GB 8921-2011Limit standards for 226Ra in phosphate fertilizer and its compound fertilizer (English PDF)

Foreword

Chapter 4, Section 5.1, and Chapter 6 in this Standard are compulsory; the rest are recommendatory.

This Standard was drafted according to the rules given by GB/T 1.1-2009.

This Standard replaces GB 8921-1988 Limit standards for 226Ra in phosphate fertilizer and its compound fertilizer. Compared with GB 8921-1988, the modifications of this Standard mainly include.

- The applicable scope is expanded from phosphate fertilizer to phosphate fertilizer and its compound fertilizer;

- This revision reserves the GB 8921-1988's limit requirements of 226Ra in phosphate fertilizer; and deletes the requirements to phosphate ore.

- Provide the methods of sample collection and preparation in the form of Annex; and add the method of analyzing 226Ra with gamma energy spectrum.

This Standard was proposed and shall be centralized by the Ministry of Health of the People's Republic of China.

This Standard shall be interpreted by the Ministry of Health of the People's Republic of China.

Drafting organization of this Standard. Health Supervision Institute of Jinlin Health Department.

Main drafters of this Standard. Yan Chuang, Sun Wuchang, Li Tao, Shi Yan, An Fucai, Piao Yongde, and Wang Kexin.

The previous version replaced by this Standard is.

- GB 8921-1988.

1 Scope

This Standard stipulates the 226Ra's limited indicators in phosphate fertilizer and its compound fertilizer (hereafter abbreviated as phosphate fertilizer), as well as the corresponding sampling, inspection requirements, and the result judgment.

This Standard applies to the agricultural (including vegetables, fruits and other food crops) phosphate fertilizer.

2 Normative references

The articles contained in the following documents have become part of this document when they are quoted herein. For the dated documents so quoted, all the modifications (including all corrections) or revisions made thereafter shall be applicable to this document.

GB 11713 Standard methods of analyzing low specific gamma radioactivity samples by semiconductor gamma spectrometers

GB 11743 Determination of radionuclides in soil by gamma spectrometry

3 Terms and definitions

For the purpose of this Standard, the following terms and definitions shall apply.

5 Inspection requirements

5.1 The quality inspection department of manufacturer shall conduct sample collection once a year; collect the samples when the production process or raw materials or mix proportion are changed; and send to the qualified testing agency for inspection.

5.2 The collection and preparation of samples of phosphate fertilizer and its compound fertilizer shall be carried out according to the method given in Annex A.

5.3 The measurement and arbitration of 226Ra content in phosphate fertilizer and its compound fertilizer shall be conducted according to emanation scintillation method given in Annex B.

5.4 The measurement of 226Ra content in phosphate fertilizer and its compound fertilizer shall be conducted according to gamma energy spectrum method given in GB 11713 and GB 11743.

6 Result judgment

If the 226Ra content in phosphate fertilizer is tested to be less than 500 Bq·kg-1, it is deemed as qualified. If the 226Ra content in phosphate fertilizer is tested to be more than 500 Bq·kg-1, it shall re-collect the test samples; if the retest result still exceeds 500 Bq·kg-1, it is deemed as unqualified.

Accurately weigh 1.00g of sample; put it into the nickel crucible; add 2 - 4 g of anhydrous sodium carbonate and 6g of sodium peroxide; stir evenly; then uniformly cover a layer of about 3g of sodium peroxide. Put the crucible into 650-700°C muffle furnace; melt it for 7-8 minutes; when the melt is in red fluid, take it out and slightly cool it.