Simultaneous determination of atmospheric sulfur and nitrogen oxides using a battery-operated portable filter pack sampler

Abstract

We developed a method to analyze atmospheric SO_x (particulate SO₄ ²⁻ + gaseous SO₂) and NO_x (NO + NO₂) simultaneously using a battery-operated portable filter pack sampler. NO_x determination using a filter pack method is new. SO_x and NO_x were collected on a Na₂CO₃ filter and PTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl) + TEA (triethanolamine) filters (6 piled sheets), respectively. Aqueous solutions were then used to extract pollutants trapped by the filters and the resulting extracts were pre-cleaned (e.g. elimination of PTIO) and analyzed for sulfate and nitrite by ion chromatography. Recoveries of SO₂ and NO_x from standard pollutant gases and consistency of the field data with those from other instrumental methods were examined to evaluate our method. SO_x and NO_x could be analyzed accurately with determination limits of 0.2 ppbv and 1.0 ppbv (as daily average concentrations), respectively. The sampler can determine SO_x and NO_x concentrations at mountainous or remote sites without needing an electric power supply.