GB/T 5750.5-2023Standard examination methods for drinking water—Part 5: Inorganic nonmetallic indices (English PDF)

4.1 Barium sulfate turbidimetric method

4.1.1 Minimum detection mass concentration

The minimum detection mass of this method is 0.25mg, if the 50mL water sample is taken to determine the minimum detection mass concentration of 5mg / L. This method is applicable to the determination of sulfate mass concentration of less than 40mg / L water samples. Stirring speed, time, temperature and reagent addition method can affect the determination of barium sulfate turbidimetric method, therefore requires strict control of the operating conditions consistent.

5.1 Silver nitrate volumetric method

5.1.1 Minimum detection mass concentration

The minimum detection mass of this method is 0.05mg, if 50mL sample is taken to determine the minimum detection mass concentration of 1.0mg / L. Australide and iodide can cause the same reaction, and the mass of the equivalent of chloride into the results. Sulfide, sulfite, thiosulfate and more than 15mg / L of oxygen consumption can interfere with the determination of this method. Sulfite and other interference can be removed by hydrogen peroxide treatment. Higher oxygen consumption of water samples can be treated with potassium permanganate or steamed dry after ashing.

6.1 ion selective electrode method

6.1.1

The minimum detection mass concentration of this method is 2g, if the 10mL water sample is measured, the minimum detection mass concentration of 0.2mg/L. Chromaticity, turbidity and more interfering substances can be directly determined by this method. In order to eliminate the interference of OH~ on the determination, the pH value of the measured water sample is controlled at 5.5~6.5.

7.1 Isonicotinic acid - Vishnu ketone spectrophotometric method

7.1.1

The minimum detectable mass concentration of this method is 0.1g, if 250L water sample is taken for evaporation, the minimum detectable mass concentration is 0.002mg/L. Oxidants such as residual chlorine can destroy cyanide, and 0.1g/L sodium sulfite or less than 0.1g/L sodium thiosulfate can be added to the water sample to remove the interference.

7.1.2 Principle

In the solution of pH=7.0, the cyanide is transformed into cyanuric chloride by chloramine T, and then interacted with isonicotinic acid-ketone (1-phenyl-3-methyl-5-viologen ketone) to produce blue dye for colorimetric quantification.

8.1 Muscimol spectrophotometric method

8.1.1 Minimum detection mass concentration

The minimum detection mass of this method is 0.5g of nitrate (in N), if 1.0 water samples are taken to determine the minimum detection mass concentration of 0.5mg / L.

Nitrite is positive interference with this method, the use of sulfamic acid money to remove: chloride is negative interference with this method, the use of silver sulfate to eliminate sulfide

9.1.1 Minimum detection mass concentration

The minimum detection mass of this method is 1.0g, if the 50mL water sample is taken for determination, the minimum detection mass concentration is 0.02g/L.

9.1.2

Principle of sulfide and N,N-diethyl-p-phenylenediamine and ferric chloride to produce a stable blue color, colorimetric quantification at 665nm

9.1.3 Reagent

10.1 Phosphorus key blue spectrophotometric method

10.1.1 Minimum detection mass concentration

This method is suitable for the determination of phosphate (HPOF) mass concentration of less than 10mg / L of water samples.

10.1.2 Principle

In a strongly acidic solution of phosphate and acid money to generate phosphorus key heteropolyacid, can be reduced by reducing agents (stannous chloride, etc.) to produce a blue complex, when the phosphate content is low, its color intensity is proportional to the phosphate content.

10.1.3 Reagents

11.1 Nah reagent spectrophotometric method

11.1.1 Minimum detectable mass concentration

The minimum detection mass of this method is 1.0g of nitrogen (in N) If a 50L water sample is taken for determination, the minimum detection mass concentration is

0.02mg/L.

12.1 diazo coupling spectrophotometry

12.1.1 Minimum detection mass concentration

The minimum detection mass of this method is 0.05g of nitrite (in N) If 50L water samples are taken to determine the minimum detection mass concentration of 0.001mg / L.

Trichloramine in water produces red interference. Iron, lead plasma can produce precipitation caused by interference. Copper ions play a catalytic role in the decomposition of diazo salts to low results. Colored ions have interference.

13.1 Sulfuric acid pavement catalytic spectrophotometry

13.1.1 Minimum detection mass concentration

Iodide content in the range of 0g / L ~ 20g / L, the minimum detection quality of this method is 2.4ng (to count) if 2.0mL water samples are taken to determine the minimum detection quality concentration of 1.2g / L; g / L ~ 200g / L range detection method minimum detection quality of 1.6ng (to count), if 0.3mL water samples are taken to determine the minimum detection quality concentration of 5.3g / L.

This method is suitable for the determination of iodide in the low concentration range of 0g/L~20g/L and in the high range of g/L~200g/L

14.1 ion chromatography - hydroxide system drenching solution

14.1.1 Minimum detection mass concentration

This method is only used for the determination of perchlorate in domestic drinking water.