Co-reporter:Zhaoxian Zhang, Qing Zhang, Beibei Gao, Gaozhang Gou, Lianshan Li, Haiyan Shi, and Minghua Wang
Journal of Agricultural and Food Chemistry September 20, 2017 Volume 65(Issue 37) pp:8241-8241
Publication Date(Web):August 27, 2017
DOI:10.1021/acs.jafc.7b02903
An efficient and sensitive chiral analytical method was established for the determination of the chiral fungicide prothioconazole and its major chiral metabolite prothioconazole-desthio in agricultural and environmental samples using ultraperformance liquid chromatography–tandem mass spectrometry. The optical rotation and absolute configuration of enantiomers were identified by optical rotation detector and electronic circular dichroism spectra. The elution order of prothioconazole and its chiral metabolite enantiomers was R-(+)-prothioconazole-desthio, S-(−)-prothioconazole-desthio, R-(−)-prothioconazole, and S-(+)-prothioconazole. The mean recoveries from the samples was 71.8–102.0% with intraday relative standard deviations (RSDs) of 0.3–11.9% and interday RSDs of 0.9–10.6%. The formation of prothioconazole-desthio was studied in soil under field conditions and enantioselective degradation was observed for chiral prothioconazole. Remarkable enantioselective degradation was observed: R-prothioconazole degraded preferentially with EF values from 0.48 to 0.37. Although prothioconazole-desthio is the most remarkably bioactive metabolite, no obvious enantioselective behavior was observed in soil. These results may help to systematically evaluate prothioconazole and its metabolites in food and environmental safety.Keywords: absolute configuration; chiral metabolite; enantioseparation; prothioconazole; UPLC−MS/MS;
Co-reporter:Xiude Hua;Hongjie You;Peiwen Luo;Zhexuan Tao
Analytical and Bioanalytical Chemistry 2017 Volume 409( Issue 29) pp:6885-6892
Publication Date(Web):03 October 2017
DOI:10.1007/s00216-017-0653-7
A sensitive fluorescence immunoassay for the detection of imidaclothiz was established by using magnetic nanoparticles (MNPs) as concentration elements and upconversion nanoparticles (UCNPs) as signal labels. The NaYF4/Yb,Er UCNPs and MNPs were conjugated with imidaclothiz monoclonal antibody and imidaclothiz antigen, respectively. Imidaclothiz could compete with the antigen-conjugated MNPs for binding to the antibody-conjugated UCNPs and resulted in a decreased fluorescence signal when the MNPs were separated by an external magnet. Under the optimal conditions, the concentration of imidaclothiz producing 50% inhibition of the signal (IC50), limit of detection (LOD, IC10), and the linear assay range (IC10–IC90) were 14.59, 0.74, and 0.74–289.30 ng mL−1, respectively. The immunoassay exhibited no obvious cross-reactivity with analogues of imidaclothiz except for imidacloprid, with 89.2% cross-reactivity. The average recoveries measured in paddy water, pear, soil, peach, rice, tomato, wheat, and pakchoi were 75.7–105.2%, and the relative standard deviations (RSDs) were less than 11.2%. In addition, the results of the immunoassay correlated well with that of high-performance liquid chromatography (HPLC) for authentic samples.
Co-reporter:Xiude Hua, Yuan Ding, Jiachuan Yang, Ming Ma, Haiyan Shi, Minghua Wang
Science of The Total Environment 2017 Volume 583(Volume 583) pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.scitotenv.2017.01.056
•QDFIA and TRFIA were developed and applied to the monitoring of imidaclothiz.•QDFIA and TRFIA showed higher sensitivity than reported ELISA and FPIA.•Eight kinds of matrix were studied by spiked recovery experiment.•The amounts of imidaclothiz in real samples detected by QDFIA and TRFIA were correlated with that detected by HPLC.A direct quantum dots-based fluoroimmunoassay (QDFIA) and a time-resolved fluoroimmunoassay (TRFIA) for imidaclothiz (IMI) were developed by using the quantum dots (QDs)-labeled antibody and the europium (Eu3 +)-labeled antibody, respectively. After optimization, the half-maximal inhibition concentration (IC50) and the limit of detection (LOD, IC10) are 20.41 and 0.52 μg L− 1 for the QDFIA, while 6.91 and 0.018 μg L− 1 for the TRFIA, respectively. The cross-reactivities (CRs) with the analogues are negligible except for imidacloprid with CRs of 29.0% for the QDFIA and 26.6% for the TRFIA. The spiked recoveries of IMI in paddy water, soil, pear, tomato, rice, apple, cabbage and cucumber are 72.7–117.6% with a standard deviation (RSD) of 2.4– 13.5% for the QDFIA, and 81.3–117.7% with a RSD of 1.6– 7.5% for TRFIA. The detection results of the analyses for the real paddy water and pear samples are markedly correlated with these of high-performance liquid chromatography (HPLC).Download high-res image (147KB)Download full-size image
Co-reporter:Ming Ma;Mo Chen;Lu Feng;Hongjie You;Rui Yang
Food Analytical Methods 2016 Volume 9( Issue 9) pp:2471-2478
Publication Date(Web):2016 September
DOI:10.1007/s12161-016-0434-5
A homogeneous fluorescence polarization immunoassay (FPIA) based on a monoclonal antibody for the detection of imidaclothiz was developed. Two fluorescein-labeled imidaclothiz tracers containing two different bridge lengths were synthesized and purified. Under optimal conditions, the 4-aminofluorescein-labeled imidaclothiz conjugate (AMF-labeled imidaclothiz), which contains a shorter bridge length, showed a higher sensitivity in the FPIA for detecting imidaclothiz, and the full analysis was achieved in less than 11 min. The IC50 and limit of detection (LOD, IC10) were 87.94 ± 10.18 and 0.57 ± 0.16 μg/L, respectively. The spiked recoveries were 83 to 117 % measured in tomato, pear, rice, apple, cucumber, cabbage, and paddy water, with RSDs of 5 to 12 %. Furthermore, the results of FPIA for the authentic samples correlated well with those acquired by HPLC. Overall, the developed FPIA provided a simple, rapid, sensitive, and accurate method that was used for the quantitative detection of imidaclothiz in agricultural samples.
