GB/T 8573-2010Determination of available phosphorus content for compound fertilizers (English PDF)

Foreword

This Standard is one of the series of standards for compound fertilizer test methods.

These series of national standards are listed below.

- GB/T 8571-2008 "Preparation of laboratory samples for compound fertilizers";

- GB/T 8572-2010 "Determination of total nitrogen content for compound fertilizers

titrimetric method after distillation";

- GB/T 8573-2010 "Determination of available phosphorus content for compound

fertilizers";

- GB/T 8574-2010 "Determination of potassium content for compound fertilizers

potassium tetraphenylborate gravimetric method";

- GB/T 8576-2010 "Determination of free water for compound fertilizers - Vacuum

oven method";

- GB/T 8577-2010 "Determination of free water for compound fertilizers - Karl

Fischer method";

- GB/T 24890-2010 "Determination of chloride content for compound fertilizers";

- GB/T 24891-2010 "Determination of particle size for compound fertilizers".

This Standard replaces GB/T 8573-1999 "Determination of available phosphorus

content for compound fertilizers".

Main difference between this edition and the previous edition is. the standard format is

rewritten according to the rules of standardization work.

This Standard is proposed by China Petroleum and Chemical Industry Association.

This Standard is under the jurisdiction of National Technical Committee on Fertilizers

and Soil Conditioners of Standardization Administration of China (SAC/TC 105).

Responsible drafting organizations of this Standard. National Center for Quality

Supervision and Testing of Fertilizers (Shanghai), Stanley Fertilizer Co., Ltd.

Main drafters of this Standard. Zhang Minghong, Liu Yun, Wu Juan, Gao Jinhua.

This Standard was first issued in 1988 and revised for the first time in 1999.

Determination of available

phosphorus content for compound fertilizers

1 Scope

This Standard specifies the extraction and determination method for water-soluble

phosphorus content and available phosphorus content for compound fertilizers and

specifies the calculation method for the percentage of water-soluble phosphorus in

available phosphorus.

This Standard applies to compound fertilizers containing phosphorus (including mixed

fertilizers), does not apply to compound fertilizers, such as ammonium phosphate,

nitric acid phosphate and potassium dihydrogen phosphate, that are synthesized by

chemical method.

2 Normative references

The following standards contain provisions which, through reference in this Standard,

constitute provisions of this Standard. For dated reference, subsequent amendments

to (excluding corrections to), or revisions of, any of these publications do not apply.

However, the parties to agreements based on this Standard are encouraged to

investigate the possibility of applying the most recent editions of the standards. For

undated references, the latest edition of the normative document referred to applies.

GB/T 8571 Preparation of laboratory samples for compound fertilizers

HG/T 2843 Chemical fertilizer products - Standard volumetric standard reagent and

indicator solutions for chemical analysis

3 Principle

USE water and ethylenediamine tetraacetic acid disodium (EDTA) solution to extract

water-soluble phosphorus and available phosphorus from compound fertilizers. In acid

medium, orthophosphate ions in the extract react with quimociac reagent and produce

yellow quinoline phosphomolybdate precipitates. USE quinoline phosphomolybdate

gravimetric method to determine the phosphorus content.

7 Expression of analysis results

25 - the value of the volume of the pipetted sample solution, in milliliters (mL);

250 - the value of the total volume of the sample solution, in milliliters (mL);

m3 - in determination of available phosphorus, the value of the mass of the quinoline

phosphomolybdate precipitates obtained, in grams (g);

m4 - in determination of available phosphorus, the value of the mass of the quinoline

phosphomolybdate precipitates obtained in the blank test, in grams (g);

mB - in determination of available phosphorus, the value of the mass of the sample,

in grams (g).

The calculation results are expressed as two digits after the decimal point, and the

arithmetic mean of the parallel determination results is taken as the determination

result.