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A residual analysis method for mefentrifluconazole in banana and mango was established using ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) detection technology. The field trial was conducted in banana and mango at six sites during one year according to NY/T 788-2018 the "Guideline for the Testing of Pesticide Residues in Crops" to study the degradation dynamics and residual distribution of mefentrifluconazole. After the application of the formulation of mefentrifluconazole 400 g/L suspension concentration (SC) on banana and mango crops, fruit samples were extracted with acetonitrile, purified with combined adsorbents of GCB and C18, and analyzed by UPLC-MS/MS. The results showed that at four spiked levels of 0.001-1 mg/kg, the average recovery of mefentrifluconazole in whole banana and flesh was 83%-93% with the relative standard deviation (RSD) 2.3% to 5.9%, and the average recovery of mefentrifluconazole in whole mango and flesh was 82%-91% with the RSD 2.9% to 6.0%, respectively; and the limit of quantification (LOQ) was 0.001 mg/kg. The field trials in banana showed that, under the condition of applying mefentrifluconazole 400 g/L SC at dosage of 133.3 mg/kg for 3 times with application interval of 7-10 days, the residues of mefentrifluconazole at 21 and 28 days after the last application were 0.03-0.09 mg/kg in whole banana and <0.001-0.004 mg/kg in the flesh. In the field trials of mango, under the condition of applying mefentrifluconazole 400 g/L SC at dosage of 160 mg/kg for 3 times with application interval of 7-10 days, residues of mefentrifluconazole were 0.04-0.28 mg/kg in whole mango and 0.001-0.003 mg/kg in the flesh at 14 and 21 days after the last application. The research results can provide a reference for guiding the scientific and rational use of mefentrifluconazole in banana and mango, as well as for the establishment of its maximum residue limit (MRL) values. [ABSTRACT FROM AUTHOR]

An analytical method was established for simultaneous determination of chlorantraniliprole, cyantraniliprole and its metabolite J9Z38 in litchi by high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) combined with a modified QuEChERS procedure. The target compounds were extracted from the samples with acetonitrile and then cleaned up with primary secondary amine (PSA) and octadecylsilane (C18). The analytes were separated on a C18 column using V (formic acid aqueous solution) : V (acetonitrile)=15 : 85 as mobile phase and analyzed in multiple reaction monitoring (MRM) mode with positive electrospray ionization (ESI+ ). Quantitative analysis was performed by external standard method using matrix-matched calibration curves. The results showed that the linearity of the target compounds was good (r >0.99) in the range of 0.005-1 mg/L. The limits of quantification (LOQs) were 0.000 5-0.01 mg/kg. The average recoveries of the three pesticides in litchi (whole fruit and pulp) ranged from 76% to 98% at the spiked levels of 0.000 5-0.5 mg/kg, with the relative standard deviations of 2.5% to 9.6%. The method was applied for the detection of twenty commercial litchi samples in Guangzhou City. The results showed that the residues of chlorantraniliprole were 0.001-0.01 mg/kg, and neither cyantraniliprole nor its metabolite J9Z38 were found. The proposed method is convenient, effective and rapid, and is suitable for the simultaneous determination of chlorantraniliprole, cyantraniliprole and its metabolite in litchi. [ABSTRACT FROM AUTHOR]

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An effective method was developed for the determination of fosthiazate residue in sugar cane and soil. Field trials were designed to evaluate the dissipation and residue of fosthiazate in sugar cane and soil in Guangdong Province and Guangxi Province. The dietary exposure and risk assessment were also conducted. The samples were extracted by acetonitrile, cleaned up by NH2-solid phase extraction and detected by GC-FPD. The results showed that, in terms of sugar cane samples, good average recoveries of 83%-84% with relative standard deviations of 2.6%-3.4% at the spiked level of 0.01, 0.1 and 1 mg/kg were achieved. As for soil samples, recoveries of 84%-86% with RSDs 4.1%-6.7% were obtained. The limit of detection (LOD) was 0.01 mg/kg and the limit of quantification (LOQ) was 0.01 mg/kg. The results demonstrated that residue of fosthiazate in sugar cane decreased first, then increased, and finally decreased again. The maximum concentration were 0.027 mg/kg which was detected 14-21 d after the application. Dissipation of fosthiazate in soil was in accordance with the first order kinetic equation with half-lives from 8.6 to 9.6 d. The terminal residue was below 0.01 mg/kg at harvest time. The acute dietary intake risk probability of fosthiazate was 225%, which was hazardous to people. It is necessary to combine the metabolic behavior data of fosthiazate in human body for comprehensive evaluation. The chronic dietary intake risk probability of fosthiazate was 57%, which was not hazardous to people. [ABSTRACT FROM AUTHOR]

