Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
Anal Chem. 2010 Oct 1;82(19):8034-8. doi: 10.1021/ac101700q.
The nano aerosol mass spectrometer (NAMS) irradiates individual, size selected nanoparticles with a high energy laser pulse to generate a mass spectrum consisting of multiply charged atomic ions. The elemental composition of the particle is determined from the ion signal intensities of each element, which requires deconvoluting isobaric ion signals at 4 m/z (O(4+) and C(3+)) and at 8 m/z (O(2+) and S(4+)). A method to deconvolute these ion signals using sucrose and ammonium sulfate as calibrants is presented. The approach is based on the assumption that the charge state distribution of a given element is independent of the chemical form of that element in the particle. Relative to previously reported methodology, the new approach permits accurate and precise determination of sulfur, which is crucial for interpretation of ambient nanoparticle data sets. With this approach, the differences between expected and measured elemental ratios of C, O, N, and S for a variety of test particles were generally much less than 10%, although a difference as high as 16% was observed.
纳米气溶胶质谱仪（NAMS）用高能激光脉冲辐照单个、尺寸选择的纳米颗粒，以产生由多电荷原子离子组成的质谱。通过测量每个元素的离子信号强度来确定颗粒的元素组成，这需要对 4 m/z（O(4+) 和 C(3+)）和 8 m/z（O(2+) 和 S(4+)）处的等摩尔离子信号进行解卷积。本文提出了一种使用蔗糖和硫酸铵作为校准物来解卷积这些离子信号的方法。该方法基于以下假设：给定元素的电荷态分布与其在颗粒中的化学形态无关。与之前报道的方法相比，该新方法可以准确、精确地测定硫，这对于解释环境纳米颗粒数据集至关重要。使用该方法，各种测试颗粒的 C、O、N 和 S 的预期和实测元素比之间的差异通常小于 10%，尽管观察到高达 16%的差异。
