Low-pressure anion-cation chromatographic-spectrophotometric method for simultaneous online automatic analysis of trace ammonium ions and nitrite ions in water sample

Abstract

The invention provides a low-pressure anion-cation chromatographic-spectrophotometric method for simultaneous online automatic analysis of trace ammonium ions and nitrite ions in a water sample; the method employs analytical apparatuses, such as a low-pressure pump, a sample injection valve, a sample injection ring, a low-pressure anion exchange column, a low-pressure cation exchange column, an oxidation reactor, a color rendering reactor, an optical flow cell, an optical detector, a computer processing system, a first mixer and a second mixer, and comprises the steps of (1) drawing a baseline; (2) drawing a spectrum of NH4+ and NO2- in a sample; (3) drawing a standard working curve; (4) calculating the concentrations of NH4+ and NO2- to be detected in the sample according to peak height values of the spectrum of NH4+ and NO2- and a regression equation of the standard working curve. It is the first time for the method to provide simultaneous online analysis for trace NH4+ and NO2- in a water sample by the joint use of low-pressure ion chromatography and spectrophotometry, and the method has the advantages of low analytical cost and high analytical efficiency.

Description

technical field [0001] The invention belongs to NH 4 + with NO 2 - The field of detection and analysis, especially involving trace amounts of NH in water samples 4 + and NO 2 - Simultaneous online automatic analysis method. Background technique [0002] Nitrogen-containing compounds will not only pollute water quality, but also be extremely harmful to human health. NH 4 + , NO 2 - and NO 3 - Through the oxidation, nitrification and denitrification of microorganisms, they can be transformed into each other. NH 4 + Oxidation will significantly reduce the concentration of dissolved oxygen in the water, resulting in a decline in water quality, leading to a sharp increase in photosynthetic microorganisms, and eutrophication of the water. High concentration of NH 4 + May affect the permeability of aquatic organisms and may cause acute ammonia poisoning and even death. NH 4 + It is not only a factor affecting the sensory water quality, but also an important co...

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Problems solved by technology

[0003] Currently, ion chromatography analyzes NH in water samples 4 + and NO 2 - When using high-pressure ion chromatography, the two ions need to be sampled separately and detected separately, that is, an anion chromatographic column and a supporting anion elution system are usually used, and the conductivity detection is used to analyze the NO 2 - , using a cation chromatographic column and a matching cation elution system to separate and detect NH 4 + , unable to achieve NH 4 + and NO 2 - Simultaneous analysis of

Existing analysis of NH in water samples 4 + and NO 2 - The current ion chromatography method has the following disadvantages: separate sampling and separate detection have the disadvantages of slow analysis speed and low analysis efficiency; high pressure ion chromatography adopts high pressure operation, the price of high pressure ion chromatography is high, and the supporting chromatographic column is consumable products, whose price is generally 10,000 to 20,000 yuan / piece, so the analysis cost of this method is extremely high, and it is difficult to popularize and apply; at the same time, the column packing of the chromatographic column used in high-pressure ion chromatography is a thin-shell ion resin. The exchange capacity is very low, only 0.01-0.02mmol / g. When analyzing wastewater with complex components such as tannery wastewater, the chromatographic column is easily polluted, resulting in shortened service life of the chromatographic column and reduced anti-interference ability of the analysis system. Therefore, it is difficult to popularize and apply in the tannery wastewater analysis industry

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