In this study, the most effective salting-out effect has been examined in terms of application of various inorganic salts (NaCl, Na₂S0₄, NaHSO₃) using Alkali impregnated filter-Headspace-GC/FID. Five various VFAs (propionic acid (99.5%), r-butyric acid (99%), butyric acid (99%), i-valerie acid (99%), valerie acid (99%)) have been used. VFAs have been analyzed by adding 30%, 70%, 100%, 150%, 200% of different inorganic salts with HS-GC/FID. The efficiency of salting-out effect was obtained from the values of peak area in chromatogram. The most effective salting-out effect for applired inorganic salts was observed at 100% saturation. It was confirmed NaHSO₃ for salting-out effect was the best among inorganic salts. In addition, NaHSO₃ showed more efficiency of salting-out effect than NaCl as molecular weight of VFAs increases.

In this study, alkali impregnated filter sampling method was considered for VFAs in ambient air. When KOH concentration was 0.5 N and sampling flow velocity was 5~10 L/min the sampling efficiency was higher than 90 percent. More than 3 minute shaking make the sampled filter to be suspended in the 22.3 mL Vial. Alkali impregnated filter sampling method showed more than 4 times higher response compared to alkali solution sampling method, when the sample was analysed by headspace-gas chromatography. Five kinds of volatile fatty acids (propionic acid, i-butyric acid, n-butyric acid, i-valeric acid, valeric acid) were detected within 1.0~9.8 ppbv in the cow shed by alkali impregnated filter method and headspace gas chromatography. The alkali impregnated filter method was the most suitable sampling method for ambient volatile fatty acids with headspace gas chromatography analysis.