HG/T 5515-2019Monoammonium phosphate and diammonium phosphate containing alginic acid (English PDF)

3.1 Alginic acid

a polysaccharide that is formed by a linear polymerization of monouronic acid, which is a block copolymer formed by 1,4 glycosidic bonds using monomers of beta-1,4-

3.2 Monoammonium phosphate and diammonium phosphate containing alginic acid

products with a function of lowering a phosphorus fixation rate are prepared by adding seaweed liquid or seaweed powder prepared after extraction with seaweed as a main raw material into monoammonium phosphate and diammonium phosphate production processes

3.3 Fixation variance rate of water-soluble phosphorus

the water-soluble phosphorus in the monoammonium phosphate and diammonium phosphate reacts with calcium ions to form a precipitate. By measuring the remaining water-soluble phosphorus, a water-soluble phosphorus fixation rate of the monoammonium phosphate or diammonium phosphate (a ratio of the water-soluble phosphorus fixed by the calcium ions to total water-soluble phosphorus) and a water-soluble phosphorus fixation rate of the monoammonium phosphate or diammonium phosphate containing alginic acid are calculated, and a ratio of a difference between the two water-soluble phosphorus fixation rates to the former water-soluble phosphorus fixation rate is calculated

4.1 Appearance

The products are brown granular or powdery and free of mechanical impurities.

4.2 Technical Indicators

Monoammonium phosphate and diammonium phosphate containing alginic acid shall meet the requirements of Table 1.

5.1 General Regulation

Unless otherwise specified, the water used in this standard shall be in accordance with HG/T 2843; reagents used in this standard refer to analytical reagents when other requirements are not specified. Standard volumetric solutions, standard solutions preparations, reagent solutions and indicator solutions used in this standard shall be prepared in accordance with HG/T 2843 when a preparation method is not specified.

5.2 Appearance

Visual observation.

5.3 Total Nitrogen Content

In accordance with GB/T 10209.1.

5.5 Alginic Acid

In accordance with Appendix A.

5.6 Fixation Variance Rate of Water-Soluble phosphorus

In accordance with Appendix B.

5.7 Determination of Water Content

In accordance with GB/T 10209.3.

5.8 Particle Size

In accordance with GB/T 10209.4.

6.1 Inspection Categorization and Inspection Items

Product inspection includes ex-factory inspection and type inspection. Except for the fixation variance rate of water-soluble phosphorus, other items in Chapter 4 belong to ex-factory inspection. Type inspection items, including all the items in Chapter 4, shall be conducted:

- A new product design finalization and batch pilot production finalization need to be appraised.

- After normal production, structures, raw materials or production processes change significantly, and product quality indicators may be affected;

- During normal production, type inspection should be carried out periodically and at least once every 6 months;

- Production resumes after suspension for a long time;

- When product quality supervision agencies put forward a request for type inspection.

6.2 Batching

Products are inspected in batches. An output of one shift or one day is considered to be one batch. The maximum batch is 1,000 t.

6.3.1 Bagged products

When there are no more than 512 bags, determine the minimum number of sampling bags according to Table 2; when more than 512 bags, determine the minimum number of sampling bags according to a calculation result of the formula (1), and if encounters a decimal, it is rounded up.

According to the calculation result of Table 2 or formula (1), randomly select the number of sampling bags, insert a sampler from the longest diagonal of each bag to a 3/4 position of the bag to take more than or equal to 100 g of a sample and the sample amount for each batch shall be more than or equal to 2 kg.

6.3.2 Bulk products

Sampling in accordance with GB/T 6679.

6.4 Sample Splitting and Sample Preparation

6.4.1 Sample Splitting

Split the collected sample quickly to 600~1,200 g with a splitting device or a quartering method, sub-package the split sample into two clean and dry wild-mouth bottles with ground glass stoppers or polyethylene bottles, stick labels and mark the name of a manufacturer, product name, product category, batch number or production date, sampling date and the name of a sample taker. One bottle is used for product quality analysis and one bottle is stored for two months for future use.

