This standard specifies the method for determining the free caustic content in soap using the anhydrous ethanol method. This standard applies to sodium soaps of ordinary fatty acids (measured in NaOH), not to potassium soaps or compound soaps. Generally, free caustic refers to sodium hydroxide (NaOH) for sodium soaps and potassium hydroxide (KOH) for potassium soaps. QB/T 2623.1-2003 Soap test method Determination of free caustic content in soap QB/T2623.1-2003 Standard download decompression password: www.bzxz.net

ICS71.100
Classification number: Y43
Registration number: 13167-2004
Light Industry Standard of the People's Republic of China
QB/T2623.1-2003
Replaces QB/T3748-1999
Test methods of soaps
Determination of free caustic alkali content in soaps(ISO 456: 1973, Surface active agents--Analysis of soaps-Determination offree caustic alkali-Method A, MOD) Issued on December 11, 2003
National Development and Reform Commission of the People's Republic of China Implemented on May 1, 2004
QB/T2623.1-2003
This standard is the first standard in the QB/T2623 "Soap Test Method" series of standards. This series of standards consists of eight standards, the names of which are as follows:
1 Soap test method
QB/T2623.1
Determination of free alkali content in soap
Soap test method Determination of total free alkali content in soap QB/T2623.2
Determination of total alkali and total fatty matter content in soap QB/T2623.3
QB/T2623.4
QB/T2623.5
QB/T2623.6
QB/T2623.7|| tt||Test methods for soap
Determination of moisture and volatile matter in soap
Test methods for soap
Test methods for soap
Determination of ethanol insoluble matter in soap
Determination of chlorinated matter in soap bZxz.net
Determination of unsaponifiable and unsaponifiable matter in soap
QB/T2623.8 Test methods for soap
Determination of phosphate content in soap This standard is a revision of QB/T3748-1999 "Test methods for soap - Determination of free caustic content in soap". This standard is modified to adopt the A method in ISO456:1973 "Analysis of surfactant soap - Determination of free caustic content" (English version), i.e. the anhydrous ethanol method.
This standard is redrafted based on ISO456:1973. According to my country's national conditions and experimental space verification, this standard was modified when adopting the international standard. These technical differences are marked with a vertical single line in the right margin of the clauses they involve. A list of technical differences and their reasons is given in Appendix B for reference. For ease of use, this standard has also made the following editorial changes: a) The term "this international standard" is changed to "this standard\; the decimal point "," is used instead of the comma "," as a decimal point; b)
c) The foreword of the international standard is deleted;
d) Normative Appendix A is added to guide use. Appendix A of this standard is a normative appendix, and Appendix B is an informative appendix. This standard was proposed by the China Light Industry Federation. This standard is under the jurisdiction of the National Surfactant Detergent Standardization Center. This standard was drafted by the National Detergent Quality Supervision and Inspection Center (Taiyuan). The main drafters of this standard are Liang Hongyan and Yan Fang. This standard was first issued as the national standard GB/T7455-1987 in March 1987 and converted into the national standard GB/T7455-1987 in April 1999. This is the light industry standard QB/T3748-1999, and this is the first revision. From the date of implementation, this standard replaces the light industry standard QB/T3748-1999 "Determination of free caustic soda content in soap" issued by the former State Bureau of Light Industry.
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QB/T2623.12003
Soap test method Determination of free caustic soda content in soap 1 Scope
This standard specifies the method for determining the free caustic soda content in soap using the anhydrous ethanol method. This standard is applicable to sodium fatty acid soaps of ordinary nature (measured in NaOH), not to potassium, nor to complex soaps. Generally, free caustic soda refers to sodium hydroxide (NaOH) for sodium soap and to sodium hydroxide (NaOH) for potassium. Soap refers to potassium hydroxide (KOH). 2 Normative references
The clauses in the following documents become clauses of this standard through reference in this standard. For any dated reference, all subsequent amendments (excluding errata) or revisions are not applicable to this standard. However, parties to an agreement based on this standard are encouraged to investigate whether the latest versions of these documents can be used. For any undated reference, the latest version applies to this standard. GB/T601-2002 Preparation of standard titration solutions for chemical reagents GB/T603-2002 Preparation of preparations and products used in test methods for chemical reagents 3 Test methods
Unless otherwise specified, only reagents confirmed as analytically pure and distilled water or deionized water are used in the analysis. Ionized water or water of equivalent purity. 3.1 Principle
Dissolve the soap in neutral ethanol, and then titrate the free caustic soda with a standard hydrochloric acid ethanol titration solution. 3.2 Reagents and materials
a) Anhydrous ethanol (GB/T678);
Potassium hydroxide (GB/T2306), 0.1mol/L ethanol solution, prepared according to 4.24.1 of GB/T601-2002; b)
Hydrochloric acid (GB/T622), c (HCI) = 0.1mol/L ethanol standard titration solution, prepared and calibrated according to Appendix A: c
Phenol butter (GB/T10729), 10g/L indicator solution, prepared according to 4.1.4.22 of GB/T603-2002. d
3.3 Apparatus
General laboratory apparatus and
3.3.1 Erlenmeyer flask, with reflux condenser, 250 mL. 3.3.2 Reflux condenser, 6 bulbs.
3.3.3 Closed electric furnace, equipped with temperature regulator. 3.4 Preparation and storage of samples
Divide the soap sample for test into eight portions by cutting three times perpendicularly in the middle of each piece. Cut the two diagonally opposite portions into thin slices, mash them, mix them thoroughly, and put them into a clean, dry, sealed container for later use. 3.5 Procedure
The same sample is measured in duplicate.
