土壤中有机磷农药的提取纯化和气相色谱-氮磷检测器测定

The objectives of this study were to optimize instrumental parameters and conditions for analysis of selected organophosphorus pesticides (OPPs) by gas chromatography (GG) with nitrogen-phosphorus detection (NPD) (GG-NPD); to select an appropriate solvent system; to conduct a comparison of sonication and shaking extractions; and to select an appropriate procedure for extracting organophosphorus pesticides from soils. Procedure Ⅰ consisted of n-hexane or petroleum ether together with acetone used as solvents, while Procedure II contained several solvents including acetone,methanol, dichloromethane, and n-hexane or petroleum ether. Experimental results indicated that a mixture of petroleum ether/acetone (2:1, v/v) could be used in place of n-hexane/acetone (2:1, v/v) as it was a less expensive solvent system.In addition, shaking under a water bath at 20℃ was more effective than sonication. Also, Procedure Ⅰ was more effective,safer, and more timesaving than Procedure Ⅱ. Procedure Ⅰ was applied to three soil types of different organic matter content, with recoveries of the OPPs from the yellow-brown soils, which had a higher organic matter content, being lower than those from the yellow and red soils.     

Comparison of Two Procedures for Extraction and Clean-up ofOrganophosphorus and Pyrethroid Pesticides in Sediment

Two procedures were compared for extraction and clean-up of 20 organophosphorus and 19 pyrethroid pesticidesin sediment to identify the more effective procedure for groups of pesticides or individual compounds. In Procedure I,methanol/water and n-hexane were used for extraction, and 1:10 (v/v) dichloromethane in n-hexane and acetone wereused as eluents for eluting the analyte through the cartridge, with one evaporating steps on a rotary evaporator and twoeluting steps on the cartridge, n-hexane/acetone (2:1, v/v) was used for extraction and elution in Procedure II with oneevaporating step on a rotary evaporator and one eluting step oll the cartridge. All extractions were performed underan ultrasonic bath and gas chromatography and mass spectrometry were utilized for measurements. Procedure II wasdeveloped as a rapid, timesaving, less costly and safer substitute for Procedure I which was an old method. ProcedureII was more effective for almost all the organophosphorus pesticides tested and 11 of the 19 pyrethroid pesticides, whileProcedure I was more appropriate for analysis of 5 pyrethroid pesticides. However, recoveries of most pyrethroid pesticideswere fairly low. Thus, further studies should focus on adjustment and formulation of solvents for more efficient extractionand clean-up of pyrethroid pesticides from sediment samples.     

提取、纯化沉积物中有机磷农药和菊酯类农药的两种程序的比较

Two procedures were compared for extraction and clean-up of 20 organophosphorus and 19 pyrethroid pesticides in sediment to identify the more effective procedure for groups of pesticides or individual compounds. In Procedure Ⅰ, methanol/water and n-hexane were used for extraction, and 1:10 (v/v) dichloromethane in n-hexane and acetone were used as eluents for eluting the analyte through the cartridge, with one evaporating steps on a rotary evaporator and two eluting steps on the cartridge, n-hexane/acetone (2:1, v/v) was used for extraction and elution in Procedure Ⅱ with one evaporating step on a rotary evaporator and one eluting step on the cartridge. All extractions were performed under an ultrasonic bath and gas chromatography and mass spectrometry were utilized for measurements. Procedure Ⅱ was developed as a rapid, timesaving, less costly and safer substitute for Procedure Ⅰ which was an old method. Procedure Ⅱ was more effective for almost all the organophosphorus pesticides tested and 11 of the 19 pyrethroid pesticides, while Procedure I was more appropriate for analysis of 5 pyrethroid pesticides. However, recoveries of most pyrethroid pesticides were fairly low. Thus, further studies should focus on adjustment and formulation of solvents for more efficient extraction and clean-up of pyrethroid pesticides from sediment samples.     

