing linearity ranges, detection limits, precision, and accuracy. The method detection limit ranged between 0.01 and 10.00ng/g dry weight and accuracy from 81 to 122%. A good precision was achieved, with relative standard deviation <10%. The applicability of the methodology was tested using different types of soils. Both synthetic musks and ultraviolet filters were detected in all soil samples. The most frequently detected compounds were benzophenone, octocrylene, 2-ethylhexyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-methoxycinnamate, and galaxolide. Higher levels were detected for benzophenone (maximum value of 158ng/g dry weight) and octocrylene (137ng/g dry weight). In comparison with conventional techniques, this method uses lower amounts of solvents and sorbents, producing less waste ("greener" technique) and comparable performances. In addition, it presents as main advantages the simplicity, speed (short extraction/cleaning time), low cost, and minimum handling of extracts, which can minimize the possibility of samples cross-contamination.

Multiresidue Method for Analysis of 240 Pesticides in Soils of Tomato Planting by Ultra Performance Liquid Chromatography Coupled to Mass Spectrometry

In this work, an analytical method for the determination of residues for the pesticides-focus was optimized: Azoxystrobin, Boscalide, Carbendazim, Chloranthranilprole, Clothianidin, Diafentiuron, Difenoconazole, Dimetomorfe, Espinetoram, Espinosade A, Espinosade D, Fenurox, Metalaxyl M, Methoxyfenozide, Tiametoxan in soil derived from tomato planting, in order to compare the levels of contamination of these compounds in soil samples. The modified QuEChERS extraction method and Ultra Performance Liquid Chromatography coupled with Sequential Mass Spectrometry were used, with ionization source by Electronebulization in ESI mode (+/-). The method consisted of extracting 15.0 g of soil with 15 ml of saturated calcium hydroxide solution pH 12.3 and 15 ml of acetonitrile, with a consequent partition in the “salting out” effect through 6.0 g of sulfate of anhydrous magnesium and 1.5 g of sodium chloride. The phases were separated by centrifugation at 3700 rpm for 7 min. The extracts were diluted with MeOH licrossolv® grade and injected in a chromatograph. The method was validated based on the parameters of linearity, LOD, LOQ, precision and accuracy. Linearity between 0.2 and 20.0 µg L-1, determination coefficients greater than 0.99. The LOQ values ​​for the method were 13 µg kg-1 for Spinosad and 7.0 µg kg-1 for the other pesticides. The method showed good precision, with RSD values ​​&lt;20%, and accuracy, with recoveries between 70 and 120% for the vast majority of the analyzed compounds. The analytical curves were prepared with reference white soil extracts, in order to minimize the Matrix Effect. The method was considered adequate for the analysis of pesticide residues in soil, since it satisfies the validation parameters of chromatographic methods (European Commission, 2018). After validation, the method was used to analyze the residues of these pesticides in soil samples from conventional, organic and sustainable tomato plantations. Making it possible to compare the levels of environmental impacts generated. In addition to validating the analytical method for the pesticides-focus of the study, it was also possible to validate 240 more compounds, between authorized and unauthorized for use in tomato planting.

ПОГРЕБАЛЬНАЯ ПОСУДА И ПИЩЕВЫЕ СТРАТЕГИИ В ДРЕВНОСТИ

The article continues the publication of the results of multidisciplinary study of the Bronze Age cemetery Nepluyevsky in the Southern Trans-Urals, presenting the experience of studying the soil contents of ceramic vessels from kurgan 1. The pottery collection consists of 95 pots found intact or fragmentated in burials, food offerings pits and cenotaphs, as well as outside structures, i. e. on the ancient surface horizon. All studied structures were attributed to the Srubnaya culture, mainly to its Srubnaya-Alakul variant. The undertaken reconstruction of funeral food is based on comparative analysis of chemical compounds in soil samples from 54 archaeologically intact pots using X-ray and mass-spectrometry. The studied pottery includes decorated and non-decorated pots of different shapes. There are no any traces of utilization, that is why one may presume its ritual meaning. During laboratory analyses, its soil content marks high points titers of biogenic elements such as P, K, Ca and Mg, which used to be the difference in funereal meals. The results obtained made it possible to reconstruct the original contents of ritual ceramics. Thus, there is no evidence of meat, the vessels could contain both milk/fermented milk products and water/herbal drinks, or they could be empty as well. There is not any strong connection between the age of the deceased and the food offerings. The absence of cereals residues in the studied samples is noteworthy, which is typical for groups with a predominantly meat and dairy diet.