Co-reporter:Wei Yin, Xiude Hua, Xiaofeng Liu, Haiyan Shi, Shirley J. Gee, Minghua Wang, Bruce D. Hammock
Analytical Biochemistry 2015 Volume 481() pp:27-32
Publication Date(Web):15 July 2015
DOI:10.1016/j.ab.2015.04.015
Abstract
A monoclonal antibody (3A5) that can recognize thiacloprid was produced, and a linear 8-residue peptide phage library was constructed. Six phage-displayed peptides were isolated from the linear 8-residue peptide phage library and a cyclic 8-residue peptide phage library. A phage enzyme-linked immunosorbent assay (ELISA) was developed to detect thiacloprid using a phage-displayed peptide. Under the optimal conditions, the half-maximal inhibition concentration (IC50) and the limit of detection (IC10) of the developed phage ELISA were 8.3 and 0.7 μg/L, respectively. Compared with the conventional ELISA, the sensitivity was improved more than 3-fold. The cross-reactivity (CR) was less than 0.08% for the tested structural analogues and was regarded as negligible. The recoveries of thiacloprid ranged from 80.3% to 116.3% in environmental and agricultural samples, which conformed to the requirements for residue detection. The amount of thiacloprid detected by phage ELISA in the samples was significantly correlated with that detected by high-performance liquid chromatography. The current study indicates that isolating phage-displayed peptides from phage display libraries is an alternative method for the development of a sensitive immunoassay and that the developed assay is a potentially useful tool for detecting thiacloprid in environmental and agricultural samples.
Co-reporter:Meiyun Wang;Xiude Hua;Qing Zhang;Yu Yang;Haiyan Shi ;Minghua Wang
Chirality 2015 Volume 27( Issue 2) pp:109-114
Publication Date(Web):
DOI:10.1002/chir.22397
Absract
Enantioselective biodegradation of chiral pesticide metalaxyl in grape, tomato, and rice plants under field conditions were studied. Metalaxyl enantiomers were completely separated with a resolution (Rs) of 5.01 by high-performance liquid chromatography (HPLC) based on a cellulose tris (3-chloro-4-methyl phenyl carbamate) chiral column (Lux Cellulose-2). Metalaxyl enantiomers from matrixes were extracted by acetonitrile and purged using Cleanert Alumina-A solid phase extraction (SPE). The linearity, recovery, precision, sensitivity, and matrix effect of the method were assessed. The result showed that significant stereoselectivity occurred in grape, tomato, and rice plants. In grape, (+)-S-metalaxyl with a half-life of 5.5 d degraded faster than (–)-R-metalaxyl with that of 6.9 d, and the enantiomer fraction (EF) value reached 0.37 at 21 d. The same enantioselectivity was observed in tomato, and the half-life was 2.2 d for the S-enantiomer and 3.0 d for the R-enantiomer. The EF values decreased from 0.49 of 0 d to 0.26 of 14 d. On the other hand, a preferential degradation of the R-form was found in rice plants, with an EF value of 0.70 at 14 d, and the corresponding half-life was 2.3 d for the R-form and 2.8 d for the S-form. Chirality 27:109–114, 2015. © 2014 Wiley Periodicals, Inc.
Co-reporter:Xiude Hua, Wei Yin, Haiyan Shi, Ming Li, Yanru Wang, Hong Wang, Yonghao Ye, Hee Joo Kim, Shirley J. Gee, Minghua Wang, Fengquan Liu, and Bruce D. Hammock
Analytical Chemistry 2014 Volume 86(Issue 16) pp:8441
Publication Date(Web):August 4, 2014
DOI:10.1021/ac5020657
Two immuno-loop-mediated isothermal amplification assays (iLAMP) were developed by using a phage-borne peptide that was isolated from a cyclic eight-peptide phage library. One assay was used to screen eight organophosphorus (OP) pesticides with limits of detection (LOD) between 2 and 128 ng mL–1. The iLAMP consisted of the competitive immuno-reaction coupled to the LAMP reaction for detection. This method provides positive results in the visual color of violet, while a negative response results in a sky blue color; therefore, the iLAMP allows one to rapidly detect analytes in yes or no fashion. We validated the iLAMP by detecting parathion-methyl, parathion, and fenitrothion in Chinese cabbage, apple, and greengrocery, and the detection results were consistent with the enzyme-linked immunosorbent assay (ELISA). In conclusion, the iLAMP is a simple, rapid, sensitive, and economical method for detecting OP pesticide residues in agro-products with no instrumental requirement.
Co-reporter:Qing Zhang, Mingming Tian, Meiyun Wang, Haiyan Shi, and Minghua Wang
Journal of Agricultural and Food Chemistry 2014 Volume 62(Issue 13) pp:2809-2815
Publication Date(Web):March 10, 2014
DOI:10.1021/jf405689n
A novel and effective method for enantioselective determination of flutriafol enantiomers in food and environmental matrices (cucumber, tomato, grape, pear, wheat, soil, and water) has been developed. The (R)-(−)-flutriafol was first eluted and measured from electronic circular dichroism spectra using a cellulose tris(3-chloro-4-methyl phenyl carbamate) chiral column. The mean recoveries from the samples ranged from 82.9% to 103.4%, with intraday relative standard deviations (RSD) of 2.2–8.3% and interday RSD of 3.4–7.9%. Good linearity (R2 ≥ 0.9989) was obtained for all analytes matrix calibration curves within the range of 0.1–10 mg/kg. The limits of detection for two enantiomers in the seven matrices were all below 0.015 mg/kg. The results show that the proposed method is convenient and reliable for the enantioselective detection of the flutriafol in the real samples and is applicable to the environmental stereochemistry of flutriafol in food and environmental matrices.