太湖、巢湖、龙感湖沉积物中磷的地球化学形态

A sequential extraction method for the fractionation of phosphorus （P） in lake sediments was used to analyze phos- phorus fractions of sediments taken from three large, shallow. eutrophic freshwater lakes of China-Talhu Lake. Chaohu Lake, and Long.an Lake. All three lakes are located in the lower reaches of the Changjiang River （Yangtze River）. In Taihu Lake and Chaohu Lake, algae blooms occurred every year, while Longgan Lake was a macrophyte-dominated lake. Results showed that exchangeable phosphorus fractions were much higher in the eutrophic lake sediments than in the macrophyte-flourishing lake sediment. Also, the ratio of Fe：P in the sediments of the algae-predomlnant lakes was generally much lower than that in the macrophyte-predominant lakes. Thus, the geochemical fractions of phosphorus in sediments had a closer relationship with the type of aquatic vegetation.     

磷处理土壤中磷的释放动力学研究

Phosphate release from three selected soils after treatments of 1.6 and 2.4 mmol L^-1 P was investigated using sequential extractions and fitted using six kinetic models, including zero order （Z）, first order （F）, second order （S）,parabolic diffusion （PD）, two constant rate （TC）, and Elovich type （ET） equations. The results showed that the rate of P release was initially rapid and then gradually declined with time. Also, P release increased with added P. Total P release followed the order： paddy soil with 2.4 mmol L^-1 P 〉 red soil with 2.4 mmol L^-1 P 〉 paddy soil with 1.6 mmol L^-1 P〉 fluvo-aquic soil with 2.4 mmol L^-1 P 〉 fluvo-aquic with 1.6 mmol L^-1 P 〉 red soil with 1.6 mmol L^-1 P. For the two P treatments P release from the paddy soils in the first extraction was 44.3% and 45.6% of total released P, respectively,which were higher than those from red and fluvo-aquic soils. The ratio of P release at the end of release time was 14.0%and 13.1% in the paddy soil treated with 1.6 and 2.4 mmol L^-1 P, respectively, but only 5.1% and 9.2% in the red soil and 7.0% and 5.2% in the fluvo-aquic soil, respectively. Comparison of the coefficients of determination （R^2） indicated that ET, TC, and PD equations could describe the P release data better than Z, F, and S equations.     

有机溶剂对有机氯农药污染场地土壤淋洗修复效用研究

Problems associated with organochlorine pesticide (OCP)-contaminated sites in China have received wide attention. To solve such problems, innovative ex-situ methods of site remediation are urgently needed. We investigated the feasibility of the extraction method with different organic solvents, ethanol, 1-propanol, and three fractions of petroleum ether, using a soil collected from Wujiang (WJ), China, a region with long-term contamination of dichlorodiphenyltrichloroethanes (DDTs). We evaluated different influential factors, including organic solvent concentration, washing time, mixing speed, solution-to-soil ratio, and washing temperature, on the removal of DDTs from the WJ soil. A set of relatively better parameters were selected for extraction with 100 mL L 1 petroleum ether (60-90℃): washing time of 180 min, mixing speed of 100 r min 1 , solution-to-soil ratio of 10:1, and washing temperature of 50℃. These selected parameters were also applied on three other seriously OCP-polluted soils. Results demonstrated their broad-spectrum effectiveness and excellent OCP extraction performance on the contaminated soils with different characteristics.     