Identification of Unknown Brominated Bisphenol S Congeners in Contaminated Soils as the Transformation Products of Tetrabromobisphenol S Derivatives.

Compared with tetrabromobisphenol A (TBBPA) and its derivatives, the skeletally similar chemicals tetrabromobisphenol S (TBBPS) and its derivatives have been rarely studied, and very little is known about their structures, environmental occurrence, and behaviors. In this study, a total of 84 soil samples from a chemical industrial park have been collected and analyzed to investigate the occurrence of TBBPS and its derivatives and to identify novel TBBPS analogs. TBBPS, TBBPS bis(2,3-dibromopropyl ether) (TBBPS-BDBPE), and three byproducts, TBBPS mono(allyl ether) (TBBPS-MAE), TBBPS mono(2-bromoallyl ether) (TBBPS-MBAE), and TBBPS mono(2,3-dibromopropyl ether) (TBBPS-MDBPE), have been detected with contents ranging from below detection limits to 1934.6 ng/g dw and with detection frequencies of 21.4-97.6%. In addition, another 5 unknown TBBPS analogs, tribromobisphenol S (TriBBPS), 2,2',6'-TriBBPS-MAE (TriBBPS-MAE3.2), 2,6,2'-TriBBPS-MAE (TriBBPS-MAE3.4), 2',6'-DBBPS-MAE (DBBPS-MAE2.0), and 2,6-DBBPS-MAE (DBBPS-MAE2.6), have been identified in these soil samples by untargeted mass spectrometry screening. These unknown analogs have also been observed in laboratory transformation experiments of TBBPS-MDBPE conducted under reducing conditions. TriBBPS-MAE3.4 and DBBPS-MAE2.6 were more likely to be produced than TriBBPS-MAE3.2 and DBBPS-MAE2.0 due to the stereoselectivity of the transformation. TriBBPS-MAE3.4 and DBBPS-MAE2.0 were more stable, resulting in higher detection frequencies of these compounds in soil samples. Ether bond breakage and debromination contributed to the generation of these novel products. The results provide new information on the behaviors of TBBPS and its derivatives in the environment.

Investigation of heavy metal distributions along 15 m soil profiles using EDXRF, XRD, SEM‐EDX, and ICP‐MS techniques

The research of soil contamination by heavy metal is an important field due to its environmental and health implications. The goal was to study the elemental mobility as a function of depth. For this reason, the distribution of heavy metals (V, Cr, Co, Ni, Cu, Zn, As, Sn, and Pb) was investigated along soil profiles up to a depth of 15 m at 9 sampling sites in the Nilufer industrial district (Bursa, Turkey). Elemental analyses were done with the Epsilon 5 energy dispersive X‐ray fluorescence and inductively coupled plasma mass spectrometry equipment. Particle analysis was performed with a JEOL scanning electron microscope equipped with a Si(Li) X‐ray detector. The crystallographic compositions of oxide compounds in soil samples were identified by a Rigaku X‐ray diffraction instrument. Different parameters such as the soil's chemical (mineralogical structure, pH, and electrical conductivity) and physical properties (the number of blows, the stiffness index, the liquidity index, the plasticity index, and the water content) were analyzed. To assess the mobility of the heavy metals, diffusion (D) and convection coefficients (ʋ) were calculated with the finite difference method. Convection was determined to dominate the studied region. In addition, the mobility coefficient was determined for each metal. High mobilities were determined for Zn and V, moderate mobilities for Cr, Ni, Cu, and As, and low mobilities were determined for Co and Pb. The results revealed that elements had reached depths of up to 15 m, causing irreversible soil contamination that may lead to environmental health issues.

A new approach for the extraction of tetracyclines from soil matrices: application of the microwave-extraction technique.

The widespread use of tetracyclines (TCs) in animal husbandry is associated with their constant penetration into the environment and the threat they might pose to living organisms. While the literature data on the analysis of these substances in such matrices as food, tissues, or wastewater are quite extensive, there are still only a few methods presented for the determination of these compounds in soil samples. Moreover, among the literature methods for the extraction of TCs from soil samples, microwave-assisted solvent extraction (MAE) was used only once and in combination with liquid chromatography with spectrophotometric detection (LC-UV). However, according to the EU Commission Decision 2002/657/EC, the use of LC-UV for the determination of compounds, including pharmaceuticals, in environmental samples is not sufficient. Therefore, the development and application of a sensitive and selective method using the MAE-SPE-LC-MS/MS(MRM) technique for the isolation and identification of a mixture of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in soils is presented in our study. The credibility of this method has been confirmed with good parameters of validation. The optimal extraction conditions of three TCs using MAE techniques were to conduct double extraction for 10min each, at 60°C, using a mixture of ACN:McIlvaine buffer:0.1M EDTA (2:1:1, v/v/v) and an additional cleaning of the extracts by SPE. The effectiveness of the extraction of these compounds was assessed based on two different ways (absolute recovery from 46 to 65.1% and relative recovery from 101.1 to 109.5%). Finally, the validated MAE-SPE-LC-MS/MS(MRM) method was used for the analysis of six samples from agricultural areas of northern Poland. OTC and TC, at concentrations of 11.7 and 14.5μgkg-1 were determined in two different samples. An assessment of risk quotients was also performed. The presented method was proven to be a useful tool in the analysis of residues of selected TCs in the soil ecosystem. Obtained data on the presence of these drugs in Polish soils is the first report for this country.

