GB/T 5009.34-2003 Determination of sulfite in food

This standard specifies the determination method of sulfite in food. This standard is applicable to the determination of sulfur dioxide residue in food. The detection concentration of this standard is 1 mg/kg. GB/T 5009.34-2003 Determination of sulfite in food GB/T5009.34-2003 Standard download decompression password: www.bzxz.net

ICS67.040
National Standard of the People's Republic of China
GB/T5009.34--2003
Replaces GB/T5009.34--1996
Determination of sulphite in foods
Determination of sulphite in foodsIssued on August 11, 2003
Ministry of Health of the People's Republic of China
Standardization Administration of the People's Republic of China
Implementation on January 1, 2004
GB/T5009.34—2003
This standard replaces GB/T5009.34—1996 "Determination of sulfite in foods". Compared with GB/T5009.34-1996, this standard has been modified as follows: the Chinese name of the standard has been modified, and the Chinese name of the standard has been changed to "Determination of sulfite in food"; the structure of the original standard has been modified in accordance with GB/T20001.4--2001 "Standard Preparation Rules Part 4: Chemical Analysis Methods".
Appendix A of this standard is an informative appendix.
This standard is proposed and managed by the Ministry of Health of the People's Republic of China. The first method of this standard was drafted by the Beijing Municipal Health and Epidemic Prevention Station, Guangdong Provincial Health and Epidemic Prevention Station, and the Food Sanitation Supervision and Inspection Institute of the Ministry of Health. The second method of this standard was drafted by the Food Sanitation Supervision and Inspection Institute of the Ministry of Health, Beijing Municipal Health and Epidemic Prevention Station, Shandong Provincial Food Sanitation Supervision and Inspection Institute, Hebei Provincial Health and Epidemic Prevention Station, and Beijing Chongwen District Health and Epidemic Prevention Station. This standard was first issued in 1985 and revised for the first time in 1996. This is the second revision. 268
1 Scope
Determination of sulfite in food
This standard specifies the determination method of sulfite in food. This standard is applicable to the determination of sulfur dioxide residue in food. The detection concentration of this standard is 1mg/kg.
Method 1 Pararosaniline hydrochloride method
2 Principle
GB/T5009.34—2003
Sulfite reacts with sodium tetrachloromercurate to form a stable complex, which then reacts with formaldehyde and pararosaniline hydrochloride to form a purple-red complex and is compared with the standard series for quantitative analysis.
3 ReagentsWww.bzxZ.net
3.1 Sodium tetrachloromercurate absorption solution: Weigh 13.6g of mercuric chloride and 6.0g of sodium fluoride, dissolve in water and dilute to 1000mL, leave overnight, filter and set aside.
3.2 Ammonium sulfamate solution (12g/L).
3.3 Formaldehyde solution (2g/L): Absorb 0.55mL of formaldehyde (36%) without polymerized precipitation, dilute to 100mL with water, and mix well. 3.4 Starch indicator solution: Weigh 1g of soluble starch, mix it into a paste with a little water, slowly pour it into 100mL of boiling water, stir while adding, boil, cool and set aside. This solution should be prepared when it is used. 3.5 Potassium ferrocyanide solution: Weigh 10.6g of potassium ferrocyanide [KFe (CN), ·3H2O], dissolve it in water and dilute to 100mL. 3.6 Zinc acetate solution: Weigh 22g of zinc acetate [Zn (CH, COO), ·2H, O], dissolve it in a small amount of water, add 3mL of glacial acetic acid, and dilute to 100mL with water.
3.7 Hydrochloric acid solution of pararosaniline: Weigh 0.1g of pararosaniline hydrochloride (CisHusNzCl·4H.O, p-rosanilinehydrochloride) in a mortar, add a small amount of water to grind until dissolved and dilute to 100mL. Take out 20mL, put it in a 100ml volumetric flask, add hydrochloric acid (1+1), shake it thoroughly to make the solution turn from red to yellow. If it does not turn yellow, add a small amount of hydrochloric acid until yellow appears, then add water to dilute to the scale, mix and set aside (if there is no pararosaniline hydrochloride, hydrochloric acid fuchsin can be used instead). Purification method of pararosaniline hydrochloride: Weigh 20g of pararosaniline hydrochloride in 400mL of water, acidify with 50mL of hydrochloric acid (1+5), stir slowly, add 4g~5g of activated carbon, heat and boil for 2min. Pour the mixture into a large funnel and filter (filter while hot using an insulating funnel). The filtrate is left overnight, and a product appears. Then it is filtered with a Buchner funnel, and the crystals are suspended in a mixture of 1000mL of ether-ethanol (10:1), shaken for 3min~5min, filtered with a Buchner funnel, and repeatedly washed with ether until the ether layer is colorless, dried in a sulfuric acid dryer, ground and stored in a brown bottle. 3.8 Iodine solution [c(1/21,)=0.100mol/L]. 3.9 Sodium thiosulfate standard solution Lc(NazS.O·5H,0)=0.100mol/LJ. 3.10 Sulfur dioxide standard solution: Weigh 0.5g sodium bisulfite, dissolve in 200mL sodium tetrachloromercurate absorption solution, leave overnight, and filter the supernatant with quantitative filter paper for later use.
