HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR THE SIMULTANEOUS DETERMINATION OF TOCOPHEROLS, CAROTENES, AND RETINOL AND ITS GEOMETRIC ISOMERS IN ITALIAN CHEESES

In the present study we describe a high-performance liquid chromatogra phic method for the simultaneous determination of alpha-, beta-, gamma - and delta-tocopherol, cis and trans isomers of retinol, and total ca rotenes in different Italian cheeses. The method involves sample extra ction and saponification followed by normal-phase high-performance liq uid chromatography (HPLC). Monitoring of the absorbance and fluorescen ce is achieved using a programmable spectrophotometer and a programmab le spectrafluorometer connected in series. The proposed method, which has the advantage of being able to evaluate simultaneously the fat-sol uble vitamins considered by us in this work, has been applied to some Italian cheeses (Percorino romano, Taleggio, Provolone, and Caciotta) and milk samples (cows', goats', and sheep milk). The HPLC analytical procedure provides excellent reproducibility of results and is less su bject to interferences from the sample matrix than wet chemical techni ques. These factors combine to make the simultaneous determination of alpha-, beta-, gamma-, and delta-tocopherol, cis and trans isomers of retinol, and total carotenes by HPLC a practical technique for routine quality control and chemical and nutritional research applications.