Particle size and chemical composition effects on elemental analysis with the nano aerosol mass spectrometer

Figures & data

Figure 1. NAMS platform for analyzing particles between 40 and 150 nm in diameter.

Figure 2. Summary of sucrose charge state distributions in single particle mass spectra from four monodisperse aerosol datasets, 100 spectra each. For each mass spectrum, the percentage of total signal intensity attributed to multiply charged atomic ions was calculated, and the data were sorted from highest percentage on the left to lowest percentage on the right.

Table 1. Measured O/C ratios for monodisperse sucrose aerosols using two different quantification methods. Measurement uncertainties are reported as 1 standard deviation. (Expected O/C ratio is 0.917).

Mobility Diameter (nm)	% Hot Spectra	^a(O/C)hot only	^b(O/C)hot&cold
20	98	0.92±0.05	1.26±0.01
40	92	0.92±0.06	1.15±0.06
60	75	0.92±0.08	1.07±0.05
100	71	0.91±0.06	1.95±0.09

^a Values obtained using only calibration and sample spectra with >90% signal contribution from multiply charged ions (“hot” spectra).

^b Values obtained using all available spectra (“hot” and “cold”) for both the calibration and sample sets.

Figure 3. Average mass spectrum of 100 particles from a polydisperse aerosol composed of a 2:1 molar ratio HEPES and cesium iodide. Measurement uncertainties are reported as 1 standard deviation. Atomic ions from the various elements are marked by the bars above the spectrum.

Table 2. Expected and measured elemental mole ratios from aerosols composed of HEPES and cesium iodide.

Mole Ratio		C	O	N	S	Cs	I
1:1	Expected	8	4	2	1	1	1
	Measured	8	3.94±0.07	2.02±0.02	1.01±0.02	1.02±0.02	1.01±0.03
2:1	Expected	8	4	2	1	0.5	0.5
	Measured	8	4.05±0.09	2.03±0.04	1.01±0.01	0.51±0.02	0.51±0.01
5:1	Expected	8	4	2	1	0.2	0.2
	Measured	8	4.1±0.1	2.02±0.07	1.02±0.04	0.21±0.01	0.21±0.01
9.5:1	Expected	8	4	2	1	0.105	0.105
	Measured	8	4.1±0.1	2.05±0.07	1.05±0.05	0.09±0.04	0.09±0.04

Figure 4. Average mass spectrum of 100 particles from a polydisperse aerosol composed of a 1:1 molar ratio lead(II) nitrate and HEPES. Measurement uncertainties are reported as 1 standard deviation. Atomic ions from the various elements are marked by the bars above the spectrum.

Figure 5. Average mass spectrum of 100 particles from a polydisperse aerosol composed of a 1:1 molar ratio iron(III) nitrate and HEPES. Measurement uncertainties are reported as 1 standard deviation. Atomic ions from the various elements are marked by the bars above the spectrum.

Figure 6. Plot of percentage of total signal intensity attributed to singly charged ions in the average mass spectrum of aerosol containing a specific element vs. (a) boiling point and (b) melting point of that element.

Figure 7. Elements for which quantitative analysis is/is not possible by LIPI under the conditions used in this study.