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GB 5009.34-2022 PDF in English


GB 5009.34-2022 (GB5009.34-2022) PDF English
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GB 5009.34-2022: PDF in English

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 of 0.05mol/L EDTA-2Na solution. Mix well. Add water
to dilute and set volume to 100mL. Store in a refrigerator to keep refrigerated.
10.2.4 Formaldehyde buffered absorption solution: Measure an appropriate amount of
formaldehyde buffered absorption stock solution. Use water to dilute 100 times. Prepare
17 Reagents and materials
Unless otherwise specified, the reagents used in this method are all analytically pure,
and the water is grade one water specified in GB/T 6682.
17.1 Standard product
Sulfate ion standard solution (1000μg/mL): with national certification and awarded the
standard material certificate.
17.2 Materials
Microporous membrane: 0.45μm.
18 Instruments and equipment
18.1 Steam distillation device or equivalent steam distillation equipment: equipped with
gas flow meter. See Annex B for the schematic diagram of the device.
18.2 Ion chromatograph: equipped with conductivity detector and suppressor.
19 Analysis steps
19.1 Specimen preparation
Same with 5.1.
19.2 Specimen processing
19.2.1 Solid or semi-fluid specimen
Weigh 10g of solid or semi-fluid specimen (to the nearest of 0.01g). Place in the round
bottom flask D in Figure B.1. Add 50mL of water. Shake it to evenly disperse. Turn on
nitrogen protection. Control its flow to 1.0L/min~ 2.0L/min. Connect to the steam
distillation bottle A. In the absorption bottle H (a 100mL Nessler colorimetric tube),
add 20mL of 3% hydrogen peroxide solution (3.2.1) as the absorption solution. The
lower end of the absorption tube is inserted below the liquid level of the absorption
solution. In bottle D, quickly add 10mL of hydrochloric acid solution (6mol/L) (3.2.2)
along the bottle wall. Quickly seal. Start the distillation. Keep bottle A boiling and
adjust distillation power. Make the outflow rate of the distillate at the end of the
absorption tube about 2mL/min. Distill until the total volume of the solution in bottle
H is about 95mL (time is 30min~40min). Use water to wash the end tube. Transfer it to
a 100mL volumetric flask. Use water to set volume to the scale. Shake well. Place for
1h. Filter with microporous membrane (0.45μm) to obtain the testing sample solution.
Do not add the specimen to conduct the blank test in the same method.
19.2.2 Liquid specimen
Accurately measure 10mL~50mL of liquid specimen or weigh 10g~50g of liquid
specimen (to the nearest of 0.01g). When the liquid sampling is less than 50mL, add
water to make up the volume to 50mL. The rest operation is same with 19.2.1.
19.3 Instrument reference conditions
19.3.1 Chromatographic column: A high-capacity anion exchange column that uses
ethylvinylbenzene-divinylbenzene superporous emulsion gel polymer resin with
alkanol quaternary ammonium as functional group as the packing material (packing
material diameter is 9μm, 250mm×4mm) or equivalent column; Anion exchange
column that the guard column uses the same packing material (packing material
diameter is 13μm, 50mm×4mm).
19.3.2 Column temperature: 30°C.
19.3.3 Eluent: 20mmol/L potassium hydroxide solution (or equivalent eluent).
19.3.4 Flow rate: 1.0mL/min.
19.3.5 Suppressor: Anion suppressor. The suppressing current is 50mA (or equivalent
suppressor).
19.3.6 Detector: Conductivity detector. The detection cell temperature is 35°C.
19.3.7 Injection volume: 100μL.
19.4 Preparation of standard curve
Accurately pipette 5.00mL of sulfate ion standard solution. Place in a 50mL volumetric
flask. Add water to set volume to the scale. From the above-mentioned solution,
accurately pipette 0.10mL, 0.20mL, 0.50mL, 1.00mL, 2.00mL, 4.00mL. Put in 10mL
volumetric flasks. Add water to set volume to the scale. Prepare the solutions that
respectively contain 1.0μg/mL, 2.0μg/mL, 5.0μg/mL, 10.0μg/mL, 20.0μg/mL and
40.0μg/mL sulfate ions. Precisely absorb 100μL of sulfate ion standard solution.
Conduct sequential injection from low concentration to high concentration. Obtain the
chromatogram of the above concentration standard solution. Draw a standard curve
with the sulfate ion concentration as the abscissa and the peak area or peak height as
the ordinate. See Figure C.1 in Annex C for the chromatogram of the sulfate ion
standard solution.
19.5 Determination of specimen solution
Inject the test solution under the same chromatographic conditions as the calibration
curve. The test solution is quantified by peak area or peak height. Obtain the sulfate ion
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.