A rapid and automated solid phase microextraction (SPME) stable isotope dilution gas chromatography/mass spectrometry (GC-MS) method for 2-methoxy-3-isobutylpyrazine (MIBP) quantification in red wine was developed. Wines with 30% (w/v) NaCl and 2-methoxy-(2)H(3)-3-isobutylpyrazine internal standard were sampled with a 2 cm divinylbenzene/carboxen/poly(dimethylsiloxane) SPME fiber for 30 min at 40 degrees C and analyzed by GC-MS. The method was used to measure MIBP concentrations in Cabernet Sauvignon wines that were produced from six winter pruning treatments over two vintages. MIBP concentrations were significantly negatively correlated with buds per vine. In addition, the MIBP concentration was directly related to sensory vegetal intensity ratings obtained by descriptive analysis.