GB/T 19203-2003 English PDF (GBT19203-2003)

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GB/T 19203-2003: Determination of calcium, magnesium and sulphur content for compound fertilizer
GB/T 19203-2003
GB
NATIONAL STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
ICS 65.080
G 20
Determination of calcium, magnesium and
sulphur content for compound fertilizer
ISSUED ON. JUNE 23, 2003
IMPLEMENTED ON. DECEMBER 1, 2003
Issued by. General Administration of Quality Supervision, Inspection
and Quarantine of People’s Republic of China
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Test methods ... 4 
Foreword
This Standard refers to the International standard ISO 10084.1992 Solid
fertilizers - Determination of mineral-acid-soluble sulfate content - Gravimetric
method for the determination of sulphur content for compound fertilizer. The
determination of calcium and magnesium content uses EDTA volumetric
method.
This Standard was proposed by China Petroleum and Chemical Industry
Association.
This Standard shall be under the jurisdiction of National Technical Committee
on Fertilizers and Soil Conditioning Agents of Standardization Administration of
China.
The drafting organizations of this Standard. Shanghai Chemical Industry
Research Institute, China-Arab Fertilizer Company Limited.
Main drafters of this Standard. Fan Bin, Wang Lianjun, Zhang Qiuzhen, Wang
Yin, Du Xianlan, Liu Gang, Liu Yun.
Determination of calcium, magnesium and
sulphur content for compound fertilizer
1 Scope
This Standard specifies the determination of total calcium, magnesium and
sulphur content in compound fertilizer.
This Standard is applicable to the determination of total calcium, magnesium
and sulphur content in all kinds of compound fertilizers.
2 Normative references
The following standards contain the provisions which, through reference in this
Standard, constitute the provisions of this Standard. For dated references,
subsequent amendments (excluding corrections) or revisions do not apply to
this Standard. However, the parties who enter into agreement based on this
Standard are encouraged to investigate whether the latest versions of these
documents are applicable. For undated reference documents, the latest
versions apply to this Standard.
GB/T 8571 Preparation of laboratory samples for compound fertilizers
HG/T 2843-1997 Chemical fertilizer Products-standard volumetric,
standard, reagent and indicator solutions for chemical analysis
3 Test methods
3.1 General provisions
The preparation of reagents, water and solutions used in this Standard, in the
absence of specifications and preparation methods, it shall be in accordance
with the provisions of HG/T 2843-1997.
3.2 Laboratory sample preparation
Prepare the laboratory sample according to the provisions of GB/T 8571.
3.3 Preparation of sample solution
3.3.1 Reagents and materials
3.4.2.6 Ammonia-ammonium chloride buffer solution. pH ≈ 10; prepare it
according to the method in 9.5.1 of HG/T 2843-1997;
3.4.2.7 Disodium edetate (EDTA) standard titration solution. c(EDTA) = 0.02
mol/L;
3.4.2.8 Malachite green indicator solution. 1 g/L;
3.4.2.9 Calcein - methyl thymol blue indicator (referred to as calcein indicator).
grind and well mix 0.10 g of calcein and 0.10 g of methyl thymol blue (or methyl
thymol blue), 0.03 g of thymol phenolphthalein, 5 g of potassium chloride; store
in grinding mouth bottle, it is ready for later use;
3.4.2.10 Acid chrome blue K-naphthol green B mixed indicator (referred to as
K-B indicator).
3.4.3 Apparatus
General laboratory instruments.
3.4.4 Analysis steps
3.4.4.1 Determination of total calcium content
3.4.4.1.1 Content determination
Accurately pipet a certain amount of sample solution (less than 15 mg, in Ca)
in an Erlenmeyer flask. Add 50 mL of water, 10 mL of starch solution, 8 mL of
triethanolamine solution, 1 mL of ethylenediamine, 1 drop of malachite green
indicator solution. Drop-add potassium hydroxide solution till it is colorless. And
add an excess of 10 mL. Add 0.1 g of hydroxylamine hydrochloride (each
reagent must be well shaken when it is added). Add 0.1 g ~ 0.3 g of calcium
yellow indicator. On a black background, immediately use disodium edetate
(EDTA) standard titration solution to titrate till green fluorescence disappears. It
shall be the end of titration when it appears in purple-red.
3.4.4.1.2 Blank test
Except that sample is not added, it must use reagents, dosage and analysis
steps which are identical with sample determination to carry out the parallel test.
3.4.5 Expression of analysis results
3.4.5.1 Total calcium (in Ca) content w1, expressed in mass fraction (%), shall
be calculated according to equation (1).