Co-reporter:Yulong Yuan, Xiude Hua, Ming Li, Wei Yin, Haiyan Shi and Minghua Wang
RSC Advances 2014 vol. 4(Issue 46) pp:24406-24411
Publication Date(Web):16 May 2014
DOI:10.1039/C4RA01845A
An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on monoclonal antibodies (MAbs) for benzothiostrobin has been developed. The hapten of benzothiostrobin was synthesized and conjugated to bovine serum albumin and ovalbumin to generate an immunogen and a coating antigen. The immunogen was used to immunize BALB/c mice, resulting in anti-benzothiostrobin MAb. Under optimal conditions, the half maximal inhibition concentration (IC50) and the limit of detection (IC10) of the developed ic-ELISA were 7.55 and 0.428 μg L−1, respectively. The cross-reactivity (CR) was less than 0.05% for the tested structural analogues and regarded as negligible except for pyraclostrobin, which exhibited a CR of 0.34%. The recoveries of benzothiostrobin ranged from 80.43 to 113.83% in environmental and agricultural samples, respectively, which conformed to the requirements for residue detection. The amount of benzothiostrobin detected by ic-ELISA in the samples was significantly (R2 = 0.9894, y = 1.0867x + 0.0318) correlated with that detected by high-performance liquid chromatography (HPLC). The current study indicates that the established ic-ELISA is a potentially useful tool for detecting benzothiostrobin in environmental and agricultural samples.
Co-reporter:Chengying Lu;Xing Yin;Xiaofeng Liu ;Minghua Wang
Photochemistry and Photobiology 2014 Volume 90( Issue 6) pp:1219-1223
Publication Date(Web):
DOI:10.1111/php.12314
Abstract
Hexaflumuron, one of the benzoylphenylurea insect growth regulators, can be leached into surface water and thus having a potential impact on aquatic organisms. In this study, the photodegradation processes of hexaflumuron under high-pressure mercury lamp irradiation were assessed. The photodegradation kinetics were studied, as were the effects of pH, different light sources, organic solvents and environmental substances, including nitrate ions (NO3−), nitrite ions (NO2−), ferrous ions (Fe2+), ferric ions (Fe3+), humic acid, sodium dodecyl sulfate (SDS) and hydrogen peroxide (H2O2). Three photodegradation products in methanol were identified by gas chromatography-mass spectrometry (GC-MS). In general, the degradation of hexaflumuron followed first-order kinetics. In the four media studied, the photodegradation rate order was n-hexane > methanol > ultrapure water > acetone. Faster degradation was observed under high-pressure mercury lamp irradiation than under xenon lamp irradiation. The pH had a considerable effect, with the most rapid degradation occurring at pH 5.0. The photodegradation rate of hexaflumuron was promoted in the presence of NO3−, NO2−, Fe2+, humic acid, SDS and H2O2, but inhibited by Fe3+. Moreover, the presumed photodegradation pathway was proposed to be the cleavage of the urea linkage.
Co-reporter:Ming Li, Xiaofeng Liu, Xiude Hua, Wei Yin, Qingkui Fang and Minghua Wang
Analytical Methods 2014 vol. 6(Issue 16) pp:6541-6547
Publication Date(Web):12 Jun 2014
DOI:10.1039/C4AY00987H
A homogeneous fluorescence polarization immunoassay (FPIA) based on a monoclonal antibody was successfully developed and applied in the determination of clothianidin in agricultural samples. Three fluorescein-labeled clothianidin tracers containing different bridge lengths (2-, 4- and 6-carbon bridges) were synthesized and employed to investigate the effect of tracer structures on the FPIA. Under optimal conditions, the fluoresceinthiocarbamyl hexamethylenediamine-labeled clothianidin conjugate (HMDF-labeled clothianidin), which contains a 6-carbon bridge, performed most sensitively in the FPIA for detecting clothianidin, and the detection was achieved by one step in 12 min with a limit of detection of 5.53 ng mL−1 and an IC50 of 0.0873 μg mL−1. There were no obvious cross-reactivities of the antibodies with the analogues except for dinotefuran. Recoveries, measured in spiked water, soil, rice, apple, and cabbage samples, ranged from 78.7% to 108.2% with relative standard deviations less than 12.9%. Furthermore, the FPIA for authentic samples showed reliability and high correlations with ELISA of 0.9845 and HPLC of 0.9653. The developed FPIA demonstrated high sensitivity and accuracy, and could be ideally suitable for rapid, simple, and high-throughput screening for clothianidin contamination in agricultural samples.
