Xiaolin Cao
Chinese Ministry of Agriculture
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Featured researches published by Xiaolin Cao.
Food Chemistry | 2017
Zejun Jiang; Hui Li; Xiaolin Cao; Pengfei Du; Hua Shao; Fen Jin; Maojun Jin; Jing Wang
A rapid and sensitive method based on modified QuEChERS for hymexazol determination in 26 plant-derived foods using liquid chromatography tandem-mass spectrometry (LC-MS/MS) was developed. Variables affecting the separation (LC column, mobile phase additives) and clean-up effects of various dispersive phases, such as PSA, C18, GCB, MWCNTs, PEP-2, Al2O3, Florisil, and PVPP were evaluated. The method was validated using 26 matrices at spiked levels of 0.01 or 0.02, 0.05, 0.1, and 0.5mg/kg (0.05, 0.2, 0.5, and 1.0mg/kg for green tea). Mean recoveries were between 71.2% and 113.8%, and intra and inter-day precisions were below 14.8%. The limit of quantitation for 26 matrices ranged from 10 to 50μg/kg. Matrix-matched calibration was used. The method was subsequently applied for real sample analysis, and hymexazol was detected in a cucumber (below the LOQ) and was not detected in any other sample. The method is simple and effective, and meets the routine monitoring requirements for hymexazol residue in foods.
RSC Advances | 2016
Xiaolin Cao; Guangyang Liu; Yongxin She; Zejun Jiang; Fen Jin; Maojun Jin; Pengfei Du; Fengnian Zhao; Yanxin Zhang; Jing Wang
MOF-199/Fe3O4 nanoparticles were explored for the first time to purify environmental water samples and adsorb neonicotinoid insecticides as hybrid adsorbents. The composites were successfully synthesized by an in situ method at room temperature with electrostatic interaction to chemically stabilize the nanoparticles and metal ions. The nanoparticles were uniformly encoded with metal organic frameworks (MOFs). With the lowest loading amount of Fe3O4 applied to magnetic solid-phase extraction (MSPE) of six neonicotinoid insecticides in environmental water samples followed by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) analysis, the extraction efficiency was the highest. The main influencing factors including the solution ionic strength, solution pH, extraction time, desorbing organic solvent, and solvent volume, were also evaluated. Considering the adsorbing conditions and insecticide structures, the adsorbing mechanism was preliminarily discovered to be largely dependent upon the π–π interaction with the benzene ring in MOF-199 and delocalized large π bonds in the insecticide molecules. Under optimal conditions, the limits of detection (LODs) were 0.3–1.5 ng mL−1 with a signal-to-noise ratio (S/N) of 3. All the analytes exhibited good linearity with correlation coefficients (r2) of higher than 0.9947. The relative standard deviations (RSDs) for six neonicotinoid insecticides in environmental samples in five replicates ranged from 1.5% to 11.6%, and good recoveries from 88.0% to 107.0% were obtained, indicating that the MOF-199/Fe3O4 composites are feasible for analysis of trace analytes in environmental water samples.
Journal of Chromatography B | 2017
Fengnian Zhao; Yongxin She; Chao Zhang; Xiaolin Cao; Shanshan Wang; Lufei Zheng; Maojun Jin; Hua Shao; Fen Jin; Jing Wang
A selective analytical method for the simultaneous determination of 20 triazole fungicides and plant growth regulators in cucumber samples was developed using solid-phase extraction with specific molecularly imprinted polymers (MIPs) as adsorbents. The MIPs were successfully prepared by precipitation polymerization using triadimefon as the template molecule, methacrylic acid as the functional monomer, trimethylolpropane trimethacrylate as the crosslinker, and acetonitrile as the porogen. The performance and recognition mechanism for both the MIPs and non-molecularly imprinted polymers were evaluated using adsorption isotherms and adsorption kinetics. Liquid chromatography-tandem quadrupole mass spectrometry was used to identify and quantify the target analytes. The solid-phase extraction using the MIPs was rapid, convenient, and efficient for extraction and enrichment of the 20 triazole pesticides from cucumber samples. The recoveries obtained at three concentration levels (1, 2, and 10μgL-1) ranged from 82.3% to 117.6% with relative standard deviations of less than 11.8% (n=5) for all analytes. The limits of detection for the 20 triazole pesticides were all less than 0.4μgL-1, and were sufficient to meet international standards.
RSC Advances | 2018
Sihui Hong; Yongxin She; Xiaolin Cao; Miao Wang; Chao Zhang; Lufei Zheng; Shanshan Wang; Xingbin Ma; Hua Shao; Maojun Jin; Fen Jin; Jing Wang
In this study, a direct competitive biomimetic enzyme-linked immune-sorbent assay (BELISA) based on a molecularly imprinted nanomembrane as an artificial antibody was developed for the determination of triazophos in real samples. The imprinted film was directly synthesized on the well surface of a 96-well plate using a dummy molecular template under the conditions of thermal polymerization. The developed BELISA using a hapten of triazophos as an enzyme-labeled probe is much more sensitive, simple, quick, steady and inexpensive than the other instrumental and immuno assay methods. Under optimal conditions, the linear range of the method was 0.001–10 000 μg L−1 with a good regression coefficient of 0.977. The sensitivity (IC50) and the limit of detection (LOD) of BELISA were 428 μg L−1 and 0.001 μg L−1, respectively. This method was performed to detect triazophos in cabbage and apple samples, and showed excellent recovery and relative standard deviations (RSDs) ranging from 70.5 to 119.8% and from 5.2 to 19.7%, respectively. The results correlated well with those obtained using high performance liquid chromatography-tandem mass spectrometry.
