Edwards Gavin D, Cantrell Christopher A, Stephens Sherry, Hill Brian, Goyea Olusegun, Shetter Richard E, Mauldin R Leon, Kosciuch Edward, Tanner David J, Eisele Fred L
Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado 80305, USA.
Anal Chem. 2003 Oct 15;75(20):5317-27. doi: 10.1021/ac034402b.
Laboratory characterizations of the peroxy radical chemical ionization mass spectrometer (PerCIMS) instrument have been performed. The instrument functions by drawing ambient air through a 50-microm-diameter orifice into an inlet held at low pressure. Peroxy radicals (HO2 and RO2) within this air are detected by amplified chemical conversion into a unique ion (HSO4-) via the chemistry initiated by the addition of NO and SO2 to the inlet. HSO4- ions are then quantified by a quadrupole filter mass spectrometer. PerCIMS provides measurements of the sum of peroxy radicals, HO2 + RO2 (HOxROx mode), or the HO2 component only (HO2 mode), achieved through the control of concentration of NO and SO2 added to the instrument. The characterization and response of this instrument have been evaluated through modeling of inlet chemistry and laboratory experiments and have also been demonstrated through successful deployment during field campaigns. The performance of PerCIMS with respect to calibration pressure and relative humidity is reported, as are the sensitivities of the instrument to organic peroxy radicals with different hydrocarbon groups. These data show PerCIMS to be a practical field instrument for the fast and accurate evaluation of the concentration of peroxy radicals over a variety of atmospheric conditions. The estimated accuracy of the derived [HOxROx] concentrations is +/- 35% (at the 95% confidence interval), while [HO2] measurements have accuracies of +/- 41% (at the 95% confidence interval). Typical precision of measurements well above the detection limit is 10%, and typical detection limits are 1 x 10(7) radicals cm(-3) for 15-s averaging times.
已对过氧自由基化学电离质谱仪（PerCIMS）进行了实验室表征。该仪器的工作原理是将环境空气通过一个直径50微米的小孔吸入一个保持低压的进样口。通过向进样口中添加NO和SO2引发化学反应，将空气中的过氧自由基（HO2和RO2）放大化学转化为独特的离子（HSO4-），从而检测到这些过氧自由基。然后通过四极滤质器质谱仪对HSO4-离子进行定量。PerCIMS通过控制添加到仪器中的NO和SO2浓度，实现对过氧自由基总和HO2 + RO2（HOxROx模式）或仅HO2成分（HO2模式）的测量。通过进样口化学建模和实验室实验对该仪器的特性和响应进行了评估，并且在实地测量活动中的成功部署也证明了这一点。报告了PerCIMS在校准压力和相对湿度方面的性能，以及该仪器对不同烃基有机过氧自由基的灵敏度。这些数据表明，PerCIMS是一种实用的实地仪器，可在各种大气条件下快速准确地评估过氧自由基浓度。推导的[HOxROx]浓度的估计准确度为±35%（在95%置信区间），而[HO2]测量的准确度为±41%（在95%置信区间）。远高于检测限的典型测量精度为10%，对于15秒的平均时间，典型检测限为1×107个自由基厘米-3。
