[Identifying animal-derived components in camel milk and its products by ultra-high performance liquid chromatography-tandem mass spectrometry].

A method for identifying specific peptide biomarkers of animal-milk-derived components in camel milk and its products was established using proteomics. Samples were prepared by defatting, protein extraction, and trypsin hydrolysis, and proteins and peptides were identified using ultra-high performance liquid chromatography-quadrupole/electrostatic orbitrap-high resolution mass spectrometry (UHPLC-Q/Exactive-HRMS) and Protein Pilot software. Twenty two peptide biomarkers from eight species (i.e., Camelus, Bos taurus, Bubalus bubalis, Bos grunniens/Bos mutus, Capra hircus, Ovis aries, Equus asinus, Equus caballus) were identified by comparing the basic local alignment search tool (BLAST) with the Uniprot database. Verification of these marker peptides were performed quantitatively using a UHPLC-triple-quadrupole mass-spectrometry (QqQ-MS) system by multiple reaction monitoring (MRM). The pretreatment method of casein in camel milk was optimized, such as defatting, protein precipitation, and re-dissolving buffer solution. The effects of various mass-spectrometry parameters, such as atomization gas, heating- and drying-gas flow rates, and desolvation-tube (DL) and ion-source-interface temperatures on ion-response intensity were optimized. Camel milk signature peptides were detected in a mixture of milk from other seven species to ensure specificity for the selected biomarker peptides. The signature peptides of seven other species were also detected in camel milk. No mutual interference between the selected biomarker peptides of the various species was observed. Adulterated camel milk and milk powder were also quantitatively studied by adding 0, 2.5%, 5%, 10%, 25%, 50%, 75%, and 100% bovine milk or goat milk to camel milk. Similarly, the same mass proportion of bovine milk powder or goat milk powder was added to camel milk powder. A quantitative standard curve for adulteration was constructed by plotting the peak areas of characteristic cow or goat peptide segments in each mixed sample against the mass percentage of the added adulterant. The adulteration standard curves exhibited good linearity, with correlation coefficients (r2) greater than 0.99. The limits of detection and quantification (LODs and LOQs, respectively) of the method were determined as three- and ten-times the signal-to-noise ratio (S/N). The minimum adulteration LODs of bovine milk and goat milk in camel milk were determined to be 0.35% and 0.49%, respectively, and the minimum LOQs were 1.20% and 1.69%, respectively. The minimum adulteration LODs of bovine milk powder and goat milk powder in camel milk powder were determined to be 0.68% and 0.73%, respectively, and the minimum LOQs were 1.65% and 2.45%, respectively. The accuracy of the adulteration quantification method was investigated by validating the quantitative detection results for 1∶1∶1 (mass ratio) mixtures of camel milk, bovine milk, and goat milk, as well as camel-milk powder, bovine milk powder, and goat-milk powder, which revealed that this method exhibits good linearity, strong anti-interference, high sensitivity, and good repeatability for adulterated liquid-milk/solid-milk-powder samples. The adulteration results for both liquid milk and milk powder are close to the theoretical values. Finally, 11 actual commercially available samples, including five camel-milk and six camel-milk-powder samples were analyzed, which revealed that only camel signature peptides were detected in 10 samples, while camel and bovine signature peptides were both detected in one camel-milk-powder sample. The ingredient list of the latter sample revealed that it contained whole milk powder from an unidentified source; therefore, we infer that the bovine signature peptides originate from the whole milk powder. These signature peptides also demonstrate the necessity and practical significance of establishing this identification method.

Research method of rapid determination of chiral pesticide fenpropathrin enantiomers in fruit and vegetable puree by supercritical fluid chromatography.

