Improved determination method for total nitrogen in water

Abstract

The invention provides an improved determination method for total nitrogen in water. The method comprises the following steps: respectively taking colorimetric pipes, adding a potassium nitrate standard working solution, adding water to dilute the potassium nitrate standard working solution to 10.00 ml, then adding a potassium persulphate solution, tightly plugging and fastening pipe plugs and then drying and cooling the colorimetric pipes; determining absorbance of the colorimetric pipes respectively at 220 nm and 275 nm so as to obtain correction absorbance Ar; after calculation of the correction absorbance, calculating a difference between the correction absorbance of a standard series and the correction absorbance of a blank solution and drafting a standard curve according to A and corresponding mass concentrations of nitrogen in nitrate; and detecting the content of total nitrogen in a sewage sample. According to the invention, since an electrothermal constant-temperature drying box is used for digestion, operation is simple, temperature is easily controllable, experimental requirements are met, so digestion with the constant-temperature drying box enables problems in digestion with an autoclave to be overcome; moreover, the constant-temperature drying box has great space and can treat a plurality of samples at the same time.

Description

technical field [0001] The invention relates to a method for measuring total nitrogen, in particular to an improved method for measuring total nitrogen in water. Background technique [0002] The total nitrogen content in water is one of the important indicators to measure water quality. Its determination is helpful to evaluate the pollution and self-purification status of water bodies. When the nitrogen and phosphorus substances in the surface water exceed the standard, the microorganisms will multiply, the plankton will grow vigorously, and the state of eutrophication will appear. [0003] The original standard HJ 636-2012 is conducive to the detection of total nitrogen content in wastewater by alkaline potassium persulfate ultraviolet spectrophotometry. The autoclave is used as a digestion tool. The capacity of the autoclave is small, so it cannot measure large quantities of samples, and it is tested in batches. It not only wastes time but also wastes energy. For labora...

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Problems solved by technology

[0003] The original standard HJ 636-2012 is conducive to the detection of total nitrogen content in wastewater by alkaline potassium persulfate ultraviolet spectrophotometry. The autoclave is used as a digestion tool. The capacity of the autoclave is small, so it cannot measure large quantities of samples, and it is tested in batches. Not only a waste of time but also a waste of energy. For laboratories with relatively poor conditions, there is no special pressure steam sterilizer, which needs to be shared with microorganisms, causing inconvenience, and it requires a lot of money to configure the steam sterilizer

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