Co-reporter:Xu Yan;Xiaojian Tang;Hongxia Li;Enze Sheng;Dongdong Yang
Food Analytical Methods 2014 Volume 7( Issue 6) pp:1186-1194
Publication Date(Web):2014 July
DOI:10.1007/s12161-013-9732-3
A bi-enzyme tracer direct competitive enzyme-linked immunosorbent assay (dc-ELISA) based on two generic antibodies was developed. The effects of several physicochemical factors, such as heterologous antigen–horseradish peroxidase (HRP), methanol concentration, ionic strength, and pH value, were optimized to obtain satisfactory sensitivity of the assay. Under the optimized conditions, the 50 % inhibition concentration (IC50) value for parathion, parathion-methyl, imidaclothiz, and imidacloprid was 57.28 ± 2.73, 169.82 ± 5.64, 52.48 ± 3.46, and 53.08 ± 2.05 μg L−1, with a limit of detection (LOD, IC10) of 0.56, 3.16, 0.62, and 0.51 μg L−1, respectively. There was no obvious cross-reactivity (CR) with most of the neonicotinoids and organophosphorus pesticides. The recoveries of parathion, parathion-methyl, imidaclothiz, and imidacloprid in environmental and agricultural samples, including river water, soil, and cabbage, ranged from 82.54 to 116.29 %. The relative standard deviation (RSD) ranged from 1.59 to 8.09 %. The ELISA results were confirmed by gas chromatography (GC) with a high correlation coefficient of 0.9882. These results showed that the bi-enzyme tracer competitive enzyme-linked immunosorbent assay could be used as a sensitive tool for monitoring parathion, parathion-methyl, imidaclothiz, and imidacloprid in environmental samples and agricultural products.
Co-reporter:Ming Li;Enze Sheng;Yulong Yuan
Environmental Science and Pollution Research 2014 Volume 21( Issue 9) pp:5803-5809
Publication Date(Web):2014 May
DOI:10.1007/s11356-014-2506-7
Europium (Eu3+)-labeled antibody was used as a fluorescent label to develop a highly sensitive time-resolved fluoroimmunoassay (TRFIA) for determination of clothianidin residues in agricultural samples. Toward this goal, the Eu3+-labeled polyclonal antibody and goat anti-rabbit antibody were prepared for developing and evaluating direct competitive TRFIA (dc-TRFIA) and indirect competitive TRFIA (ic-TRFIA). Under optimal conditions, the half-maximal inhibition concentration (IC50) and the limit of detection (LOD, IC10) of clothianidin were 9.20 and 0.0909 μg/L for the dc-TRFIA and 2.07 and 0.0220 μg/L for the ic-TRFIA, respectively. The ic-TRFIA has no obvious cross-reactivity with the analogues of clothianidin except for dinotefuran. The average recoveries of clothianidin from spiked water, soil, cabbage, and rice samples were estimated to range from 74.1 to 115.9 %, with relative standard deviations of 3.3 to 11.7 %. The results of TRFIA for the blind samples were largely consistent with gas chromatography (R2 = 0.9902). The optimized ic-TRFIA might become a sensitive and satisfactory analytical method for the quantitative monitoring of clothianidin residues in agricultural samples.
Co-reporter:Zhen-jiang Liu, Xu Yan, Xiu-ying Xu and Ming-hua Wang
Analyst 2013 vol. 138(Issue 11) pp:3280-3286
Publication Date(Web):05 Apr 2013
DOI:10.1039/C3AN00205E
A novel and sensitive enhanced chemiluminescence enzyme-linked immunosorbent assay (ECL-ELISA) for the simultaneous analysis of imidaclothiz and thiacloprid is described. The concentrations of coating antibodies and enzyme tracers were optimised by three different ECL-ELISA formats. Under the optimised conditions, when anti-imidaclothiz polyclonal and anti-thiacloprid polyclonal antibodies were immobilised in a single well, single-enzyme tracer ECL-ELISA was used to screen the corresponding pesticide residue, and multi-enzyme tracer ECL-ELISA was used for the analysis of imidaclothiz and thiacloprid residue mixtures. The average recoveries of the two pesticides from spiked tomato, cabbage, and rice samples were in the range of 83.7–117%. Meanwhile, the results showed that the multi-enzyme tracer ECL-ELISA could be applied to the accurate analysis of different proportions of imidaclothiz and thiacloprid (1:4 to 4:1, m/m) when the gross residues ranged from 20 to 250 μg kg−1. The results of the multi-enzyme tracer ECL-ELISA in the real tomato samples correlated well with those of high-performance liquid chromatography, with a correlation coefficient of 0.996. Therefore, this new strategy for developing immunoassays is suitable for the simultaneous quantitative detection of imidaclothiz and thiacloprid residues in agricultural samples.
Co-reporter:Ming Li, Enze Sheng, Lujing Cong, and Minghua Wang
Journal of Agricultural and Food Chemistry 2013 Volume 61(Issue 15) pp:3619-3623
Publication Date(Web):March 25, 2013
DOI:10.1021/jf400055s
Two enzyme-linked immunosorbent assays (ELISAs) based on polyclonal antibodies (PcAbs) for clothianidin are described: colorimetric detection format (ELISA) and pattern of chemiluminescent assay (CLEIA). Clothianidin hapten was synthesized and conjugated to bovine serum albumin (BSA) and ovalbumin (OVA) to produce immunogen and coating antigen. Anticlothianidin PcAbs were obtained from immunized New Zealand white rabbits. Under optimal conditions, the half-maximal inhibition concentration (IC50) and the limit of detection (LOD, IC20) of clothianidin were 0.046 and 0.0028 mg/L for the ELISA and 0.015 and 0.0014 mg/L for the CLEIA, respectively. There were no obvious cross-reactivities of the antibodies with its analogues except for dinotefuran. Recoveries of 76.4–116.4% for the immunoassays were achieved from spiked samples. The results of immunoassays for the spiked and authentic samples were largely consistent with gas chromatography. Therefore, the proposed immunoassays would be convenient and satisfactory analytical methods for the monitoring of clothianidin in agricultural products.