Ecotoxicology and Environmental Safety | 2018
Shanshan Wang; Fen Jin; Xiaolin Cao; Yong Shao; Jian Wang; Yongxin She; Yan Qi; Chao Zhang; Hui Li; Maojun Jin; Jing Wang; Hua Shao; Lufei Zheng
Flonicamid, a novel selective systemic pesticide, can effectively control a broad range of insect pests. However, the dissipation behaviors and the terminal residues of flonicamid and its metabolites in some crops and soils remain unclear. Herein, an easy, sensitive and reliable method using a modified QuEChERS extraction coupled with LC-MS/MS for the simultaneous analysis of flonicamid and its metabolites in cabbage and soil was developed. Based on this method, the dissipation behaviors of flonicamid and its metabolites as well as their persistence in cabbage and soil during harvest were investigated. Flonicamid degraded rapidly, and the half-lives of flonicamid only and total residues (the sum of flonicamid and its metabolites) were 1.49-4.59 and 1.97-4.99 days in cabbage, and 2.12-7.97 and 2.04-7.62 days in soil, respectively. When 50% flonicamid WG was sprayed once or twice at the recommended dose and 1.5-fold the recommended dose, the highest residues of total flonicamid in cabbage and soil from different pre-harvest intervals (3, 7 and 14 days) were 0.070 and 0.054 mg kg-1, respectively. The risk quotient (RQ) of flonicamid based on the consumption data from China was below 16.84%, indicating that the use of flonicamid is non-hazardous to humans. These results could not only guide the safe and responsible use of flonicamid in agriculture but also help the Chinese government establish the maximum residue level (MRL) for flonicamid in cabbage.
Chromatographia | 2018
Hui Li; Zejun Jiang; Xiaolin Cao; Hang Su; Hua Shao; Fen Jin; Lufei Zheng; A. M. Abd El-Aty; Jing Wang
Pesticide adjuvants, chemicals with various toxicities, are added to pesticide formulations to improve their stability and efficacy. In the present study, an analytical method was developed for the simultaneous determination of the adjuvants, 2-pyrrolidone, N-Methyl-2-pyrrolidone, and N-Ethyl-2-pyrrolidone, in liquid pesticide formulations. Samples were diluted with ethyl acetate, purified using Oasis HLB as solid-phase extraction (SPE) cartridges, and analyzed by gas chromatography–mass spectrometry (GC–MS) using the external standard method. SPE in interferences retention mode was used herein and key parameters were optimized. Moreover, the necessity for the purification step was evaluated through comparison with direct measurement of diluted samples with no cleanup procedure. SPE was deemed necessary to remove contaminants from targets in liquid pesticide formulations with satisfactory accuracy and precision. The developed and validated SPE/GC–MS method is simple, accurate, and efficient for the simultaneous determination of the three polar adjuvants in complex liquid pesticide formulations.Graphical Abstract
Journal of Chromatography B | 2017
Xiaolin Cao; Zejun Jiang; Shanshan Wang; Sihui Hong; Hui Li; Chao Zhang; Yong Shao; Yongxin She; Fen Jin; Maojun Jin; Jing Wang
UIO-66 crystals were explored for the first time to adsorb neonicotinoid insecticides in environmental water samples. HPLC coupled with tandem MS was used for quantification and determination of neonicotinoid insecticides. UiO-66 crystals was successfully synthesized by a simple constant-temperature bath method. Synthesized UiO-66 was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry and nitrogen adsorption porosimetry (NAP), which demonstrated a uniform particle size, a large Brunauer-Emmett-Teller (BET) surface area and high thermostability. The adsorbing results showed that UIO-66 crystals could be used as a promising adsorbents for rapid extraction of neonicotinoid insecticides and be reused at least 10 times. Under the optimized conditions, the limits of detection (LODs, S/N = 3) and limits of quantification (LOQs, S/N = 10) for the five insecticides were found to be 0.02-0.4 ng/mL and 0.05-1.0 ng/mL, respectively. This developed approach not only provided more simple and sensitive method, as well as possessing satisfactory recovery for neonicotinoid insecticides, but also for other traces in environmental samples.
Journal of Chromatography A | 2017
Zejun Jiang; Xiaolin Cao; Hui Li; Chan Zhang; A. M. Abd El-Aty; Fen Jin; Hua Shao; Maojun Jin; Shanshan Wang; Yongxin She; Jing Wang
Analytica Chimica Acta | 2018
Chan Zhang; Pengfei Du; Zejun Jiang; Maojun Jin; Ge Chen; Xiaolin Cao; Xueyan Cui; Yudan Zhang; Ruixing Li; A. M. Abd El-Aty; Jing Wang
Mikrochimica Acta | 2017
Pengfei Du; Maojun Jin; Ge Chen; Chan Zhang; Xueyan Cui; Yudan Zhang; Yanxin Zhang; Pan Zou; Zejun Jiang; Xiaolin Cao; Yongxin She; Fen Jin; Jing Wang