Detail of NY/T 3174-2017

Introduction of NY/T 3174-2017

Water-soluble fertilizers - Determination of alginic acid content 1 Scope This standard specifies the m-hydroxybiphenyl spectrophotometry test method for the determination of alginic acid (algin) content in water-soluble fertilizers. This standard is applicable to liquid or solid water-soluble fertilizers made from Laminaria japonica, Sargassum, Ascophyllum nodosum and other brown algae through biological, chemical and physical extraction and processing. This method is not applicable to water-soluble fertilizers containing nitrate radical, humic acids and other substances interfering the colorimetric process. Annex A hereto lists the carbazole-sulfuric acid spectrophotometry test method for the determination of alginic acid content. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. HG/T 3696 Inorganic chemicals for industrial use - Preparations of standard and reagent solutions for chemical analysis NY/T 887 Liquid fertilizers - Determination of density 3 Principle Polyhexuronic acid can react with m-hydroxybiphenyl to form a purplish red compound in the presence of sulfuric acid containing sodium tetraborate. Then measure its absorbance at a wavelength of 520 nm. In a certain concentration range, the absorbance of the compound is in direct proportion to the concentration of uronic acid which, therefore, can be determined by spectrophotometry. 4 Reagents and materials For the purpose of this standard, unless otherwise specified as to the specification or the preparation method, the preparation of the reagents, water, and solutions shall comply with those specified in HG/T 3696. 4.1 Concentrated sulfuric acid: guaranteed reagent. 4.2 Sodium tetraborate-sulfuric acid solution, c(Na2B4O7•10H2O) = 0.012 5 mol/L. Accurately weigh 0.478 g of the sodium tetraborate decahydrate with a 100-mL beaker, then dissolve it with concentrated sulfuric acid (4.1), and then transfer it to a 100-mL volumetric flask and dilute to constant volume with concentrated sulfuric acid (4.1). 4.3 Sodium hydroxide solution: ρ(NaOH)=5 g/L. 4.4 m-hydroxybiphenyl solution: ρ(C12H10O)=1.5 g/L. Weigh 0.15 g of m-hydroxybiphenyl, then dissolve it in 100 mL of sodium hydroxide solution (4.3), and then put it in a brown bottle and store it in a dark place. 4.5 Sodium alginate standard solution: ρ(Sodium alginate) = 0.100 g/L. Accurately weigh 0.100 g of sodium alginate with a 100-mL beaker, then dissolve it with water, and then transfer it to a 1,000-mL volumetric flask and dilute to constant volume with water.

Contents of NY/T 3174-2017

Foreword i 1 Scope 2 Normative references 3 Principle 4 Reagents and materials 5 Instruments 6 Analytical procedure 7 Expression of analysis results 8 Tolerance 9 Conversion of mass concentration Annex A (Informative) Carbazole-sulfuric acid spectrophotometry test method for determination of alginic acid content