Increasing the quantitative credibility of open-path FT-IR spectroscopic data with focus on several properties of the background spectrum

Shao, L. and Wang, Wanping and Griffiths, P.R. and Leytem, A.B. (2013) Increasing the quantitative credibility of open-path FT-IR spectroscopic data with focus on several properties of the background spectrum. Journal of Applied Spectroscopy. 67(3):335-341. 1 March 2013.

PDF 1470.pdf Download (618kB)

Abstract

The choice of the type of background spectrum affects the credibility of open-path Fourier transform infrared (OP/FT-IR) spectroscopic data, and consequently the quality of data analysis. We systematically investigated several properties of the background spectrum. The results show that a short-path background measured with the lowest amplifier gain could significantly reduce noise in the calculated absorbance spectrum, by at least 30% in our case. We demonstrated that by using a short-path background, data analysis is more resistant to interferences, such as wavenumber shift or resolution alteration that occurs as a consequence of hardware aging or misalignment. We also discussed a systematic error introduced into quantitative analyses by the short-path background, and developed a procedure to correct the error. With this correction approach, a short-path background measured five years ago was still found to be valid. By incorporating these findings into the protocol for quantitative analysis, we processed the measurements by two OP/FT-IR instruments set up side by side in the vicinity of a large dairy farm to monitor NH3, CH4 and N2O. The two sets of calculated concentrations showed high agreement with each other. The findings of our investigations are helpful to atmospheric monitoring practitioners of OP/FT-IR spectroscopy and could also be a reference for future amendment to the protocols outlined in the guidelines of the US Environmental Protection Agency (USEPA), the American Society for Testing and Materials (ASTM), and the European Committee for Standardization (ECS).

Item Type:	Article
NWISRL Publication Number:	1470
Subjects:	Air Quality > Air Emissions
Depositing User:	Users 6 not found.
Date Deposited:	20 Aug 2013 18:10
Last Modified:	20 Aug 2013 18:10
Item ID:	1507
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1507