This standard specifies the principle, instruments and utensils, determination steps and result calculation method for the determination of total ash content in tea. This standard is applicable to the determination of total ash content in tea. GB/T 8306-2002 Determination of total ash content in tea GB/T8306-2002 Standard download decompression password: www.bzxz.net

GB/T8306--2002
Specialized in Determination of Total Ash Content. This standard is equivalent to ISO1575:1987 "Tea. This standard is a revision of GB/T8306-1987 "Determination of Total Ash Content of Tea".
The main difference between this standard and ISO1575:1987 is that the sample mass is 2g and no vegetable oil is added during the ashing process. This standard is revised mainly in accordance with the requirements of GB/T1.1-1993 Guidelines for Standardization Work Unit 1: Drafting and Presentation Planning Part 1: Basic Provisions for Standardization", and some modifications have been made to GB/T8306-1987 in terms of format and text, but the specific technical content has not changed.
This standard will be implemented from the date of implementation and will replace GB/T8306-1987. This standard was proposed by the All-China Federation of Supply and Marketing Cooperatives. This standard is under the jurisdiction of the Hangzhou Tea Research Institute of the All-China Federation of Supply and Marketing Cooperatives. The drafting unit of this standard is the Hangzhou Tea Research Institute of the All-China Federation of Supply and Marketing Cooperatives. The main drafters of this standard are Guan Huixian and Sha Haitao. The Hangzhou Tea Research Institute of the All-China Federation of Supply and Marketing Cooperatives is responsible for the interpretation of this standard. 121
GB/T8306--2002
ISO Foreword
ISO () (International Organization for Standardization) is an international alliance of national standardization organizations (IS () member groups). Usually, the work of formulating international standards is undertaken by the IS () technical committee. Each member group has the right to become a representative of the project committee if interested. Official or unofficial international standard organizations related to IS () also participate in the work. ISO) and the International Electrotechnical Commission (IEC) work closely on electrotechnical standard documents.
The draft international standards adopted by the technical committee are submitted to the member groups for voting. The publication of international standards must obtain the approval votes of not less than 75% of the member groups.
International Standard ISO) 1575 was prepared by IS/TC34 Technical Committee for Agri-food Products. The third edition (ISO) 1575:1987) replaces the second edition (ISO1575:1980), which has been revised. 122
1 Scope
National Standard of the People's Republic of China
Determination of total ash
Tea--Determination of total ash contentGB/T8306—2002
cqv 1ISO 1575:1987
Replaces GB/T8306-1987
This standard specifies the principle, apparatus and utensils, determination steps and result calculation method for the determination of total ash in tea. This standard applies to the determination of total ash in tea. 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown are valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T8302-2002 Tea sampling
GB/T8303--2002 Preparation of ground tea samples and determination of dry matter content 3 Definitions
This standard adopts the following definitions.
Total ash
The residue obtained after tea leaves are burned to ashing at 525℃±25℃ under specified conditions. 4 Principle
The sample is heated and burned at 525℃±25 to decompose organic matter to a constant amount. 5 Instruments and appliances
Routine laboratory instruments and the following items:
5.1 Crucible: porcelain, high type, capacity 30mL. 5.2 Electric heating plate.
5.3 High-temperature electric furnace: 525℃±25℃.
5.4 Dryer: Contain effective desiccant.
5.5 Glass tongs.
5.6 Analytical balance: Sensitivity 0.001g.
6 Determination steps
6.1 Sampling
According to the provisions of GB/T8302.
6.2 Sample preparationbZxz.net
According to the provisions of (GB/T8303.
Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on June 17, 2002 and implemented on December 1, 2002
6.3 Preparation of crucible
GB/T8306-2002
Place the clean crucible in a high-temperature furnace at 525℃±25℃ and burn for 1h. When the furnace temperature drops to about 300℃, take out the crucible, cool it to room temperature in a desiccator, and weigh it (accurate to 0.001g). 6.4 Determination
Weigh 2g of the mixed ground sample (accurate to 0.001g) into the crucible and heat it slowly on an electric hot plate to fully carbonize the sample until there is no smoke. Move the crucible into a high-temperature furnace at 525℃±25℃ and burn until there are no carbon particles (not less than 2h). When the furnace temperature drops to about 300°C, take out the crucible, place it in a dryer to cool to room temperature, and weigh it. Move it to a high-temperature furnace and burn it at the above temperature for 1 hour, take it out, cool it, and weigh it. Move it to a high-temperature furnace again, burn it for 30 minutes, take it out, cool it, and weigh it. Repeat this operation until the difference between two consecutive weighings does not exceed 0.001g. The minimum weighing shall prevail.
6.5 If necessary, the total ash can be retained for the determination of water-soluble ash and water-insoluble ash. 7 Result calculation
7.1 Calculation method
The total ash of tea is expressed as a dry mass fraction. The total ash (%) is calculated according to formula (1):
-mass of the sample and crucible after burning, g;
Where: M—-
M2—increased mass, g;
M. Sample mass, g;
Dry matter content of the sample, %.
Mi - M2
M。 X m
If the repeatability meets the requirements of (7.2), take the arithmetic mean of the two measurements as the result (keep one decimal place). 7.2 Repeatability
The difference between the two measured values ​​of the same sample shall not exceed 0.2g per 100g of sample. 124
：(1)
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