Studies on development of headspace - gas chromatographic determination of volatile fatty acids in troublesome environmental samples

Abstract

A research was done to develop procedure of determination of volatile fatty acids (VFAs) in heavily polluted wastewaters using an automated static headspace (HS) unit combined with gas chromatograph (GC) with flame ionization detector (FID). Separation conditions were determined under which VFAs with 2-8 carbon atoms in a molecule separate well on a Stabilwax capillary column. Factors such as sample volume, and time and temperature of sample-HS conditioning have been selected for acetic, propionic, iso-and n-butyric, isoand n-valeric and n-capronic acids in the concentration range 0.1-1000 mg/L. HS conditions were: maintaining the system at 95 o C for 30 min, 2mL sample volume placed in 15 mL extraction vial, acidified to pH 2 and salted out with 0.75 g NaCl. In quantitation better results were obtained when was calibration curve divided to the part close to detection limit and to the part for higher concentrations. Validation process has been started.