中国长江中下游地区浅水湖泊沉积物有机磷研究

Thirteen sediment core samples （0 10 cm） were taken from the seven lakes in the middle and lower reaches of the Yangtze River to determine the contents and distributions of organic phosphorus （P） fractions in the sediments of the shallow lakes in the area. The organic P fractions in the sediments were in the order of moderately labile organic P （MLOP） 〉 moderately resistant organic P （MROP） 〉 highly resistant organic P （HROP） 〉 labile organic P （LOP）, with average proportional ratios of 13.2：2.8：1.3：1.0. LOP, MLOP, and MROP were significantly related to the contents of total organic carbon （TOC）, water-soluble P （WSP）, algal-available P （AAP）, NaHCO3-extractable P （Olsen-P）, total P （TP）, organic P （OP）, and inorganic P （IP）. However, HROP was significantly related to OP and weakly correlated with TOC, WSP, AAP, Olsen-P, TP or IP. This suggested that organic P, especially LOP and MLOP in sediments, deserved even greater attention than IP in regards to lake eutrophication. In terms of organic P, sediments were more hazardous than soils in lake eutrophication. Although OP concentrations were higher in moderately polluted sediment than those in heavily polluted sediment, LOP and MLOP were higher in the heavily polluted sediment, which indicated that heavily polluted sediment was more hazardous than moderately polluted sediment in lake eutrophication.     

Integrated Evaluation of Ecological Security at Different Scales Using Remote Sensing： A Case Study of Zhongxian County,the Three Gorges Area, China

Based on related literature and this research, an ecological security evaluation from the pixel scale to the small watershed or county scale was presented using remote sensing data and related models. With the driver-pressure, state and exposure to pollution-response （DPSER） model as a basis, a conceptual framework of regional ecological evaluation and an index system were established. The extraction and standardization of evaluation indices were carried out with GIS techniques, an information extraction model and a data standardization model. The conversion of regional ecological security results from the pixel scale to a small watershed or county scale was obtained with an evaluation model and a scaling model. Two conceptual scale conversion models of regional ecological security from the pixel scale to the county scale were proposed： 1） scale conversion of ecological security regime results from plxel to small watershed; and 2） scale conversion from pixel to county. These research results could provide useful ideas for regional ecological security evaluation as well as ecological and environmental management.     

从沉积物中分离重金属不同提取方法的比较

Three extraction methods, ultrasonic assisted extraction (USE), microwave assisted extraction (MSE), and conventional single extraction (CSE), in conjunction with the modified three-stage BCR sequential extraction procedure (SEP) were applied to examine the contents of Cd, Cu, Cr, Ni, Pb and Zn from lake sediment samples, to know whether these techniques can reduce extraction time and improve reproducibility. The SEP and developed alternative single extraction methods were validated by the analysis of certified reference material BCR 601. By the use of optimized sonication and microwave conditions, steps 1, 2 and 3 of the BCR sequential extraction methods (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication and microwave) could be completed in 15-30 min and 60- 150 s, respectively. The recoveries of total extractable metal contents in BCR 601, obtained by three single extractions ranged from 93.3%-102%, 88.9%-104% and 81.2%-96.2% for CSE, USE and MSE, respectively. The precision of the single extraction methods was found in the range of 3.7%-9.4% for all metals (n = 6).     

PESA对污泥中铬的萃取研究

An environmentally benign biodegradable chelant,polyepoxysuccinic acid(PESA),was used to separate heavy metals from sewage sludge from the Shanghai Taopu Wastewater Treatment Plant,China,based on chemical extraction technology.The extraction of chromium(Cr) from sewage sludge with an aqueous solution of PESA was studied under various conditions.It was found that the extraction of Cr using PESA was more efficient than that using ethylenediaminetetraacetic acid(EDTA) and S,S-ethylenediaminedisuccinic acid(EDDS) under similar conditions.PESA was capable of extracting Cr from the sewage sludge,and the extraction efficiency was obviously dependent on both the pH and the concentration of the chelating reagent.The extraction efficiency decreased gradually with increasing pH,and the dependence on pH decreased as the concentration of PESA increased.The extraction efficiency reached 58% under conditions of pH = 4 and a ratio of PESA to total heavy metals of 10:1.The extraction efficiency was maintained above 40% within the pH range from 1 to 7 at the high ratio of PESA to total heavy metals of 10:1.Comparing the contents of heavy metals in the sewage sludge before and after the extraction,it was found that the extracted Cr came mainly from the reducible and oxidizable fractions.     

