GB 5009.14-2017National food safety standard - Determination of Zinc in Foods (English PDF)

Foreword

This Standard replaces GB/T 2009.14-2003 Determination of Zinc in Foods,

GB 5413.21-2010 National food safety standard Determination of calcium,

iron, zinc, sodium, potassium, magnesium, copper and manganese in foods

for infants and young children, milk and milk products, GB/T 23375-2009

Determination of copper, iron, zinc, calcium, magnesium and phosphorus

content in vegetables and derived products, GB/T 9695.20-2008 Meat and

meat products - Method for determination of zinc, GB/T 14609-2008

Inspection of grain and oils - Determination of copper, iron, manganese, zinc,

calcium, magnesium in cereals and derived products by atomic absorption

and flame spectrophotometry, GB/T 18932.12-2002 Method for the

determination of potassium, sodium, calcium, magnesium, zine, iron, copper,

manganese, chromium, lead, cadmium contents in honey - Atomic absorption

spectrometry, NY/T 1201-2006 Determination of copper iron and zinc content

in vegetables and derived products.

Compared with GB/T 2009.14-2003, the main modifications in this Standard

are as follows.

- modified the name of the standard to "National Food Safety Standard -

Determination of Zinc in Foods";

- in the pretreatment method, maintained the dry ashing method, added

the wet digestion, pressure tank digestion and microwave digestion;

- preserved flame atomic absorption spectrometry as Method 1, dithizone

colorimetric method as Method 4;

- added inductively coupled plasma emission spectroscopy as Method 2;

- added inductively coupled plasma mass spectrometry as Method 3;

- added microwave digestion procedures and flame atomic absorption

spectrometer for instrument reference conditions as appendix.

National Food Safety Standard –

Determination of Zinc in Foods

1 Scope

This Standard specifies the flame atomic absorption spectrometry method,

the inductively coupled plasma emission spectroscopy method, the

inductively coupled plasma mass spectrometry method and the dithizone

colorimetric method in the determination of zinc in foods.

This Standard is applicable to the determination of zinc in foods, irrespective

of materials.

Method 1 -- Flame atomic absorption spectrometry

2 Principle

After digestion of the sample, the absorbance shall be measured at 213.9 nm

by flame atomization. The absorbance of zinc in a certain concentration range

shall be proportional to the zinc content, quantitatively compared with the

standard series.

3 Reagents and materials

Unless otherwise noted, the reagents used in this method shall be

guaranteed reagents, and water shall be Grade Two water specified in GB/T

6682.

4 Apparatus

NOTE All glassware and polytetrafluoroethylene digestion tanks shall be soaked by

nitric acid (1+5) overnight, repeatedly rinsed with tap water, and finally washed clean

with water.

5 Analysis steps

6 Expression of analysis results

When the zinc content >=10.0 mg/kg (or mg/L), the results shall be retained to

three effective figures. When the zinc content < 10.0 mg/kg (or mg/L), the

calculation results shall be retained to two significant figures.

7 Precision

The absolute difference between the two independent determinations

obtained under repeatability shall not exceed 10% of the arithmetic mean.

8 Other

When the sampling volume is 0.5 g (or 0.5 mL), the set volume is 25 mL, the

detection limit of this method shall be 1 mg/kg (or 1 mg/L) and the limit of

quantification shall be 3 mg/kg (or 3 mg/L).

9 Principle

After digestion of the sample, when pH is at 4.0 ~ 5.5, zinc ions and dithizone

shall form a purple red complex.

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