SILANIZATION OF DHBAs AND MEASUREMENT OF GAS PHASE HYDROXYL RADICALS USING GAS CHROMATOGRAPHY-MASS SPECTROMETRY

This study developed a measurement method of OH radicals in the atmosphere using salicylic acid(SA)to(trap) OH radicals and then GC-MS to analyze the trimethylsilyl(TMS)derivatives of the reaction products of SA and OH:dihydroxybenzonic acid(DHBA).By optimizing GC-MS parameters,the TMS derivatives of SA and DHBAs were well separated and the detection limits of 10.2 fmol and 9.9 fmol were obtained for the TMS derivatives of 2,3-DHBA and 2,5-DHBA.After using SA soaked filters to collect OH radicals from an OH generating sources,2,3-DHBA and 2,5-DHBA were extracted from the filters and converted to TMS derivatives,which were measured with GC-MS and the production yields of 2,3-DHBA and 2,5-DHBA from the gas phase OH radical reaction with solid phase SA on filter were determined as 52% and 48%.