6.4.2 Sample Preparation

Take a bottle of the sample from 6.4.1, take out about 100 g of the sample after multiple splitting, grind the sample until all passes through a sieve with a mesh diameter of 0.50 mm, mix well, and place the treated sample in a clean and dry bottle. If it is a granular product, the remaining sample is for a particle size determination.

6.5 Result Determination

6.5.1 Whether the items of the product are qualified is determined by the "rounding value comparison method" of GB/T 8170.

6.5.2 When all inspection results of the inspection items meet the requirements of this standard, the batch of products is deemed to be qualified.

6.5.3 During the factory inspection, if one of the indicators in the inspection results does not meet the requirements of this standard, retake twice the samples from packaging bags for inspection, and in reinspection results, even if one indicator does not meet the requirements of this standard, the entire product batch is deemed to be unqualified.

6.5.4 Each batch of the conforming factory products shall be accompanied by a quality certificate whose content includes: the name and address of the manufacturer, product name, product category, batch number or production date, total nutrient, formula or main nutrient content, alginic acid content, fixation variance rate of water-soluble phosphorus (marked with the result of the most recent type inspection), the number of this standard and the content that must be marked by laws and regulations.

A.1 Method Abstract

Alginic acid is hydrolyzed into uronic acid under the reaction with sodium tetraborate-containing sulfuric acid solution, the uronic acid further reacts with m-hydroxybiphenyl to form a red derivative. Within a certain concentration range, an absorbance value of this derivative at a wavelength of 520 nm presents a linear positive correlation with the uronic acid content. Thus, the uronic acid content can be determined by spectrophotometry.

A.2 Reagents and Solutions

A.2.1 A D-glucuronic acid (C6H10O7) stock solution: 10 mg/mL.

Weigh 10.00 g of D-glucuronic acid, dissolve in water, and dilute to a constant volume of 1 L. A.2.2 A D-Glucuronic acid standard solution: 0.1 mg/mL.

Pipette 1.00 mL of the D-glucuronic acid stock solution (A.2.1) in a 100 mL volumetric flask, and dilute with water to a constant volume. A.2.3 A sodium tetraborate/sulfuric acid solution.

Weigh 4.78 g of sodium tetraborate and dissolve in 1 L of concentrated sulfuric acid for use. A.2.4 A M-hydroxybiphenyl solution: 1.5 mg/mL.

Weigh 0.15 g of m-hydroxybiphenyl and dissolve in 100 mL of a sodium hydroxide solution with a concentration of 5 mg/mL.

A.3 Instruments

A.3.1 Visible spectrophotometer.

A.3.2 Common laboratory devices.

A.4 Test Procedure

A.4.1 Plotting of standard curve

Respectively pipette 0 mL, 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL and 1.0 mL of the D-glucuronic acid standard solution (A.2.2) into a 20 mL graduated test tube, and make up to 1 mL with water respectively. The mass of the obtained D-glucuronic acid of the standard series is 0 µg, 20 µg, 40 µg, 60 µg, 80 µg and 100 µg, respectively. Place the test tube in an ice water bath, slowly add 6 mL of the sodium tetraborate/sulfuric acid solution (A.2.3) along a wall of the test tube while shaking, start at about one drop per second, increase to about two drops per second after adding half of it, seal the test tube with a stopper, heat in a boiling water bath for 5 min, cool to a room temperature in an ice water bath, add 100 µL of 1.5 mg/mL of the M-hydroxybiphenyl solution, mix well, put still at room temperature for 10 min, use 0 µg/mL of the D-glucuronic acid standard solution for zero setting and perform a colorimetry at 520 nm by using a cuvette with an optical path of 1 cm. Plot a standard curve with the mass of […]

A.4.2 Determination

Weigh 2 g~10 g (accurate to 0.0002 g) of a sample obtained by passing a 0.5-mm sieve into a beaker, add 50 mL of water, heat the sample to boiling, transfer the sample with all the residue to a 100 mL volumetric flask, and perform cooling, constant volume setting and uniform shaking. After putting still for clarification, accurately pipette 1.00 mL of a sample solution into a 20 mL test tube with a stopper. The following steps are the same as the plotting of the standard curve.

