GB/T 8310-2013Tea -- Determination of crude fibre content (English PDF)

Foreword

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

This standard replaces GB/T 8310-2002 "Determination of crude fiber tea." This standard compared with GB/T 8310-2002, the main technical change of the following.

--- Preparation methods increased 1.25% sulfuric acid solution;

--- Preparation methods increased 1% hydrochloric acid solution;

--- Repeatability. the difference between the results of two determinations, crude fiber per 100g sample should not exceed 0.5g, modified to duplicate the conditions hereinafter A sample assay results obtained absolute difference shall not exceed 5% of the arithmetic mean.

This standard uses redrafted Law Amendment uses ISO 15598:1999 "Tea crude fiber determination." This standard and ISO 15598:1999 Compared to the main technical differences are as follows.

--- Ash-free filter paper modify pore size 50µm (equivalent to 300 mesh) nylon cloth;

--- Blast electric oven. 103 °C ± 2 °C modify blast electric oven. 120 °C ± 2 °C; high temperature furnace.

550 °C ± 10 °C amended as high-temperature furnace. 525 °C ± 25 °C;

--- Remove the ISO 15598:1999 Chapter 11 accuracy;

--- Remove the ISO 15598:1999 Chapter 3 grouping and definitions;

--- Remove the ISO 15598:1999 Chapter 12 lab report.

This standard also made the following structural modifications.

--- The ISO 15598:1999 Sampling Chapter 7, Chapter 8 samples were prepared, measured steps to modify Chapter 9 of this standard 6.1, respectively, 6.2, 6.3.

This standard also made the following editorial changes.

--- Remove the ISO 15598:1999 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 crude fiber assay reagents and solutions, apparatus and appliances, measurement methods, procedures and results calculation.

This standard applies to the determination of crude fiber in tea.

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) Principle 3 with a certain concentration of acid, alkali digestion sample, and then the ash residue weighed. Crude fiber content calculated from the mass loss during ashing.

4 Apparatus and appliances

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

4.2 Nylon. aperture 50µm (equivalent to 300 mesh).

4.3 quality sand core glass crucible. an average pore diameter of 80µm ~ 160µm, volume 30mL.

4.4 Furnace temperature. 525 °C ± 25 °C.

4.5 blast electric oven. temperature 120 °C ± 2 °C.

4.6 dryer. containing more effective desiccant.

5 Reagents and solutions

5.1 Unless otherwise indicated, the methods used were of analytical grade reagents (AR), distilled water.

5.2 1.25% solution of sulfuric acid. lessons 6.9mL of concentrated sulfuric acid (density 1.84g/mL, mass fraction of 98.3%), a small amount of water was added slowly After cooled, the volume to 1L, shake.

5.3 1.25% sodium hydroxide solution.

5.4 volume fraction of 1% hydrochloric acid solution. take 10mL of concentrated hydrochloric acid (density of 1.18g/mL, mass fraction of 37.5%), add water to 1L, shake.

5.5 Ethanol (95%).

5.6 acetone.