Screening and Quantification of Organic Pollutants in Soil Using Comprehensive Two-dimensional Gas Chromatography with Time-of-flight Mass Spectrometry

ABSTRACTThe identification and quantification of organic compounds in leaching basin soil is important for the evaluation of soil pollution. In this study, a non-target screening strategy and a quantitative analytical method were developed based on the accelerated solvent extraction method followed by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry. First, a screening method for potential risk compounds in soil samples was established, and the major compounds were screened under the conditions such as matching similarity, signal-to-noise ratio, and relative area ratio. Second, a quantitative method was further developed by internal calibration curves for 50 main organic pollutants in the soil samples, including 27 polycyclic aromatic hydrocarbons and their derivatives (PAHs), 10 phthalic acid esters, eight phenolic compounds, and five benzene derivatives. The quantitative procedure exhibited good selectivity, accuracy, precision, low limits of detection (0.03–1.02 ng/g), and quantification (0.1–3.0 ng/g) for all target compounds. Finally, the proposed strategy was applied to the soil samples that were collected from a leaching basin and polluted by electroplating wastewater. Abundant PAHs and phenolic compounds were detected in the topsoil sample, which were mainly released from the electroplating wastewater. The application of this multi-dimensional strategy in leaching basin soil samples can also be used for the assessment of organic pollution in other complex soil samples.

Bacteriological and Physicochemical Properties of Petroleum-Contaminated Soil Collected from a Mechanic Site in Abuja, North-Central Nigeria

Elevated levels of petroleum hydrocarbon and certain heavy metal compounds in soil samples due to environmental and manmade operations can amount to concentrations considered as toxic. Soil samples from 3 different locations, 30 meters from each other were collected and assessed for polycyclic aromatic hydrocarbon (PAH), total petroleum hydrocarbon (TPH), selected heavy metal concentrations, pH, Electrical Conductivity, texture, organic matter, moisture content and bacterial population. The results on the test sites showed that pH range for the workshop soil samples was between 5.08-5.45 in comparison to the control 6.74. Data obtained also revealed that the tested site A alone contained lead (44.91 mg/g) and cadmium (0.01 mg/g). The heavy metal content for sites A, B and C where higher than that of the control site D for which the enrichment factors was determined for sodium (1.07, 3.34, 4.12), copper (2.73, 2.63, 1.57), iron (9.84, 10.67, 9.21), zinc (4.78, 2.58, 2.98), nickel (1.44, 1.11, 1.56) and manganese (2.57, 2.23, 3.77) respectively. The moisture content and electrical conductivity ranged between 44.7-46.5% and 985.6-1124.7 (µS/cm) respectively as opposed to 44.9%, 846.3 (µS/cm) for the control. Total bacterial enumeration revealed a count of 2.28 x 104 (cfu/g), 2.01 x 104 (cfu/g), 1.98 x 103 (cfu/g) and 2.71 x 105 (cfu/g) at sites A, B, C and D respectively. The presence of hydrocarbon and heavy metal pollutants due to the activities at the mechanic workshop resulted in change of known physicochemical properties which in turn affects the ecology as well as life forms in the area.

