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GB/T 24396-2009 English PDF (GBT24396-2009)

GB/T 24396-2009 English PDF (GBT24396-2009)

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GB/T 24396-2009: Test method of adsorption resin for food industrial use

This Standard specifies the test method of adsorption resin for food industrial use. This Standard applies to the determination of appearance, heavy metals and organic residues in adsorption resin for food industrial use that is copolymerized under the action of initiator, of which, the polymeric monomer is styrene, divinylbenzene, acrylics, acrylonitrile, and the pore-foaming agent is toluene or liquid paraffin.
GB/T 24396-2009
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 67.250
G 31
Test Method of Adsorption Resin
for Food Industrial Use
ISSUED ON: SEPTEMBER 30, 2009
IMPLEMENTED ON: DECEMBER 01, 2009
Issued by: General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Method summaries ... 4
3 Reagents and materials ... 4
4 Instruments and equipment ... 5
5 Analysis steps ... 5
Appendix A (Informative) Organic residue determination reference gas
chromatography operating conditions ... 10
Test Method of Adsorption Resin
for Food Industrial Use
1 Scope
This Standard specifies the test method of adsorption resin for food industrial use.
This Standard applies to the determination of appearance, heavy metals and organic residues in adsorption resin for food industrial use that is copolymerized under the action of initiator, of which, the polymeric monomer is styrene, divinylbenzene, acrylics, acrylonitrile, and the pore-foaming agent is toluene or liquid paraffin.
2 Method summaries
2.1 Heavy metal detection
In the weak-acidic solution, sodium sulfide precipitates heavy metal ions into the corresponding sulfides; the resulting color is visually compared to the standard color.
2.2 Organic residue detection
The organic residue in the sample is ultrasonically extracted by absolute ethanol; it is injected into the gas chromatograph and carried by the carrier gas into the column for separation; the effluent is detected by a hydrogen flame ionization detector; the content of organic residue is calculated according to the external standard method.
3 Reagents and materials
WARNING: Some of the reagents which are used in this test method are
toxic or corrosive; therefore, some test procedures may cause dangerous conditions, and the operator shall take appropriate safety and health
measures.
3.1 Hydrochloric acid: analytical reagent.
3.2 Acetic acid solution: 1 + 4.
3.3 Sodium sulfide solution: 100 g/L.
Weigh 2.0 g of sample (dry basis) which is dried at 105??C ?? 2??C for 2 h; accurate to 0.01 g; place it in the evaporating dish; carbonize it and then burn it at 500??C ?? 25??C until the complete ashing; cool it; then, add 2 mL of hydrochloric acid; evaporate it to dryness on a water bath; cool it; then, use 4 mL of acetic acid solution and 20 mL of water to dissolve the residue. Carry out filtration as necessary; use 5 mL of water to wash the residue on the filter paper each time, and wash it for three times in total. Combine the filtrate and the washing solution; dilute to 50 mL as the test solution. Take 25 mL of test solution to a 50 mL colorimetric tube, which is the tube A.
5.2.2 Preparation of lead (Pb) standard colorimetric solution
Transfer 2 mL of acetic acid solution into a 50 mL colorimetric tube (matching tube A); add 1.50 mL of lead standard solution; add water to 25 mL, which is the tube B.
5.2.3 Determination
Add two drops of freshly-prepared sodium sulfide solution to tubes A and B respectively; mix quickly; shake well; place them in the dark for 5 min; observe under a white background. If the dark color of the tube A is not deeper than the tube B, they are judged as qualified.
5.3 Determination of organic residue
5.3.1 Preparation of samples
Place 10 mL of the sample in a centrifuge tube; centrifuge at 2000 r/min ?? 200 r/min for 5 min. Take the upper layer of the sample from which the surface free water has been removed; weigh 2 g (wet weight, accurate to 0.000 1 g); place it in a 50 mL brown volumetric flask; add 10 mL of absolute ethanol; cover with a stopper; use a sealing film to seal; ultrasonically oscillate (add an appropriate amount of ice cubes to the ultrasonic oscillator to reduce the temperature) for 20 min; let stand for 10 min; take the supernatant; use a filter to filter for later use.
5.3.2 Preparation of standard solution
5.3.2.1 Preparation of mixed standard solution mother solution
According to the order of styrene, o-xylene, m-xylene, p-xylene, chlorobenzene, toluene, methyl methacrylate, divinylbenzene, 1,2-dichloroethane, benzene, acrylonitrile, weight 0.1 g of each of the above standards (accurate to 0.000 1 g); place in a 100 mL brown volumetric flask; use absolute ethanol to dilute to the mark; shake well.
Appendix A
(Informative)
Organic residue determination reference gas chromatography operating
conditions
According to the used gas chromatograph, adjust the appropriate temperature and flow rate to achieve the proper separation effect. Reference
chromatographic conditions are shown as below:
a) column: polyethylene glycol 20M column (30 m ?? 0.25 mm ?? 0.25 ??m);
b) temperature of the injector: 250??C;
c) temperature of the detector: 280??C;
d) column temperature: 35??C (7 min) 150??C (4 min);
e) carrier gas: high-purity nitrogen; line speed of 30 cm/s (that is, column flow of 1.25 mL/min);
Injection method: split injection, split ratio: 1 : 50;
Injection volume: 1.0 ??L.
The gas chromatogram of 11 organic residues is shown in Figure A. 1.
Note: Since the separation effect that is achieved by different instruments under the same chromatographic conditions cannot be exactly the same, the
chromatographic conditions can be adjusted according to the actual instrument used, as long as the appropriate separation effect is achieved.

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