J. chromatogr. A J. chromatogr. A Determination of 2-, 3-, 4-methylpentanoic and cyclohexanecarboxylic acids in wine: development of a selective method based on solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry and its application to different wines and alcoholic beverages Gracia-Moreno E. López R. Universidad de Zaragoza Ferreira V. Universidad de Zaragoza 2015 research-article