Sampling of Atmospheric Carbonyls with Small DNPH-Coated C18 Cartridges and Liquid Chromatography Analysis with Diode Array Detection

Abstract

Carbonyls in air are sampled using small DNPH-coated C18 cartridges and analyzed by liquid chromatography with diode array detection. Carbonyl structure confirmation is obtained by comparing diode array spectral scans of samples to the uv-visible spectra (190–600 nm) of some 20 carbonyl hydrazones recorded in the CH₃CN—H₂O eluent used for LC analysis. Analytical detection limits are 0.09–3.4 nanograms carbonyl and correspond to 0.14–1.24ppb in 60 L air samples. Accuracy was ±5% as measured for independently prepared hydrazone standards. The precision was 1–5% for multiple injections of hydrazone standards and 2–10% for replicate analysis of indoor and outdoor air samples. Excellent agreement was obtained in an interlaboratory comparison that included hydrazone standards as well as indoor air samples.

Cartridge collection efficiency has been tested over a range of conditions (sampling flow rate, volume of air sampled, presence of co-pollutants including photochemical oxidants) and is >0.95 for monofunctional carbonyls, unsaturated carbonyls, and alpha dicarbonyls. Carbonyl recovery by cartridge elution is >0.99 for all carbonyls tested. Examples of applications are given in the fields of atmospheric chemistry, indoor air pollution in museums, and outdoor air quality.