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.

Volatile fatty acids (VFAs) are malodor compounds which are produced from the decomposition of animal or plant species. It is very difficult to detect VFAs due to their strong adsorptive properties. In this study we develop an analytical method using headspace-GC/FID with an alkali-impregnated filter sampling. The addition of NaCl and H₂S0₄ makes the salt-out and pH-lowering effect, respectively. The high boiling points (141~185℃) and vapor pressures require a high temperature and long heating time for the standard sample in vials to reach an equilibrium. The analytical response was highest when the absolute quantity in the sample was 5 mL in a 22 mL vial. The addition of NaCl for the salt-out effect can give a higher sensitiviry by a factor of 1.1~4.2 than that of Na₂SO₄. The mass amount of 4.6 g of NaCl can result in a higher sensitivity, which is higher than the supersaturated solubility of 4.2 g. The concentration of H₂SO₄ is as low as 2% (v/v). When the concentration range is 8.3 -562.1 ppb, a coefficient of R²~0.99 can be obtained for the five VFAs samples. The analytical errors in a reproducibility test are less than 10% and the detection limit is estimated to be 0.05~0.1 ppb. Our headspace-GC/FID analytical method can be utilized to effectively detect the five kinds of VFAs which shall be restricted in Republic of Korea from the year of 2010.