Silica-titania xerogel doped with Mo,P-heteropoly compounds for solid phase spectrophotometric determination of ascorbic acid in fruit juices, pharmaceuticals, and synthetic urine

BACKGROUND: Ascorbic acid is one of the most important vitamins to monitor in dietary sources (juices and vitamins) and biological liquids. RESULTS: Silica and silica-titania xerogels doped with Mo,P-heteropoly compounds (HPC) have been synthesized varying titanium(IV) and HPC content in sol. Their surface area and porosity have been studied with nitrogen adsorption and scanning electron microscopy, their elemental composition has been studied with energy-dispersive X-ray analysis. The redox properties of the sensor material with sufficient porosity and maximal HPC content have been studied with potentiometry and solid phase spectrophotometry and it has been used for solid phase spectrophotometric determination of ascorbic acid. The proposed method is characterized by good selectivity, simple probe pretreatment and broad analytical range (2–200 mg/L, LOD 0.7 mg/L) and has been applied to the analysis of fruit juices, vitamin tablets, and synthetic urine. CONCLUSIONS: New sensor material has been used for simple and selective solid phase spectrophotometric procedure of ascorbic acid determination in fruit juices, vitamin tablets, and synthetic urine. [Figure: see text]