GB 5009.278-2016 English PDF (GB5009.278-2016)

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GB 5009.278-2016: National Food Safety Standard -- Determination of Tetraacetate in Food
GB 5009.278-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard – Determination of
ethylenediaminetetraacetates in foods
ISSUED ON. DECEMBER 23, 2016
IMPLEMENTED ON. JUNE 23, 2017
Issued by. National Health and Family Planning Commission of the
People’s Republic of China;
China Food and Drug Administration.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principle ... 4
3 Reagents and materials ... 4
4 Apparatus ... 6
5 Analytical procedures ... 6
6 Expression of analytical results ... 9
7 Precision ... 11
8 Others ... 11
Annex A Liquid chromatograms of standard solutions of disodium
ethylenediaminetetraacetate dihydrate complex and calcium disodium
ethylenediaminetetraacetate hydrate ... 12
National food safety standard – Determination of
ethylenediaminetetraacetates in foods
1 Scope
This Standard specifies the liquid chromatography for the determination of
ethylenediaminetetraacetates in foods.
This Standard applies to the determination of disodium ethylenediaminetetraacetate
dihydrate in jams, preserved fruits, canned pickled vegetables, vegetable purees
(sauces) except tomato sauce, canned nuts and seeds, canned mixed congees,
compound seasonings and beverages, and the determination of calcium disodium
ethylenediaminetetraacetate hydrate in compound seasonings. This Standard does
not apply to the determination of sodium iron (III) ethylenediaminetetraacetate
trihydrate in iron fortified soy sauce.
2 Principle
Sample of disodium ethylenediaminetetraacetate dihydrate to be tested is extracted
using water; the extract is added with ferric chloride for complexation; it is then purified
using the ProElut PXA solid-phase extraction column, tested using the liquid
chromatography and quantitated using the external standard method. During the
determination of compound seasonings. first determine the total content of ferric
chloride complex of ethylenediaminetetraacetates; determine the content of calcium
disodium ethylenediaminetetraacetate hydrate; then determine the content of disodium
ethylenediaminetetraacetate dihydrate based on the two results.
3 Reagents and materials
Unless specified otherwise, all reagents used in this Method are analytically pure; the
water is grade one water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Methanol (CH3OH). chromatographically pure.
3.1.2 Hydrochloric acid (HCl).
working solutions of 0.5 μg/mL, 2.0 μg/mL, 5.0 μg/mL, 10.0 μg/mL and 50.0 μg/mL.
3.4.3 Calcium disodium ethylenediaminetetraacetate hydrate standard solution.
accurately weigh an appropriate amount of calcium disodium
ethylenediaminetetraacetate hydrate standard substance; use water to dissolve and
make up to a brown volumetric flask of 100 mL to obtain a standard stock solution of
concentration 10 mg/mL; transfer the solution to a receiver for storage below 4°C.
3.4.4 Calcium disodium ethylenediaminetetraacetate hydrate standard serial solutions.
absorb 1 volume of calcium disodium ethylenediaminetetraacetate hydrate standard
solution and 9 volumes of water to dilute to a standard medium solution of
concentration 1 mg/mL. Then use water to dilute the calcium disodium
ethylenediaminetetraacetate hydrate standard solution to serial standard working
solutions of 1.0 μg/mL, 10.0 μg/mL, 20.0 μg/mL, 50.0 μg/mL and 100.0 μg/mL.
4 Apparatus
4.1 Liquid chromatograph. equipped with an ultraviolet detector.
4.2 Electronic balance. sensitivities 0.1 mg and 0.01 g.
4.3 Centrifugal machine. rotational speed ≥ 7,500 r/min.
4.4 Vortex oscillator.
4.5 Ultrasonic cleaner.
4.6 pH meter. accuracy 0.01.
4.7 24-hole solid phase extraction apparatus.
4.8 Micropore filter membrane. 0.45 μm.
4.9 ProElut PXA solid phase extraction column. 150 mg/6 mL or equivalent. The main
ingredient of PXA is quaternary ammonium groups bonded on the copolymer of
polystyrene and divinyl benzene containing hydrophilic groups.
5 Analytical procedures
5.1 Sample preparation
5.1.1 Solid sample
Use a pulverizer to crush sample; mix up before loading into a clean container; seal
and mark the container. Sample having a high content of sugar needs to be frozen
(only referring to compound seasonings)
5.2.2.1 Extraction
As in 5.2.1.1.
5.2.2.2 Purification
Use in succession 5 mL of methanol and 5 mL of water to activate the PXA column;
pass all solution to be purified through the column; use in succession 5 mL of water
and 5 mL of methanol to rinse; drain; use 5 mL of 5% formic acid-methanol aqueous
solution for elution; drain; collect the eluant to make up to 5 mL; filter; determine on a
liquid chromatograph.
5.3 Instrument reference conditions
a) chromatographic column. Plus-C18 column, 250 mm in length, 4.6 mm in inner
diameter and 5.0 μm in grain size, or an equivalent chromatographic column;
b) moving phase for the detection of disodium ethylenediaminetetraacetate
dihydrate complex. methanol. tetrabutylammonium bromide-sodium acetate
mixed solution (pH 4.0) = 15.85;
c) moving phase for the detection of calcium disodium ethylenediaminetetraacetate
hydrate. tetrabutylammonium bromide-sodium acetate mixed solution (pH 2.5) =
15.85;
d) flow rate. 0.8 mL/min;
e) column temperature. 35°C;
f) wavelength. 254 nm;
g) volume of sample. 10 μL.
5.4 Plotting of standard curve
5.4.1 Determination of total content of ethylenediaminetetraacetates
Absorb respectively 0 μL, 25 μL, 100 μL, 250 μL, 500 μL and 2,500 μL of disodium
ethylenediaminetetraacetate dihydrate standard medium solution of concentration 1
mg/mL to pour into a colourimetric tube of 50 mL; add 25 mL of water and 1.0 mL of
ferric chloride solution; use vortex to mix up; carry out ultrasonic extraction for 20 min;
cool to room temperature before using water to make up to scale; the concentrations
of the standard serial working solutions obtained through complexation are
respectively 0 μg/mL, 0.5 μg/mL, 2.0 μg/mL, 5.0 μg/mL, 10.0 μg/mL and 50.0 μg/mL.
Then inject them into the liquid chromatograph; measure the corresponding peak
m1 – the mass of sample weighed, in g;
1,000 – the conversion coefficient.
The result of calculation is deducted by blank value. The result of calculation is rounded
off to three significant digits.
6.2 Compound seasonings
The content of ethylenediaminetetraacetates in sample shall be expressed by dividing
into disodium ethylenediaminetetraacetate dihydrate and calcium disodium
ethylenediaminetetraacetate hydrate. The content of calcium disodium
ethylenediaminetetraacetate hydrate is calculated in accordance with Equation (2).
where.
X2 – the content of calcium disodium ethylenediaminetetraacetate hydrate in sample,
in mg/kg;
ρ2 – the mass concentration of calcium disodium ethylenediaminetetraacetate hydrate
in sample solution, μg/mL/mL;
V – the total volume of sample to be tested, in mL;
m2 – the mass of sample weighed, in g;
1,000 – the conversion coefficient.
The result of calculation is deducted by blank value. The result of calculation is rounded
off to three significant digits.
The content of disodium ethylenediaminetetraacetate dihydrate is calculated in
accordance with Equation (3).
where.
X3 – the content of disodium ethylenediaminetetraacetate dihydrate in sample, in
mg/kg;
X1 – the content of disodium ethylenediaminetetraacetate dihydrate obtained from the
calculation of disodium ethylenediaminetetraacetate...