New cavity design suitable for monitoring gaseous samples by molecular emission cavity analysis Original Research Article

A new flame-containing cavity for molecular emission cavity analysis (MECA) was designed. The reliability of the proposed design was evaluated using SO2 as a representative sulfur-containing compound. The blue emission of excited S2 was monitored by a photomultiplier tube (PMT) or a photodiode (PD). Nitrogen gas and water cooling system were eliminated and flow rates of hydrogen and air were reduced drastically with respect to previous reports. It was shown that as little as 18 and 24 ng of sulfur as SO2 can be detected by PMT and PD, respectively. The relative standard deviation of the method for 200 and 500 ng sulfur was 1.5 and 1%, respectively, for PMT detection and 2.3 and 1.2% for 2 and 3 μg sulfur with photodiode detection. It was shown that the method could be applied to the determination of SO2 in gaseous samples. The sulfur contents of real samples were also determined.