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GB 5009.34-2022: National food safety standard - Determination of sulfur dioxide in foods
GB 5009.34-2022
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard - Determination of sulfur
dioxide in foods
ISSUED ON: JUNE 30, 2022
IMPLEMENTED ON: DECEMBER 30, 2022
Issued by: National Health Commission of the People's Republic of China;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Principle ... 4 
3 Reagents and materials ... 4 
4 Instruments and equipment ... 5 
5 Analysis steps ... 5 
6 Presentation of analysis results ... 7 
7 Precision ... 7 
8 Detection limit and quantification limit ... 7 
9 Principle ... 8 
10 Reagents and materials ... 8 
11 Instruments and equipment ... 9 
12 Analysis steps ... 9 
13 Presentation of analysis results ... 10 
14 Precision ... 11 
15 Detection limit and quantification limit ... 11 
16 Principle ... 11 
17 Reagents and materials ... 12 
18 Instruments and equipment ... 12 
19 Analysis steps ... 12 
20 Presentation of analysis results ... 14 
21 Precision ... 14 
22 Detection limit and quantification limit ... 14 
Annex A Schematic diagram of distillation device for acid-base titration ... 16 
Annex B Schematic diagram of steam distillation device ... 17 
Annex C Typical spectrum of sulfur dioxide standard working solution ... 18 
National food safety standard - Determination of sulfur
dioxide in foods
1 Scope
This document specifies the determination method of sulfur dioxide in foods.
Method One: Acid-base titration method is applicable to the determination of sulfur
dioxide in foods. Method Two is Spectrophotometry. Direct extraction method is
suitable for the determination of sulfur dioxide in white sugar and white sugar products,
starch and starch products and raw wet flour products. Nitrogen-filled steam extraction
method is suitable for the determination of sulfur dioxide in wine and brown sugar.
Method Three: Ion chromatography is applicable to the determination of sulfur dioxide
in foods.
Method One -- Acid-base titration method
2 Principle
Use nitrogen-filled steaming method to treat the specimen. After the specimen is
acidified, under heating conditions, a series of substances such as sulfites release sulfur
dioxide. Use hydrogen peroxide solution to absorb the distillate. Sulfur dioxide is
dissolved in the absorption liquid and oxidized to form sulfuric acid. Use standard
sodium hydroxide solution to titrate. Calculate the content of sulfur dioxide in the
specimen according to the consumption of sodium hydroxide standard solution.
3 Reagents and materials
Unless otherwise stated, the reagents used in this method are all analytically pure; the
water is grade three water specified in GB/T 6682.
3.1 Reagents
3.1.1 Hydrogen peroxide (H2O2): 30%.
3.1.2 Absolute ethanol (C2H5OH).
3.1.3 Sodium Hydroxide (NaOH).
3.1.4 Methyl red (C15H15N3O2).
Take specimens of beer, wine, fruit wine, other fermented wine, prepared wine, and
beverages. The sampling volume shall be greater than 1L. For packaging specimens
such as bagged specimens and bottled specimens, at least 3 packages (same batch or
number) shall be collected. Put all liquids in one container. Mix well. Seal and mark for
testing.
5.1.2 Solid specimen
Take specimens of grain processed products, solid condiments, biscuits, potato products,
candy products (including chocolate and products), substitute tea, pickled vegetables,
dried vegetable products, edible mushroom products, other vegetable products, candied
fruit, dried fruit products, roasted seeds and nuts and nut products (baked, fried, other),
sugar, dried aquatic products, cooked animal aquatic products, edible starch, starch
products, starch sugar, non-fermented soy products, vegetables, fruits, seawater
products, raw and dried nuts and seeds. The sampling weight shall be greater than 600g.
According to the different properties and characteristics of specific products, conduct
sampling directly. Completely mix well or use a suitable pulverizing means such as a
grinder to grind the edible part. Completely mix well. Store in a clean sample bag. Seal
and mark for testing.
5.1.3 Semi-fluid specimen
For packaging specimens such as bagged specimens and bottled specimens, at least 3
packages (same lot or number) need to be collected. For sauces, canned fruits and
vegetables and other semi-fluid specimens, the sampling amount shall be greater than
600g. Use the tissue masher to mash and mix well. Store in a clean sample bag. Seal
and mark for testing.
5.2 Specimen determination
Take 20g~100g of solid or semi-fluid specimen (to the nearest of 0.01g; the sampling
amount depends on the content). Take 20mL(g)~200mL(g) of liquid specimen. Place
the weighed specimen in the round bottom flask A in Figure A.1. Add 200mL~500mL
of water. Install the device. Turn on the switch of the reflux condenser to supply water
(condensate temperature < 15°C). Place the glass tube connected to the port E at the
upper end of the condenser tube at the bottom of the 100mL conical flask. Add 50mL
of 3% hydrogen peroxide solution to the conical flask as the absorption solution (the
end of the glass tube shall be below the liquid level of the absorption solution). Add 3
drops of 2.5g/L methyl red ethanol solution indicator to the absorption solution. Use
sodium hydroxide standard solution (0.01mol/L) to titrate until it turns yellow as the
end point (if it exceeds the end point, the absorption solution shall be discarded). Turn
on nitrogen. Adjust the gas flow meter to 1.0L/min~ 2.0L/min. Open the plunger of the
separatory funnel C. Make 10mL of 6mol/L hydrochloric acid solution quickly flow
into the steamer. Immediately heat the solution in the flask to boiling. Keep it slightly
boiled for 1.5h. Stop heating. Cool the absorption solution and shake well. Use sodium
hydroxide standard solution (0.01mol/L) to titrate till it turns yellow and not fade for
9 Principle
The sample is directly soaked in methyl acetate buffer absorbent or nitrogen-filling with
acid and steamed-released sulfur dioxide is absorbed by the formaldehyde solution.
Generate stable hydroxymethanesulfonic acid addition compound. Under acidic
conditions, with pararosaniline hydrochloride, generate a blue-violet complex. The
absorbance value of this complex is proportional to the concentration of sulfur dioxide.
10 Reagents and materials
Unless otherwise stated, the reagents used in this method are all analytically pure, and
the water is grade three water specified in GB/T 6682.
10.1 Reagents
10.1.1 Ammonium sulfamate (H6N2O3S).
10.1.2 Disodium EDTA (C10H14N2Na2O8).
10.1.3 Formaldehyde (CH2O): 36%~38%; there shall be no polymer (no precipitation
and no separation of the solution).
10.1.4 Potassium hydrogen phthalate (KHC8H4O4).
10.1.5 2% pararosaniline hydrochloride (C20H20ClN3) solution.
10.1.6 Glacial acetic acid (C2H4O2).
10.1.7 Phosphoric acid (H3PO4).
10.2 Reagent preparation
10.2.1 Sodium hydroxide solution (1.5mol/L): Weigh 6.0g of NaOH (3.1.3). Dissolve
in water and dilute to 100mL.
10.2.2 Disodium EDTA solution (0.05mol/L): Weigh 1.86g of disodium
ethylenediaminetetraacetate (abbreviated as EDTA-2Na). Dissolve in water and dilute
to 100mL.
10.2.3 Formaldehyde buffered absorption stock solution: Weigh 2.04g of potassium
hydrogen phthalate. Dissolve in a small amount of water. Add 5.5mL of 36%~38%
formaldehyde solution, 20.0mL...