Extraction of Antioxidants from Wheat Bran Using Conventional Solvent and Microwave-Assisted Methods

Total phenolic and tocopherol contents and free radical scavenging capability of wheat bran extracted using conventional and microwave-assisted solvent extraction methods were studied. Three different solvents (methanol, acetone, and hexane) were used in the conventional solvent extraction. Methanol was the most effective solvent, producing higher extraction yield (4.86%), total phenolic compound content (241.3 μg of catechin equivalent/g of wheat bran), and free radical scavenging capability (0.042 μmol of trolox equivalent/g of wheat bran) than either acetone or hexane. However, there was no significant difference in the total tocopherol contents (13.6–14.8 μg/g of wheat bran) among the three different solvent extraction methods. Microwave-assisted solvent extraction using methanol significantly increased the total phenolic compound content to 467.5 and 489.5 μg of catechin equivalent; total tocopherol content to 18.7 and 19.5 μg; and free radical scavenging capability to 0.064 and 0.072 μmol of trolox equivalent/g of wheat bran at extraction temperatures of 100 and 120°C, respectively. However, extraction yields of conventional methanol solvent and microwave-assisted methanol extractions at different temperatures were not significantly different.     

Assessing the Potential of Organic Solvents on Total Petroleum Hydrocarbon Extraction from Diesel-Contaminated Soils

The total petroleum hydrocarbon (TPH) extraction potential of organic solvents including dichloromethane (DCM), pentane, hexane, methanol, ethanol, propanol, and acetone was investigated along with the effect of water content in solvents for their efficiency of extraction. The extent of TPH extraction was analyzed using various extraction schemes (i.e., solvent/solid ratio, treatment time, extraction method, solvent/water ratio) to better understand the physical and chemical factors controlling TPH release from contaminated soils. More TPH was extracted with increasing solvent/solid ratio and increasing time. The extent of TPH extracted also varied depending on the extraction method, solvent type, and solvent/water ratio, but was highest when using the total extraction method and 100% DCM. However, the efficiency of TPH extraction decreased dramatically with the increase in the water content in organic solvents. The results also showed that TPH extraction using DCM was the best option for achieving cost-effective, eco-friendly outcomes along with remediation goals. DCM used in solvent extraction to remediate diesel-contaminated soils showed low toxicity, low cost, high recycling potential, and high efficiency compared to the other solvents tested in this study.     

Comparison of methods for the exhaustive extraction of hypericins, flavonoids, and hyperforin from Hypericum perforatum L

Renewed interest in plant-derived drugs has led to an increased need for efficient extraction methods. Hypericum perforatum L. contains several groups of bioactive compounds with noteworthy pharmacological activities. Direct sonication of H. perforatum was investigated and compared with conventional maceration, indirect sonication, Soxhlet extraction, and accelerated solvent extraction (ASE). Highly selective liquid chromatography/tandem mass spectrometry analysis showed that the content of six investigated active compounds (hypericin, pseudohypericin, hyperoside, rutin, quercitrin, and hyperforin) in extracts obtained by direct sonication was significantly higher than in extracts obtained by the other methods. The active compound contents increased on increasing the ultrasonic power from 40 to 60 W when using direct sonication. Conventional maceration gave the lowest amount of analyzed active compounds. Soxhlet extraction gave better results than ASE or indirect sonication.     

