LED based optical dip-probe spectrophotometer for in situ monitoring of uranyl and uranous ions in aqueous process stream

•Miniature UV–vis spectrophotometry was developed for U(IV,VI) on-line monitoring.•Dip-probe, LED light source, and fiber optics were used in the miniature design.•Absorbance at 665 nm of U(IV) varied linearly with experimentally measured amount.•Absorbance at 485 nm could be used for U(VI) without effects of variation of HNO3.•Data on measured U(VI) showed reasonably good analytical merits for real samples.