Abstract: A Gas and Aerosol Collector (GAC) can continuously collect and measuregaseous and particulate water-soluble ions. Comparisons were performed betweena GAC and other instruments including a SO₂ analyzer, Differential Optical Absorption Spectroscopy (DOAS), a Particle into Liquid Sampler (PILS) and filter-based measurements. The results indicated that the GAC could absorb SO₂ completelyand give reliable SO₂ measurement results. The GAC gave higher HONO mass concentrations than DOAS because NO₂ may interfere with HONO measurement under high relative humidity. The mass concentrations of sulfate, nitrate and chloride measured by the GAC had good correlations with those by the PILS. After modifying the PM₁₀ by chemical size distribution, the GAC-sulfate and PILS-sulfate mass concentration had a difference within -2%. The sulfate mass concentration measured by theGAC had very good correlation with that by filtering. The GAC-nitrate mass concentration was poorly correlated with that by filtering; the filter-nitrate mass concentration was lower than the GAC-nitrate mass concentration because of loss of nitrate in the sampling process.