GB/T 24396-2009Test Method of Adsorption Resin for Food Industrial Use (English PDF)

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.

3.1 Hydrochloric acid. analytical reagent.

3.2 Acetic acid solution. 1 + 4.

3.3 Sodium sulfide solution. 100 g/L.

4.1 Oven.

4.2 Muffle furnace.

4.3 Water bath.

4.8 Centrifuge. 0 r/min ~ 4 000 r/min (adjustable).

4.9 Brown volumetric flasks. 100 mL, 50 mL, and 10 mL.

4.10 Pipette. 1 µL ~ 10 µL, 10 µL ~ 100 µL, 100 µL ~ 1 000 µL and 0.5 mL ~ 5

mL.

4.11 Pipette. 5 mL, 10 mL.

4.12 Needle filter. 0.45 µm.

5.1 Determination of appearance

Place the sample in a clean white porcelain dish; place it in a bright place, and

visually inspect it under natural light.

5.2 Determination of heavy metal

5.2.1 Preparation of test solution

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;

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.

5.3 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

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.

5.3.3 Determination of standard series solution

Turn on the gas chromatograph and set the chromatographic conditions

according to Appendix A. After the baseline is stable, take the series standard

solutions which are prepared in 5.3.2.2 for injection analysis; record the peak

area of each time; draw the following standard curve.

5.3.4 Determination of the sample

Take the sample solution that is prepared in 5.3.1 for injection analysis; record

the chromatographic peak area; according to the concentration range of each

residue in the sample, substitute the appropriate standard curve to find the

corresponding residue mass concentration rho (µg/mL).

5.3.5 Calculation of analysis result

Calculate the content of residues in the sample according to Formula (1).

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.

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