GB/T 8308-2013Tea -- Determination of acid-insoluble ash content (English PDF)

Foreword

This standard was drafted in accordance with GB/T 1.1-2009 given rules.

This standard replaces GB/T 8308-2002 "tea acid insoluble ash content." This standard compared with GB/T 8308-2002, the main Technical differences are as follows.

--- Modify the repeatability requirement. Each 100g sample shall not exceed 0.02g, revised as measured under the same conditions repeated sample obtained Given absolute difference may not exceed 10% of the arithmetic mean.

This standard uses redrafted law revision using ISO 1577. 1987 "tea acid insoluble ash content." This standard and ISO 1575.

Compared to 1987, the main technical changes are as follows.

--- Preparation ash does not add vegetable oil;

--- When measured by the turbidity of the solution process becomes transparent, heating was continued for 5min, then washed neutral;

--- Repeatability. the difference between the results of two measurements per 100g sample of acid-insoluble ash shall not exceed 0.02g, modified to repeat the absolute difference of the same sample obtained under the conditions of the measurement result shall not exceed 10% of the arithmetic mean;

--- Remove the ISO 1575. 1987 Chapter 9 test reports.

This standard also made the following editorial changes.

--- Remove the ISO 1575. 1987 Foreword.

The standard proposed by China Federation of Supply and Marketing Cooperatives.

This standard by the National Standardization Technical Committee of tea (SAC/TC339) centralized.

This standard was drafted. China Federation of Supply and Marketing Cooperatives Hangzhou Tea Research Institute, the National Tea Quality Supervision and Inspection Center.

1 Scope

This standard specifies the tea acid insoluble ash content of reagents and solutions, apparatus and appliances, measurement methods, procedures and results calculation.

This standard applies to the determination of Tea by acid-insoluble ash.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version suitable for use herein Member. For undated references, the latest edition (including any amendments) applies to this document.

GB/T 8302 sampling Tea (GB/T 8302-2013, ISO 1839. 1980, NEQ) GB/T 8303 Tea grated dry matter content of the sample preparation and measurement (GB/T 8303-2013, ISO 1572. 1980, MOD) GB/T 8306 Tea Determination of total ash (GB/T 8306-2013, ISO 1575. 1987, MOD)

3 Terms and Definitions

The following terms and definitions apply to this document.

Acid insoluble ash Under specified conditions, the remaining part of the total ash with hydrochloric acid after the treatment.

Principle 4

Total ash treated with hydrochloric acid solution, filtered, and burning the residue weighed after ignition.

5 Reagents and solutions

10% hydrochloric acid solution. 24mL AR concentrated hydrochloric acid (density 1.18g/mL, mass fraction of 37.5%) was diluted with distilled water to 100mL.

6 Apparatus and appliances

6.1 Crucible. Platinum porcelain or other conditions will not be affected by the determination of the material. High type, capacity 50mL.

6.2 Electric hot plate.

6.3 high-temperature furnace. temperature 525 °C ± 25 °C.

6.4 water bath.

6.5 dryer. containing more effective desiccant.

6.6 Analysis of balance. a sense of the amount of 0.001g.