A.5 Expression of Test Results

Use formula (A.1) to calculate the determined value X of the alginic acid in a mass fraction whose value is expressed in %: […]

A.6 Allowable Tolerance

The relative difference of parallel determination results is less than or equal to 20%;

Appendix B (Normative Appendix) Determination of Fixation Variance Rate of Water-Soluble Phosphorus A Calcium Chloride Precipitation Method Warning - - The concentrated sulfuric acid, sodium hydroxide and their solutions in the reagents are corrosive, and the user is responsible for taking appropriate safety and health measures which meet the requirements of the relevant national laws and regulations.

B.1 Principle

Under certain pH condition, the water-soluble phosphorus in the monoammonium phosphate and diammonium phosphate reacts with calcium ions to form a precipitate. By measuring the remaining water-soluble phosphorus, the water-soluble phosphorus fixation rate of the analytical monoammonium phosphate or diammonium phosphate (a ratio of the water-soluble phosphorus fixed by the calcium ions to total water-soluble phosphorus) and the water-soluble phosphorus fixation rate of the monoammonium phosphate or diammonium phosphate containing alginic acid are calculated, and a ratio of a difference between the two water-soluble phosphorus fixation rates to the former water-soluble phosphorus fixation rate is calculated.

B.2 Reagents and Materials

B.2.1 Calcium chloride solutions

B.2.1.1 An analytical monoammonium phosphate or analytical diammonium phosphate calcium chloride solution.

According to the weighing amount a0 of analytical monoammonium phosphate (P2O5 content: 61.7%) and analytical diammonium phosphate (P2O5 content: 53.8%) and water-soluble phosphorus content P0, weigh 40a0P0 g CaCl2·2H2O (accurate to 0.001g), add 60 mL of water to dissolve it, dilute it to a constant volume of 100 mL, and perform even shaking for a standby application. B.2.1.2 A sample calcium chloride solution.

According to the weighing amount of monoammonium phosphate containing alginic acid and diammonium phosphate containing alginic acid and water-soluble P2O5 content P1 in the sample, weigh 40aP1 g CaCl2·2H2O (accurate to 0.0001g), add 60 mL of water to dissolve, dilute to a constant volume of 100 mL, and perform even shaking for a standby application. B.2.2 An ammonium molybdate vanadate solution.

A solution A: dissolve 25 g of ammonium molybdate in 400 mL of water;

A solution B: dissolve 1.25 g of ammonium metavanadate in 300 mL of boiling water, add 250 mL of concentrated nitric acid after cooling, and then cool to a room temperature.

Pour the solution A into the solution B slowly, stir continuously, dilute to 1 L with water, and store in a brown bottle. B.2.3 A sodium hydroxide solution [c(NaOH)=6 mol/L].

Weigh 24 g of sodium hydroxide, dissolve in water and dilute to 100 mL.

B.2.4 A sulfuric acid solution c(H2SO4) =6 mol/L Measure 17 mL of concentrated sulfuric acid and slowly add 50 mL of water, perform stirring while adding, and dilute to 100 mL with water after cooling. B.2.5 A dinitrophenol indicator.

Weigh 0.2 g of 2,6-dinitrophenol or 2,4-dinitrophenol and dissolve in 100 mL of water. B.2.6 A phosphorus (calculated as P2O5) standard solution: rho=100 mg/L.

