GB 5009.8-2023National food safety standard - Determination of fructose, glucose, sucrose, maltose and lactose in foods (English PDF)

3.1 Reagents

3.2 Preparation of reagents

3.3 Standards

3.4 Preparation of standard solutions

3.5 Materials

3.5.2 Syringe.

4.1 High performance liquid chromatograph. equipped with a differential refractive

index detector or an evaporative light scattering detector.

4.2 Analytical balance. the sensitivity is 1 mg and 10 mg.

4.3 Vortex mixer.

4.4 Centrifuge. speed >= 4 000 r/min.

4.5 Ultrasonic cleaner.

4.6 Sample crushing equipment. high-speed crusher.

4.7 Constant-temperature drying oven.

4.8 Constant-temperature water bath device.

5.1 Sample pretreatment

5.1.2 Sample extraction

5.1.3 Purification

For the above sample extract solution, use a filter paper to filter (discard the primary filtrate) or centrifuge to obtain the supernatant; then, use a 0.45 um water-based membrane syringe to filter into a sample bottle for analysis by a high-performance liquid chromatograph.

5.2 Apparatus reference conditions

Apparatus reference conditions are as below.

90 °C; nitrogen flow rate 2.5 L/min.

5.3 Preparation of the standard curve

Inject the mixed standard working solution into the high-performance liquid chromatograph in order from low to high concentration, and measure the corresponding peak areas or peak heights of fructose, glucose, sucrose, maltose and lactose. For the differential refractive index detector, use the concentration of the standard working fluid as the abscissa and the peak area or peak height as the ordinate to draw a standard curve;

5.4 Determination of sample solution

Inject the sample solution into the high-performance liquid chromatograph;

qualitatively record the peak area or peak height of the target substance based on the retention time; obtain the concentrations of fructose, glucose, sucrose, maltose and lactose in the sample solution based on the standard curve.

5.5 Blank test

Except that no sample is added, proceed according to the above steps.

10.1 Reagents

10.1.1 Sodium hydroxide (NaOH). chromatographic pure.

10.1.2 Glacial acetic acid (CH3COOH).

10.2 Preparation of reagents

10.3 Standards

10.3.1 Fructose (C6H12O6, CAS number. 57-48-7). purity >=99%, or standard material

certified by the country and awarded a standard material certificate.

10.3.2 Glucose (C6H12O6, CAS number. 50-99-7). purity >=99%, or standard material

certified by the country and awarded a standard material certificate.

10.4 Preparation of standard solution

10.5 Materials

10.5.1 0.45 um water-based membrane syringe filter (except cellulose membrane).

10.5.2 Purification column. C18 solid-phase extraction cartridge (1.0 mL) or one with

equivalent performance.

10.5.3 Syringe.

11.1 Ion chromatograph. equipped with pulse ampere detector.

11.2 Sample crushing equipment. high-speed crusher.

11.3 Ultrasonic cleaner.

11.4 Analytical balance. sensitivity 1 mg.

11.5 Vortex mixer.

11.6 Centrifuge. speed >= 4 000 r/min.

11.7 Constant-temperature drying oven.

11.8 Constant-temperature water bath device.

12.1 Sample pretreatment

12.1.1 Sample preparation

Take an appropriate amount of representative sample; for drinks and other liquid homogeneous samples, shake directly; for non-uniform samples, homogenize or crush evenly; for frozen drinks, melt at room temperature, stir thoroughly and, if necessary, heat and stir in a water batch at 30 °C ~ 40 °C; for sauces, grind or homogeneously mix;

for chocolate, heat and melt in a water bath at 50 °C ~ 60 °C, and stir thoroughly while it is hot.

12.1.2 Sample extraction

12.1.3 Sample purification

The sample extraction solution can be diluted by an appropriate multiple according to the target sugar content in the sample. When detecting lactose in infant formula milk powder, dilute it 1 000 times and then purify it; when detecting high sugar content in honey and candy, dilute it 500 times and then purify it.

After filtering or centrifuging the above sample extraction solution or dilution solution to obtain the supernatant, pass it through a 0.45 um aqueous membrane syringe filter and a C18 solid phase extraction cartridge (1.0 mL) in sequence; discard the first 3 mL;

collect subsequent eluates for testing.

12.2 Apparatus reference conditions

Apparatus reference conditions are as below.

12.3 Drawing of standard working curve

Inject the mixed standard working solution into the ion chromatograph in order from low to high concentration, and measure the corresponding peak areas of fructose, glucose, sucrose, maltose and lactose. Taking the concentrations of fructose, glucose, sucrose, maltose and lactose in the standard working solution as the abscissa and the peak area as the ordinate, draw the standard curves, respectively. See Appendix B for the ion chromatograms of standard solutions of fructose, glucose, sucrose, maltose and lactose.

12.4 Determination of sample solution

Inject the sample solution into the ion chromatograph, identify it based on the retention time, record the peak area, and obtain the concentrations of fructose, glucose, sucrose, maltose and lactose in the sample solution based on the standard curve.

12.5 Blank test

Except that no sample is added, proceed according to the above steps.