PDF《REFERENCES》

1 Overview of analytical methods for difenoconazole Method Matrix Extraction Clean-Up Detection, LOQ AG-676 High water High protein High starch Refluxing with methanol/ conc. ammonium hydroxide (8:2 v/v) Liquid-liquid partitioning against hexane followed by acetonitrile, SPE on silica and phenyl GC-NPD LOQ: 0.01 mg/kg QuEChERS method High water Acetonitrile/water (1/1, v/v) Dispersive SPE with PSA HPLC-MS/MS m/z 406→251, 406→337 LOQ: 0.005 mg/kg REM 147.08 High protein High starch Refluxing with methanol/ conc. ammonium hydroxide (8:2 v/v) SPE on HLB cartridge HPLC-MS/MS m/z 406→251 LOQ: 0.01 mg/kg Modified Korean Food Code Method High water Dry Homogenization with acetone Liquid-liquid partitioning against dichloromethane followed SPE on a silica column HPLC-UV and HPLC- MS/MS m/z 406→251, 406→337 LOQ: 0.03 mg/kg Plant materials Method AG-676 (Campbell &

Oakes, 2000, DIFENOCO_001) Method AG-676 has not previously been evaluated by the JMPR. It is an updated version of AG-575B which has been previously evaluated by the JMPR. Residues of difenoconazole were extracted from sweet corn matrices by refluxing with methanol/conc. ammonium hydroxide (8:2 v/v). The resulting extract was filtered, diluted with water and saturated sodium chloride solution and subsequently partitioned with hexane. The hexane fraction was partitioned with acetonitrile and the acetonitrile fraction was then purified using silica and phenyl Difenoconazole

610 solid phase extraction (SPE). Samples were eluted from the SPE cartridge, evaporated to dryness and reconstituted in toluene prior to analysis. Difenoconazole residues were determined by GC-NPD with a validated LOQ of 0.01 mg/kg for all sweet corn matrices. Table

2 Recovery data for method AG-676 measuring difenoconazole in sweet corn matrices using GC-NPD Commodity Fortification level (mg/kg) No. of analyses (n) Recovery (%) Mean recovery (%) RSD (%) Sweet corn forage 0.01

12 89.5, 123, 121, 116, 117, 94.8, 78.8, 98.6, 71.8, 105, 93.4, 95.3

100 16.4 0.02

1 114

114 - 0.05

12 130, 110, 103, 123, 121, 93.2, 115, 89.2, 102, 103, 110,

115 110 11.1 Sweet corn ears 0.01

3 108, 96.2,

104 103 5.8 0.05

9 88.9, 94.0, 111, 98.2, 121, 80.2, 123, 112,

112 104 14.2 Sweet corn stover 0.01

3 119, 92.4, 77.6

96 21.8 0.05

9 111, 124, 115, 116, 102, 76.2, 120, 112, 93.8

108 13.9 QuEChERS (citrate) method (Noegrohati, 2016, DIFENOCO_002 and DeFrancesco, 2016, DIFENOCO_003) Samples were shaken with acetonitrile/water (1/1, v/v) in the presence of sodium citrate, sodium hydrogen citrate sesquihydrate, magnesium sulfate and sodium chloride. After centrifugation the acetonitrile layer was purified by shaking with PSA and dried with magnesium sulfate. Samples were analysed with LC-MS/MS in positive electrospray ionization using BEH C18 column and monitoring the ion transitions m/z 406→251 and 406→337. Quantitation was done with external standards in solvent. Table

3 Recovery data for the QuEChERS method measuring difenoconazole in dragon fruit and guava Matrix Fortification level (mg/kg) n Recovery (%) Mean recovery (%) RSD (%) Dragon fruit (whole fruit) 0.005

11 105.1, 100.7, 96.2, 96.4, 87.6, 97.0

97 6 0.01

3 108.3, 100.3, 109.4

106 5 0.1

8 104.1, 108.6, 108.5, 99.4

105 4 1.0

8 107.0, 103.8, 108.2, 91.8

103 7 Dragon fruit (peel) 0.005

8 97.2, 103.4, 102.5, 77.9, 103.8, 74.1

93 15 0.01

3 91.5, 105.3, 94.3

97 8 0.1

5 104.6, 112.2, 107.4, 90.4

104 9 1.0........