Development and deployment of an instrument for measurement of atmospheric peroxy radical by chemical amplification

An instrument for measurement of peroxy radical by chemical amplification (PERCA) has been developed at Peking University (PKU) and deployed in several field campaigns. PKU PERCA measures peroxy radical via amplification of NO₂ by peroxy radical in the presence of NO and CO through a chain reaction. The amount of amplified NO₂ is detected by a NO₂-luminal chemiluminescence detector. The chain length (CL) of 75±20 (1σ ) was determined routinely during field campaigns using a HO₂ source from photolysis of water vapor at 185 nm in air. The detection limit for peroxy radical measurement was (1–5)×10⁻¹² (volume ratio) with integration time of 1 min, mainly relying on the variation of the ambient O₃ and NO₂. The systematic uncertainty in the measurement of peroxy radical was estimated to be ±60%. The effect of water vapor on PKU PERCA was observed and determined in the laboratory. The measurements of peroxy radical during the Program of Regional Integrated Experiments of Air Quality over Pearl River Delta 2006 (PRIDE-PRD2006) campaign are presented to show the performance of the PERCA instrument and the behavior of the observed peroxy radical is discussed briefly. Supported by Industry, University and Research Institute Cooperation Program of Beijing Municipal Commission of Education (Grant No. CXY100010401) and National Basic Research Program of China (Grant No. 2002CB410801)