GB 5009.74-2014 PDF in English
GB 5009.74-2014 (GB5009.74-2014) PDF English
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| GB 5009.74-2014 | English | 70 |
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National Food Safety Standard -- Method for Limit Test of Heavy Metals in Food Additives
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Standards related to: GB 5009.74-2014
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GB 5009.74-2014: PDF in English GB 5009.74-2014
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard -
Method for Limit Test of Heavy Metals in Food Additives
ISSUED ON. SEPTEMBER 21, 2015
IMPLEMENTED ON. MARCH 21, 2016
Issued by. National Health and Family Planning Commission of the
People’s Republic of China
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Table of Contents
Foreword ... 3
1 Application Scope ... 4
2 Principle ... 4
3 Reagents and Materials ... 4
4 Apparatus ... 5
5 Specimen Treatment ... 6
6 Determination ... 7
Foreword
This Standard replaces GB/T 5009.74-2003, Method for Limit Test of Heavy Metals in
Food Additives.
Compared with GB/T 5009.74-2003, the major changes of this Standard are as follows.
-- the standard name is changed into “National Food Safety Standard – Method for
Limit Test of Heavy Metals in Food Additives”;
-- the pressure digestion tank digestion method is added.
National Food Safety Standard -
Method for Limit Test of Heavy Metals in Food Additives
1 Application Scope
This Standard specifies the method for limit test of heavy metals in food additives.
This Standard applies to the limit test of heavy metals in food additives.
2 Principle
Under the weak acid (pH 3~4) conditions, the heavy metal ions in the specimen react
with hydrogen sulphide to generate a brownish black colour; then it is compared with
the lead standard solution which is processed using the same method.
3 Reagents and Materials
NOTE Unless stated otherwise, in this Standard, the reagents used are analytically
pure and the water is grade 1 water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3).
3.1.2 Sulphuric acid (H2SO4).
3.1.3 Hydrochloric acid (HCl).
3.1.4 Ammonium hydroxide (NH3·H2O).
3.1.5 Ammonium acetate (C2H7NO2).
3.1.6 Phenolphthalein (C2OH14O4).
3.1.7 Hydrogen peroxide (H2O2).
3.1.8 Hydrogen sulphide (H2S).
3.1.9 Perchloric acid (HClO4).
3.2 Preparation of reagents
take out after cooling, add 2 mL of hydrochloric acid (6 mol/L) to moisten the
residual and evaporate on a water bath until dry. Use 1 drop of concentrated
hydrochloric acid to moisten the residual, add 10 mL of water, heat once again
on a boiling water bath for 2 min, transfer the solution to a 20 mL volumetric flask,
conduct filtration if necessary, use a small quantity of water to wash the crucible
and filter, transfer the filtrate together into a volumetric flask, mix up after adding
dropwise to the scale. Each 10 mL of the solution is equivalent to 1.0 g of
specimen. While the specimen is ashed, take another crucible and conduct
reagent blank tests at the same time.
c) pressure digestion tank digestion method. weigh an appropriate quantity of
specimen (accurate to 0.001 g) in accordance with the operating instructions to
the pressure digestion tank to place into the inner tank of TTeflon, and add 2 mL
~ 4 mL of nitric acid to soak overnight. Then add 2 mL ~ 3 mL of hydrogen
peroxide (the total volume shall not exceed 1/3 of the volume of the tank). Put
on the inner cap, screw down the stainless steel outer casing, place in a
thermostatic desiccator, maintain for 3 h ~ 4 h at 120°C ~ 140°C, cool to room
temperature in the desiccator, use a dropper to wash or filter (depending on the
salt content of the specimen after digestion) the digestive liquid to the volumetric
flask, use a small quantity of water to wash the tank for multiple times, combine
the washings into the volumetric flask and add dropwise to the scale, and mix up
as standby; and meanwhile, conduct reagent blanks tests.
6 Determination
6.1 Tube A (standard tube). absorb the lead standard working solution (containing
not less than 10 μg), whose lead content is equivalent to the specified heavy metal
limit, pour into a 50 mL Nessler tube (if the specimen is treated, the same quantity of
reagent blank solution as the specimen solution shall be absorbed meanwhile), add
water to 25 mL, mix up, add 1 drop of phenolphthalein indicator solution, use diluted
hydrochloric acid (6 mol/L) or diluted ammonia hydroxide (1 mol/L) to adjust the pH to
neutral (when the phenolphthalein red just fades), add 5 mL of acetate buffer solution
of pH 3.5, and mix up as standby.
6.2 Tube B (specimen tube). take one Nessler tube matched with tube A, add 10 mL
~ 20 mL (or an appropriate quantity) of specimen solution, add water to 25 mL, mix up,
add 1 drop of 1% phenolphthalein indicator solution, use diluted hydrochloric acid (6
mol/L) or diluted ammonia hydroxide (1 mol/L) to adjust the pH to neutral (when the
phenolphthalein red just fades), add 5 mL of acetate buffer solution of pH 3.5, and mix
up as standby.
6.3 Tube C. take a Nessler tube matched with tube A and tube B, add the same
quantity of the same specimen solution as tube B, then add the same quantity of lead
standard working solution (10 μg/mL) as tube A, add water to 25 mL, mix up, add 1
drop of 1% phenolphthalein indicator solution, use diluted hydrochloric acid (6 mol/L)
or diluted ammonia hydroxide (1 mol/L) to adjust the pH to neutral (when the
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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