A method is first established for the separation and determination of fenpropathrin enantiomer residues in apple puree, strawberry puree, and tomato puree considered a supplementary food for infants by supercritical fluid chromatography. After the sample was extracted with acetonitrile and cleaned up by a solid-phase extraction column, then it was separated by a CHIRALPAK AD-3 chiral column with gradient elution at a flow rate of 1.5 mL/min using methanol and supercritical carbon dioxide as the mobile phase, detected by ultraviolet detector at 230 nm wavelength and quantified with the external standard method. The limits of quantification of the two fenpropathrin enantiomers were both 0.2 mg/kg, the linear ranges were 1.0-20.0 mg/L with linear correlation coefficients greater than 0.9992, the recoveries in the spiked samples at 0.2, 0.4 and 2.0 mg/kg were from 80.6 to 105%, and the relative standard deviation reached 2.6-7.7%. This method has the advantages of convenient operation, good resolution, and environmental protection, which can satisfy the requirement of determination for fenpropathrin enantiomer residues in fruit and vegetable puree as supplementary food for infants.

[Separation and determination of clenbuterol enantiomers by ultra-performance convergence chromatography].

Clenbuterol enantiomers differ greatly in their bioactivities. By optimizing the conditions for chromatographic separation and method validation, ultra-performance convergence chromatography (UPC2) was adopted to separate the enantiomers of clenbuterol. Standard solutions of (+)-clenbuterol and (-)-clenbuterol were stored at -18 ℃ for 1, 3, 5, 7, 14, 30, and 60 d, and then, their stability was monitored. The impacts of different chromatographic columns, cosolvents, system backpressure, and chromatographic column temperature on the separation of the two enantiomers were investigated. Acquity Trefoil AMY1 (150 mm×3.0 mm, 2.5 µm) was used for separation, and CO2-0.5% (v/v) ammonium acetate was used as the mobile phase. Gradient elution at a flow rate of 2.0 mL/min was adopted. The detection wavelength was set to 241 nm, and the injection volume was set to 10 µL. The backpressure was set to 13.8 MPa, and the column temperature was maintained at 40 ℃. The two enantiomers showed good linear relationships in the range of 1.0 to 20.0 mg/L with correlation coefficients greater than 0.9997. The limits of detection (LODs, S/N=3) of (+)-clenbuterol and (-)-clenbuterol were both 0.5 mg/L. The relative standard deviation (RSD, n=6) for the peak area of the 10.0 mg/L mixed standard working solution with six replicate injections ranged from 0.65% to 0.76%. The effectiveness and practicability of this method were demonstrated by using it to detect standard clenbuterol racemate. The (+)-clenbuterol and (-)-clenbuterol contents were 5.6 mg/L and 5.5 mg/L, respectively, in the standard clenbuterol racemates, as determined by the external standard method of quantification. The detection results suggested that the content ratio of (+)-clenbuterol and (-)-clenbuterol was close to 1.02∶1.00, which is consistent with the literature data. The established method has the advantages of rapid analysis, good separation effect, and low consumption of organic solvents, and it is suitable for the separation of clenbuterol enantiomers. This method can also provide technical support for the separation of other chiral drugs, analysis of the effects of chiral drugs, and assessment of product quality.

Enhanced trichloroethylene biodegradation: Roles of biochar-microbial collaboration beyond adsorption.

Trichloroethylene (TCE) is a pollutant widely found in groundwater, especially in the heavily contaminated industrial sites. Biological dechlorination method is environmentally friendly and low-cost. However, microorganisms grow slowly and their activity is susceptible to environmental fluctuations. This study used biochar as an additive to promote anaerobic biodegradation of TCE with mixed culture. Results showed that biochar with dose of 0.1-0.4% (w/v) brought a rapid initial decrease of TCE concentration by 39.4-88.8% in 24 h via adsorption mechanism. Biochar produced at 500 °C pyrolysis temperature (BC500) achieved the highest TCE adsorption in comparison to BC300 and BC700. Subsequently, a significantly shortened microbial stagnation phase (from 85 h to 37 h) was observed in the system with the presence of biochar. During the exponential growth phase, BC700 outperformed BC300 and BC500 in terms of TCE degradation efficiency. Electrochemical analysis demonstrated that BC700 possessed the greatest electron transfer capability. Finally, biochar shortened the time for achieving 100% removal of TCE by 54.5-69.7% (from approximate 330 h to 100-150 h). Even at high concentration of TCE (20-30 mg·L-1) that could lead to serious microbial growth inhibition, the TCE degradation efficiency could be recovered in the presence of BC500. The high-throughput sequencing data revealed that biochar promoted the relative abundance of co-metabolizing dechlorinating microorganisms (Pseudomonas, Burkholderia) in the aqueous solution, and simultaneously led to the selective colonization of reductive dechlorinating microorganisms (Enterobacteriaceae, Clostridium) attached on biochar surface. On the other hand, biochar addition decreased the relative abundance of hydrogen-competing microorganisms, thereby forming an efficient co-metabolism-reductive dechlorination system. These findings allow a better understanding of the promotion mechanism of biochar for microbial dechlorination technology supporting the biochar-assisted bioremediation in practice.