The residue behaviors of thiamethoxam in Benincasa hispida Cogn. var. chieh-qua How (chieh-qua) were investigated. The residue field trials of thiamethoxam were designed and conducted in Guangdong and Shanghai in 2015. An effective method was developed for the determination of the thiamethoxam and clothianidin. The chieh-qua samples were extracted by acetonitrile, purified with aminopropyl solid phase extraction and detected using HPLC-MS/MS (high performance liquid chromatography-tandem mass spectrometry). The dissipation and terminal residues of thiamethoxam and clothianidin in chieh-qua samples in Guangdong and Shanghai were determined based on the above analytical method. The results indicated that the half-lives of thiamethoxam in chieh-qua was 4.98-5.84 d. The chieh-qua was sprayed 2 to 3 times with 7-10 days spray interval using 25% WG at the dosage 75 and 112.5 g/hm2 during the young fruit period. The samples were collected 3 to 7 days after the last spray. The terminal residues of thiamethoxam and clothianidin were 0.010-0.422 mg/kg and <0.010- 0.020 mg/kg, respectively, which were determined by the conditions above. The risk quotients (RQ) was 0.044, which revealed its low risk. According to the results, it is suggested that the MRL of thiamethoxam in chieh-qua in China should be set as 1 mg/kg. [ABSTRACT FROM AUTHOR]

An effective method was developed for the determination of sodium 4-chlorophenxyacetate residue in litchi. Field trials were designed to evaluate the dissipation and residue of sodium 4-chlorophenxyacetate in litchi at two locations:Guangdong and Guangxi. Samples were extracted by solution of sodium hydroxide, and further distributed by ethyl acetate after adjusting pH value into 2.5 by HCl and detected by high performance liquid chromatography with photo-diode array. The results showed that average recoveries ranged from 81% to 85% with relative standard deviations of 1.9%-4.6% at the spiked level of 0.01, 0.1 and 1 mg/kg. The limit of detection was 0.005 mg/kg and the limit of quantification was 0.01 mg/kg. Half-lives of sodium 4-chlorophenxyacetate ranged from 3.2 to 5.9 days in litchi and from 15.2 to 20.6 days in soil, respectively. The terminal residues of sodium 4-chlorophenxyacetate in litchi were below 0.01 mg/kg. [ABSTRACT FROM AUTHOR]

The residue behaviors of fluxaproxad and pyraclostrobin in mango were investigated. The residue and decline dynamics for field trials of fluxaproxad and pyraclostrobin were designed and conducted in Guangdong and Guangxi during the years of 2012 and 2013. An effective method was developed for the determination of the above two pesticides. The mango samples were extracted by acetone, followed by liquid-liquid-extraction with ethyl acetate and detected with HPLC-PDA (high performance liquid chromatography with photo-diode array). The dissipation and terminal residues of fluxaproxad and pyraclostrobin in mango samples were studied with the above analytical method. The results indicated that the half-lives of fluxaproxad and pyraclostrobin in mango were 7.2-9.1 and 8.0 -11.0 d, respectively. The mango trees were sprayed for 3 to 4 times with 10-15 days application interval using 42.4% SC at the dosage 200 and 300 mg/L at the young fruit period. The samples were collected at 7 to 14 days after the last spray. The terminal residues of those two pesticides were 0.004-0.053 mg/kg and 0.004-0.072 mg/kg determined by the above conditions. The residue of pyraclostrobin met the maximum residue limit (MRL, 0.05 mg/kg), according to the trial results. It is suggested that the MRL of fluxaproxad in mango in China should be set as 0.2 mg/kg. [ABSTRACT FROM AUTHOR]

An effective method was developed for determination of mesotrione residue in sugar cane and soil. Field trials were designed to evaluate the dissipation and residue of mesotrione in sugar cane and soil at two locations: Guangdong and Guangxi. The samples were extracted by acetonitrile, and further distributed by dichloromethane and detected by high performance liquid chromatography with photo-diode array (HPLC-PDA). The results showed average recoveries of 82%-84% with relative standard deviations of 1.9%-3.4% at spiked levels of 0.01, 0.1 and 1 mg/kg. The limit of detection was 0.005 mg/kg and the limit of quantification was 0.01 mg/kg. It was found that under field trial conditions, residue levels of mesotrione in sugar cane decreased first, then increased, and decreased again. The half-lives ranged from 12.3 to 14.7 days in soil. The terminal residue was all below 0.01 mg/kg at harvest time. [ABSTRACT FROM AUTHOR]