Determination of benzoic acid in air

A gas chromatographic method is described for direct determination of free benzoic acid in air samples. Benzoic acid is absorbed from air on Porapak Q packing in the presence of other compounds, thermally desorbed at 240 degrees C with helium flow into a capillary column, and detected with a flame ionization detector. The method is calibrated by injecting benzoic acid standard solutions into the Porapak Q. The method was validated with dynamic standards and recovery yields were good. Benzoic acid levels of 0.1-1.0 ppm (v/v) in air can be determined with sampling volumes of 8-24 L.