Put 10.0mL of sodium bisulfite-sodium tetrachloromercurate solution in a 250mL iodine volumetric flask, add 100mL of water, accurately add 20.00mL of iodine solution (0.1mol/L), 5mL of glacial acetic acid, shake well, place in a dark place, and quickly titrate with sodium thiosulfate (0.100mol/L) standard solution until it turns light yellow after 2 minutes, add 0.5mL of starch indicator solution, and continue to titrate until it is colorless. Take another 100ml of water, accurately add 20.0mL of iodine solution (0.1mol/L) and 5mL of glacial acetic acid, and perform a reagent blank test in the same way. 269
GB/T5009.34—2003
The concentration of sulfur dioxide standard solution is calculated according to formula (1). X=(-V)Xc×32.03
Wherein:
-concentration of sulfur dioxide standard solution, in milligrams per milliliter (mg/mL); V,-volume of sodium thiosulfate standard solution consumed by sodium bisulfite-sodium mercury tetraoxide solution for determination, in milliliter (mL); V,-volume of sodium thiosulfate standard solution consumed by reagent blank, in milliliter (mL);-molar concentration of sodium thiosulfate standard solution, in moles per liter (mol/L); 32.03-
mass of sulfur dioxide equivalent to each milliliter of sodium thiosulfate Lc(NazS,O，·5H.O)1.000mol/L] standard solution, in milligrams (mg).
3.11 Sulfur dioxide working solution: Before use, dilute the sulfur dioxide standard solution with sodium tetrachloromercury absorption solution to 2μg sulfur dioxide per milliliter.
3.12 Sodium hydroxide solution (20g/L).
3.13 Sulfuric acid (1+71).
4 Instruments
Spectrophotometer.
5 Analysis steps
5.1 Sample treatment
5.1.1 Water-soluble solid samples such as white sugar can be weighed about 10.00g of uniform sample (the sample amount can be determined according to the content), dissolved with a small amount of water, placed in a 100mL volumetric flask, added with 4mL of sodium hydroxide solution (20g/L), 5min later, added with 4mL of sulfuric acid (1+71), and then added with 20mL of sodium tetrachloromercurate absorption solution, and diluted to the scale with water. 5.1.2 For other solid samples such as biscuits and vermicelli, 5.0g~10.0g of the sample can be weighed and ground evenly, moistened with a small amount of water and transferred to a 100mL volumetric flask, then 20mL of sodium tetrachloromercurate absorption solution can be added and soaked for more than 4h. If the upper solution is not clear, 2.5mL of potassium ferrocyanide (3.5) and zinc acetate (3.6) solution can be added, and finally diluted with water to 100mL scale, filtered and set aside. 5.1.3 For liquid samples such as wine, 5.0mL~10.0mL of the sample can be directly absorbed, placed in a 100mL volumetric flask, diluted with a small amount of water, 20mL of sodium tetrazomercurate absorption solution can be added, shaken, and finally water can be added to the scale, mixed, and filtered if necessary. 5.2 Determination
Pull 0.50mL5.0mL of the above sample treatment solution into a 25mL stoppered colorimetric tube. Take 0, 0.20, 0.40, 0.60, 0.80, 1.00, 1.50, 2.00mL of sulfur dioxide standard solution (equivalent to 0, 0.4, 0.8, 1.2, 1.6, 2.0, 3.0, 4.0μg sulfur dioxide) and place them in 25mL stoppered colorimetric tubes. Add sodium tetrachloromercurate absorption solution to 10mL in the sample and standard tubes, then add 1mL of ammonium sulfamate solution (12g/L), 1mL of formaldehyde solution (2g/L) and 1mL of pararosaniline hydrochloride solution, shake and let stand for 20min. Use a 1cm colorimetric cup and zero tube to adjust the zero point, measure the absorbance at a wavelength of 550nm, and draw a standard curve for comparison. 5.3 Calculation
The content of sulfur dioxide in the sample is calculated according to formula (2). Ax1000
m×V/100×1000×1000
Wherein:
X is the content of sulfur dioxide in the sample, in grams per gram (g/kg); A—the mass of sulfur dioxide in the sample solution for determination, in micrograms (ug); m
the mass of the sample, in grams (g);
V—the volume of the sample solution for determination, in milliliters (mL). The calculation result shall be expressed to three significant figures. 5.4 Precision
The absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 10%. Note: For tips on this method, see Appendix A. Method 2 Distillation method
6 Principle
GB/T5009.34—2003
In a closed container, the sample is acidified and heated for distillation to release the sulfur dioxide therein, and the released substance is absorbed by lead acetate solution. After absorption, it is acidified with concentrated acid and then titrated with iodine standard solution. The sulfur dioxide content in the sample is calculated based on the amount of iodine standard solution consumed. This method is applicable to colored wine, glucose syrup, and preserved fruit. 7 Reagents
7.1 Hydrochloric acid (1+1): Concentrated hydrochloric acid is diluted 1 time with water. 7.2 Lead acetate solution (20g/L): Weigh 2g of lead acetate, dissolve it in a small amount of water and dilute to 100mL. 7.3 Iodine standard solution [c(1/2Iz)=0.010mol1/L: Dilute the iodine standard solution (0.100mol/L) with water 10 times. 7.4 Starch indicator solution (10g/L): Weigh 1g of soluble starch, mix it into a paste with a little water, slowly pour it into 100mL boiling water, stir while adding, boil for 2min, cool and set aside. This solution should be freshly prepared before use. 8 Instruments
8.1 All-glass filling steamer.
8.2 Iodine volume bottle.
8.3 Acid burette.
9 Analysis steps
9.1 Sample treatment
Cut the solid sample into small pieces with a knife or scissors, then mix and weigh about 5.00g of the homogenized sample (the sample amount can be determined according to the content). For liquid samples, 5.0mL~10.0mL of the sample can be directly absorbed and placed in a 500mL round-bottom distillation flask. 9.2 Determination
9.2.1 Distillation: Place the weighed sample in a round-bottom distillation flask, add 250mL of water, and install a condensation device. The lower end of the condenser tube should be inserted into the 25mL lead acetate (20g/L) absorption solution in the iodine volume flask. Then add 10mL of hydrochloric acid (1+1) to the distillation flask, immediately cover the stopper, and heat for distillation. When the distillate is about 200mL, make the lower end of the condenser tube leave the liquid surface and distill for another 1min. Rinse the device part inserted into the lead acetate solution with a small amount of distilled water. A blank test should be performed while testing the sample. 9.2.2 Titration: Add 10mL of concentrated hydrochloric acid and 1mL of starch indicator solution (10g/L) to the removed iodine volume flask in turn. After shaking, titrate with iodine standard titration solution (0.010mol/L) until it turns blue and does not fade within 30s. 9.3 Calculation
The total sulfur dioxide content in the sample is calculated according to formula (3). X=(AB)×0.01×0.032×1 000
Wherein:
total sulfur dioxide content in the sample, in grams per kilogram (g/kg); X
the volume of the iodine standard titration solution (0.01 mol/L) used to titrate the sample, in milliliters (mL); (3)
GB/T5009.34—2003
B—the volume of the iodine standard titration solution (0.01 mol/L) used to titrate the reagent blank, in milliliters (mL); m
the mass of the sample, in grams (g);
the mass of sulfur dioxide equivalent to 0.032—1mL of iodine standard solution [c(1/212)=1.0 mol/L], in grams (g). 272
Appendix A
(Informative Appendix)
Explanation of the Hydrochloric Acid Pararosaniline Method
GB/T5009.34-2003
A.1 Sulfurous acid combines with aldehydes (acetaldehyde, etc.), ketones (ketoglutaric acid, pyruvic acid) and sugars (glucose, fructose, mannose) in food, and exists in food as combined sulfite. Adding alkali releases sulfur dioxide in sugar, and adding sulfuric acid is to neutralize the alkali, because the overall color reaction is carried out under slightly acidic conditions. A.2 After adding sodium tetrachloromercurate, the wine was measured at different times. The measured value increased with the standing time, reached the maximum value after 72 hours, and was consistent with the iodine titration value, see Table A.1.
