HJ 536-2009Water quality - Determination of ammonia nitrogen - Salicylic acid spectrophotometry (English PDF)

Foreword

In order to implement the Environmental Protection Act of the People's Republic of China

and the Water Pollution Prevention Act of the People's Republic of China, protect the

environment, guarantee human health and standardize the monitoring methods of

ammonia nitrogen in water, hereby this standard is announced.

This standard specifies the determination of ammonia nitrogen in water by salicylic acid

spectrophotometry.

This standard is revision to Water quality - Determination of ammonium- salicylic acid

spectrophotometry (GB 7481-87).

This standard was initially published in 1987. And the original drafting organization was

Jiangxi Province Ganzhou Environmental Monitor Station. This standard is revised for the

first time. The main revised contents are as follows.

— The name of the standard is revised from Water quality - Determination of

ammonium - Salicylic acid Spectrophotometry TO Water quality - Determination of

ammonium nitrogen - Salicylic acid spectrophotometry.

— Add the 30mm cuvette test method. Reduce the detection limits. Broaden the

application range of the method. Clearly specify the lower and upper limits of the

method.

— Combine the result calculation formulae.

— Modify the normative appendix.

The Water quality-Determination of ammonium-Salicylic acid Spectrophotometry (GB

7481-87) approved and released by the former State Environmental Protection Agency on

March 14, 1987 shall be abolished, from the date of implementation of this standard.

Appendix A of this standard is normative. Appendix B is informative.

This standard was organized and formulated by Department of Science, Technology and

Standards, Ministry of Environmental Protection of the People's Republic of China.

This standard was mainly drafted by. Municipal Environmental Monitoring Center Station

of Shenyang.

This standard was approved by Ministry of Environmental Protection on December 31,

2009.

This standard shall be implemented from April 1, 2010.

The Ministry of Environmental Protection is responsible for the interpretation of this

standard.

Water quality-Determination of ammonia nitrogen-

Salicylic acid spectrophotometry

1 Application scope

This standard specifies the salicylic acid spectrophotometry to determine ammonia

nitrogen in water.

This standard applies to determination of ammonia nitrogen in groundwater, surface water,

domestic sewage, and industrial wastewater.

When the sample volume is 8.0 ml and the 10 mm cuvette is used, the detection limit of

this method is 0.01 mg/L, the determination lower limit is 0.04mg/L, and the determination

upper limit is1.0mg/L (all counted in N).

When the sample volume is 8.0 ml and the 30mm cuvette is used, the detection limit of

this method is 0.004 mg/L, the determination lower limit is 0.016mg/L, and the

determination upper limit is 0.25mg/L (all counted in N).

2 Method principle

Under the condition that the alkaline medium (pH=11.7) and the sodium nitroprusside

exist, chemical reactions happen AMONG the ammonia, ammonium ions AND the

salicylate AND hypochlorite ions in water, to generate blue compound. Measure the

absorbency with a spectrophotometer at 697nm.

3 Interference and elimination

This method applies to the possible interfering substance and quantity limit during water

sample analysis, see Appendix B for details.

Severe interferences generated by aniline and ethanol amine are rare. Usually the

interference is generated by primary amine. When it contains chloramines, excessively

high acidity, alkalinity, or when it contains substances that make hypochlorite ions

reduction, the interferences may be generated.

If the color of the water sample is too dark, or the salt is excessive, or when the masking

ability of the potassium tartrate to the metal ions in the water sample is insufficient, or

when there is high concentration of calcium, magnesium and chloride in the water sample,

pre-distillation is required.

4 Reagents and materials

Unless otherwise specified, the reagents used in analysis shall be analytical pure

hydroxide solution (4.6), until the salicylic acid is fully dissolved. And use 1mol/L of sulfuric

acid to adjust PH of the solution to 6.0-6.5.

Appendix A

(Normative)

The preparation method of sodium hypochlorite solution and calibration of

effective chlorine concentration and free-base concentration

A.1 The preparation method of sodium hypochlorite solution

Put hydrochloric (rho=1.19g/ml) acid, drop by drop, on the solid of potassium permanganate.

Guide the escaping chlorine into 2mol/L of sodium hydroxide absorption liquid for

absorption, so as to generate the sodium hypochlorite solution in light grass green. Store

in a plastic bottle. As this solution is not stable, the effective chlorine concentration shall

be calibrated prior to use.

A.2 The measurement of effective chlorine in the sodium hypochlorite solution

Absorb 10.0ml of sodium hypochlorite (4.8) into 100mml volumetric flash. Add water to

dilute to marked line. Mix well. Move 10.0ml of diluted sodium hypochlorite solution into

250ml iodine flask. Add 40ml of distilled water and 2.0g potassium iodide. Mix well. Add