Development of an RP-HPLC method for the simultaneous determination of benzoic acid, sorbic acid, natamycin and lysozyme in hard and pasta filata cheeses.

A single method, based on RP-HPLC with UV detection, was developed with the aim of simultaneously quantifying four preservatives in cheeses: benzoic acid, sorbic acid, natamycin and lysozyme. The preservatives were extracted from different cheeses by using the same procedure, and separated by a single RP-HPLC gradient elution showing good resolution, in a short time. Recoveries were always higher than 91%; MDLs ranged from 0.4 to 4.0µgg(-1), and MQLs were included between 1.3 and 13.3µgg(-1); RDS ranged from 1% to 7%. Quantitation was performed in reference to a matrix matched calibration curve. The method was also applied to real samples for the determination of the four preservatives, with satisfying results.