Extractability and Subsequent Biodegradation of PAHs from Contaminated Soil

The biodegradation of polyaromatic hydrocarbons (PAHs) has been well documented; however, the biodegradation of PAHs in contaminated soil has proved to be problematic. Sorption of PAHs to soil over time can significantly decrease their availability for extraction much less than for biodegradation. In this study the ability of various organic solvents to extract PAHs from coal tar-contaminated soil obtained from former manufactured gas plant (MGP) sites was investigated. Solvents investigated included acetone/hexane, dichloromethane, ethanol, methanol, toluene, and water. The extraction of MGP soils with solvents was investigated using soxhlet extraction, multiple soxhlet extractions, sonication, and brief agitation at ambient temperature with a range of solvent concentrations. Of particular interest was the documentation of the recalcitrance of PAHs in weathered MGP soils to extraction and to bioremediation, as well as to demonstrate the ease with which PAHs extracted from these soils can be biodegraded. The efficiency of extraction of PAHs from MGP soils was found to be more dependent upon the choice of solvent. The environmentally-benign solvent ethanol, was shown to be equal to if not better than acetone/hexane (the EPA recommended solvent) for the extraction of PAHs from MGP soils, brief contact/agitation times (minutes) using small quantities of ethanol (2 volumes or less) can achieve nearly quantitative extraction of PAHs from MGP soils. Moreover aqueous slurries of an MGP soils experienced less than 10% biodegradation of PAHs in 14 days while in the same period about 95% biodegradation was acieved using PAHs extracted from this soil by ethanol and subsequently added to aqueous bacterial suspensions.     

Development of a rapid method for the sequential extraction and subsequent quantification of fatty acids and sugars from avocado mesocarp tissue

Methods devised for oil extraction from avocado (Persea americana Mill.) mesocarp (e.g., Soxhlet) are usually lengthy and require operation at high temperature. Moreover, methods for extracting sugars from avocado tissue (e.g., 80% ethanol, v/v) do not allow for lipids to be easily measured from the same sample. This study describes a new simple method that enabled sequential extraction and subsequent quantification of both fatty acids and sugars from the same avocado mesocarp tissue sample. Freeze-dried mesocarp samples of avocado cv. Hass fruit of different ripening stages were extracted by homogenization with hexane and the oil extracts quantified for fatty acid composition by GC. The resulting filter residues were readily usable for sugar extraction with methanol (62.5%, v/v). For comparison, oil was also extracted using the standard Soxhlet technique and the resulting thimble residue extracted for sugars as before. An additional experiment was carried out whereby filter residues were also extracted using ethanol. Average oil yield using the Soxhlet technique was significantly (P < 0.05) higher than that obtained by homogenization with hexane, although the difference remained very slight, and fatty acid profiles of the oil extracts following both methods were very similar. Oil recovery improved with increasing ripeness of the fruit with minor differences observed in the fatty acid composition during postharvest ripening. After lipid removal, methanolic extraction was superior in recovering sucrose and perseitol as compared to 80% ethanol (v/v), whereas mannoheptulose recovery was not affected by solvent used. The method presented has the benefits of shorter extraction time, lower extraction temperature, and reduced amount of solvent and can be used for sequential extraction of fatty acids and sugars from the same sample.     

Investigation of Australian olive mill waste for recovery of biophenols

Olive mill waste is a potential source for the recovery of phytochemicals with a wide array of biological activities. Phytochemical screening of hexane, methanol, and water extracts revealed a diversity of compounds, perhaps overlooked in previous studies through intensive cleanup procedures. Methanol and water extracts contained large amounts of biophenols, and further testing of polar extraction solvents, including ethyl acetate, ethanol, propanol, acetone, acetonitrile, and water/methanol mixtures, highlighted the latter as the solvent of choice for extraction of the widest array of phenolic compounds. Stabilization of the resulting extract was best achieved by addition of 2% (w/w) sodium metabisulfite. Quantitative data are reported for nine biophenols extracted using 60% (v/v) methanol in water with 2% (w/w) sodium metabisulfite. Six compounds had recoveries of greater than 1 g/kg of freeze-dried waste: hydroxytyrosol glucoside, hydroxytyrosol, tyrosol, verbascoside, and a derivative of oleuropein.     

