GB/T 8307-2013Tea -- Determination of water-soluble ash and water-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 8307-2002 "tea-soluble ash and water - insoluble ash content." This standard and GB/T 8307-Compared to 2002, the main technical changes are as follows.

--- Increased the determination of water insoluble ash retention for acid insoluble ash;

--- Repeatability. the difference between the results of two determinations, soluble ash per 100g sample should not exceed 0.2g, modified to duplicate conditions the absolute difference between the measurement results of the same sample must not exceed 5% of the arithmetic mean.

This standard uses redrafted law revision using ISO 1576. 1988 "tea-soluble ash and water-insoluble ash determination." The standard Aligned with the ISO 1576. 1988 as compared to the main technical differences are as follows.

--- 5g sample quality measurement modify 2g, ashing process does not add vegetable oil;

--- Assay filtrate and washings from 60mL volume into 150mL;

--- Repeatability. the difference between the results of two determinations, soluble ash per 100g sample should not exceed 0.2g, modified to duplicate conditions the absolute difference between the measurement results of the same sample must not exceed 5% of the arithmetic mean;

--- Remove the ISO 1576. 1988, Chapter 8 test reports.

This standard also made the following editorial changes.

--- Remove the ISO 1576. 1988 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 soluble ash and water-insoluble ash measurement apparatus and appliances, measurement methods, procedures and results calculation.

This standard applies to the determination of tea soluble ash and water-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.

Soluble ash water-solubleash Under specified conditions, some of the water of the total ash dissolved.

Water-insoluble ash Under specified conditions, the total ash content of the water-insoluble part.

Principle 4

Total ash was extracted with hot water, the ash-free filter paper, burning, weighing the residue measured water insoluble ash; from the total ash and water-insoluble Poor quality of the ash calculation soluble ash.

5 Instruments and appliances

5.1 Crucible. Platinum porcelain or other conditions will not be affected by the determination of the material. High type, capacity 30mL.

5.2 Electric hot plate.

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

5.4 crucible tongs.

5.5 boiling water bath.

5.6 dryer. containing more effective desiccant.

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