[Determination of 50 non-edible additives in health food using the QuEChERS method and liquid chromatography-tandem mass spectrometry].

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for the determination of 50 non-food additives in health food. The samples were extracted with methanol and purified using the QuEChERS method. The separation was performed on an Agilent Phoroshell SB C18 column (150 mm×3.0 mm, 2.7 µm) with a mobile phase of 0.1% (v/v) formic acid aqueous solution and acetonitrile. The determination was performed by MS/MS in positive or negative electrospray ionization and multiple reaction monitoring mode. The results demonstrated that all 50 compounds could be well separated with a good linear relationship (r2>0.99). The limits of detection (LODs, S/N ≥ 3) and limits of quantification (LOQs, S/N ≥ 10) were in the range of 0.010-1 mg/kg and 0.020-2 mg/kg, respectively. The matrix effects in five kinds of typical health foods (oral liquid, tablets, ointments, pills, and capsules) were evaluated and reduced by means of matrix matching. At the spiked levels of 1 LOQ, 2 LOQ, and 10 LOQ, the recoveries of all drugs varied from 63.1% to 115.7% with relative standard deviations (RSDs) of no more than 8.9% (n=6). The method is simple, sensitive, practical, and suitable for monitoring 50 non-edible additives in health food.

[Simultaneous determination of 21 illegally added compounds in health foods by ultra high performance liquid chromatography-tandem mass spectrometry with solid phase extraction].

A rapid method for the simultaneous determination of 21 illegally added compounds in health foods was developed based on solid phase extraction (SPE) combined with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After ultrasonic extraction with acetonitrile, the samples were purified on an HLB SPE column, separated on a Waters BEH C18 column (100 mm×2.1 mm, 1.7 µm) using 10 mmol/L ammonium acetate aqueous solution and methanol as the mobile phases. The compounds were detected by an electrospray ionization (ESI) source in positive ion mode with multi-reaction monitoring (MRM). The 21 illegal additives showed good linear relationships with correlation coefficients no less than 0.995. The limits of detection (LODs) were 3-160 µg/kg for different matrixes. The recoveries ranged from 61.8% to 109.3%, and the relative standard deviations ranged from 1.6% to 14.7%. The method can be used for the simultaneous determination of the illegally added drugs in the losing weight, lipid-lowering, anti-diabetic and anti-hypertension health foods.

[Rapid untargeted screening and determination of unknown contaminants in aquatic products by high performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry].

A method has been developed for rapid untargeted screening and determination of unknown contaminants in aquatic products by high performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry. The samples were extracted by acetonitrile, dried under nitrogen, dissolved in methanol-water (3:7, v/v), and analyzed via the full MS scan/data dependent MS2 mode during the screening process. The Trace Finder software was used to match the precise mass, the isotope abundance ratio, the fragment ion to search for unknown contaminants in aquatic samples. The optimized QuEChERS method is used to purify the samples when quantifying. The quantitative analyses of triazole, caffeine, and ethoxyquinoline were performed via the target-MS2 mode. The correlation coefficients of the three compounds in fish and shrimp samples were higher than 0.99 in the linear range of 5-1000 µg/L. The limit of detection was 1 µg/kg, and the limit of quantitation was 5 µg/kg. The average recoveries were between 70.5% and 90.9% with the relative standard deviations ranging from 5.4% to 12.8%. The screening method has the advantages of fast, accurate, and high throughput; when combined with the quantitative method, it can be used to screen and determine unknown contaminants in the actual aquatic products.

