Study on the measurement of isoprene by Differential Optical Absorption Spectroscopy

Abstract. In this paper, the continuous on-line measurements of isoprene in the atmosphere have been carried out by using the Differential Optical Absorption Spectroscopy (DOAS) in the band of 202.71–227.72 nm for the first time. Under the zero optical path in the laboratory, different equivalent concentrations of isoprene were measured by the combination of known concentration gas and series calibration cells. The correlation between the measured concentrations and the equivalent concentrations was 0.9996, and the slope was 1.065. The correlation coefficient between DOAS and on-line VOCs instrument is 0.85 and the slope is 0.86 in the comparison of 23 days field observation. It is estimated that the detection limit of isoprene with DOAS is about 0.1 ppb at an optical path of 75 m, and it is verified that isoprene could be measured in the ultraviolet absorption band using DOAS method with high temporal resolution and low maintenance cost.