A simple and efficient method for imidazolinone herbicides determination in soil by ultra-high performance liquid chromatography–tandem mass spectrometry

The use of pesticides in agriculture has generated numerous consequences to the environment, requiring analysis of the persistent residues in soil, water and air. The variability of soil properties interferes in the extraction of pesticide residues with robustness and accuracy. The group of imidazolinones herbicides, widely used for weed control, becomes an additional task in multiresidue extraction procedures because of their low pKa values. In order to determine these compounds in soil samples, different methods have been proposed, however they can be very laborious and require more time and well trained analysts. Thus, this study aimed to develop a simple and efficient method for determination of imidazolinones (imazamox, imazapic, imazapyr, imazaquin and imazethapyr) residues in soil, using an extraction with aqueous ammonium acetate solution (0.5M) and clean-up with dispersive solid phase extraction employing PSA, followed by UHPLC–MS/MS analysis. Satisfactory values of accuracy (70–93%) and RSD (≤17%) were achieved, as well as lower limit of quantification (5.0μgkg−1). Considering the matrix and compounds complexity, the developed and validated method proved to be an excellent tool for rapid analysis (20min), with reliability for application in real samples with wide pH range. In the analysis of 22 real samples, the method allowed the quantification of imazapic (5.84 and 12.1μgkg−1), imazapyr (5.3μgkg−1) and imazethapyr (24.0 and 37.7μgkg−1) in three samples.

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 3h, respectively. Recoveries of MTA depended on concentrations of spiked MTA-d3 during method validation. Lowest spiked MTA-d3 concentration (0.24mgkg−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 1mgkg−1. The newly developed method is fully automated, and requires much lower time, labor and financial resources compared to known methods.

Gas chromatographic detection of some nitro explosive compounds in soil samples after solid‐phase microextraction with carbon ceramic copper nanoparticle fibers

In this research, a new solid-phase microextraction fiber based on carbon ceramic composites with copper nanoparticles followed by gas chromatography with flame ionization detection was applied for the extraction and determination of some nitro explosive compounds in soil samples. The proposed method provides an overview of trends related to synthesis of solid-phase microextraction sorbents and their applications in preconcentration and determination of nitro explosives. The sorbents were prepared by mixing of copper nanoparticles with a ceramic composite produced by mixture of methyltrimethoxysilane, graphite, methanol, and hydrochloric acid. The prepared sorbents were coated on copper wires by dip-coating method. The prepared nanocomposites were evaluated statistically and provided better limits of detection than the pure carbon ceramic. The limit of detection of the proposed method was 0.6μg/g with a linear response over the concentration range of 2-160 μg/g and square of correlation coefficient >0.992. The new proposed fiber has been demonstrated to be a suitable, inexpensive, and sensitive candidate for extraction of nitro explosive compounds in contaminated soil samples. The constructed fiber can be used more than 100 times without the need for surface generation.

Identification of autotoxic compounds in fibrous roots of Rehmannia (Rehmannia glutinosa Libosch.).

Rehmannia is a medicinal plant in China. Autotoxicity has been reported to be one of the major problems hindering the consecutive monoculture of Rehmannia. However, potential autotoxins produced by the fibrous roots are less known. In this study, the autotoxicity of these fibrous roots was investigated. Four groups of autotoxic compounds from the aqueous extracts of the fibrous roots were isolated and characterized. The ethyl acetate extracts of these water-soluble compounds were further analyzed and separated into five fractions. Among them, the most autotoxic fraction (Fr 3) was subjected to GC/MS analysis, resulting in 32 identified compounds. Based on literature, nine compounds were selected for testing their autotoxic effects on radicle growth. Seven out of the nine compounds were phenolic, which significantly reduced radicle growth in a concentration-dependent manner. The other two were aliphatic compounds that showed a moderate inhibition effect at three concentrations. Concentration of these compounds in soil samples was determined by HPLC. Furthermore, the autotoxic compounds were also found in the top soil of the commercially cultivated Rehmannia fields. It appears that a close link exists between the autotoxic effects on the seedlings and the compounds extracted from fibrous roots of Rehmannia.

Fingerprinting of petroleum hydrocarbons (PHC) and other biogenic organic compounds (BOC) in oil-contaminated and background soil samples