[Determination of characteristic compound in manuka honey by automatic on-line solid phase extraction-liquid chromatography-high resolution mass spectrometry].

A method for the determination of characteristic compound 3,5-dimethoxybenzoate-4-diglucoside (leptosperin) in manuka honey was developed by automatic on-line solid phase extraction-liquid chromatography-high resolution mass spectrometry (SPE-LC-HRMS). The samples were separated on a Dikma Diamonsil Plus C18 column (150 mm×4.6 mm, 5 µm) using the mobile phases of 0.1% (v/v) formic acid aqueous solution and acetonitrile with gradient elution. The compound was detected with negative electrospray ionization (ESI-) in Target-MS2 mode. The results showed that the linear range was 0.5-100.0 mg/L, the correlation coefficient was 0.9993. The limit of detection (LOD, S/N ≥ 3) and limit of quantification (LOQ, S/N ≥ 10) of the method was 3 mg/kg and 10 mg/kg, respectively. The recoveries at the spiked levels of 50.0, 100.0, 200.0 mg/kg (10.0, 20.0, 50.0 mg/kg in black locust samples) were in the range of 82.0%-95.2% with the relative standard deviations ranging from 2.7% to 9.7% (n=6). The proposed method was applied to 95 mature honey samples from hives in New Zealand including 12 different kinds and 50 commercial honey samples from four different countries. The method is fast, sensitive and accurate to provide technical support to solve the judgment of the manuka honey imported from New Zealand.

[Determination of 20 pyrethroid residues in vegetable foods by gas chromatography-tandem mass spectrometry].

A method of gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed for the simultaneous determination of 20 pyrethroid residues in vegetable foods. The samples were extracted by acetone-n-hexane (1:1, v/v), cleaned up by activated charcoal column and quantified by external standard method. The correlation coefficients (r2) of all the 20 pyrethroid pesticides in the range of 0.005-1.0 mg/L were not less than 0.990. The limits of detection (LODs) were 2.0 µ g/kg when signal/noise (S/N) > 3. The limits of quantification (LOQs) were 5.0 µ g/kg (S/N > 10). For recovery test, there were three levels (low, medium and high) spiked in 11 matrices. The average recoveries of the method were 75.2%-107% and the relative standard deviations (RSDs, n=6) were 3.08%-12.1%. The results demonstrated that the method is simple and has specific pretreatment steps. The method is suitable for the screening and confirmation of the 20 pyrethroid pesticides in vegetable foods.

[Rapid screening of fipronil and its metabolites in egg and egg products by solid phase extraction-liquid chromatography-quadrupole time-of-flight mass spectrometry].

A method for rapid screening of fipronil and its metabolites in egg and egg products was developed by liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-QTOF MS). The samples were extracted by acid-acetonitrile, cleaned up by PRiME HLB SPE. The separation was performed on a Poroshell 120 EC C18 column (150 mm×3 mm, 2.7 µm) with gradient elution using water and acetonitrile as mobile phases. The target compounds were monitored under negative ionization mode with electrospray ionization (ESI) source and two databases of accurate mass and fragment ions were created. The matrix effects in four kinds of egg and egg products were considered and the quantification was carried out by internal standard method. The results demonstrated that the linear ranges were from 0.1 to 5 µg/L with good correlation coefficients (r2>0.99). The limits of detection (LODs, S/N>3) and limits of quantitation (LOQs, S/N>10) were 0.2 µg/kg and 1 µg/kg, respectively. The recoveries of fipronil and its metabolites in different matrixes spiked with 1, 2 and 5 µg/kg varied from 82.6%-98.1%, and the relative standard deviations (RSDs) were between 3.8%-9.9% (n=6). The method can effectively correct the ionization suppression. It is sensitive, accurate and suitable for the rapid screening of fipronil, fipronil sulfide, fipronil sulfone and fipronil desulfinyl in egg, egg noodle, cake and mayonnaise.

