Rapid automated determination of biphenyl in citrus fruit rind

Abstract

A totally automated analytical procedure for determining the fungistat biphenyl in citrus fruit rind has been developed. Small pieces of hand-peeled rind are automatically homogenised in water and steam-distilled to liberate the biphenyl, which is trapped in cyclohexane solution; this solution is exhaustively extracted to remove interfering steam volatiles, and the biphenyl remaining is read at 246 mµ in a continuous flow recording spectrophotometer. Time required from the introduction of rind samples to read out of biphenyl present is 9 minutes, with about 15 minutes for the first sample. The useful range is from 1 to about 150 p.p.m. on a whole-fruit basis with a reproducibility of about 3 per cent. The method has been applied most extensively to Valencia oranges.