1 Scope
This standard specifies the method for determination of zinc in foods.
This standard is applicable to the determination of zinc in foods.
The method detection limits are: 0.4mg/kg for atomic absorption method and 2.5mg/kg for dithizone colorimetric method.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments (excluding correction contents) to, or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition is applicable to this standard.
GB/T 5009.11-2003 "Determination of Total Arsenic and Abio-arsenic in Food"
METHOD I Atomic Absorption Spectrometry
3 Principle
The sample shall be treated and led into the atomic absorption spectrophotometer, then the sample will be atomized and begin absorbing 213.8nm resonance line, the absorption value is proportional to the zinc content and the zinc content shall be quantified through comparison with the standard series.
4 Reagents
4.1 4-methyl amylketone-2(MIBK, also known as methyl isobutyl ketone).
4.2 Phosphoric acid (1+10).
4.3 Hydrochloric acid (1+11): Measure and take 10mL hydrochloric acid and add it into right amount of water, and dilute the solution to 120mL.
4.4 Mixed acid: nitric acid+ perchloric acid (3+1).
4.5 Zinc standard solution: Accurately weigh 0.500g metallic zinc (99.99%) and dissolve them in 10mL hydrochloric acid, heat then solution over the water bath to evaporate it near to dry, dissolve the solids with a small amount of water and transfer the solution into one 1000mL volumetric flask, dilute the solution with water up to the scale of flask, store the solution in one polythene bottle, and every 1mL of this solution is equivalent 0.50mg zinc.
4.6 Zinc standard working solution: Suck 10.0mL standard solution and put it into one 50mL volumetric flask, dilute the solution with hydrochloric acid (0.1mol/L) up to the scale, then each 1mL of this solution is equivalent to 100.0μg zinc.
Contents
Foreword I
1 Scope
2 Normative References
METHOD I Atomic Absorption Spectrometry
3 Principle
4 Reagents
5 Instrument
6 Analytical Procedures
7 Result Calculation
8 Precision
METHOD II Dithizone Colorimetric Method
9 Principle
10 Reagents
11 Instrument
12 Analytical Procedures
13 Result Calculation
14 Precision
METHOD III Dithizone Colorimetric Method (Once Extraction)
15 Principle
16 Reagents
17 Instrument
18 Analytical Procedures
19 Result Calculation
20 Precision
