A critical review of advanced analytical techniques for water-soluble organic matter from atmospheric aerosols

Water-soluble organic matter (WSOM) from air particles plays a potentially important role in the climate system, yet little is known about its molecular composition and physico-chemical properties. During the past decade, the rapidly-evolving field of analytical instrumentation has produced sophisticated tools capable of providing molecular level information on this organic-aerosol fraction.This article presents a critical review of the major applications of these advanced analytical methods in WSOM analysis. We emphasize off-line methods relying on nuclear magnetic resonance and infrared spectroscopies, and high-resolution mass spectrometry. We also discuss the most prominent analytical methods for near real-time measurements of particulate WSOM. We address the limitations of advanced off-line and on-line instrumental techniques, and, finally, outline the major challenges ahead to improve the current knowledge on the chemical structures of aerosol WSOM.