Search result: GB/T 394.2-2008 (GB/T 394.2-1994 Older version)
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| GB/T 394.2-2008 | English | 509 |
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General methods of analysis for ethanol
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GB/T 394.2-2008
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| GB/T 394.2-1994 | English | 839 |
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General methods for determination of ethanol
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GB/T 394.2-1994
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| Standard ID | GB/T 394.2-2008 (GB/T394.2-2008) | | Description (Translated English) | General methods of analysis for ethanol | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | X04 | | Classification of International Standard | 67.160.10 | | Word Count Estimation | 22,214 | | Date of Issue | 2008-12-31 | | Date of Implementation | 2009-06-01 | | Older Standard (superseded by this standard) | GB/T 394.2-1994 | | Quoted Standard | GB/T 601; GB/T 603; GB/T 6682 | | Drafting Organization | China Research Institute of Food and Fermentation Industries | | Administrative Organization | National Standardization Technical Committee wine | | Regulation (derived from) | National Standard Approval Announcement 2008 No.21 (Total No.134) | | Proposing organization | China Light Industry Federation | | Issuing agency(ies) | Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China; Standardization Administration of China | | Summary | This standard specifies the consumption of alcohol and alcohol products industry analysis. This section applies to detect all types of alcohol products. |
GB/T 394.2-2008
General methods of analysis for ethanol
ICS 67.160.10
X04
National Standards of People's Republic of China
Replacing GB/T 394.2-1994
General analysis method of alcohol
2008-12-31 released
2009-06-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Issued by China National Standardization Management Committee
Contents
Foreword I
1 Scope 1
2 Normative references 1
3 General 1
4 Appearance 1
5 Alcohol level 2
6 Sulfuric acid test color 3
7 Oxidation time 4
8 aldehyde 5
9 Higher alcohol 7
10 Methanol 10
11 acid 12
12 Ester 13
13 Non-volatile matter 14
14 Heavy metals 15
15 Cyanide 16
Appendix A (Normative Appendix) Alcohol Meter Temperature (T), Alcohol Degree (ALC) (Volume Fraction) Conversion Table (20 ℃) 18
Foreword
GB/T 394 is divided into the following two parts.
--- GB/T 3941 "Industrial Alcohol";
--- GB/T 394.2 "General Analysis Methods for Alcohol".
This part is GB/T 394.2 "General Analysis Methods for Alcohol".
This section replaces GB/T 394.2-1994 "General Test Methods for Alcohol".
Compared with GB/T 394.2-1994, the main changes in this part are as follows.
--- The standard name was changed to alcohol general analysis method;
--- Modified, deleted, and merged the contents of the General Provisions Chapter, from 14 clauses to 6 clauses.
Appendix A of this section is a normative appendix.
This part is proposed by China National Light Industry Council.
This part is under the jurisdiction of the National Brewing Standardization Technical Committee.
This section was drafted by. China Food Fermentation Industry Research Institute, Henan Tianguan Enterprise Group Co., Ltd., Jilin Tuo brand agricultural product development
Limited company.
The main drafters of this section. Guo Xinguang, Wang Zhiqiang, Zhao Qiuying, Zhang Wei, Yin Qiumei, Kang Yongpu, Chang Wuzhan.
The release of previous versions of the standard replaced by this part are.
--- GB/T 394.2-1994.
General analysis method of alcohol
1 Scope
This part of GB/T 394 specifies the analysis methods for edible alcohol and industrial alcohol products.
This section applies to the detection of various types of alcohol products.
2 Normative references
The clauses in the following documents become the clauses of this part through the quotation of this part of GB/T 394. All quotes with dates
Documents, all subsequent amendments (not including errata content) or revisions do not apply to this section, however, encourage
The parties to the agreement study whether the latest versions of these documents are available. For the cited documents without date, the latest version applies to this
section.
GB/T 601 Preparation of chemical reagent standard titration solution
GB/T 603 Preparation of preparations and products used in the test methods of chemical reagents (GB/T 603-2002, ISO 6353-1. 1982, NEQ)
GB/T 6682 Analytical laboratory water specifications and test methods (GB/T 6682-2008, ISO 3696. 1987, MOD)
3 General
3.1 The various analytical instruments (such as analytical balance, spectrophotometer, etc.) used in this part should be regularly verified; the density bottle, pipette,
Volumetric flasks and other glass measuring instruments should be calibrated in accordance with relevant verification procedures.
3.2 The colorimetric tubes used in the test should be complete, and the glass material and color should be consistent. General glassware is cleaned with detergent or chromium pickling liquid;
Utensils with excessive potassium permanganate must be washed with oxalic acid and then rinsed with water.
3.3 The water used in this section, unless otherwise specified, should meet the requirements of GB/T 6682. Reagents used, unless otherwise noted
When referring to specifications, all refer to analytically pure (AR).
