title: [In-situ measurement of background atmospheric HCFC-142b using GC-MS and GC-ECD method].
abstract: Custom-made GC-MS and GC-ECD in-situ measurement systems were established at the Shangdianzi GAW Regional station. From May 2010 to May 2011, the precisions for GC-MS and GC-ECD systems were 0.23% and 0.88%, respectively, and the HCFC-142b mole fraction during the observation period ranged from 21 x 10(-12) to 355 x 10(-12). The result of the independent-sample T test was P > 0.05, and there was no significant difference in HCFC-142b mole fraction measured by the two systems. The small difference of HCFC-142b mole fraction measured by GC-MS and GC-ECD might be associated with the different sampling time and precision of the two systems. A statistical filter of "robust local regression" was applied to separate HCFC-142b background and pollution data. The mean difference, median difference, 25 and 75 percent difference of background data measured by GC-MS and GC-ECD were all within the precisions. The pollution events captured by the two systems showed similar characters. Results from both systems showed a higher HCFC-142b level in summer and autumn than in winter. The pollution mole fraction of the two systems showed similar seasonal changes.
authors.affiliation: Institute of Meteorological Science of Heilongjiang Province, Harbin 150030, China. kevin8257@163.com
authors.forename: Li-feng
authors.initials: LF
authors.lastname: Guo
authors.forename: Bo
authors.initials: B
authors.lastname: Yao
authors.forename: Ling-xi
authors.initials: LX
authors.lastname: Zhou
authors.forename: Pei-chang
authors.initials: PC
authors.lastname: Li
authors.forename: Lin
authors.initials: L
authors.lastname: Xu
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001272:Atmosphere / Q000032:analysis*; D002681:China; D017402:Chlorofluorocarbons / Q000032:analysis*; D002849:Chromatography, Gas / Q000295:instrumentation / Q000379:methods*; D004583:Electrons; D004784:Environmental Monitoring; D008401:Gas Chromatography-Mass Spectrometry; D057230:Limit of Detection
chemical_list: D000393:Air Pollutants; D017402:Chlorofluorocarbons; C067537:2-chloro-1,1-difluoroethane