Standing time after adding sodium tetrachloromercurate/h
Measured value/(g/kg)
The result of the iodine titration method was 0.05g/kg. After adding sodium tetrachloromercurate, the free sulfur dioxide is measured by colorimetry. After being placed for more than 72 hours, sodium tetrachloromercurate slowly reacts with bound sulfur dioxide. The following is a comparison of the three determination methods, see Table A.2. A.2
Sample name
Peach red wine
White grape wine
Dynasty wine
Sodium tetraammine colorimetry
Determination results/(g/kg）
Colorimetry after distillation
Iodine titration after steaming
Note: The above information is from "Food Hygiene Inspection Method (Physical and Chemical Part) Note" (Food Hygiene Supervision and Inspection Institute of the Ministry of Health, 1997). 27301mol/L) volume, in milliliters (mL); m
sample mass, in grams (g),
0.032-1mL iodine standard solution [c(1/212)=1.0mo1/L] equivalent mass of sulfur dioxide, in grams (g). 272
Appendix A
(Informative Appendix)
Description of the hydrochloric acid pararosaniline method
GB/T5009.34-2003
A.1 Sulfurous acid combines with aldehydes (acetaldehyde, etc.), ketones (ketoglutaric acid, pyruvic acid) and sugars (glucose, fructose, mannose) in food, and exists in food as combined sulfurous acid. Adding alkali releases sulfur dioxide in sugar, and adding sulfuric acid is to neutralize the alkali, because the overall color reaction is carried out under slightly acidic conditions. A.2 After adding sodium tetrachloromercurate, the wine was measured at different times. The measured value increased with the storage time, reached the maximum value after 72 hours, and was consistent with the value measured by iodine titration, see Table A.1.
Storage time after adding sodium tetrachloromercurate/h
Measured value/(g/kg)
The result of iodine titration was 0.05g/kg. After adding sodium tetrachloromercurate, it was immediately measured by colorimetry, which was the measurement of free sulfur dioxide. After being placed for more than 72 hours, sodium tetrachloromercurate slowly reacted with bound sulfur dioxide. The following is a comparison of the three measurement methods, see Table A.2. A.2
Sample name
Peach red wine
White grape wine
Dynasty grape wine
Sodium tetraammine bismuth colorimetric method
Measurement result/(g/kg）
Colorimetric method after distillation
Iodine titration method after steaming
Note: The above information is from "Food Hygiene Inspection Method (Physical and Chemical Part) Note" (Food Hygiene Inspection Institute of the Ministry of Health, 1997). 27301mol/L) volume, in milliliters (mL); m
sample mass, in grams (g),
0.032-1mL iodine standard solution [c(1/212)=1.0mo1/L] equivalent mass of sulfur dioxide, in grams (g). 272
Appendix A
(Informative Appendix)
Description of the hydrochloric acid pararosaniline method
GB/T5009.34-2003
A.1 Sulfurous acid combines with aldehydes (acetaldehyde, etc.), ketones (ketoglutaric acid, pyruvic acid) and sugars (glucose, fructose, mannose) in food, and exists in food as combined sulfurous acid. Adding alkali releases sulfur dioxide in sugar, and adding sulfuric acid is to neutralize the alkali, because the overall color reaction is carried out under slightly acidic conditions. A.2 After adding sodium tetrachloromercurate, the wine was measured at different times. The measured value increased with the storage time, reached the maximum value after 72 hours, and was consistent with the value measured by iodine titration, see Table A.1.
Storage time after adding sodium tetrachloromercurate/h
Measured value/(g/kg)
The result of iodine titration was 0.05g/kg. After adding sodium tetrachloromercurate, it was immediately measured by colorimetry, which was the measurement of free sulfur dioxide. After being placed for more than 72 hours, sodium tetrachloromercurate slowly reacted with bound sulfur dioxide. The following is a comparison of the three measurement methods, see Table A.2. A.2
Sample name
Peach red wine
White grape wine
Dynasty grape wine
Sodium tetraammine bismuth colorimetric method
Measurement result/(g/kg）
Colorimetric method after distillation
Iodine titration method after steaming
Note: The above information is from "Food Hygiene Inspection Method (Physical and Chemical Part) Note" (Food Hygiene Inspection Institute of the Ministry of Health, 1997). 273
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.