Determination of Total Aerosol Nitrogen by Thermal Evolution

Figures & data

FIG. 1 Block diagram of the aerosol nitrogen analyzer.

FIG. 2 N thermoevolution peaks of a few standard nitrogen species and an aerosol sample using a fast thermoevolution temperature program. Analysis conditions: Front oven, 800°C; MnO₂ catalyst oven, 870°C; Mo converter, 315°C; Carrier gas flow 500 mL/min.

FIG. 3 Response curve of the aerosol nitrogen analyzer to the amount of N in ammonium sulfate. The linear curve is generated using calibration standards of 0.5–15 μgN.

TABLE 1 Recoveries of a few nitrogenous standards as measured by the aerosol nitrogen analyzer

Nitrogenous standard	Spiked-N (μg N)	Recovery (n = 3) ^a (%)
Ammonium chloride	4.69	79.9 ± 0.8
Potassium nitrate	5.07	129.6 ± 0.6
Sodium nitrite	5.00	85.5 ± 1.0
Ammonium nitrate	2.74	104.1 ± 1.4
Ammonium sulfate	5.66	99.2 ± 5.6
Ammonium hydrogen sulfate	5.04	101.7 ± 1.2
Methylamine	2.95	105.1 ± 3.6
Urea	6.61	94.9 ± 0.4
Amino acid mixture ^b	4.54	106.4 ± 1.4

FIG. 4 Comparison of total nitrogen measurements by the aerosol nitrogen analyzer and the elemental analyzer.

TABLE 2 TN, ON, and IN concentrations in twelve ambient aerosol samples

	Sample information		TN (μ gN/cm^2)
Sample no.	Date	Site	Aerosol N analyzer	Elemental analyzer	TN (μ gN/m^3)	NH4 ^+-N (μ gN/m^3)	NO3 ^−-N (μ gN/m^3)	ON (μ gN/m^3)	ON/TN
1	Oct. 11, 2002	Hong Kong (PM 2.5)	6.65 ± 0.34	6.21 ± 0.21	1.75	1.53	0.03	0.19 ± 0.12	11 ± 7%
2	Oct. 12, 2002	Kong Hong (PM 2.5)	6.42 ± 0.07	6.14 ± 0.24	1.69	1.41	0.04	0.25 ± 0.06	14 ± 4%
3	Oct. 13, 2002	Kong Hong (PM 2.5)	6.49 ± 0.19	6.14 ± 0.12	1.71	1.44	0.04	0.23 ± 0.08	14 ± 5%
4	Oct. 14, 2002	Kong Hong (PM 2.5)	4.92 ± 0.03	5.04 ± 0.12	1.29	1.13	0.02	0.15 ± 0.06	11 ± 4%
5	Oct. 15, 2002	Kong Hong (PM 2.5)	8.02 ± 0.11	8.21 ± 0.60	2.11	2.07	0.01	0.04 ± 0.08	1.7 ± 4.0%
6	Oct. 16, 2002	Hong Kong (PM 2.5)	6.72 ± 0.25	6.62 ± 0.21	1.75	1.70	< 0.01	0.05 ± 0.09	2.8 ± 5.4%
7	Apr. 12, 2002	Jeju, S. Korea (PM 5)	4.33 ± 0.02	4.35 ± 0.21	2.09	0.50	1.01	0.57 ± 0.03	27 ± 1%
8	Apr. 16, 2002	Jeju, S. Korea (PM 5)	1.91 ± 0.01	2.41 ± 0.12	0.78	0.49	0.14	0.11 ± 0.02	18 ± 3%
9	Apr. 28, 2002	Jeju, S. Korea (PM 5)	1.71 ± 0.12	1.73 ± 0.32	0.76	0.31	0.03	0.42 ± 0.06	55 ± 9%
10	Sep. 22, 2001	Nanjing, China (PM 2.5)	2.83 ± 0.07	2.90 ± 0.21	1.49	0.26	0.54	0.68 ± 0.05	46 ± 3%
11	Sep. 24, 2001	Nanjing, China (PM 2.5)	11.53 ± 0.06	11.79 ± 0.42	5.83	4.42	0.62	0.79 ± 0.17	14 ± 3%
12	Sep. 28, 2001	Nanjing, China (PM 2.5)	5.81 ± 0.10	5.93 ± 0.24	3.05	1.81	0.38	0.87 ± 0.12	28 ± 4%

FIG. 5 N thermograms of selected organic and inorganic nitrogen species and two aerosol samples using a two-step temperature program. Front oven temperature program: initially 300°C for 120 s, cooling for 60 s, 800°C for 120 s.