GB/T 9104-2022 (GB/T 9104-2008) PDF English
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Test methods for industrial stearic acids
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Test methods for industrial stearic acids
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The test methods for industrial stearic acids--Determination of iodine value
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NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.100.40
Y 43
Replacing GB/T 9104.1~9104.9-1988
Test methods for industrial stearic acids
Issued on: MAY 28, 2008
Implemented on: DECEMBER 01, 2008
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword... 3
1 Scope... 5
2 Normative references... 5
3 Terms and definitions... 5
4 Determination of iodine value... 6
5 Determination of saponification value... 8
6 Determination of acid value... 10
7 Determination of color... 11
8 Determination of titer... 13
9 Determination of water... 15
10 Determination of inorganic acid... 15
11 Determination of ash content... 16
12 Determination of composition... 17
13 Test report... 20
Test methods for industrial stearic acids
1 Scope
This Standard specifies test methods for industrial stearic acids, including
determination methods for iodine value, saponification value, acid value, color,
titer, water, inorganic acid, ash, composition.
This Standard is applicable to the determination of industrial stearic acids (the
main components are octadecanoic acid and palmitic acid) that are produced
and refined by animal or vegetable oils through hydrolysis or distillation.
2 Normative references
The provisions in following documents become the provisions of this Standard
through reference in this Standard. For dated references, the subsequent
amendments (excluding corrigendum) or revisions do not apply to this Standard,
however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
QB/T 2739-2005, Preparations of standard volumetric solutions of general
test methods for washing products
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Iodine value
halogen absorbed by 100g of stearic acid sample, expressed in equivalent
amount of iodine
3.2 saponification value
under the specified test conditions, the number of milligrams of potassium
hydroxide consumed to saponify 1g of stearic acid sample
3.3 acid value
the number of milligrams of potassium hydroxide consumed to neutralize 1g of
stearic acid sample
4.2.8 Starch indicator solution (10g/L). is prepared according to 5.3 in QB/T
2739-2005.
4.2.9 Sodium thiosulfate (GB/T 601), c(Na2S2O3) = 0.1mol/L standard titration
solution, is prepared and calibrated according to 4.12 in QB/T 2739-2005.
4.2.10 Iodine chloride solution (Wijs solution). dissolve 13g of iodine (4.2.6) in
1000mL of acetic acid (4.2.1) (slightly heat while dissolving). Then place in a
1000mL brown bottle. After cooling, pour 100mL~200mL into another brown
bottle. Place in a dark place for adjustment use. Make chlorine (4.2.7) access
to the remaining 800mL~900mL of iodine solution until the solution gradually
fades from a dark color till it appears orange and transparent. After the access
amount of chlorine is corrected according to the correction method, use the
preserved iodine solution to adjust.
Correction method. Respectively take 25.0mL of iodine solution and the freshly-
prepared Wijs solution. Respectively add 20mL of potassium iodide solution
(4.2.2). Then respectively add 100mL of distilled water. Use 0.1mol/L sodium
thiosulfate standard titration solution (4.2.9) to titrate the solution. When it
appears light yellow, add 1mL of starch indicator (4.2.8) to continue titrating until
blue disappears. The volume of sodium thiosulfate standard titration solution
consumed by freshly-prepared Wijs solution shall be close to twice iodine
solution’s volume.
4.3 Apparatus
Common laboratory apparatus and
4.3.1 Iodometric flask. 250mL.
4.3.2 Plugged burette. 25mL, brown.
4.3.3 Volumetric flask. 1000mL, brown.
4.3.4 Pipette. 10mL, 25mL.
4.4 Test procedures
Weigh 2g~3g of dry sample (to the nearest of 0.001g; according to the level of
iodine price, the weighing can be increased or decreased) in the iodometric
flask (4.3.1). Add 20mL of cyclohexane-acetic acid solution (4.2.4). After the
sample is dissolved, use pipette (4.3.4) to add 25.0mL of Wijs solution (4.2.10).
Completely shake well and place at a dark place around 25°C to store for 30min.