[Simultaneous determination of melamine and cyanuric acid in foodstuffs by solid phase extraction-hydrophilic interaction chromatography-tandem mass spectrometry].

A method based on solid phase extraction-liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of melamine and cyanuric acid in foodstuffs is presented. The melamine and cyanuric acid residues were extracted by acetonitrile and water, degreased by hexane, and the extract was cleaned-up by a mixed-mode solid phase-extraction column (MCT) of hydrophilic functional silica gel sorbent and cation exchange resin. The LC separation was performed on a hydrophilic interaction chromatograph, the melamine and cyanuric acid were determined by MS/MS in positive-negative switched electrospray ionization mode, multiple reaction monitoring (MRM) mode, and quantified by isotope internal standard method. The melamine and cyanuric acid were linear in the range of 10-2 500 microg/L with the correlation coefficients (r) higher than 0.99, and the limits of quantification were 25 microg/kg and 50 microg/kg, respectively. The recoveries of melamine and cyanuric acid spiked in animal-derived foods, plant-derived foods, milk and milk products were in the range of 70.0%-129.6% and 70.0%-128.6%, respectively, with the relative standard deviations (RSD) of 1.4%-23.3% and 2.8%-18.7%, respectively. The method can meet the requirement for the determination of melamine and cyanuric acid in foodstuffs simultaneously.

[Determination of multi-pesticides in black tea by subcritical water extraction and gas chromatography-tandem mass spectrometry].

A gas chromatography-tandem mass spectrometry (GC-MS/MS) method with subcritical water extraction was developed for the determination of 21 organochlorine and pyrethroid pesticides in black tea. Under the extraction pressure of 5 MPa, the target compounds were extracted with subcritical water at the temperature of 150 degrees C for 15 min, transferred into acetone-n-hexane (1:1, v/v), and cleaned-up by an ENVI-Carb solid phase extraction (SPE) column. The GC separation was performed on a DB-5 capillary column. The pesticides were determined by MS/MS in multiple reaction monitoring (MRM) mode and quantified by matrix-matched internal standard method. The calibration curves showed good linearities in the range of 5.0-320.0 microg/L with the correlation coefficients greater than 0.99. The limit of quantification (S/N > 10) was 50 ng/g, and the limit of detection (S/N > 3) was 10 ng/g. The recoveries of pesticides spiked in the tea at three levels of 50, 100 and 200 ng/g were ranged from 70. 18% to 119.98% with the relative standard deviations (RSDs) of 5.01%-11.76%. The sensitivity, accuracy and precision of the method meet the technical standard of the pesticide determination. The method can be applied to the determination of organochlorine and pyrethroid pesticides in black tea.

Determination of methanol in cosmetics by headspace and multidimensional gas chromatography with mass spectrometric detection.

A novel, reliable, and robust analytical method using headspace and multidimensional GC coupled to MS was successfully developed for determining the methanol content in cosmetics. The methanol was quantitatively analyzed and confirmed by heart-cutting multidimensional GC and mass selective detection in full scan mode. The average recovery was 99.8% with an RSD of 4.3%; the LOQ was 5 mg/kg. The proposed method showed good accuracy and precision while minimizing erroneous results due to false positives compared with conventional single-column GC analysis.

[Determination of commonly abused dyes in food by liquid chromatography-tandem mass spectrometry].

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of commonly abused dyes in candy, sirup, liquid milk and fruit juice. The test sample was dissolved and diluted with water, then cleaned up by polyamide solid phase extraction. The LC separation was performed on an Agilent XDB-C18 column with 20 mmol/L ammonium acetate solution and acetonitrile as the mobile phase in a gradient elution mode. The dyes were determined by MS/MS in negative electrospray ionization mode, and quantified by matrix-matched external standard method. The calibration curves showed good linearity in the range of 0.5 - 50 mg/L with the correlation coefficients (r) greater than 0.99. The limits of quantitation (S/N > 10) were 0.5 mg/kg, and the limits of detection (S/N > 3) were 0.1 mg/kg. The recoveries of dyes in food samples at the three spiked levels of 0.5, 5 and 50 mg/kg were in the range of 62.6% - 115.3% with the relative standard deviations (RSDs) of 2.6% - 26.3%. The method can meet the requirements for the determination of the dyes in food samples for import and export inspection.

