A rapid and simple method for the quantitative determination of volatile fatty acids (VFAs; propionic acid, n-butyric acid, i-valeric acid and n-valeric acid) and indoles (phenol, p-cresol, 4-ethyl phenol, indole and skatole) in pig slurry and dog excrement using solid-phase micro-extraction (SPME) coupled to gas chromatography was evaluated. 50/30 ㎛ DVB/CAR/PDMS (Divinylbenzene/Carboxen/Polydimethylsiloxane) fiber was used to extract the target compounds in aqueous media. Sample amount and adsorption time was standardized for the routine analysis. Detection limits were from 0.11 to 0.15 ㎍/L for VFAs and from 0.12 to 0.28 ㎍/L for indoles and the correlations observed (R2) were 0.975～1.000. This method was applied to the pig slurry, fertilizer, compost and dog excrement. In nearly all cases, the indoles were detected in concentrations of higher than their limits of detection (DOLs). But the VFAs in swine manure were below their DOLs.

Abstract
 1. Introduction
 2. Materials and methods
  2.1. Reagents and SPME
  2.2. Preparation of standard solution and calibration line
  2.3. Analysis of field samples
 3. Result and discussion
  3.1. Preparation of calibration lines
  3.2. Reproducibility
  3.3. Analysis of field sample
 3. Conclusions
 References

• Hyun-Jung Kim(Department of Chemistry, University of Ulsan)
• Mee-Seon Yu(Department of Chemistry, University of Ulsan)
• Sung-Bong Yang(Department of Chemistry, University of Ulsan) Corresponding author