Search

A simple sample pretreatment for simultaneous determination of nine fungicides (triadimefon, picoxystrobin, kresoxim-methyl, diniconazole, epoxiconazole, trifloxystrobin, triticonazole, difenoconazole, and azoxystrobin) in chrysanthemum was developed using matrix extraction-vortex-assisted dispersive liquid-liquid microextraction (ME-VADLLME) prior to gas chromatography with electron capture detection. The target fungicides were firstly extracted with acetonitrile and cleaned with the mixture of primary secondary amine and graphite carbon black. The VADLLME procedure was performed by using toluene with lower density than water as the extraction solvent and the acetonitrile extract as the dispersive solvent, respectively. After vortexing and centrifugation, the fine droplet of toluene was collected on the upper of the mixed toluene/acetonitrile/water system using a 0.1-mL pipettor. Under the optimum conditions, the relative recoveries ranged from 73.9 to 95.1% with relative standard deviations of 3.5-9.7% for all of the analytes. The limits of detection were in the range of (0.005-0.05)×10(-3) mg kg(-1). In the proposed method, the ME step provides more effective cleanup for the chrysanthemum matrix, and VADLLME introduces higher sensitivity with the remarkable enrichment factors up to 88-fold compared with the conventional QuEChERS or SPE. The good performance has demonstrated that ME-VADLLME has a strong potential for application in the multi-residue analysis of complex matrices., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Investigations of the transfer of pesticide residues from tea to its infusion can be important in the assessment of the possible health benefits of tea consumption. In this work the transfer of difenoconazole and azoxystrobin residues from chrysanthemum tea to its infusion was investigated at different water temperatures, infusion intervals and times. The transfer percentages were in the range of 18.7-51.6% for difenoconazole and of 38.1-71.2% for azoxystrobin, and increased considerably with longer infusion intervals. The results indicated that azoxystrobin with a lower octanol-water partition coefficient of 2.5, showed a higher transfer than that of difenoconazole with a relatively high octanol-water partition coefficient of 4.4. Water temperature had no significant effect on the transfer of the two residues, and no obvious loss of difenoconazole and azoxystrobin occurred during the infusion process. The concentrations in the infusions decreased gradually from 0.67 to 0.30 μg kg(-1) for difenoconazole and from 2.3 to 0.46 μg kg(-1) for azoxystrobin after five infusions. To assess the potential health risk, the values of estimate expose risk were calculated to be 0.016 for difenoconazole and 0.0022 for azoxystrobin, meaning the daily residue intake of the two analytes from chrysanthemum tea was safe. This research may help assure food safety and identify the potential exposure risks from pesticides in chrysanthemum that may be health concerns.

The widespread use of insecticides in Chinese herbal medicines has created a compelling need for the development of a multiresidue analytical method to help assure herbs safety. The operating variables affecting the performance of the multiresidue analysis of 34 organochlorine and 12 pyrethroid pesticides in chrysanthemum, a widely used kind of Chinese herbal medicines, were evaluated. Three different extraction solvents including n-hexane and its mixtures with acetone and petroleum ether were compared, and n-hexane was found to be an appropriate option. A combination of gel permeation chromatography and SPE was selected as the optimum cleanup, in comparison with dispersive SPE, or the two former methods alone. The determination of the 46 pesticide residues in the spiked chrysanthemum samples was performed by GC with electron capture detection. The average recoveries ranged from 71.3 to 102.6% with RSDs of 1.4-15.7% for all of the pesticides. The LOQs were in the range of 0.0015-0.2 mg/kg, while the LODs were between 0.0005 and 0.1 mg/kg. The satisfactory accuracy, and precision, in combination with a good separation and few interferences, have demonstrated the strong potential of this technique for its application in chrysanthemum analysis., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)