Instrument Busy Time and Mass Measurement using Aerosol Time-of-Flight Mass Spectrometry
Instrument Busy Time and Mass Measurement using Aerosol Time-of-Flight Mass Spectrometry
复制标题
使用气溶胶飞行时间质谱法进行仪器繁忙时间和质量测量
DOI：
10.1080/02786820600754623
复制
发表时间：
2006
影响因子：
5.2
通讯作者：
K. Prather
中科院分区：
文献类型：
--
作者：
J. Allen;Prakash V. Bhave †;Jeffrey R. Whiteaker;K. Prather
气溶胶飞行时间质谱仪(ATOFMS)已被广泛用于测量环境中单个气溶胶颗粒的大小和组成。ATOFMS数据不能直接和定量地表示气溶胶成分，因为这些仪器对颗粒浓度、大小和成分表现出非线性响应。我们的方法是利用现场采样数据分别分析非线性ATOFMS响应的分量，以便了解ATOFMS对环境气溶胶的响应，从而使ATOFMS数据能够更接近地代表环境气溶胶。在这项工作中，我们研究了仪器繁忙时间的影响，主要是处理和保存数据的时间，对ATOFMS对1999年贝克斯菲尔德仪器对比研究(BIIS)期间采样的环境气溶胶的响应的影响。在这项研究中，ATOFMS仪器交替地在正常和快速散射数据采集模式下运行。在快速散射模式下，仪器不记录质谱图，最大限度地减少仪器的繁忙时间；这些数据用于确定粒子到达速率。正常模式下的忙碌时间是通过将检测到的颗粒数量与修改为包括忙碌时间的泊松过程的预期数量进行比较而得到的。在BIIS实验期间，ATOFMS仪器在标称采样时间的5%到95%之间忙碌；因此，对于ATOFMS数据的准确定量分析来说，忙碌时间是不容忽视的。ATOFMS数据根据在线时间和传输效率进行了定标，这是通过与参考气溶胶测量结果进行比较得出的，目的是估计细颗粒物质量浓度。ATOFMS定标数据显示的精细气溶胶质量浓度与使用Beta衰减监测器进行的独立测量的半定量一致。我们建议对ATOFMS仪器进行改进，以直接测量繁忙时间。现地址：美国北卡罗来纳州研究三角公园邮站876006，美国国家海洋和大气管理局大气科学模型部。
Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) instruments have been used widely to measure the size and composition of single ambient aerosol particles. ATOFMS data do not directly and quantitatively represent aerosol composition because the instruments exhibit non-linear response to particle concentration, size, and composition. Our approach is to analyze separately the components of non-linear ATOFMS response using field sampling data in order to understand ATOFMS response to ambient aerosols so that ATOFMS data can be scaled to more closely represent ambient aerosols. In this work we examine the effect of instrument busy time, mainly the time to process and save data, on ATOFMS response to ambient aerosols sampled during the 1999 Bakersfield Instrument Intercomparison Study (BIIS). During this study an ATOFMS instrument was operated alternately in normal and fast scatter data acquisition modes. In fast scatter mode, the instrument does not record mass spectra, minimizing instrument busy time; these data were used to determine particle arrival rates. Busy time in normal mode was found by a comparison of the number of particles detected to that expected for a Poisson process modified to include busy time. During the BIIS experiment, the ATOFMS instrument was busy between 5 and 95% of the nominal sampling time; thus busy time cannot be ignored for accurate quantitative analysis of ATOFMS data. ATOFMS data were scaled for on-line time and transmission efficiency, found by comparison with reference aerosol measurements, in order to estimate fine particle mass concentrations. Fine aerosol mass concentrations from scaled ATOFMS data demonstate semi-quantitative agreement with independent measurements using Beta Attenuation Monitors. We recommend that ATOFMS instruments be modified to measure busy time directly. Present Address: National Oceanic and Atmospheric Administration, Atmospheric Sciences Modeling Division, Mail Stop 876006, Research Triangle Park, North Carolina, USA.