Aqueous biphasic system in differential extraction of arseno and phospho molybdenum blue: Consequent sensing of glutathione in acid-free medium

Polyoxometalates (POMs) are the oxyanion clusters of early transition metals (mostly molybdenum (VI), tungsten (VI) and vanadium (V)) and they show interesting properties particularly in the field of catalysis and sensing chemistry. In this work molybdenum blue (MB), phosphomolybdenum blue (PMB) and arsenomolybdenum blue (AsMB) are prepared using glutathione (GSH) as reducing agent in acid–free condition. The MB species are further characterised by UV–vis spectroscopy, Raman spectroscopy, XPS, powder XRD and FTIR spectroscopy. The prepared MB solutions showed an exciting behaviour in Aqueous Biphasic Systems (ABS) using PEG#4000 and Na₂SO₄ as phase forming components. MB and PMB partition to the micellar medium of PEG upto 44 % and 66 % respectively but AsMB is not at all partitioned. Therefore the method is useful for differentiating PMB and AsMB. PEG has been recovered using ultra-filtration technique after the ABS. The experiment also reveals that GSH, a biomolecule with high physiological impact, can be detected at trace concentrations by PMB formation method both in water and blood serum media.