System and method for synchronous on-line measurement of concentrations of glyoxal and methylglyoxal in atmosphere

Abstract

The invention discloses a system and a method for synchronous on-line measurement of concentrations of glyoxal and methylglyoxal in atmosphere. The synchronous on-line measurement of the glyoxal and the methylglyoxal in the atmosphere can be realized based on cavity enhanced absorption spectroscopy technology, a cage structure cavity frame constructed by a cage plate and a fiber rod support is used as a carrier to construct, by two high-reflectivity reflectors, an optical resonant cavity for measurement of characteristic spectral absorption of the glyoxal and the methylglyoxal in the wavelength range of 440-460 nm to quantify the concentrations of the glyoxal and the methylglyoxal in a sampled gas. . The interference of nitrogen dioxide on the glyoxal and the methylglyoxal in a spectrum analysis process is reduced by photolysis of the nitrogen dioxide in the sample gas, the sensitivity and the accuracy of the on-line measurement of the concentrations of the glyoxal and the methylglyoxal can be improved, and the system and the method have the advantages of high temporal-spatial resolution, high sensitivity, high stability, high degree of automation, low detection limit and low cost.

Description

technical field [0001] The invention belongs to the technical field of air quality detection, in particular to online measurement of glyoxal and methylglyoxal in the atmosphere, and in particular to a synchronous concentration of glyoxal and methylglyoxal in the atmosphere based on broadband cavity enhanced absorption spectroscopy technology On-line measurement system and on-line measurement method. Background technique [0002] At present, atmospheric compound pollution has become an important issue restricting my country's economic and social development. 2 ) cycle regeneration mechanism is the key to explain the cause of atmospheric compound pollution. Glyoxal and methylglyoxal are typical atmospheric oxidation intermediate products, and their sources and removal pathways can well verify, improve and perfect the existing atmospheric HOx free radical cycle mechanism. Therefore, it is of great scientific significance to accurately quantify the concentrations of glyoxal an...

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Problems solved by technology

[0003] The existing methods for measuring the concentration of glyoxal and methylglyoxal in the atmosphere can be divided into three categories: liquid-phase chemical method, mass spectrometry and spectroscopic method, and most of the off-line methods use derivatization sampling + high performance liquid chromatography (HPLC) or Gas chromatography / mass spectrometry (GC / MS) analysis method, the sampling time of this method is long (3-12 hours), it is difficult to meet the needs of the atmospheric chemical reaction process; proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) in When measuring glyoxal and methylglyoxal, they will be interfered by acetone and acrylic acid, which have the same molecular mass, respectively, and the measurement results are uncertain; the measurement technology based on spectroscopy mainly uses glyoxal and methylglyoxal The characteristic absorption of aldehydes in the ultraviolet or infrared bands is used for quantification, among which tunable diode laser absorption spectroscopy (TDLAS) and quantum cascade lasers (QCL), as well as laser-induced fluorescence (LIF) and laser-induced phosphorescence (LIP) in Sensitivity and time resolution are superior to the first two types of methods, but the design of the optical path system and optical cavity, laser modulation, signal acquisition and analysis are the difficulties in the application of laser methods; differential absorption spectroscopy (DOAS) can only measure the range of its optical path Average concentration within , with poor spatial resolution (>2km)

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