Then take the iodometric flask out from the dark place. Add 20mLof potassium
iodide solution (4.2.2). Then add 100mL of distilled water. Use sodium
thiosulfate standard titration solution (4.2.9) to titrate. Perform titration while
shaking till the solution appears light yellow. Add 1mL of starch indicator solution
5.2 Apparatus
Common laboratory apparatus and
5.2.1 Erlenmeyer flask. 250mL.
5.2.2 Plugged burette. 50mL.
5.2.3 Constant-temperature water bath or hot plate.
5.3 Test procedures
Weigh 2g of specimen (to the nearest of 0.001g) in the Erlenmeyer flask (5.2.1).
Use pipette to add 50.0mL of potassium hydroxide ethanol solution (5.1.1).
Then install a reflux condenser. Place in water bath or hot plate (5.2.3) to
maintain the slight boiling state for 1h. Do not allow vapor to escape from the
condenser. After removing, add 6 drops of phenolphthalein indicator solution
(5.1.3). While it is still hot, use hydrochloric acid standard titration solution (5.1.2)
to titrate till red just disappears. Conduct the blank test at the same time.
5.4 Result calculation
5.4.1 The saponification value of stearic acid (SV) is expressed in milligrams
per gram (mg/g). It is calculated according to formula (2).
Where,
V2 - Volume of hydrochloric acid standard titration solution consumed by blank
test, in milliliters (mL);
V1 - Volume of hydrochloric acid standard titration solution consumed by test
portion, in milliliters (mL);
c - Concentration of hydrochloric acid standard titration solution, in Moores per
liter (mol/L);
56.1 - Molar mass of potassium hydroxide expressed by grams in test, in grams
per millimoles (g/mmol);
m - Mass of test portion, in grams.
Use the arithmetic mean of the results of two parallel measurements to indicate
to one digit after the decimal point as the determination result.
5.4.2 Precision. The absolute difference between two independent test results
per liter (mol/L);
56.1 - Molar mass of potassium hydroxide expressed by grams in test, in grams
per millimoles (g/mmol);
m - Mass of test portion, in grams (g).
Use the arithmetic mean of the results of two parallel measurements to indicate
one digit after decimal place, as determination result.
6.4.2 Precision. The absolute difference between two independent test results
obtained under repetitive conditions is not more than 0.5mg/g. The premise is
that the situation greater than 0.5mg/g does not exceed 5%.
7 Determination of color
7.1 Principle
Since fatty acid and platinum-cobalt standard color have similar spectral
absorption characteristics, use a spectrophotometer, at a certain wavelength,
to determine a range of standard chromatic absorbances and draw the working
curve. At the same wavelength, determine the absorbance of specimen.
Compare with the drawn working curve, find the corresponding fatty acid color
value. Use platinum-cobalt color unit (Hazen) to express.
7.2 Reagents
7.2.1 Cobalt chloride hexahydrate (CoCl2·6H2O) (GB/T 1270).
7.2.2 Potassium chloroplatinate.
7.2.3 Hydrochloric acid (GB/T 622), density (ρ20) is about 1.19g/mL.
7.3 Apparatus
Common laboratory apparatus and
7.3.1 Spectrophotometer, wavelength range is 360nm~800nm, with a 10cm
cuvette.
7.3.2 Constant-temperature water bath.
7.3.3 Beaker, 50mL.
7.3.4 Volumetric flask, 1000mL.
7.4 Procedures
6 - water bath;
7 - solidification tube;
8 - wild-mouth bottle;
10 - heavy object;
11 - beaker.
Figure 1 -- Apparatus for determination of titer
8.1.1 Thermometer. 50°C~100°C; division is 0.1°C; calibration required.
8.1.2 Solidification tube. diameter is about 25mm; the length is 100mm; there
is a scale at a position 57mm from the bottom; the tube mouth is equipped with
a soft cork; the soft cork has two holes; the middle hole is inserted into the
thermometer and the other hole is inserted into glass (or stainless steel) blender.
8.1.3 Wide-mouth bottle. 450mL; the inner diameter of the bottle neck is about
38mm; the bottle mouth is equipped with a soft cork of which the diameter is
25mm hole.
8.1.4 Blender. glass or stainless steel; the lower end is bent into a ring of which
the diameter is 20mm to be perpendicular to the rod.
8.2 Procedures
Melt about 30g of specimen to make its temperature at least 10°C higher than
titer. Place in the solidification tube to the scale. Insert the thermometer and the
blender to make the mercury ball of the thermometer about 45mm below the
scale.