Weigh 1.9176 g of potassium dihydrogen phosphate (dry at 130 °C for 2 h) in a 400-mL beaker, dissolve it with a small amount of water, transfer the dissolved potassium dihydrogen phosphate into a 1-L volumetric flask, add water to 400 mL, add 5 mL of concentrated nitric acid, dilute an obtained mixture to a constant volume with water, perform even shaking well, and thus obtain a phosphorus stock solution with a concentration of 1,000 mg/L. Accurately pipette 50 mL of the phosphorus stock solution into a 500-mL volumetric flask, dilute to a constant volume with water, perform even shaking and thus obtain a phosphorus standard solution with a concentration of 100 mg/L.

B.3 Instruments

B.3.1 Visible light spectrophotometer.

B.3.2 Thermostatic oscillator.

B.3.3 Common laboratory devices.

B.4 Test Procedure

B.4.1 Parallel determination

A parallel determination of two samples is conducted.

B.4.2 Plotting of standard curve

Respectively pipette 0 (blank), 10., 2.0, 4.0, 8.0 and 10.0 mL of 100 mg/L of the phosphorus standard solution into a 50-mL volumetric flask, add water to about 30 mL, add 2 drops of the dinitrophenol indicator, adjust the solution color to slightly yellow by using the sodium hydroxide solution (B.2.3) and the sulfuric acid solution (B.2.4), accurately add 10 mL of the ammonium molybdate vanadate solution, dilute it to a constant volume with water, perform even shaking and placing at room temperature for 20 min, perform colorimetry at a wavelength of 470 nm on the spectrophotometer, use a blank solution for zero setting of an absorbance and measure an absorbance value of the solution. The mass concentration of the standard series solution phosphorus (calculated as P2O5) is 0 mg/L, 2 mg/L, 4 mg/L, 8 mg/L, 16 mg/L and 20 mg/L, respectively. Plot a standard curve with the absorbance value as an X-axis and the phosphorus concentration as a Y-axis.

B.4.3 Water-soluble phosphorus precipitation steps

Prepare the calcium chloride solution (B.2.1.1) for analytical monoammonium phosphate or analytical diammonium phosphate and the calcium chloride solution (B.2.1.2) for samples, respectively. Take an appropriate amount of the sample, grind the sample and pass all the ground sample through a 0.5-mm sieve, weigh 1 g (accurate to 0.0001 g) of the sieved sample in a 250-mL extraction flask, add 30 mL of water, adjust the solution pH to 8.0 (measured with an acidity meter) by using the sodium hydroxide solution (B.2.3), then transfer the liquid in the extraction flask into a 50-mL volumetric flask, performing a volume-constant setting, transfer all the liquid in the volumetric flask to the same extraction flask again, wash the volumetric flask 4 times with 40 mL distilled water, pour the liquid into the extraction flask, finally add 10 mL of the corresponding calcium chloride solution, tighten a cap, perform a reciprocating oscillation in the thermostatic oscillator at a vibration speed of 180 times/min at 30°C for 1 h, dry filter with double-layer filter paper, and discard an initial filtrate.

B.4.4 Determination of water-soluble phosphorus content in filtrate

Pipette 1 mL of the filtrate in a 50-mL volumetric flask, perform other operation steps the same as in B.4.2, and determine an absorbance value. The obtained color-developing solution phosphorus content of the monoammonium phosphate containing alginic acid or diammonium phosphate containing alginic acid from the standard curve is recorded as rho1. The obtained color-developing solution phosphorus content of the analytical monoammonium phosphate or analytical diammonium phosphate from the standard curve is recorded as rho0.

B.5 Expression of Test Procedure

B.5.1 Use formula (B.1) to calculate the water-soluble phosphorus fixation rate f (%) of monoammonium phosphate or diammonium phosphate containing alginic acid, the value is expressed in %:

B.5.2 Use formula (B.2) to calculate the water-soluble phosphorus fixation rate f0 (%) of analytical monoammonium phosphate or analytical diammonium phosphate