GC Determination of Volatile Fatty Acids in Waste Water with HS-SPME

GC with headspace-solid phase micro-extraction(HS-SPME) was applied to the determination of 6 fatty acids,i.e.,acetic acid,propionic acid,butyric acid,pentanoic acid,isopentanoic acid and hextanoic acid,in waste water.To attain a higher efficiency in SPME,the polar 85 μm PA coating was selected for the micro-extractor,and the extraction was carried out at 25 ℃ for 20 min from the sample solution having the acidity of pH 1.5,and with addition of 3.5 g of NaCl to 20 mL of sample solution as salting out agent.The analyte were separated with Stabilwax-DA capillary column and detected by FID.Linear relationships between values of peak area and mass concentration of 6 fatty acids were kept in definite ranges.Values of RSD′s(n=10) of the 6 fatty acids found were less than 10.0%.