GB/T 12496.9-2015 English PDF (GBT12496.9-2015)

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GB/T 12496.9-2015: Test methods of wooden activated carbon -- Determination of decolorization of caramel
GB/T 12496.9-2015
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.020
B 73
Replacing GB/T 12496.9-1999
Test Methods of Wooden Activated Carbon -
Determination of Decolorization of Caramel
ISSUED ON: JULY 03, 2015
IMPLEMENTED ON: NOVEMBER 02, 2015
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Method Summary ... 4
4 Main Instruments ... 4
5 Main Reagents ... 5
6 Preparation and Identification of caramel Liquid ... 5
7 Operation Procedures ... 7
8 Expression of Caramel Decolorization Results ... 8
Test Methods of Wooden Activated Carbon -
Determination of Decolorization of Caramel
1 Scope
This Standard specifies the test method for the decolorization ratio of caramel
pigments by wood activated carbon.
This Standard is applicable to the determination of the decolorization ratio of caramel
by various types of activated carbon for decolorization.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) are applicable to this document.
GB/T 6682-2008 Water for Analytical Laboratory Use - Specification and Test
Methods
GB/T 9721-2006 Chemical Reagent - General Rules for the Molecular Absorption
Spectrophotometry (Ultraviolet and Visible)
3 Method Summary
The sample and caramel are mixed and absorbed, then filtered; and use a
spectrophotometer to measure the absorbance of the filtrate.
4 Main Instruments
4.1 1000mL three-neck flask.
4.2 Electric mixer (variable speed).
4.3 Glass thermometer (scale 0°C ~ 200°C).
sodium carbonate dissolved in 50mL of water) to the three-neck flask; and keep stirring
until the foam disappears. Pour out after identifying it is qualified; store it into the bottle
with the ground stopper; and place in the dark; the use period is one month. If it is
stored in the refrigerator, store it at -1°C ~ 5°C, the use period is one year.
NOTE: For Sugar-A, the preparation temperature of sugar solution is (125±1) °C; for Sugar-B,
it is (118±1) °C, which is the temperature under standard state. If the altitude changes, the
holding time shall be adjusted appropriately.
6.1.2 Identification of Method-A caramel stock solution
Take 0.833g of caramel stock solution; add water to dissolve and make constant
volume to 500mL. Then use the spectrophotometer to measure the absorbance in a
cuvette with a wavelength of 426nm and a light path length of 1cm; and the absorbance
difference with the potassium dichromate color standard solution I under the same
conditions shall be no greater than ±0.03. If the absorbance exceeds the above
provisions, add a little water to the original solution or evaporate a little water to achieve
the specified absorbance.
6.2 Method-B caramel
6.2.1 Preparation of Method-B caramel stock solution
Take 250g of anhydrous glucose; place it in a 1000mL three-neck flask; add 250mL of
water; install an electric mixer and thermometer; and open the other neck. Place the
flask in a glycerin bath (the glycerin may be heated in advance), so that the level of the
sugar liquid in the flask is consistent with the level of the glycerin bath. After all the
sugar is dissolved, start the mixer to raise the temperature of the oil bath and keep it
at (145±5) °C. When the sugar liquid began to boil, sequentially add 5.0g of anhydrous
sodium carbonate and continuously mix; maintain the uniform temperature-rise rate.
Within 25min~30min, the addition of anhydrous sodium carbonate shall be completed;
and raise the temperature of the sugar solution evenly to (118±1) °C; keep at this
temperature for 30min (the temperature of the oil bath shall be appropriately reduced
during the heat preservation). If the temperature of sugar solution exceeds the
specified temperature, a little cold water may be added dropwise. After the heat
preservation is completed, remove the heating device; slowly add 50 mL of sodium
carbonate solution (5.0g of anhydrous sodium carbonate dissolved in 50mL of water)
to the three-neck flask; and keep stirring until the foam reduces. Pour out after
identifying it is qualified; store it into the bottle with the ground stopper; and place in
the dark; the use period is one month. If it is stored in the refrigerator, store it at -1°C
~ 5°C, the use period is one year.
NOTE: For Sugar-A, the preparation temperature of sugar solution is (125±1) °C; for Sugar-B,
it is (118±1) °C, which is the temperature under standard state. If the altitude changes, the
holding time shall be adjusted appropriately.
6.2.2 Identification of Method-B caramel stock solution
Take 1.00g (accurate to 0.01g) of caramel stock solution; add water to dissolve and
make constant volume to 500mL. Then use the spectrophotometer to measure the
absorbance in a cuvette with a wavelength of 426nm and a light path length of 1cm;
and the absorbance difference with the potassium dichromate color standard solution
I under the same conditions shall be no greater than ±0.03. If the absorbance exceeds
the above provisions, add a little water to the original solution or evaporate a little water
to achieve the specified absorbance.
6.3 Potassium dichromate color standard solution
6.3.1 Potassium dichromate color standard solution I
The potassium dichromate is ground in a mortar; and place it in an electric drying oven
adjusted to (115±5) °C to dry to constant weight. Take 0.420g; add water to dissolve
and transfer to a 1000mL volumetric flask to make constant volume.
6.3.2 Potassium dichromate color standard solution II
The potassium dichromate is ground in a mortar; and place it in an electric drying oven
adjusted to (115±5) °C to dry to constant weight. Take 0.325g, dissolve it with water
and transfer to a 1000mL volumetric flask to make constant volume.
6.4 Preparation of caramel test solution
Take 17.00g (accurate to 0.01g) of the certified caramel stock solution of Method A or
Method B; dissolve it with water and transfer to a 500mL volumetric flask to make
constant volume. After preparation, use it on the same day; or store it in the refrigerator
at -1°C ~ 5°C; the period of use is 3 months. Test solution preparation may be reduced
or increased in proportion.
7 Operation Procedures
7.1 Method-A caramel decolorization
Take 0.400g (accurate to 1mg) of the dried sample crushed to a particle size ≤71μm
(through a 200-mesh sieve); place it in a 100mL conical flask with a stopper; add 25mL
of caramel test solution by a pipette; and shake it slightly to wet the sample. Cover the
glass stopper and insert a filter paper strip about 1cm wide between the glass stopper
and the bottle mouth to maintain a slight gap between the glass stopper and the bottle
mouth. Place the flask in a boiling water bath and heat for 30 min (shake the flask once
every 5min); take out and cool it; then filter it by the 12.5cm-diameter medium-speed
qualitative filter paper. After discarding about 5mL of the initial filtrate, the remaining
liquid is transferred into a cuvette with 1cm light path; use a spectrophotometer to