DETERMINATION OF LOW-MOLECULAR-WEIGHT ORGANIC-ACIDS COLLECTED ON SILICA-GEL AIR SAMPLING TUBES BY USING ION-EXCLUSION CHROMATOGRAPHY

Ion-exclusion chromatographic separation of organic acids by using tridecafluoroheptanoic acid solution as the eluent and conductivity detection were studied. Air samples were collected on silica gel tubes and desorbed in water. The proposed method was applicable to the separation of formic, acetic, propionic, and butyric acids. The recovery of these four acids was above 95% when air was passed through the spiked tubes at a flow rate of 0.2 L/min for 3 hr. The method was validated for all four compounds at one-half the threshold limit value (TLV), at the TLV, and two times the TLV. No changes in recovery were observed in samples stored for up to 7 days. Desorbed samples were stable for up to 20 days.