Co-reporter:Zhenjiang Liu, Xu Yan, Xiude Hua and Minghua Wang
Analytical Methods 2013 vol. 5(Issue 14) pp:3572-3576
Publication Date(Web):08 May 2013
DOI:10.1039/C3AY00033H
A fast and sensitive indirect competitive time-resolved fluoroimmunoassay (TRFIA) for thiacloprid is developed. Europium-labeled goat anti-rabbit antibody was used as the tracer. Under optimal conditions, the TRFIA showed a 50% inhibition concentration (IC50) value of 2 μg L−1 with a limit of detection (LOD, IC10) of 1.9 ng L−1. The recoveries from agricultural samples, including water, soil, pear and tomato, were in the range from 83.4% to 121% with a relative standard deviation of 2.40–11.3%. The TRFIA results for real soil samples were confirmed by high performance liquid chromatography with a high correlation coefficient of 0.9854. This analytical method demonstrates good sensitivity and stability, and its potential for practical applications.
Co-reporter:Hu Zhang, Xinquan Wang, Shulin Zhuang, Nuo Jin, Xiangyun Wang, Mingrong Qian, Hao Xu, Peipei Qi, Qiang Wang, and Minghua Wang
Journal of Agricultural and Food Chemistry 2012 Volume 60(Issue 41) pp:10188-10195
Publication Date(Web):September 26, 2012
DOI:10.1021/jf302620s
An enantioselective method is presented for the determination of isocarbophos in soil by liquid chromatography coupled with tandem mass spectrometry. The pesticide residues in soil samples were extracted with acetonitrile, and complete enantioseparation was obtained on an amylose tris(3,5-dimethylphenylcarbamate) chiral column using acetonitrile/2 mM ammonium acetate solution containing 0.1% formic acid (60:40, v/v) as the mobile phase. The absolute configuration of isocarbophos enantiomers was determined by the combination of experimental and calculated electronic circular dichroism spectra. The method was utilized to investigate the degradation of isocarbophos in soils (Changchun, Hangzhou, and Zhengzhou) under sterilized or native conditions. Isocarbophos enantiomers were configurationally stable in the selected soils, and the pesticide degradation was not enantioselective in the sterilized condition. The degradation behavior of rac-isocarbophos was different under native conditions, with no enantioselectivity in the Changchun soil and with the S-(+)-isocarbophos enriched in the Hangzhou and Zhengzhou soils.
Co-reporter:Hu Zhang;Mingrong Qian;Xinquan Wang;Xiangyun Wang;Hao Xu;Qiang Wang;Minghua Wang
Journal of Separation Science 2012 Volume 35( Issue 7) pp:773-777
Publication Date(Web):
DOI:10.1002/jssc.201100889
The enantiomeric separation of 21 triazole fungicides was carried out on four polysaccharide-derived chiral stationary phases in the reversed phase separation mode using high performance liquid chromatography coupled with tandem mass spectrometry. All fungicides were detected in electrospray ionization (ESI) positive mode with selected reaction monitoring (SRM). Complete enantioseparation was achieved for 21 fungicides except for difenoconazole based on cellulose tris (3,5-dimethylphenylcarbamate) and cellulose tris (3-chloro-4-methylphenyl carbamate) columns by optimizing experimental conditions including mobile phase and column temperature. Mobile phase was 0.1% formic acid aqueous solution mixed with methanol or acetonitrile in different proportions. Among all the fungicides, 15 with two enantiomers and three with four stereoisomers (bitertanol, bromuconazole, and cyproconazole) were successfully separated at 25°C. Enantioseparation for the other three fungicides (propiconazole, triadimenol, and difenoconazole) with four stereoisomers could be achieved by changing the column temperature from 10 to 40°C. Propiconazole and triadimenol were enantioseparated on baseline at 40 and at 35°C, respectively, and difenoconazole was enantioseparated partially with the Rs > 1.1 at 25°C. Moreover, linearities and limits of detection (LODs) of 21 fungicides except for difenoconazole were studied, showing coefficients of determination (R2) higher than 0.99 and LODs lower than 2.5 μg/L.
Co-reporter:Hu Zhang;Xinquan Wang;Lixia Jin;Mingrong Qian;Xiangyun Wang;Hao Xu;Peipei Qi;Qiang Wang;Minghua Wang
Journal of Separation Science 2012 Volume 35( Issue 15) pp:1869-1876
Publication Date(Web):
DOI:10.1002/jssc.201200063
An efficient and sensitive enantioselective method for simultaneous determination of three acylamino acid fungicides in vegetables and fruits was presented by high-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry. The three fungicides (benalaxyl, furalaxyl, and metalaxyl) residues in samples were extracted with acetonitrile containing 1% acetic acid and an aliquot was cleaned up with Si-(CH2)3-NH-(CH2)2-NH2 and C18 sorbent. Complete enantioseparation of three acylamino acid fungicides enantiomers was obtained under reversed-phase conditions on a cellulose tris (4-chloro-3-methylphenylcarbamate) column at 25°C using acetonitrile–0.1% formic acid solution (45:55, v/v) as a mobile phase. The elution orders of the eluted enantiomers were determined by a circular dichroism (CD) detector. The linearity, matrix effect, recovery, and precision were evaluated. Good linearity was obtained over the concentration range of 0.5–250 μg/L for each enantiomer in the standard solution and sample matrix calibration curves. There was no significant matrix effect for three fungicides determination based on the method. The inter-day mean recoveries, intra-day repeatability, and inter-day reproducibility varied from 81.3 to 95.7%, 2.2 to 9.4%, and 2.3 to 9.6%, respectively. The method provided high selectivity and sensitivity, and limits of quantification for enantiomers of three fungicides in vegetables and fruits were both 1 μg/kg.