3.4 "Solution" in this section, unless otherwise stated, refers to an aqueous solution.
3.5 The reference ethanol used in this method is 95% (volume fraction) ethanol, and the limit of main impurities is. methanol is less than
2mg/L; n-propanol is less than 2mg/L; higher alcohol (isobutanol + isoamyl alcohol) is less than 1mg/L; can be checked by capillary chromatography in this section.
The aldehyde is less than 1mg/L, which can be checked by the iodometric method in this section. The ester is less than 1mg/L, which can be checked by the saponification method in this section. Examination of special grade alcohol
At this time, the reference ethanol that cannot be detected by each tested component should be used as the solvent.
3.6 Determination of the limit (direct comparison method) must directly take the color standard (abbreviation. color standard) corresponding to the limit index of this level and compare it with the sample
test. Visual colorimetric measurement is performed on a white background, along the axis, and visually compared with the same volume of color standard solution.
4 Appearance
Take 50mL sample directly with 50mL colorimetric tube. Observe under bright light. It should be transparent and free of visible impurities.
4.1 Chroma
4.1.1 Principle
Based on the platinum-cobalt color scale solution of the Hezen unit (number), visually observe and compare the color of the sample to find a color similar to the series color scale
The label is the color of the sample.
Note. 1 Hezen unit (number) means that each liter contains 2mg of cobalt chloride hexahydrate (CoC12 · 6H2O) and 1mg of platinum
(Calculated by chloroplatinic acid H2PtCl6) The color of platinum-cobalt solution.
4.1.2 Instruments
4.1.2.1 Spectrophotometer.
4.1.2.2 Colorimetric tube. 50mL.
4.1.3 Reagents and solutions
4.1.3.1 Hydrochloric acid. the density is 1.19g/mL (g/cm3).
4.1.3.2 500 Hezen unit platinum-cobalt color standard solution (abbreviation. No. 500 color standard solution) preparation and inspection.
a) Preparation. Weigh accurately 1.000g of cobalt chloride (CoC12 · 6H2O), 1.255g of potassium chloroplatinate (K2PtCl6), add 100mL
Dissolve hydrochloric acid (4.1.3.1) and an appropriate amount of water, dilute to 1000mL with water, shake well;
b) Check. use a 1 cm cuvette with water as the reference, and measure the absorbance at different wavelengths. If the absorbance of the solution is in the range of Table 1
Inside, it is No. 500 color standard solution. Store in a refrigerator in a brown bottle, valid for one year. After the expiration date, the absorbance of the solution
It is still within the scope of Table 1 and can continue to be used.
4.1.3.3 Dilute platinum-cobalt color standard solution (valid for one month)
a) General preparation method. Calculate and absorb the volume of No. 500 color standard solution according to formula (1), dilute with water to 100 mL, and then obtain the desired dilute platinum-cobalt color standard solution.
b) Prepare No. 2, No. 4, No. 6, No. 8, No. 10 and No. 12 color-coded series solutions according to the general preparation method.
4.1.4 Analysis steps
Use 50mL colorimetric tube to directly take the sample 50.0mL, and the same volume of dilute platinum-cobalt color standard series standard solution [4.1.3.3b)] for visual colorimetry.
4.1.5 Precision
The difference between two independent determination results obtained under repeatability conditions shall not exceed 1 color code.
4.2 Smell
Use a stopper to take a sample of 10mL, add 15mL of water, cover the plug, and mix well. Pour into a 50mL small beaker, sniff with your nose, record the gas
Taste, determine whether it is qualified.
4.3 Taste
Pipette 20mL of sample into 50mL volumetric flask, add 30mL of water, mix well, place in a water bath to adjust the liquid temperature to 20 ℃, and then pour in
In a 100mL small beaker, taste and evaluate its taste and make a record.
5 Alcohol
5.1 Principle
Use a precision alcohol meter to read the indicated value of alcohol volume fraction, and perform temperature correction according to Appendix A to obtain the volume fraction of ethanol content at 20 ℃
The number is the alcohol level.
5.2 Instruments
Precision alcohol meter. The division value is 0.1% vol.
5.3 Analysis steps
Inject the sample into a clean and dry graduated cylinder and let it sit for a few minutes. After the bubbles disappear in the wine, put it in a clean and dry alcohol meter
Press once, the thermometer should not touch the wall, insert the thermometer at the same time, balance about 5min, observe horizontally, read the scale indication at the tangent to the meniscus,
Also record the temperature. According to the measured value and temperature of the alcohol meter, check Appendix A "Alcohol meter temperature (T), alcohol level (ALC) (volume fraction)
Conversion table ", converted to the alcohol level of the sample at 20 ℃.
The result should be expressed to one decimal place.
5.4 Precision
The absolute difference between the two independent determination results obtained under repeatability conditions should not exceed 0.5% of the average.
