Abstract
A high-performance liquid chromatographic method for the simultaneous determination of diphenyl (DP) and o-phenylphenol (OPP) in citrus fruits was investigated. DP and OPP were steam-distilled into cyclohexane from a citrus fruit homogenate. The cyclohexane extract, after addition of naphthalene as an internal standard, was injected into a chromatograph without any preliminary clean-up procedure. High-performance liquid chromatography was carried out using a column packed with Zorbax ODS and an ultraviolet-visible spectrophotometric detector. Gradient elution with water-methanol effectively separated the preservatives from citrus oil components and shortened the analysis time. The time required for chromatographic separation was less than 15 minutes. The method could be successfully applied to samples of lemon, grapefruit, navel orange and Japanese citrus fruits such as Unshumikan, Hassaku, Iyokan, Ponkan, and Kinkan. The limits of detection were 1ng of DP and 1.5ng of OPP. Recoveries of DP (70ppm) and OPP (10ppm) added to Unshumikan were 95.6±4.4% and 91.2±5.5%, respectively.
