Method for determining content of Kjeldahl nitrogen in water

Abstract

The invention relates to a method for determining the content of Kjeldahl nitrogen in water. The method comprises the following steps of: S1, taking 50mL of a sample from each digestion tube, adding 10mL of 98% concentrated sulfuric acid, adding glass beads, and evaporating in a digestion furnace at 280DEG C for 1-2h; S2, adding 5g of a catalyst into the cooled sample, wherein the catalyst is a mixture of fully ground 20g of copper sulfate and 180g of potassium sulfate; S3, transferring the sample; S4, starting the Kjeldahl apparatus for testing; S5, performing titrating with a 0.01mol / L hydrochloric acid standard solution; and S6, calculating the nitrogen content in the sample. Sulfuric acid is added into the sample and heating is performed for digestion, so that amino nitrogen in an organic matter is converted into ammonium bisulfate, free ammonia and an ammonium salt are also converted into ammonium bisulfate, a proper amount of potassium sulfate is added during digestion to increase the boiling speed so as to improve the digestion rate, and copper sulfate is used as the catalyst to shorten the digestion time, so that the detection time can be greatly shortened, and the detection efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of nitrogen content detection, in particular to a method for measuring Kjeldahl nitrogen content in water quality. Background technique [0002] Eutrophication is a water pollution phenomenon caused by excessive plant nutrients such as nitrogen and phosphorus. The algae in the eutrophic water body overgrow and multiply in the sunny area on the surface of the water body, and under certain meteorological conditions, cyanobacteria blooms will break out. When the cyanobacteria bloom broke out, the dissolved oxygen content in the water was extremely low, causing a large number of aquatic organisms to die. The dead aquatic organisms were deposited at the bottom of the lake and decomposed by microorganisms. Deterioration, stink. The current situation of eutrophication in my country's water bodies is very serious. The degree of eutrophication in lakes and reservoirs is high, and frequent outbreaks of cyanobacteria...

AI Technical Summary

Problems solved by technology

In order to eliminate the interference during the above measurement, the water samples need to be pretreated differently, but the pretreatment increases the complexity of the measurement process, such as adding an appropriate amount of zinc sulfate to the water sample, and adding sodium hydroxide to make it alkaline, forming Precipitation of zinc hydroxide, and then filter to remove color and turbidity, etc. Metal ions need to be eliminated by adding an appropriate amount of masking agent, which makes the test process more cumbersome and the test efficiency is low

Images