Abstract: A method using high performance liquid chromatography with diode array detection and fluorescence detection (HPLC-DAD-FLD) was developed to simultaneously analyze 12 compounds of polymethoxyflavones (PMFs), coumarins and furocoumarins in citrus juice samples. Baseline separation of twelve compounds was achieved within 30 min using gradient elution with a ternary mobile phase composed of 0.01% phosphoric acid, methanol and acetonitrile. Qualitative identification of the components in citrus juices was confirmed by comparing their UV and fluorescence (FL) spectra and retention times with those of the reference standards. Quantitative analysis of the juice components was operated at a UV wavelength of 320 nm (OD320 nm) and a fluorescence emission of 450 nm. The calibration curves showed good linearity. The limit of quantitation (LOQ) with FLD was at as low as μg/L level so that FLD could be an important complementary tool to UV detection. The recovery tests showed a good accuracy for both UV (95.2%–104.8%) and FL (94.5%–103.5%) examination. In general, this method is accurate and reliable for qualitative and quantitative analysis of citrus juice components, especially the ones having fluorescence emission like PMFs and coumarins.

Key words: high performance liquid chromatography (HPLC), fluorescence detection, citrus juice, polymethoxyflavones, coumarins