We use the thermal desorption profile of the detected condensed phase compounds in the FIGAERO-CIMS to estimate the vapor pressure. We correlate the temperature of the maximum signal in the thermogram (1/Tmax, in 1/K) to the vapor pressure of several known organic acids by manually depositing an aliquot of a mixture of the acids using a micro syringe. The mixture was dissolved in ethanol and went through the same thermo-desorption program that is applied to the actual measurements. Table S1 summarizes the saturation concentration (C • 300 K) of