3.5.1 Test portion
Weigh about 5 g (accurate to 0.001 g) of the sample (3.4) into the Erlenmeyer flask (3.3.1). 3.5.2 Determination
Add 150 mL of anhydrous ethanol (3.2.a) to an empty conical flask (3.3.1) and connect it to a reflux condenser (3.3.2). Heat to a slight boil and keep for 5 minutes to drive off carbon dioxide. Remove the cooler. Allow it to cool to about 70°C. Add 2 drops of phenolic acid indicator (3.2.d) and neutralize with potassium hydroxide ethanol solution (3.2.b) until the solution turns light pink. 1
QB/T2623.1-2003
Pour the above treated ethanol into the conical flask containing the test sample (3.5.1) and connect the conical flask to the reflux condenser (3.3.2). Boil slowly until the soap is completely dissolved and allow it to cool to about 70°C. Titrate with hydrochloric acid ethanol standard titration solution (3.2.c) until the light pink color appears as when neutralizing ethanol, and maintain it for 30 seconds without fading. 3.6 Calculation of results
The mass percentage of free caustic soda in soap is expressed as the mass percentage of sodium hydroxide (NaOH, %), and is calculated according to formula (1): 0.040×V×c×100
Free caustic soda (NaOH, %)=-
Where:
The volume of hydrochloric acid ethanol standard titration solution consumed, mL: The concentration of hydrochloric acid ethanol standard titration solution, mol/L: 0.040-The millimole mass of sodium hydroxide expressed in grams in the test, g/mmol: m
The mass of the test portion (3.5.1), g.
The arithmetic mean of the results of two parallel determinations is expressed to two decimal places as the determination result. .(1)
3.7 Precision
The absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 0.04%, provided that the absolute difference between two independent determination results obtained under repeatability conditions shall not exceed 5%.
3.8 Test report
The test report should include the following:
a) All information required for complete identification of the sample; b)
Reference to the method used (related to this standard): the results obtained and how to express them;
Test conditions;
Any operations not specified or optional in this standard and any circumstances that may affect the results; e)
Test date.
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QB/T2623.1—2003
A.1 Reagents
Appendix A
(Normative Appendix)
Preparation and calibration of hydrochloric acid ethanol standard titration solution [c (HCI) = 0.1mol/L] a) Anhydrous sodium carbonate (GB/T1255), standard reagent: hydrochloric acid (GB/T622);
95% ethanol (GB/T679):
Langcresol green-methyl red mixed indicator solution, prepared according to 4.1.4.29 of GB/T603-2002. A.2 Preparation
Measure 9mL of hydrochloric acid (A.1.b), inject it into 1000mL of 95% ethanol (A.1.c), and shake the spoon. A.3 Calibration
Weigh 0.2g (accurate to 0.0001g) of anhydrous sodium carbonate (A.1.a) burned to constant weight at 270℃-300℃, add 10 drops of cresol green-methyl red mixed indicator solution (A.1.d), and titrate with the prepared hydrochloric acid solution (A.2) until the solution changes from green to wine red, boil for 2 minutes, cool and continue titrating until the solution turns wine red again as the end point. At the same time, perform an empty test. A.4 Calculate the concentration c(HCI) of the standard hydrochloric acid-ethanol titration solution in moles per liter (mol/L) according to formula (A.1): C(HCI)
Wherein:
C(HCI)
(VV)×0.05299
molar concentration of the standard hydrochloric acid-ethanol titration solution, mol/L; amount of the standard hydrochloric acid-ethanol titration solution used, mL: The amount of the standard hydrochloric acid-ethanol titration solution used in the empty test, mL: (A.1)
The mass of anhydrous sodium carbonate expressed in grams equivalent to 1.00mL of the standard hydrochloric acid titration solution [c(HCI)=1.000mol/L]:
-anhydrous sodium carbonate salt, g.
A.5 Precision
Parallel tests shall be conducted for no less than eight times, with two people making four parallel tests each. The ratio of the range to the average value of the four parallel test results of each person shall not exceed 0.1%. The difference between the average values ​​of the two people's test results shall not be greater than 0.1%, and the average value shall be taken. The concentration value shall be taken to four significant figures. 3
Appendix B
(Informative Appendix)
Technical differences between this standard and ISO456:1973 and their causes Table B.1 gives the technical differences between this standard and ISO456:1973 and their list. Table B.1 Technical differences between this standard and ISO456:1973 and their reasons This standard
Chapter number
This standard
Erlenmeyer flask 250mL
Preparation and preservation of sample
Add 150mL of ethanol
Add 2 drops of aliquot
Precision
Chapter number
ISO456:1973
Flask 500mL
Add 200mL of alcohol
Add phenol Donate 4 drops
Reproducibility
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QB/T2623.1-2003
Can meet the test
Necessary in the test
Can meet the test
Can meet the test
Necessary in the test
People's Republic of China
Light Industry Standard
Soap Test Method
Determination of Free Caustic Alkali Content in Soap
QB/T 2623.1-2003
Published by China Light Industry Press
Editorial Committee of Light Industry Standardization Editing and Publishing Address: No. 12 Guanghua Road, Chaoyang District, Beijing
(3rd Floor, Building 1, China Pulp and Paper Research Institute)Postal Code: 100020
Telephone: (010) 65811585
Copyright reserved. Infringements must be investigated
Book No. 5: 155019-2604
Print run: 1-200 copies
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