Place the solidification tube in the wide-mouth bottle that has a soft cork, as
shown in Figure 1.Keep the water bath temperature at around 30°C. Use the
blender that is set on the thermometer, at an amplitude of about 40mm up and
down, to evenly stir (about 80 times/min ~ 100 times/min). And observe the
temperature. When the temperature stops dropping for 30s, immediately stop
stirring. Carefully observe the sudden rise of temperature.
8.3 Result expression
8.3.1 The highest temperature of rise shall be the titer of this specimen.
Use the arithmetic mean of the results of two measurements to indicate to one
digit after the decimal point, as the determination result.
8.3.2 Precision. The absolute difference between two independent test results
obtained under repetitive conditions is not more than 0.2°C. The premise is that
the situation greater than 0.2°C does not exceed 5%.
10.1.2 Sulfuric acid c(H2SO4) = 0.001% standard solution.
Measure 6.0mL of sulfuric acid (10.1.1). Slowly pour in a small amount of
distilled water. Then dilute to 1000mL [c0(H2SO4) ≈ 0.1mol/L]. Calibrate
according to 4.4 in QB/T 2739-2005.
Use sulfuric acid that has been calibrated to calculate the number of milliliters
of sulfuric acid solution required according to 1/[c(H2SO4)×0.98]. Measure the
calculated volume of sulfuric acid solution. Pour into a 250mL volumetric flask.
Use distilled water to dilute to the scale. Completely shake well. Then pipette
25.0mL to pour into a 1000mL volumetric flask. Use distilled water to dilute to
the scale. Mix well and it shall be 0.001% standard solution.
10.1.3 Methyl orange indicator solution (1g/L), is prepared according to 5.15 in
QB/T 2739-2005.
10.2 Apparatus
Common laboratory apparatus and 5mL tube (glass one needs to be colorless).
10.3 Procedures
Weigh 5g of specimen (to the nearest of 0.1g) in a clean and dry 50mL beaker.
Heat it to make it melted. Use a measuring cylinder to add 5mL of boiled distilled
water. Heat to stir for 5min. Cool to solidify stearic acid. Take out the stearic
acid block. Pour the solution into a tube. Add one drop of methyl orange
indicator solution (10.1.3). In another tube, add an equal volume of 0.001%
sulfuric acid standard solution (10.1.2) and equivalent indicator.
10.4 Result expression
Visually compare the color of the two. The color of specimen solution is not
darker than that of sulfuric acid standard solution. It is considered that the
inorganic acid is less than 0.001%.
11 Determination of ash content
11.1 Apparatus
Common laboratory apparatus and
11.1.1 Porcelain crucible. 50mL.
11.1.2 Dryer. built-in color changing silicone.
11.1.3 High temperature electric furnace. temperature can be controlled; can
be heated to 1000°C.
12.2.3 Sulfuric acid (GB/T 625). density (ρ20) is about 1.84g/mL.
12.2.4 Ether (GB/T 12591).
12.2.5 Carrier gas. nitrogen.
12.2.6 Combustion gas. hydrogen.
12.2.7 Combustion-supporting gas. air; is supplied by a steel cylinder or air
compressor and is purified.
12.3 Apparatus
Common laboratory apparatus and
12.3.1 Gas chromatograph. with flame ionization detector, temperature
programmer.
12.3.2 Chromatographic column. filled column; the length is 2m~3m; the inner
diameter is 3mm~4mm; with built-in stationary phase (for example, DEGS is
coated on an 80 mesh ~ 100 mesh white carrier).
12.3.3 Data processor or spectrum workstation.
12.3.4 Micro-sampler. 1μL.
12.3.5 Volumetric flask. 5mL.
12.4 Procedures
12.4.1 Determination of chromatographic conditions
a) Column temperature. depend on the chromatographic column used;
DEGS column temperature is 180°C;
b) Programmed temperature rise operation. initial temperature is
150°C~180°C; heating rate is 3°C/min~5°C/min; final temperature is
200°C~240°C;
c) Vaporization chamber temperature. 300°C;
d) Detector temperature. 300°C;
e) Carrier gas flow rate. about 30mL/min~50mL/min.
12.4.2 Spectrum analysis
12.4.2.1 Methyl esterification
Take about 0.1g of specimen in a 5mL volumetric flask (12.3.5). Add 2mL~3mL
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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