[Determination of linuron and its metabolite 3,4-dichloroaniline residues in meat and meat products using liquid chromatography-tandem mass spectrometry].

A method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of linuron and its metabolite 3, 4-dichloroaniline residues in pork, liver, kidney, casings, canned steam pork and sausage. The sample was extracted with a mixture of acetone-acetonitrile (5: 95, v/v). Most of the lipids in the extract were eliminated by freezing-lipid filtration. After Florisil solid phase extraction cleanup, the linuron and its metabolite residues were determined by LC-MS/MS, and quantified by internal standard meth-od. In the range of 1 - 500 microg/L, both linuron and 3,4-dichloroaniline showed good linearity with the correlation coefficients (r) more than 0. 998. The limit of quantification (S/N > 10) was 10 microg/kg, and the limit of detection (S/N > 3) was 5 microg/kg for each analyte. The recoveries of linuron and 3,4-dichloroaniline in meat and meat products at three spiked levels were in the ranges of 88.3% - 101.2% and 91.6% - 101. 6%, and the relative standard deviations were in the ranges of 4. 8% - 13. 7% and 4. 7% - 11. 8%, respectively. The results demonstrated that the proposed method can meet the requirements for the determination of linuron and 3,4-dichloroaniline in meat and meat products.

[Determination of chlordimeform and its metabolite residues in honey using liquid chromatography-tandem mass spectrometry].

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of chlordimeform and its metabolite (4-chloro-o-toluidine) residue in acacia honey, chaste honey, comb honey, multifloral honey and wild honey. The samples were dissolved and diluted with sodium hydroxide solution, and cleaned up by a Waters Oasis HLB solid phase extraction column. The separation was performed on an Agilent XDB-C18 column with gradient elution using 0.1% formic acid solution and acetonitrile. The residues of chlordimeform and its metabolite were determined by electrospray ionization-tandem mass spectrometry, and quantified by the method of matrix-matched external standard. The calibration curves for chlordimeform and its metabolite showed good linearity in the range of 2.5 - 250 microg/L with the correlation coefficients (r) higher than 0.999. The limit of quantification was 5 microg/kg, and the limit of detection was 2.5 microg/kg. The recoveries of chlordimeform and 4-chloro-o-toluidine in honey at the spiked levels of 5, 10 and 20 microg/kg were in the ranges of 75.8% - 113.8% and 85.6% - 114.3%, respectively. The relative standard deviations were 4.8% - 10.2% and 4.7% -9.1%, respectively. The method can meet the requirements for the determination of chlordimeform and 4-chloro-o-toluidine in honey for import and export inspection.

A novel mixed-mode solid phase extraction for simultaneous determination of melamine and cyanuric acid in food by hydrophilic interaction chromatography coupled to tandem mass chromatography.

Utilizing a solid phase extraction column (MCT) containing mixed hydrophilic functional gel and cation exchange sorbent, a sensitive and rapid HPLC-MS/MS method for simultaneously determining the residues of melamine (MEL) and cyanuric acid (CYA) in human foodstuffs was developed. MEL and CYA in egg, pork, liver, kidney and pork, shrimp, sausage casing, honey, soybean milk, soybean powder and dairy product were extracted using acetonitrile/water, defatted with hexane and isolated using MCT solid phase extraction column. The residues were separated upon a hydrophilic interaction liquid chromatography (HILIC) column and analyzed by electrospray ionization under negative-positive switched mode on a triplequadrupole mass spectrometry. The selected reaction monitoring was performed on [M+H](+) of m/z 127.9 to provide the transition of 127>85 and 127>68 (MEL) while the [M-H](-) of m/z 127.1 was selected as the precursor ion for CYA resulting in product ions m/z 85 and 42. Isotope labeled internal standard ((15)N(3)-MEL and (13)C(3)-CYA) and matrix-matched calibration were both used to observe the recovery to be 70.0-129.6% and 70.0-128.9% with RSD of 1.4-23.3% and 1.5-21.7% for MEL and CYA, respectively (n=6). All the LODs and LOQs of MEL and CYA were less than 39.4 and 99.1µgkg(-1), respectively, in 18 matrices, which were sensitive enough for quantitative analysis. This method has been proven effective in simultaneous determination of melamine and cyanuric acid when inspecting unknown and positive samples.

