Identification and Quantification of Aldehydes in Mezcal by Solid Phase Microextraction with On-fiber Derivatization - Gas Cromatography

A headspace solid phase microextraction with on fiber de- rivatization procedure followed by gas chromatography and flame ionization detection was applied for the determination of aldehydes in mezcal. A derivatization agent o-(2,3,4,5,6-pentafluorobenzyl) hy- droxylamine (PFBHA) was adsorbed onto a Polydimethylsiloxane/ divinyl benzene (PDMS/DVB, 65 µm) fiber and exposed to the head- space of a vial with a mezcal sample. The aldehydes selectively reacted with PFBHA, and the oximes were desorbed into a gas chromatograph injection port. Identification of the compounds was performed with standards and confirmed by mass spectrometry. The procedure was applied to the analysis of 13 mezcal samples from different agave varieties. Calibration curves for acetaldehyde and furfural showed good linearity (r 2 > 0.99) in the studied concentration range, 1-9 μg/mL for acetaldehyde and 0.5-1 μg/mL for furfural in the diluted mezcal samples. Good precision was obtained for acetaldehyde, CV <6.3% and furfural <10%. Based on the standard for tequila NOM- 006-SCFI-2005, all mezcal samples showed concentrations of acetal- dehyde within the norm, while 2 mezcals exceeded the allowed limit for furfural.