AOAC Official Method 963
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C78E1EE645A24971AC3750FBE12500EA |
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0.01 |
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1 |
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日期： |
2024-7-30 |
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10.6.17,AOAC Official Method 963.23?,Glyodin Pesticide Residues,Spectrophotometric Method,First Action 1963,Final Action 1964,Surplus 1994,(Applicable to apples and pears. Not applicable to fruits with extensive,softening or decomposition. All glassware must be free of soap,or detergent.),A. Reagents,(a) Bromophenol blue solution.—Prepare just before use. Transfer,50 mg bromophenol blue powder into 500 mL volumetric flask,with small amount ofH2O.Add2mLCH3COOHand swirl until dye,is completely dissolved. Dilute to volume with H2O, and mix.,(b) Glyodin standard solutions.—Prepare from 2-heptadecyl,glyoxalidine, purified grade. (1) Stock solution.—1 mg/mL. Dissolve,100.0 mg 2-heptadecyl glyoxalidine in CHCl3 in 100mLvolumetric,flask, dilute to volume with CHCl3, and mix. (2) Working,solution.—0.05 mg free base/mL. Transfer 5.0 mL stock solution ,(b)(1), to 100 mL volumetric flask, dilute to volume with CHCl3, and,mix.,B. Preparation of Standard Curve,Add 0, 2, 4, 6, 8, and 10mLworking standard solution,A(b)(2), to,six 50 mL volumetric flasks. Add exactly 1 mL CH3COOH to each,flask and dilute to volume with CHCl3. Place 25mLfrom each flask,measured in graduate or fast-flow pipet, in 125 mL separator. Add,25 mL bromophenol blue solution, B(a)(1), from graduate or,fast-flow pipet to each separator, and shake vigorously 1 min. Let,separate 320 min. Filter CHCl3 layer through pledget of glass wool,in stem of separator into small glass-stoppered Erlenmeyer. Determine,A at 415 nm in spectrophotometer, using 1 cmcells and 0 standard,as reference. Plot A against mg 2-heptadecyl glyoxalidine.,C. Preparation of Test Portion,Fill tared wide-mouth gal. (3.8 L) glass jar with whole fruit so that,little or no slack is present (to prevent battering of fruit). Weigh, and,add 250mLisopropanol. Screw cap on tightly with double thickness,of cellophane placed over mouth of jar before cap is screwed on to,help prevent leakage. Tumble or shake 10 min. Filter into 500 mL,volumetric flask through small layer of glass wool in funnel. Drain,off as much liquid as possible. Repeat stripping with second 250 mL,portion of isopropanol, and filter into volumetric flask. Wash glass,wool and funnel with small portions of isopropanol and dilute to volume.,D. Determination,Transfer 25 mL aliquot of strip solution to 50 mL beaker and,evaporate to dryness on steam bath under air jet. To residue add,exactly 1 mL CH3COOH, allowing acid to drip slowly down sides,of beaker so that all residue is wetted. Cover beaker with watch glass,and heat gently on steam bath with swirling, until residue at bottom,loosens and disintegrates. Thoroughly rinse down sides with fewmL,CHCl3 and transfer to 50 mL volumetric flask. Rinse beaker with,4 additional small portions CHCl3, and transfer to volumetric flask.,Dilute to volume with CHCl3 (disregard turbidity and slight color in,solution).,Transfer 25 mL CHCl3 solution, measured in graduate or,fast-flow pipet, to 125 mL separator. Proceed as in B, beginning,“Add 25 mL bromophenol blue solution, (a), . . .”.,Perform determinations along with preparation of standard curve,using 0 standard as reference when determining extract A. Determine,amount of 2-heptadecyl glyoxalidine in aliquot from standard,curve.,Glyodin (2-heptadecyl glyoxalidine acetate) =,2-heptadecyl glyoxalidine ′1.195,Reference: JAOAC 46, 238(1963).,CAS-556-22-9 (glyodin),. 2000 AOAC INTERNATIONAL……
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