Effects of long-term alachlor exposure on hepatic antioxidant defense and detoxifying enzyme activities in crucian carp (Carassius auratus).

Alachlor has been widely used in agriculture all over the world. It is suggested that it may be a carcinogen and also an environmental estrogen. In this paper, the physiological and biochemical perturbations of crucian carp (Carassius auratus) exposed to alachlor at different concentrations over 60 days were investigated. The gonadosomatic index (GSI) and hepatosomatic index (HSI) were measured. The activity of hepatic antioxidant defense and detoxifying enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) and the content of glutathione (GSH) were determined and compared with the control group. The result showed that GSI and HSI decreased significantly (P<0.05) in almost all treatments. The activities of SOD, CAT and GST were induced continuously (P<0.05), while the content of reduced glutathione (GSH) was inhibited on the whole. These changes reflect that the antioxidant systems of the tested fishes were affected. The possible defense mechanistic implications about the changes were thus discussed. Furthermore, hepatic SOD and GST were sensitive to alachlor at low concentration, indicating that they might be potential biomarkers in early detection of alachlor contamination in aquatic ecosystems.

Determination of organophosphorus pesticide residues in the roots of Platycodon grandiflorum by solid-phase extraction and gas chromatography with flame photometric detection.

A simple and rapid sample preparation method using accelerated solvent extraction and solid-phase extraction (SPE) cleanup for determining organophosphorus (OP) pesticides in the roots of Platycodon grandiflorum was developed. The OP pesticides were concentrated by use of an SPE cartridge (ENVI-Carb) and quantitatively analyzed and confirmed by capillary gas chromatography with flame photometric detection. The pesticides were eluted from the cartridges with 20 mL acetonitrile-toluene (3 + 1, v/v). The average recovery from 10 g PF grandiflorum roots, fortified at 3 levels ranging from 0.04 to 1.00 mg/kg, was 91.9% with a relative standard deviation of 4.3%. The limits of detection ranged from 1.16 x 10(-3) mg/kg (dimethoate) to 4.64 x 10(-3) mg/kg (dichlorvos). The proposed method showed acceptable accuracy and precision while minimizing environmental concerns, time, and labor.

Residues and dynamics of probenazole in rice field ecosystem.

The simple and efficient method for determination of probenazole in soil, rice plant, and paddy water was developed, and the fate of probenazole in rice field ecosystem was also studied. Probenazole residues were extracted from sample, cleaned up by liquid/liquid partition and chromatographic column and then determined by gas chromatography with flame photometric detection. As far as the accuracy and precision was concerned, the method met certain standard. The LODs of probenazole calculated as a sample concentration (S/N ratio of 3) was 0.02 mg kg-1. The minimum detectable limit was 5x10(-10) g. The degradation of probenazole in soil, rice straw, and water was determined. The results showed that probenazole degradation in soil and rice straw coincided with C=0.576e-0.147t, C=17.858e-0.414t, respectively; the half-lives were about 4.7 and 1.7 d, respectively. The degradation rate of probenazole in rice straw was faster than that of in soil. Probenazole residue at 0.02 mg kg-1 could only be detected in paddy water within the first day after application. The final probenazole residues in soil, brown rice, and water were undetectable at levels of recommended and doubled dosage with an interval of 63 d. Therefore, a dosage of 1800-3600 g a.i. hm-2 was recommended, which could be considered as safe to human beings and animals. These would contribute to provide the scientific basis of using this fungicide.