Development of a novel particle mass spectrometer for online measurements of refractory sulfate aerosols
Development of a novel particle mass spectrometer for online measurements of refractory sulfate aerosols
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DOI：
10.1080/02786826.2020.1852168
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发表时间：
2020-11
影响因子：
5.2
通讯作者：
Yuya Kobayashi;Y. Ide;N. Takegawa
中科院分区：
文献类型：
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作者：
Yuya Kobayashi;Y. Ide;N. Takegawa
摘要硫酸盐气溶胶在大气中无处不在。城市空气中硫酸盐气溶胶的主要形态为硫铵(AS)，而偏远地区的硫酸盐(PS)、硫酸钠(SS)、硫酸镁(MS)和硫酸钙(CS)可能是主要贡献者。目前在线测量硫酸盐气溶胶的方法是基于离子色谱或热解吸气溶胶质谱仪，不能分别对非耐火和难熔硫酸盐化合物进行定量。我们开发了一种用于测量非耐火和耐火硫酸盐化合物的新型粒子质谱仪：耐火气溶胶热解吸质谱计(RTDMS)。气溶胶粒子通过空气动力学透镜单元被引入真空室，并被收集在杯状石墨靶(石墨收集器)上。聚焦的二氧化碳激光器与石墨收集器相结合，可以实现较高的解吸温度(黑体当量温度为∼1200K)，用于检测As、PS、SS和MS气溶胶。用电子电离四极质谱计探测从这些化合物中析出的气体分子。分析了与石墨收集器温度升高相关的离子信号的时间分布。在实验室中测试了rTDMS对不同类型硫酸盐颗粒的敏感性。多组分硫酸盐颗粒在m/z 48和处的离子信号的时间分布呈双峰型，可归因于非耐火和难熔硫酸盐颗粒。初步数据表明，多组分硫酸盐颗粒的离子信号可以近似为来自单组分硫酸盐颗粒的离子信号的线性组合。版权所有©2021美国气溶胶研究协会
Abstract Sulfate aerosols are ubiquitous in the atmosphere. Ammonium sulfate (AS) is generally the dominant form of sulfate aerosols in urban air, whereas potassium sulfate (PS), sodium sulfate (SS), magnesium sulfate (MS), and calcium sulfate (CS) may be large contributors in remote areas. Currently available methods for online measurements of sulfate aerosols, which are based on ion-chromatography or thermal desorption aerosol mass spectrometry, cannot separately quantify non-refractory and refractory sulfate compounds. We have developed a new particle mass spectrometer to measure non-refractory and refractory sulfate compounds: a refractory aerosol thermal desorption mass spectrometer (rTDMS). Aerosol particles are introduced into a vacuum chamber via an aerodynamic lens unit, and are collected on a cup-shaped graphite target (graphite collector). A focused CO2 laser coupled with the graphite collector enables a high desorption temperature (blackbody equivalent temperature of ∼1200 K) for detecting AS, PS, SS, and MS aerosols. The gas molecules evolved from these compounds are detected by using an electron ionization quadrupole mass spectrometer. The temporal profiles of ion signals associated with increases in the temperature of the graphite collector are analyzed. The rTDMS sensitivities to various types of sulfate particles have been tested in the laboratory. The temporal profiles of ion signals at m/z 48 and 64 originating from multi-component sulfate particles exhibited bimodal peaks, which can be attributed to non-refractory and refractory sulfate particles. Preliminary data suggested that the ion signals for multi-component sulfate particles could be approximated as the linear combination of ion signals originating from single-component sulfate particles. Copyright © 2021 American Association for Aerosol Research