摘要
采用气相色谱-氢火焰离子化检测法的环境空气非甲烷总烃(NMHC)连续自动监测设备之间的测量结果差异较大,影响光化学污染前体物的监测评价与管控.为探究测量差异原因,选取8套NMHC连续自动监测市售仪器,在不同色谱柱温度和不同标准气体条件下分析响应情况.结果表明:(1)柱温的改变对NMHC体积分数响应偏差影响较小.但在同样分析条件下,不同氢火焰离子检测器(FID)对卤代烃或含氧衍生物的响应因子不同,针对同一物质仪器之间的响应偏差较大,最大为170%.FID对物质响应的差异是导致测量结果差异大的主要原因.(2)环境空气中,各仪器现场获得的NMHC体积分数监测值变化趋势基本一致,仪器间数据的Pearson相关系数在0.8以上(P均小于0.01);但非污染时段仪器间NMHC体积分数监测值最大相差近10倍,数据可比性差.(3)针对甲苯、乙酸乙酯和三氯乙烯等代表性物质,本研究提出了响应监测值与理论值比值的范围,改进后不同设备测定值的平均标准偏差降至16%,满足监测评价要求.研究显示,分子结构及官能团极性差异是导致FID响应差异大的关键问题,经FID响应统一技术改进可提升环境空气NMHC连续自动检测数据的统一性.
The results of the continuous automatic monitoring equipment for non-methane total hydrocarbon(NMHC)in ambient air using gas chromatogram-hydrogen flame ion detection(FID)method vary greatly,which affects the evaluation and control of photochemical pollution precursor monitoring.In order to determine the reasons for the differences,eight sets of NMHC continuous automatic systems were selected,and the responses under the different chromatography columns temperature and different standard gas conditions were analyzed.The results showed that:(1)The change of column temperature had little effect on the NMHC concentration response deviation.However,the response factors of different FIDs to a halogenated hydrocarbon or oxygen-containing derivatives were different under the same analysis conditions,and the response deviation of the instruments to the same substance was large,up to 170%.The main reasons for the difference in measurement results were the different response of the FIDs to the same substance.(2)The changing trend of NMHC concentration in ambient air measured by each instrument was basically consistent,and the Pearson correlation coefficient of the NMHC monitoring concentration data of the on-site instruments was above 0.8(P<0.01),but the difference was nearly 10 times during nonpollution period,and the data comparability was poor.(3)For representative substances such as toluene,ethyl acetate,and vinyl chloride,the study specified the method of the measurement value of the monitoring equipment and the theoretical concentration ratio.After improvement,the average standard deviation of different equipment measurement was reduced to 16%,which meets the requirements of monitoring and evaluation.The study shows that by identifying the key issues that lead to large differences in NMHC monitoring concentration due to the different responses of FID to substances,the consistency of continuous automated monitoring data of NMHC in ambient air can be improved by FID response unification technology.
作者
杨勇
高松
林长青
童虓
陈曦
段玉森
车祥
李跃武
YANG Yong;GAO Song;LIN Changqing;TONG Xiao;CHEN Xi;DUAN Yusen;CHE Xiang;LI Yuewu(State Ecology and Environment Scientific Observation and Research Station for the Yangtze River Delta at Dianshan Lake(SEED),Shanghai Environmental Monitoring Center,Shanghai 200235,China;School of Environmental and Chemical Engineering,Shanghai University,Shanghai 200444,China;Shanghai Chemical Environmental Protection Monitoring Station,Shanghai 200050,China)
出处
《环境科学研究》
CAS
CSCD
北大核心
2023年第3期519-525,共7页
Research of Environmental Sciences
基金
国家重点研发计划项目(No.2017YFC0209903)
2021年度国家环保标准项目(No.2021-13)。
