• Author / Uploaded
• Javier Eduardo Muñoz Torres

• Categories
• Concentración molar
• Laboratorios
• Ciencias físicas
• Ciencia
• Química

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44.4.15 AOAC Official Method 980.23 Hydroxymethylfurfural in Honey Spectrophotometric Method First Action 1980 Final Action 1983

(Do not heat honey before this determination.) A. Apparatus and Reagents

(a) Spectrophotometer.—UV, to measure A at 284 and 336 nm. (b) Carrez solution I.—Dissolve 15 g K4Fe(CN)6⋅3H2O and dilute to 100 mL with H2O. (c) Carrez solution II.—Dissolve 30 g Zn(CH3COO)2⋅2H2O and dilute to 100 mL with H2O. (d) Sodium bisulfite solution.—0.20%. Dissolve 0.20 g NaHSO3 (technical grade is satisfactory) and dilute to 100 mL with H2O. Dilute 1 + 1 for dilution of reference solution if necessary. Prepare fresh daily. B. Determination

Accurately weigh ca 5 g honey in small beaker and transfer with total of ca 25 mL H2O to 50 mL volumetric flask. Add 0.50 mL

Carrez solution I, mix, add 0.50 mL Carrez solution II, mix, and dilute to volume with H2O. Drop of alcohol may be added to suppress foam. Filter through paper, discarding first 10 mL filtrate. Pipet 5 mL filtrate into each of two 18 × 150 mm test tubes. Add 5.0 mL H2O to 1 tube (test solution) and 5.0 mL NaHSO3 solution to other (reference). Mix well (Vortex mixer is useful) and determine A of test solution against reference at 284 and 336 nm in 1 cm cells. If A is >0.6, dilute test solution with H2O and reference solution with 0.1% NaHSO3 solution to same extent and correct A for dilution. mg Hydroxymethylfurfural (HMF) (A284 − A336 ) × 14.97 × 5 = 100 g honey g test sample Factor = 14.97 = (126/16 830)(1000/10)(100/5) where 126 = molecular weight HMF; 16 830 = molar a of HMF at 284 nm; 1000 = mg/g; 10 = centiliters/L; 100 = g honey reported; 5 = nominal test portion weight. Reference: JAOAC 62, 509, 515, 921(1979). CAS-67-47-0 (hydroxymethylfurfural)

 2005 AOAC INTERNATIONAL