Total petroleum hydrocarbons (TPH) or petroleum hydrocarbons (PHC) are one of the most widespread soil contaminants in Canada, the United States and many other countries worldwide. Clean-up of PHC-contaminated soils costs the Canadian economy hundreds of millions of dollars annually. In Canada, most PHC-contaminated site evaluations are based on the methods developed by the Canadian Council of the Ministers of the Environment (CCME). However, the CCME method does not differentiate PHC from BOC (the naturally occurring biogenic organic compounds), which are co-extracted with petroleum hydrocarbons in soil samples. Consequently, this could lead to overestimation of PHC levels in soil samples. In some cases, biogenic interferences can even exceed regulatory levels (300 μg g(-1) for coarse soils and 1300 μg g(-1) for fine soils for Fraction 3, C(16)-C(34) range, in the CCME Soil Quality Level). Resulting false exceedances can trigger unnecessary and costly cleanup or remediation measures. Therefore, it is critically important to develop new protocols to characterize and quantitatively differentiate PHC and BOC in contaminated soils. The ultimate objective of this PERD (Program of Energy Research and Development) project is to correct the misconception that all detectable hydrocarbons should be regulated as toxic petroleum hydrocarbons. During 2009-2010, soil and plant samples were collected from over forty oil-contaminated and paired background sites in various provinces. The silica gel column cleanup procedure was applied to effectively remove all target BOC from the oil-contaminated sample extracts. Furthermore, a reliable GC-MS method in combination with the derivatization technique, developed in this laboratory, was used for identification and characterization of various biogenic sterols and other major biogenic compounds in these oil-contaminated samples. Both PHC and BOC in these samples were quantitatively determined. This paper reports the characterization results of this set of 21 samples. In general, the presence of petroleum-characteristic alkylated PAH homologues and biomarkers can be used as unambiguous indicators of the contamination of oil and petroleum product hydrocarbons; while the absence of petroleum-characteristic alkylated PAH homologues and biomarkers and the presence of abundant BOC can be used as unambiguous indicators of the predominance of natural organic compounds in soil samples.

Stir bar sorptive extraction of parabens, triclosan and methyl triclosan from soil, sediment and sludge with in situ derivatization and determination by gas chromatography–mass spectrometry

The aim of this research work was the evaluation of stir-bar sorptive extraction (SBSE) in combination with an in situ derivatization to determine parabens (methylparaben, isopropylparaben, n-propylparaben, butylparaben and benzylparaben), triclosan and methyltriclosan in soil samples. This is the first time that this approach has been applied to the determination of these compounds in soil samples, providing important advantages over conventional extraction techniques, such as minimization of sampling handling, complete elimination of the use of organic solvents and simplification of the analytical procedure with reduced time consumption. The enriched target analytes were desorbed thermally using a thermodesorption system coupled to a gas chromatograph and a mass spectrometer. The optimized derivatization and SBSE extraction conditions, as well as the analytical characteristics of the method were obtained using spiked soil samples. The proposed methodology proved to be easy to use and sensitive, with limits of detection between 80 ng/kg and 1.06 μg/kg, and reproducibility values below 13%. The accuracy of the method was evaluated at two concentration levels, obtaining apparent recoveries between 91% and 110%. The matrix composition significantly influenced the extraction procedure, and a need to adopt a standard additions protocol is apparent. The analytes assayed were determined successfully in different environmental soil samples.

Headspace-Liquid Phase Microextraction for Attenuated Total Reflection Infrared Determination of Volatile Organic Compounds at Trace Levels

A combination of headspace (HS) sampling and liquid phase microextraction (LPME) has been successfully developed to solve sensitivity problems in attenuated total reflection (ATR) infrared determination of volatile organic compounds (VOCs). The HS sampling facilitates the selective extraction of the target volatile analytes from the sample matrix, while the liquid phase microextraction allows their preconcentration prior to infrared analysis. The direct determination of extracted analytes in the acceptor solvent provides high preconcentration factors of the order of 200 with a reduced consumption of organic solvents and a minimum generation of wastes, being thus the developed methodology a green alternative method. The qualitative and quantitative capability of the proposed approach has been evaluated on the basis of two different examples: (i) screening of benzene, toluene and xylene (BTX) compounds in soil samples and (ii) quantitative determination of toluene in cosmetic nail products.

Headspace-trap gas chromatography–mass spectrometry for determination of sulphur mustard and related compounds in soil

Methods for trace determination of sulphur mustard (HD) and some related cyclic sulphur compounds in soil samples have been developed using headspace-trap in combination with gas chromatography–mass spectrometry (GC–MS). Two quite different types of soil were employed in the method optimisation (sandy loam and silty clay loam). Prior to analysis, water saturated with sodium chloride was added to the samples, at a water to soil ratio of 1:1. A detection limit of 3 ng/g was achieved for HD, while the cyclic sulphur compounds 1,4-thioxane, 1,3-dithiolane and 1,4-dithiane could be detected at 0.2–0.7 ng/g. The methods were validated in the concentration range from the limit of quantification (LOQ) to hundred times LOQ. The within assay precision at fifty times LOQ was 6.9–7.3% relative standard deviation (RSD) for determination of the cyclic sulphur compounds, and 15% RSD for determination of HD. Recoveries were in the range of 43–60% from the two soil types. As the technique requires very little sample preparation, the total time for sample handling and analysis was less than 1 h. The technique was successfully employed for the determination of cyclic sulphur compounds in a sediment sample from an old dumping site for chemical munitions, known to contain HD degradation products.