GB/T 43108-2023 English PDF (GBT43108-2023)

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GB/T 43108-2023: Dyestuffs - Determination of solubility in organic solvents - Gravimetric and photometric methods
GB/T 43108-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 87.060.10
CCS G 55
Dyestuffs – Determination of Solubility in Organic Solvents
– Gravimetric and Photometric Methods
(ISO 7579:2009, MOD)
ISSUED ON: SEPTEMBER 07, 2023
IMPLEMENTED ON: APRIL 1, 2024
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 4
4 Principle ... 5
5 Solvents ... 5
6 Apparatus ... 5
7 Sampling ... 6
8 Test Methods ... 6
9 Report ... 12
Appendix A (Normative) Calculation of Solubility ... 13
Dyestuffs – Determination of Solubility in Organic Solvents
– Gravimetric and Photometric Methods
1 Scope
This Document describes 2 methods for determining the solubility of dyes in organic solvents.
This Document applies to dyes that do not undergo chemical changes under the influence of
solvents and are stable and non-volatile under specified drying conditions. The applicable dye
mass concentration is 1g/L~1000g/L. If the viscosity of the solution satisfies the conditions for
smooth operation, higher concentrations can also be used. For volatile solvents (boiling point
less than 120 ℃), the gravimetric method is used; for less volatile solvents (boiling point greater
than 120℃), the photometric method is used.
This Document does not apply to the determination of insoluble matter in dyes.
2 Normative References
The provisions in following documents become the essential provisions of this Document
through reference in 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) is applicable to this Document.
GB/T 3186 Paints varnishes and raw materials for paints and varnishes – Sampling (GB/T
3186-2006, ISO 15228:2000, IDT)
GB/T 5211.3 General methods of test for pigments and extenders - Part 3: Determination
of matter volatile at 105℃ (GB/T 5211.3-2020, ISO 797-2:1981, MOD)
GB/T 6750 Paints and varnishes - Determination of density - Pycnometer method (GB/T
6750-2007, ISO 2811-1:1997, IDT)
3 Terms and Definitions
For the purposes of this Document, the following terms and definitions apply.
3.1 Solubility
The maximum mass of dye that can be dissolved in a certain volume of a certain solvent under
certain conditions.
NOTE: Solubility is expressed in grams per liter (see Appendix A). No distinction is made between "true"
solubility and "colloidal" solubility.
4 Principle
At 23°C, dyes of different masses were dispersed in a certain volume of solvent. After mixing
for 3 h, each dispersion was centrifuged, and the solid content in the supernatant was measured
by gravimetric or photometric method.
When using the gravimetric method for measurement, the amount of dissolved dye is assessed
by measuring the amount of non-volatile matter in the solution.
When using photometric method for measurement, the amount of dissolved dye is evaluated by
comparing and determining the absorbance of the test solution and the standard solution.
5 Solvents
When using the gravimetric method, the used organic solvent shall evaporate completely below
the decomposition temperature of the dye. The density of organic solvents at 23°C shall be
known, and the density of the solvent shall be measured by using a glass pycnometer in
accordance with the provisions of GB/T 6750. The dye shall not react chemically with the
solvent.
Since organic solvents are usually not chemically pure, the purity grade (including the type and
content of major contained impurities) shall be given in the test report.
For solvents with boiling points above 120°C, it is recommended to use the photometric method.
6 Apparatus
6.1 Balance: with accuracy of 0.0001g.
6.2 Weighing bottle: flat with lid.
6.3 Container, cylinder, with capacity of approximately 50mL, made of inert material, equipped
with a sealing lid.
6.4 Pipette: with capacity of 20mL±0.03mL.
6.5 Volumetric flask: with capacity of 100mL±0.5mL.
If the limit value of the dye cannot be obtained because the viscosity continues to increase as
the amount of dye increases, the last maximum obtained value shall be recorded in accordance
with A.4.
8.2.2 Put the required amount of dye into the container (6.3); then accurately add 20mL of
solvent with a pipette (6.4); and cover it immediately to prevent the solvent from evaporating.
Shake with a mechanical vibrator for 3 h at 23°C ± 2°C; and check to confirm that there is no
significant agglomeration. If an orbital vibrator is used, it shall be stated in the test report.
8.2.3 After shaking the dye and solvent for 3 h, put the suspension into a centrifuge tube, cover
it; and centrifuge the tube at 23°C ± 2°C for 10 min. Check whether the supernatant in the
centrifuge tube is clear, for example, use a pipette to absorb the supernatant and observe
whether the solution flows smoothly. If it is not clear or in doubt, centrifuge for another 10 min;
pour the supernatant in each tube into a clean and dry container (6.3), and cover the lid.
8.3 Gravimetric determination of dissolved dye concentration
8.3.1 General
Take an appropriate amount of the supernatant prepared in 8.2.3; measure the dye concentration
according to procedure 8.3.2, and weigh it accurately to 0.2 mg.
The amount of supernatant taken for each determination shall contain at least 30 mg of dye.
Each supernatant shall be measured at least 2 times, the average value shall be recorded, and
calculated according to Formula (1).
8.3.2 Test procedures
Place about 3g of the clear supernatant into a weighing bottle with constant weight, cover it;
and weigh the mass (m0) of the supernatant. Then, remove the lid and place it in the oven (6.10);
and maintain the temperature at 10°C below the boiling point of the solvent. Take it out after
most of the solvent has evaporated (about 1 h).
Raise the temperature to about 30°C lower than the decomposition temperature of the dye, and
continue drying for 3 h.
NOTE: Most metal complex dyes can be dried at 150°C.
If the drying temperature is no higher than 50°C above the boiling point of the solvent, extend
the drying time or remove the residual solvent in a vacuum furnace so that there will be no loss
caused by dye sublimation.
After drying, place the weighing bottle and lid in a desiccator to cool, and then weigh.
If this operation is performed the first time for a specific dye/solvent combination, check that
the dye has dried to a constant mass by repeating the drying/weighing operation on a second
saturation concentration (see A.1), the repeatability is within ±5%. If the situation is as
described in A.2 and A.3, the repeatability will be very poor.
8.4 Photometric method for determination of dissolved dye concentration
8.4.1 General
This method is mainly aimed at non-volatile solvents. If used in volatile solvents, there will be
a risk of data errors due to the loss of solvent during the test process.
If a large number of samples are to be analyzed, even with less volatile solvents, consider
gravimetric analysis method as it allows for faster processing of samples in parallel.
Alternatively, use the same solvent for both the calibration solution and all other sample
solutions, so that the photometry shall be faster and there shall be no need...