Co-reporter:Xu Yan, Haiyan Shi and Minghua Wang
Analytical Methods 2012 vol. 4(Issue 12) pp:4053-4057
Publication Date(Web):01 Oct 2012
DOI:10.1039/C2AY25760B
A multi-determinant immunogen was prepared by haptens of parathion and imidacloprid conjugated to bovine serum albumin (BSA). The broad-specificity polyclonal antibody (BsPAb) was generated by male New Zealand white rabbits immunized with the multi-determinant immunogen. The antibody was screened against six different coating antigens. An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed and used for the analysis of parathion and imidacloprid simultaneously. Under the optimized conditions, the 50% inhibition concentration (IC50) value for parathion and imidacloprid was 0.052 and 1.70 mg L−1, with a limit of detection (LOD, IC10) of 0.0005 and 0.0045 mg L−1, respectively. There was no obvious cross-reactivity (CR) with most of the neonicotinoids and organophosphorus insecticides, except for imidaclothiz (23.9%) and acetamiprid (6.17%). The recoveries of parathion and imidacloprid in environmental and agricultural samples, including tap water, river water, soil and cabbage, ranged from 87.2% to 117% and 84.4% to 107%, respectively. These results showed that the ic-ELISA can be used as a sensitive tool for detecting parathion and imidacloprid simultaneously in environmental and agricultural samples.
Co-reporter:Mengmeng Cao, Ming Li, Xu Yan and Minghua Wang
Analytical Methods 2012 vol. 4(Issue 2) pp:534-538
Publication Date(Web):25 Jan 2012
DOI:10.1039/C2AY05626G
A sensitive, specific, indirect and competitive enzyme-linked immunosorbent assay (ELISA) based on a polyclonal antibody (PcAb) for S-bioallethrin was developed. The hapten-bovine serum albumin (BSA) conjugate was used as an immunogen while the hapten-ovalbumin (OVA) conjugate was applied as a coating antigen. An anti-S-bioallethrin PcAb was obtained from immunized New Zealand white rabbits, and an ELISA for S-bioallethrin was developed. The inhibition standard curve of S-bioallethrin was obtained using optimized conditions (40% methanol, 0.5 mol L−1Na+, pH 6.5). The half-maximal inhibition concentration (IC50) was 0.089 μg mL−1, and the limit of detection (LOD, IC10) was 0.0025 μg mL−1. Very low cross-reactivity (CR) was found for allethrin and other pyrethroids. The CR for the stereoisomer demonstrates that the antibody has notable stereoselectivity for S-bioallethrin. Water and dust spiked with S-bioallethrin were analyzed by ELISA and acceptable recovery rates, 90.7% to 111.7%, were obtained. The ELISA results were confirmed by gas chromatography/electron capture detection (GC-ECD) and the proposed ELISA could be a highly sensitive, stereoselective, simple, rapid and inexpensive method for the detection of S-bioallethrin in environmental samples.
Co-reporter:Hu Zhang;Mingrong Qian;Xinquan Wang;Xiangyun Wang;Hao Xu
Food Analytical Methods 2012 Volume 5( Issue 6) pp:1342-1348
Publication Date(Web):2012 December
DOI:10.1007/s12161-012-9375-9
A rapid and sensitive enantioselective method for the determination of tebuconazole and tetraconazole enantiomers in strawberry has been developed. The enantiomers were resolved by high-performance liquid chromatography on a cellulose tris (3-chloro-4-methylphenylcarbamate) (Lux Cellulose-2) column using methanol–0.1% formic acid solution (70:30, v/v) as mobile phase. The chiral liquid chromatographic separation was combined with an extract/cleanup procedure known as the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. High-performance liquid chromatography-tandem mass spectrometry with electrospray ionization was then used for qualitative and quantitative determination of the enantiomers of tebuconazole and tetraconazole. Hexaconazole was used as an internal standard. The method provided high selectivity and sensitivity, and the limits of quantification for tebuconazole and tetraconazole enantiomers in strawberry were both 2.5 μg/kg. The method was successfully utilized to investigate the probable enantioselective degradation of tebuconazole and tetraconazole in strawberry. The results showed that the degradation of the tebuconazole and tetraconazole enantiomers in strawberry followed first-order kinetics (R2 > 0.96). The results from this study revealed the degradation of tetraconazole in strawberry was not enantioselective, while the degradation of tebuconazole was enantioselective, and the (+)-tebuconazole showed a faster degradation than (−)-tebuconazole in strawberry. The results could provide a reference to fully evaluate risks of these two fungicides.
Co-reporter:Xiao-Xue Jiang, Hai-Yan Shi, Ni Wu, Ming-Hua Wang
Food Chemistry 2011 Volume 125(Issue 4) pp:1385-1389
Publication Date(Web):15 April 2011
DOI:10.1016/j.foodchem.2010.10.010
Diniconazole hapten was synthesized and conjugated to bovine serum albumin (BSA) by the carbodiimide method to produce an immunogen and to ovalbumin (OVA) by mixed anhydride method to produce a coating antigen. Polyclonal antibody against diniconazole was generated by immunizing New Zealand rabbits with the immunogen. Under optimised conditions (20% methanol, 0.4 mol/L Na+, pH 7.5), an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed for detecting diniconazole. The 50% inhibitory concentration (IC50) was 0.071 ± 0.013 mg/L and the limit of detection (LOD) was 1.28 ± 0.80 μg/L. Triazole fungicide analogues of diniconazole were tested and did not obviously cross-react, except for uniconazole (2.25%). The recoveries obtained after addition of standard diniconazole to agricultural samples, including water, soil, pear, grape, tomato and wheat flour, ranged from 70% to 120%. The ic-ELISA developed could successfully be applied to analysis of diniconazole residues in agriculture samples.Research highlights► Diniconazole hapten was synthesized and relevant polyclonal antibody was arised. ► An ic-ELISA method for detecting diniconazole was developed. ► The method was applied to analysis of diniconazole residues in agriculture samples.
