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Real-time monitoring of sulfur dioxide using ultraviolet light-emitting diode

A compact and low-cost light-emitting diode (LED) with center wavelength of 295 nm and high light density was used measure the concentration of sulfur dioxide, which has a strong structured absorption band in the ultraviolet region 300 nm. Differential optical absorption spectroscopy (DOAS) was used to determine the concentration of sulfur dioxide using reference absorption spectrum due to 1000 ppm SO2. A sensitivity of about 1.5 ppm was achieved with a gas cell in 1-s integration time, enabling real-time monitoring of sulfur dioxide.