GB/T 7383-2020 English PDF (GBT7383-2020)

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GB/T 7383-2020: Non-ionic surface active agents -- Determination of hydroxyl value
GB/T 7383-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.100.40
G 72
Replacing GB/T 7383-2007
Non-ionic Surface Active Agents - Determination of
Hydroxyl Value
(ISO 4326:1980, Non-ionic Surface Active Agents - Polyethoxylated Derivatives -
Determination of Hydroxyl Value - Acetic Anhydride Method, MOD)
ISSUED ON: DECEMBER 14, 2020
IMPLEMENTED ON: JULY 1, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 6
3 Terms and Definitions ... 6
4 Method A - Phthalic Anhydride Method (arbitration method) ... 7
5 Method B - Acetic Anhydride Method (arbitration method) ... 12
6 Method C - Near-infrared spectroscopy ... 15
7 Arbitration Method ... 19
8 Test Report ... 19
Appendix A (informative) Structural Changes between this Standard and ISO
4326:1980 ... 20
Appendix B (normative) Determination of Purity of Phthalic Anhydride ... 22
Appendix C (normative) Determination of Hydroxyl Value outside Fume Hood ... 23
Appendix D (informative) Sampling Range of Specimens with Different Water
Contents and Hydroxyl Values ... 27
Appendix E (informative) Example of Establishment of Calibration Model ... 29
Non-ionic Surface Active Agents - Determination of
Hydroxyl Value
1 Scope
This Standard specifies the determination of hydroxyl value in non-ionic surface active agents.
This Standard is applicable to the determination of hydroxyl value (the hydroxyl value of
adducts of ethylene oxide and propylene oxide of primary fatty alcohols, alkylphenols and fatty
acids, and their mixtures) of aliphatic and cycloaliphatic poly alkoxy compounds, which is
suitable for the determination of hydroxyl value in 10 ~ 1,000.
The phthalic anhydride method is suitable for the determination of the hydroxyl value of
adducts of ethylene oxide and propylene oxide of primary and secondary fatty alcohols,
alkylphenols and fatty acids, and their mixtures.
The acetic anhydride method is suitable for the determination of the hydroxyl value of adducts
of ethylene oxide of primary and secondary fatty alcohols, alkylphenols and fatty acids, but not
for the determination of the hydroxyl value of propoxylated products.
The near-infrared method is suitable for non-ionic surface active agents whose hydroxyl value
can be determined by the phthalic anhydride method or the acetic anhydride method.
Interfering substances are as follows:
---Primary and secondary amines, amides, tertiary alcohols, thiols and epoxides generate
side reactions that affect the accuracy of the method.
---Long-chain aliphatic acids and esters generate more stable anhydrides than phthalic
anhydride acetic anhydride, which cannot be completely decomposed at the end of the
determination.
---Other free acids cause interference due to the reaction with the sodium hydroxide
standard solution, and alkalis, including certain tertiary amines, cause interference due
to the reaction with the generated phthalic acid and acetic acid.
The presence of epoxides interferes with the determination. If they can be removed by the low-
temperature vacuum distillation method without changing the hydroxyl value, this method is
still applicable. The above-mentioned treatment can eliminate free ethylene oxide that causes
interferences and with a concentration (mass fraction) higher than 0.5%.
The moisture present in the specimen will react with phthalic anhydride and acetic anhydride,
but this method is still applicable if the measures described in the determination procedures are
followed for prevention.
2 Normative References
The following documents are indispensable to the application of this document. In terms of
references with a specified date, only versions with a specified date are applicable to this
document. In terms of references without a specified date, the latest version (including all the
modifications) is applicable to this document.
GB/T 601 Chemical Reagent - Preparations of Standard Volumetric Solutions
GB/T 2384 Dyes Intermediates - General Method for the Determination of Melting Range
GB/T 3143 Color Determination Method of Liquid Chemicals - Hazen Unit - Platinum - Cobalt
Scale
GB/T 6365 Surface Active Agents - Determination of Free Alkalinity or Free Acidity -
Titrimetric Method (GB/T 6365-2006, ISO 4314:1977, IDT)
GB/T 6372 Surface Active Agents and Detergents - Methods of Sample Division (GB/T 6372-
2006, ISO 607:1977, IDT)
GB/T 8170 Rules of Rounding off for Numerical Values and Expression and Judgement of
Limiting Values
GB/T 11275 Surface Active Agents - Determination of Water Content (GB/T 11275-2007, ISO
4317:1991, MOD)
GB/T 29858 Standard Guidelines for Molecular Spectroscopy Multivariate Calibration
Quantitative Analysis
ISO 4327 Non-ionic Surface Active Agents - Polyalkoxylated Derivatives - Determination of
Hydroxyl Value - Phthalic Anhydride Method
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 hydroxyl value (OH)
Hydroxyl value refers to the number of milligrams of potassium hydroxide required to
neutralize the acid generated by the esterification of hydroxyl groups in 1 g of specimen with
phthalic anhydride or acetic anhydride.
3.2 modeling samples
Modeling samples refer to a series of representative samples selected for the establishment of
the calibration model.
3.3 validation samples
Validation samples refer to a series of representative samples selected for the validation of the
calibration model.
3.4 calibration
Calibration refers to the process of establishing a model by correlating the concentration or
properties of a group of samples with their spectra.
3.5 calibration model
Calibration model refers to a mathematical expression that expresses the correlation between
the composition and concentration or properties of a group of samples and their spectra.
3.6 estimate
Estimate refers to the process of calculating the concentration or properties of sample
composition using the calibration model and the sample’s spectrum.
3.7 abnormal value
Abnormal value refers to the data points corresponding to samples for which the model estimate
value is significantly different from the reference value.
3.8 mahalanobis distance
Mahalanobis distance represents the covariance distance of the data, which is an effective
method of calculating the similarity of two unknown sample spectra.
4 Method A - Phthalic Anhydride Method (arbitration
method)
4.1 General Rules
The phthalic anhydride method shall comply with the method provided in ISO 4327.
4.2 Principle
In pyridine solution, use phthalic anhydride to esterify the hydroxyl value.
c (NaOH) = 0.5 mol/L, prepare in accordance with the stipulations of GB/T 601.
4.3.4 Phenolphthalein indicator
1 g of phenolphthalein is dissolved in 100 mL of pyridine.
4.4 Instruments and Equipment
4.4.1 Alkaline burette
The capacity is 50 mL.
4.4.2 Flat-bottomed flask
The capacity is 250 mL, with conical ground glass joints.
4.4.3 Air condenser
An air condenser with an effective length greater than 600 mm, with conical ground glass joints.
4.4.4 One-mark pipette
The capacity is 25 mL.
4.5 Determination
4.5.1 General rules
In accordance with the stipulations of GB/T 6372, prepare and store samples. In addition, in
accordance with the stipu...