Sol-gel-based SPME and GC-MS for trace determination of geosmin in water and apple juice samples

A headspace solid-phase microextraction (HS-SPME) method was developed for the trace determination of geosmin in water and apple juice samples. A poly(dimethylsiloxane) (PDMS) fiber was synthesized as coated fiber using sol-gel methodology. After performing the extraction in the headspace, the fiber was introduced directly into the injection port of a gas chromatography-mass spectrometry (GC-MS) using electron impact (EI) ionization mode. One-at-the-time optimization strategy was applied to investigate and optimize important extraction parameters such as extraction temperature and time, ionic strength, headspace volume, and desorption temperature and time. The analytical data exhibited an RSD of 2-15%, a linear calibration range of 1-1,000 ng L-1, and a detection limit of 0.30 ng L-1 using selected ion monitoring (SIM) mode. The proposed method was successfully applied to the extraction and determination of geosmin in the spiked real water and apple juice samples and a relative recovery of 95-102% were achieved. The developed method offers the advantage of being simple to use, with shorter analysis times, lower cost of equipment, very little matrix effect, and high relative recovery in comparison to conventional methods of analysis.