Method for measuring total content of nitrogen of fresh water quality

Abstract

The invention provides a method for measuring the total content of nitrogen of fresh water quality. The method comprises the steps of sampling, preparing an alkaline potassium persulfate solution, preparing a potassium nitrate standard solution, preparing a hydrochloric acid solution, drawing a calibration curve and detecting a water sample to be measured. According to the method, a polytetrafluoroethylene decomposition bottle is adopted to replace a colorimetric tube, so that the decomposition process is relatively sealed and relatively fully carried out, and the decomposition time is relatively short; cross contamination is not caused between the inside and the outside of the decomposition bottle, and interference is eliminated, so that the result is relatively accurate, and the operation is relatively simple and relatively convenient; furthermore, an opening or a plug of the colorimetric tube is prevented from being broken in the decomposition process, so that the problem of analyzing by sampling again is avoided. Furthermore, after the colorimetric tube is replaced by the decomposition bottle, and a pipette is also used, the sample can be analyzed at the constant volume without being transferred into the colorimetric tube after being decomposed, so that the method is convenient, fast and easy to operate, and the accuracy is improved.

Description

technical field [0001] The invention relates to the field of measuring water quality standards, in particular to a method for measuring total nitrogen content in fresh water. Background technique [0002] The determination of total nitrogen content in environmental water samples is a must-test item for environmental monitoring, and the accuracy of the determination has always been a problem. Potassium Sulfate Digestion Ultraviolet Spectrophotometry", specifically adding alkaline potassium persulfate solution to the colorimetric bottle containing the water sample, sealing the colorimetric bottle and putting it into a high-pressure steam sterilizer, heating and keeping the temperature at 120 -124°C for 30 minutes, after cooling to room temperature, add hydrochloric acid solution to the colorimetric tube, use a quartz cuvette on a UV spectrophotometer, use water as a reference, measure the absorbance at wavelengths of 220nm and 275nm respectively, and draw a calibration standar...

AI Technical Summary

Problems solved by technology

However, the colorimetric tube is prone to breakage of the nozzle or plug during the digestion process, and must be re-sampled for analysis; and when the colorimetric tube is digested at high temperature and high pressure, the sealing is not good, and the nitrogen in the environment affects the determination of the total nitrogen content in the water quality. It is also prone to cross-contamination; in addition, it is necessary to use gauze and thread to tie the plug of the colorimetric tube tightly, which is cumbersome to operate

Images