Co-reporter:Song Fang, Bin Zhang, Ke-wei Ren, Meng-meng Cao, Hai-yan Shi, and Ming-hua Wang
Journal of Agricultural and Food Chemistry 2011 Volume 59(Issue 5) pp:1594-1597
Publication Date(Web):February 3, 2011
DOI:10.1021/jf104241n
An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on monoclonal antibodies (MoAbs) for imidaclothiz was developed. The hapten of imidaclothiz was synthesized and conjugated to bovine serum albumin (BSA) and ovalbumin (OVA) to form the artificial antigens. MoAbs were obtained by immunizing BALB/c mice. Under the optimized conditions (10% methanol, 0.14 M Na+, and pH 7.4), the half-maximal inhibition concentration (IC50) was 0.0875 ± 0.0034 mg/L and the limit of detection (IC20) was 0.0178 ± 0.0018 mg/L for imidaclothiz. There were no obvious cross-reactivities with most of the structural analogues of neonicotinoid insecticides, except imidacloprid. The recoveries of imidaclothiz in environmental and agricultural samples, including tap water, paddy water, soil, and cabbage, ranged from 80.43 to 113.83%, well within the requirements of residue detection. These results showed that this immunoassay could be used for the determination of imidaclothiz in environmental and agricultural samples.
Co-reporter:Huajun Bao, Song Fang, Zhenjiang Liu, Haiyan Shi, Yonghao Ye and Minghua Wang
Journal of Agricultural and Food Chemistry 2010 Volume 58(Issue 14) pp:8167-8170
Publication Date(Web):July 1, 2010
DOI:10.1021/jf101152m
An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) for the herbicide haloxyfop-P-methyl is reported. Two haptens of haloxyfop-P-methyl with different spacer-arm lengths were synthesized, to which polyclonal antibodies were obtained by immunizing New Zealand rabbits. The most sensitive combination of antibody/coating antigen was selected by homologous and heterologous assays. The results indicated that the spacer-arm length of hapten can affect assay sensitivity. The optimized ic-ELISA showed that the 50% inhibitory concentration (IC50) was 0.0419 mg/L, and the limit of detection (LOD) was 0.0019 mg/L. Recoveries were obtained from the agricultural samples, including water, soil, cucumbers, cabbages, tomatoes, and potatoes; all were in the range of 87.4%−111.8%, well within the requirements of residue detection.
Co-reporter:Jun-Dong Wang, Hua-Jun Bao, Hai-Yan Shi, Ming-Hua Wang
Pesticide Biochemistry and Physiology (September 2010) Volume 98(Issue 1) pp:68-72
Publication Date(Web):1 September 2010
DOI:10.1016/j.pestbp.2010.05.001
An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) for cyhalofop-butyl was developed with a polyclonal antibody produced against a hapten (cyhalofop acid) conjugated with bovine serum albumin (BSA). The ELISA of cyhalofop-butyl showed an IC50 value of 0.067 ± 0.004 mg/l and the limit of detection (LOD, IC10) of 0.0029 ± 0.0001 mg/l at the optimal conditions. No significant cross-reaction to other structure-related compounds suggested high specificity for cyhalofop-butyl of the method. The average recoveries of cyhalofop-butyl from fortified water and soil were in the range of 83.2–119.7% and 80.1–104.0%, respectively. These data indicate that this method is a convenient analytical technique for monitoring cyhalofop-butyl in water and soil without purification steps.
Co-reporter:Juhua Chang, Shaoying Liu, Shengli Zhou, Minghua Wang, Guonian Zhu
Experimental and Toxicologic Pathology (January 2013) Volume 65(Issues 1–2) pp:205-209
Publication Date(Web):1 January 2013
DOI:10.1016/j.etp.2011.08.007
Butachlor, a chloracetamide herbicide, is widely used in China. In the present study, paired adult male and female zebrafish (Danio rerio) were exposed to various concentrations of butachlor (0, 25, 50 and 100 μg/L) for 30 days, and the effects on reproduction and endocrine disruption were evaluated using fecundity, condition factor (CF), gonadosomatic index (GSI), liver somatic index (LSI), plasma vitellogenin (VTG), sex steroids and thyroid hormone levels as endpoints. Our results showed that the mean fecundity rates were significantly decreased at 50 and 100 μg/L butachlor during the 30-day exposure period. At the end of the exposure period, no significant changes were observed in CF and LSI in both females and males, while GSI was significantly reduced in males at 50 and 100 μg/L butachlor. At 100 μg/L butachlor, plasma testosterone (T) and 17β-estradiol (E2) levels were significantly decreased in females, while plasma VTG level was significantly increased in males. Plasma thyroxine (T4) and triiodothyronine (T3) levels were significantly increased at 50 and 100 μg/L butachlor in males, and at 100 μg/L in females. This work demonstrated that butachlor adversely affected the normal reproductive success of zebrafish, and disrupted the thyroid and sex steroid endocrine systems, which provides the basis for the estimated ecological risk during butachlor exposure.