Determination of polychlorinated biphenyls in sediments, using sonication extraction and capillary column gas chromatography-electron capture detection with internal standard calibration

A sonication technique is presented for the extraction of polychlorinated biphenyls (PCBs) from sediments. In addition, a quantitation scheme is described which allows peak-specific and, in many cases, congener-specific determination of PCBs. PCBs are quantitated by capillary column gas chromatography-electron capture detection, with internal standard calibration. Results utilizing sonication extraction were compared with those obtained by Soxhlet and steam distillation extractions of 3 U.S. Environmental Protection Agency (EPA) quality control sediment samples and 3 lake sediments known to be contaminated with PCBs. Environmental lake sediments were extracted wet, with no drying prior to extraction. Recoveries by each technique varied depending on the sediment sample being extracted and degree of chlorination of PCB congeners. With proper selection of extraction solvent, the sonication technique can recover amounts of PCBs equivalent to and sometimes greater than recoveries by the Soxhlet or steam distillation techniques. A 24-h quiescent period in the extraction solvent between 2 sonications improved extraction efficiency for 2 freeze-dried sediments but did not affect results obtained for 3 environmentally contaminated sediments that were extracted without drying. Replacement of Soxhlet extraction with the sonication technique results in reduced sample preparation time, decreased volumes of solvents and sample, and substitution of common laboratory glassware in place of fragile, expensive Soxhlet glassware. Sonication extraction can also improve precision compared with Soxhlet extraction.     

土壤中石油烃预处理及含量分析方法研究进展

本文综述了近年来土壤样品中石油烃的预处理及含量分析方法的研究现状,其中预处理方法包括索氏萃取法、超声波萃取法、微波萃取法、超临界流体萃取法以及加速溶剂萃取法;测定方法有重量法、紫外分光光度法、红外分光光度法、气相色谱–质谱法和高效液相色谱法等。同时,对各种预处理和测定方法进行了归纳和比较,并在此基础上,对土壤样品中石油烃的预处理及含量分析方法的发展进行了展望。     

Comparison of yield, composition, and antioxidant activity of turmeric (Curcuma longa L.) extracts obtained using various techniques

Turmeric extracts were obtained from two lots of raw material (M and S) using various techniques: hydrodistillation, low pressure solvent extraction, Soxhlet, and supercritical extraction using carbon dioxide and cosolvents. The solvents and cosolvents tested were ethanol, isopropyl alcohol, and their mixture in equal proportions. The composition of the extracts was determined by gas chromatography-flame ionization detection (GC-FID) and UV. The largest yield (27%, weight) was obtained in the Soxhlet extraction (turmeric (S), ethanol = 1:100); the lowest yield was detected in the hydrodistillation process (2.1%). For the supercritical extraction, the best cosolvent was a mixture of ethanol and isopropyl alcohol. Sixty percent of the light fraction of the extracts consisted of ar-turmerone, (Z)-gamma-atlantone, and (E)-gamma-atlantone, except for the Soxhlet extracts (1:100, ethanol), for which only ar-turmeronol and (Z)-alpha-atlantone were detected. The maximum amount of curcuminoids (8.43%) was obtained using Soxhlet extraction (ethanol/isopropyl alcohol). The Soxhlet and low pressure extract exhibited the strongest antioxidant activities.     

Investigation of sample treatment steps for the analysis of polycyclic aromatic hydrocarbons in ground coffee

Sample treatment procedures were tested for the determination of polycyclic aromatic hydrocarbons (PAHs) in ground coffee. Pressurized liquid extraction (PLE), under different conditions, was combined with several cleanup methods, namely in situ purification, C18-silica solid-phase extraction (SPE), silica SPE, acid digestion, and alkaline saponification. Soxhlet extraction and direct alkaline saponification were also tested. Best results were obtained using PLE with hexane/acetone 50:50 (v/v) under 150 degrees C. Alkaline saponification followed by cyclohexane extraction and silica SPE was required to eliminate interferent compounds. Finally, 11 PAHs could be quantified in ground coffee with limits of detection in the range of 0.11-0.18 microg kg(-1). Application to ground Arabica coffee lots from Colombia revealed the presence of several PAHs, giving an overall toxicity equivalence in the range of 0.16-0.87 microg kg(-1). PAH identification was performed using both high-performance liquid chromatography-diode array detection and gas chromatography coupled to mass spectrometry.