6 Color test of sulfuric acid
6.1 Principle
Concentrated sulfuric acid is a strong oxidant. It has strong water absorption and oxidation properties. It is mixed with organic compounds with poor molecular structure stability.
In this case, it will be oxidized, decomposed, carbonized, and condensed to produce color. It can be compared with the platinum-cobalt color standard solution to determine the color of the sample sulfuric acid test.
6.2 Instruments
6.2.1 Flat-bottom flask. 70mL; the mass of hard glass and empty bottle is 20g ± 2g, the thickness of the ball wall should be uniform, and the dimensions are shown in Figure 1.
The unit is mm
6.2.2 Colorimetric tube. 25mL.
6.3 Reagents and solutions
6.3.1 500 hazen unit platinum-cobalt color standard solution
a) Same as 4.1.3.2;
b) If a sample with a color greater than 100 is measured, a platinum-cobalt color standard solution of 500 must be prepared separately. accurately weigh 0.300 g of cobalt chloride
(CoCl2 · 6H2O) and 1.500g potassium chloroplatinate (K2PtCl6), add 100mL hydrochloric acid (4.1.3.1) and an appropriate amount of water to dissolve,
Dilute to 1000mL with water and shake well.
6.3.2 Dilute platinum-cobalt color code series solution
a) Take No. 500 color code solution [6.3.1a)], and operate according to 4.1.3.3 to make No. 10, No. 15, No. 20, No. 30, No. 40, No. 50,
No. 60, No. 70, No. 80, No. 100 dilute platinum-cobalt color standard solution;
b) If the measured sample color is greater than No. 100, take No. 500 color standard solution [6.3.1b)], and operate according to 4.1.3.3 to make No. 110,
No. 130, No. 150, No..200, No. 300 dilute platinum-cobalt color standard series solution.
6.3.3 Sulfuric acid. superior grade pure, with a density of 1.84g/mL.
6.4 Analysis steps
Pipette 10.000mL sample into a 70mL flat-bottomed flask, add 10mL sulfuric acid evenly with a graduated cylinder or graduated pipette under constant shaking
(Control to add within 15s), mix well. Immediately place the flask in a boiling water bath, time it, boil it accurately for 5 min, take it out, and let it cool naturally.
Move into a 25mL colorimetric tube and perform visual colorimetric comparison with dilute platinum-cobalt color standard series solution.
6.5 Precision
The absolute difference between two independent determination results obtained under repeatability conditions should not exceed 10% of the average.
7 Oxidation time
7.1 Principle
Potassium permanganate is a strong oxidant. Under certain conditions, the substance that can reduce potassium permanganate in the sample reacts with potassium permanganate to make the solution
The color of potassium permanganate fades. When a certain concentration and volume of potassium permanganate standard solution is added, it reacts at a certain temperature and compares with the standard.
When the color of the sample reaches the color mark, it is the end point, which is the oxidation time.
7.2 Instruments
7.2.1 Colorimetric tube with plug. 50mL.
7.2.2 Constant temperature water bath. temperature control accuracy ± 0.1 ℃.
7.2.3 Scale straw.
7.2.4 Stopwatch.
7.2.5 G4 sand core funnel.
7.3 Reagents and solutions
7.3.1 Standard solution of potassium permanganate [犮 (1/5KMnO4) = 0.1mol/L]. Prepare and calibrate according to GB/T 601. Move into brown bottle and store in
Refrigerator spare, valid for half a year.
7.3.2 Standard use solution of potassium permanganate [犮 (1/5KMnO4) = 0.005mol/L]. when used, dissolve the standard solution of 0.1mol/L potassium permanganate
The solution is accurately diluted 20 times. This solution must be used now.
7.3.3 Hydrochloric acid. the density is 1.19g/mL (g/cm3).
7.3.4 Hydrochloric acid solution (1 + 40).
7.3.5 Sodium thiosulfate standard solution [犮 (Na2S2O3) = 0.1mol/L]. Prepare and calibrate according to GB/T 601.
7.3.6 Starch indicator solution (10g/L). Prepared according to GB/T 603.
7.3.7 Ferric chloride-cobalt chloride color scale solution
7.3.7.1 Ferric chloride solution [犮 (FeCl3) = 0.0450g/mL]
a) Preparation. Weigh out 4.7g of ferric chloride, dissolve with hydrochloric acid solution (7.3.4), and dilute to 100mL. Use G4 sand core funnel
Filter and collect the filtrate and store in the refrigerator for future use.
b) Calibration. draw 10.000mL of ferric chloride filtrate into a 250mL iodine measuring flask, add 50mL of water, hydrochloric acid (7.3.3) 3mL, iodine
Potassium 3g, shake well, and place in the dark for 30min. Add 50mL of water and titrate with sodium thiosulfate standard solution (7.3.5). Near the end,
Add 1mL of starch indicator solution (7.3.6) and continue titration until the blue color just disappears as its end point.
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