Method of OTA analysis in dry-cured ham
Analysis of pork meat was performed according to the method
recently proposed by Toscani et al. (2007), fully validated according
to the requirements reported by the EU Commission (Commission,
2002). The method performances (LOD, LOQ, recovery at 1 lg/
kg) were also evaluated for raw muscle and salami, in order to
check the reliability of this procedure also for these products.
Briefly, the extraction procedure was developed, taking into account
the protonation equilibrium of OTA, which is negatively
charged at alkaline pH whereas it is neutral at acidic pH. In particular,
a crude extract was obtained from meat by a solid–liquid
extraction with chloroform after acidification of the sample (pH
3), in order to keep OTA in its neutral form and, thus, soluble in organic
solvent. Then, OTA was extracted from the organic phase by
liquid–liquid partition, using a slightly alkaline buffer solution
(0.2 M Tris–HCl) (pH 8.5). The slightly alkaline pH allowed for
the back-extraction of the dianionic form of OTA, and purification
of the analyte from most of the interferents. The validation parameters
of the method are summarised in Table 1. The data obtained
were corrected for recovery.