Spectrophotometric determination of atmospheric sulfur dioxide

Journal Article · Sun Jan 01 04:00:00 EST 1967 · Anal. Chem.; (United States)

DOI:https://doi.org/10.1021/ac50157a031· OSTI ID:6967016

Scaringelli, F P; Saltzman, B E; Frey, S A

Two improved pararosaniline methods developed for the spectrophotometric determination of sulfur dioxide in ambient air yield greater sensitivity, greater reproducibility, and adherence to Beer's law throughout a greater working range than the West and Gaeke method. These improvements resulted from optimization of the important parameters. The pararosaniline dye was specially purified and standardized to reduce variability problems. Phosphoric acid was used in the final color development to control pH, to liberate sulfur dioxide from its mercury complex, and to complex heavy metals. The pararosaniline methyl sulfonic acid produced in the reaction exhibited a hypsochromic spectral shift and behaved as a two-color pH indicator, the color changing from magenta (peak wavelength 575 m-micron) to red (peak wavelength 548 m-micron) as the acidity is decreased. Interferences from oxides of nitrogen, ozone, and heavy metals were minimized. Results were reproducible to within 4.9% (at 95% confidence level) if the analyses were done carefully, with close attention to temperature, pH, purity of the dye and water, and standardization of the sulfite solution. The methods have been tested on air samples from major cities in the United States and have been used routinely for almost a year.

• OSTI ID: 6967016
• Journal Information: Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 39:14; ISSN ANCHA
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
ATMOSPHERIC CHEMISTRY
CHALCOGENIDES
CHEMISTRY
DYES
OXIDES
OXYGEN COMPOUNDS
POLLUTION
SPECTROPHOTOMETRY
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES