Determination of 4-ethylguaiacol and 4-ethylphenol in red wines using headspace-solid-phase microextraction-gas chromatography.

A method for analysing 4-ethylguaiacol and 4-ethylphenol in the aroma of red wines using headspace-solid-phase microextraction is presented. The fibres used were coated with 100 microm of polydimethylsiloxane. Parameters like ionic strength, agitation of the sample, sample volume, temperature of the sample and adsorption/desorption times were studied and optimised to obtain the best extraction results. The linearity of the response was studied in the usual concentration ranges in wines (4-ethylguaiacol, 40-400 microg/l; 4-ethylphenol, 200-1800 microg/l). Repeatability of the method was determined, and the relative standard deviation was about 10%. Limits of detection and limits of quantification were also determined, and the values found were 1 and 5 microg/l for 4-ethylguaiacol and 2 and 5 microg/l for 4-ethylphenol, respectively. All these values were under the sensory thresholds established for these volatile phenols. The presence of interferences due to the matrix composition implies the use of the standard addition technique for both compounds quantification.