GB5009.34-2016

GB5009.34-2022 (New National Standard)

Testing Method

Titration method

Titration method changed to: Acid-Base Titration, with the addition of Spectrophotometry and Ion Chromatography methods.

Scope of Inspection

This standard specifies the method for determining the total sulfur dioxide in foodstuffs such as dried fruits, preserved vegetables, rice noodles, vermicelli, sugar, edible mushrooms, and wine.

One method is the acid-base titration, suitable for the determination of sulfur dioxide in food.
The two methods are spectrophotometry and direct extraction. Direct extraction is suitable for the determination of sulfur dioxide in samples without oil and without color interference, such as sugar and sugar products, starch and starch products, and fresh wet noodle products; nitrogen-filled distillation extraction is suitable for the determination of sulfur dioxide in colored samples like wine and raw sugar.
Three methods include ion chromatography, suitable for the determination of sulfur dioxide in food.

Sample Preparation

5G Uniform SampleDown to 0.001g, the sampling amount can be determined based on the content level; liquid samples can be directly aspirated 5.00mL to 10.00mL; add 250ml of water; add 10ml of hydrochloric acid.

Collect solid or semi-liquid specimens20g to 100g (to 0.01g, sample size depends on the concentration); take liquid sample 20mL (g) to 200mL (g); add 20-500ml of water; add 10mL of 6mol/L hydrochloric acid.

Is Nitrogen Filling Available for Distillation?

No

Nitrogen Filling and Distillation, Flow Rate:0.2-2.0L/min

Absorbent liquid

25mL Lead Acetate Absorption Solution

50mL 3% Hydrogen Peroxide Solution (Type 1)

Distillation Method

Gather200ml distillate, redistill for 1 minute, and rinse the inserted absorption device with a small amount of distilled water.

The solution in the flask is heated to boiling and maintained at a gentle boil.1.5h。

Titration method

Add sequentially to the removed iodine bottle:10mL hydrochloric acid, 1mL starch indicator solution; after shaking well, titrate with standard iodine solution until the solution turns blue and remains so for 30 seconds without fading. Conduct a blank test simultaneously.

Cool the absorbent solution, then shake well. Add to the absorbent solution3 drops of a 2.5 mg/mL methyl red ethanol solution indicator, titrated with sodium hydroxide standard solution (0.01 mol/L) to a yellow color that does not fade after 20 seconds, while simultaneously conducting a blank test.

Detection Limit and Quantitative Limit

When picking upAt 5g solid sample, the method's Limit of Detection (LOD) is 3.0mg/kg and the Limit of Quantitation (LOQ) is 10.0mg/kg; for 10mL liquid samples, the method's LOD is 1.5mg/L and the LOQ is 5.0mg/L.