Co-reporter:Qing Zhang, Xiu-de Hua, Hai-yan Shi, Ji-song Liu, Ming-ming Tian, Ming-hua Wang
Journal of Hazardous Materials (2 March 2015) Volume 284() pp:65-72
Publication Date(Web):2 March 2015
DOI:10.1016/j.jhazmat.2014.10.033
•The R-flutriafol was more active than S-flutriafol against five target pathogens.•The acute toxicity of flutriafol to earthworm and algae were enantioselective.•The R-flutriafol exhibited 2.17–3.52 times higher acute toxicity than S-flutriafol.•The S-flutriafol degrades faster than R-flutriafol in cucumber.•The R-flutriafol was preferential degrade in tomato.The enantioselective bioactivity, acute toxicity and stereoselective degradation of the chiral triazole fungicide flutriafol in vegetables were investigated for the first time using the (R)-, (S)- and rac-flutriafol. The order of the bioactivity against five target pathogens (Rhizoctonia solani, Alternaria solani, Pyricularia grisea, Gibberella zeae, Botrytis cinerea) was found to be (R)-flutriafol > rac-flutriafol > (S)-flutriafol. The fungicidal activity of (R)-flutriafol was 1.49–6.23 times higher than that of (S)-flutriafol. The (R)-flutriafol also showed 2.17–3.52 times higher acute toxicity to Eisenia fetida and Scenedesmus obliquus than (S)-flutriafol. The stereoselective degradation of flutriafol in tomato showed that the active (R)-flutriafol degraded faster, resulting in an enrichment of inactive (S)-form, and the half-lives were 9.23 d and 10.18 d, respectively. Inversely, the (S)-flutriafol, with a half-life of 4.76 d, was preferentially degraded in cucumber. In conclusion, the systemic assessments of the triazole fungicide flutriafol stereoisomers on the enantioselective bioactivity, acute toxicity and environmental behavior may have implications for better environmental and ecological risk assessment.Download full-size image
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 16) pp:
Publication Date(Web):
DOI:10.1039/C4AY00987H
A homogeneous fluorescence polarization immunoassay (FPIA) based on a monoclonal antibody was successfully developed and applied in the determination of clothianidin in agricultural samples. Three fluorescein-labeled clothianidin tracers containing different bridge lengths (2-, 4- and 6-carbon bridges) were synthesized and employed to investigate the effect of tracer structures on the FPIA. Under optimal conditions, the fluoresceinthiocarbamyl hexamethylenediamine-labeled clothianidin conjugate (HMDF-labeled clothianidin), which contains a 6-carbon bridge, performed most sensitively in the FPIA for detecting clothianidin, and the detection was achieved by one step in 12 min with a limit of detection of 5.53 ng mL−1 and an IC50 of 0.0873 μg mL−1. There were no obvious cross-reactivities of the antibodies with the analogues except for dinotefuran. Recoveries, measured in spiked water, soil, rice, apple, and cabbage samples, ranged from 78.7% to 108.2% with relative standard deviations less than 12.9%. Furthermore, the FPIA for authentic samples showed reliability and high correlations with ELISA of 0.9845 and HPLC of 0.9653. The developed FPIA demonstrated high sensitivity and accuracy, and could be ideally suitable for rapid, simple, and high-throughput screening for clothianidin contamination in agricultural samples.
Co-reporter:Xu Yan, Haiyan Shi and Minghua Wang
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 12) pp:NaN4057-4057
Publication Date(Web):2012/10/01
DOI:10.1039/C2AY25760B
A multi-determinant immunogen was prepared by haptens of parathion and imidacloprid conjugated to bovine serum albumin (BSA). The broad-specificity polyclonal antibody (BsPAb) was generated by male New Zealand white rabbits immunized with the multi-determinant immunogen. The antibody was screened against six different coating antigens. An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed and used for the analysis of parathion and imidacloprid simultaneously. Under the optimized conditions, the 50% inhibition concentration (IC50) value for parathion and imidacloprid was 0.052 and 1.70 mg L−1, with a limit of detection (LOD, IC10) of 0.0005 and 0.0045 mg L−1, respectively. There was no obvious cross-reactivity (CR) with most of the neonicotinoids and organophosphorus insecticides, except for imidaclothiz (23.9%) and acetamiprid (6.17%). The recoveries of parathion and imidacloprid in environmental and agricultural samples, including tap water, river water, soil and cabbage, ranged from 87.2% to 117% and 84.4% to 107%, respectively. These results showed that the ic-ELISA can be used as a sensitive tool for detecting parathion and imidacloprid simultaneously in environmental and agricultural samples.
Co-reporter:
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 2) pp:
Publication Date(Web):
DOI:10.1039/C2AY05626G
A sensitive, specific, indirect and competitive enzyme-linked immunosorbent assay (ELISA) based on a polyclonal antibody (PcAb) for S-bioallethrin was developed. The hapten-bovine serum albumin (BSA) conjugate was used as an immunogen while the hapten-ovalbumin (OVA) conjugate was applied as a coating antigen. An anti-S-bioallethrin PcAb was obtained from immunized New Zealand white rabbits, and an ELISA for S-bioallethrin was developed. The inhibition standard curve of S-bioallethrin was obtained using optimized conditions (40% methanol, 0.5 mol L−1Na+, pH 6.5). The half-maximal inhibition concentration (IC50) was 0.089 μg mL−1, and the limit of detection (LOD, IC10) was 0.0025 μg mL−1. Very low cross-reactivity (CR) was found for allethrin and other pyrethroids. The CR for the stereoisomer demonstrates that the antibody has notable stereoselectivity for S-bioallethrin. Water and dust spiked with S-bioallethrin were analyzed by ELISA and acceptable recovery rates, 90.7% to 111.7%, were obtained. The ELISA results were confirmed by gas chromatography/electron capture detection (GC-ECD) and the proposed ELISA could be a highly sensitive, stereoselective, simple, rapid and inexpensive method for the detection of S-bioallethrin in environmental samples.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 14) pp:
Publication Date(Web):
DOI:10.1039/C3AY00033H
A fast and sensitive indirect competitive time-resolved fluoroimmunoassay (TRFIA) for thiacloprid is developed. Europium-labeled goat anti-rabbit antibody was used as the tracer. Under optimal conditions, the TRFIA showed a 50% inhibition concentration (IC50) value of 2 μg L−1 with a limit of detection (LOD, IC10) of 1.9 ng L−1. The recoveries from agricultural samples, including water, soil, pear and tomato, were in the range from 83.4% to 121% with a relative standard deviation of 2.40–11.3%. The TRFIA results for real soil samples were confirmed by high performance liquid chromatography with a high correlation coefficient of 0.9854. This analytical method demonstrates good sensitivity and stability, and its potential for practical applications.
