Polyfluorinated alkyl substances (PFASs) are among emerging persistent organic pollutants (POPs) that are widely present in a variety of consumer products. The typical approach for determination of volatile PFASs in ambient air is based upon the high-volume active sampling and solvent extraction (method A), which suffers from the poor portability, high noise level and significant loss of low molecular weight analytes. All these limitations have restricted its application in urban regions, especially in residential areas when conducting source apportionment analysis. In this study, method A was compared with another approach using low-volume air sampling and thermal desorption (method B). In general, method B showed a better repeatability and recovery, while method A demonstrated a lower detection limit. Application of both methods in the outdoor urban environment of Singapore indicated a higher time resolution, higher portability and lower noise level of method B. With these advantages method B appeared to be more suitable for the quantitative analysis of targeted PFASs in regions with concentrated point and variable diffusive sources.