DETERMINATION OF FURANEOL AND P-VINYLGUAIACOL IN ORANGE JUICE EMPLOYING DIFFERENTIAL UV WAVELENGTH AND FLUORESCENCE DETECTION WITH A UNIFIED SOLID-PHASE EXTRACTION

A unified sample preparation and modified chromatographic procedure we re developed to determine two major off-flavors in orange juice, p-vin ylguaiacol (PVG) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF or Fu raneol). Furaneol was quantified using the absorbance difference betwe en 335 and 292 nm. This procedure helped identify Furaneol by suppress ing an interfering peak that developed in juice during storage. The C- 18 solid phase extraction procedure isolated both PVG and Furaneol fro m orange juice into a single extract. A 30 min reversed-phase HPLC gra dient method employing UV and fluorescence detectors in series was als o developed for the determination of both off-flavors from a single in jection. The ternary solvent system consisted of water, methanol, and acetonitrile. Recovery studies yielded mean recoveries of 99.9% +/- 2. 3% for Furaneol (0.3, 1.0, and 10.0 ppm) and 100.0% +/- 1.2% for PVG ( 0.05, 2.0, and 5.0 ppm), thus demonstrating that the unified solid pha se procedure quantitatively isolated both compounds.