Determination of phosphate in food based on molybdenum yellow derivatization coupled with resonance Rayleigh...

This paper proposed a rapid, selective and sensitive molybdenum yellow derivatization coupled with Resonance Rayleigh scattering (MYD-RRS) method for detection of phosphate. Under the acidic condition, phosphate can be selectively transformed to Keggin type of phosphomolybdic acid (PMA, i.e., PMo₁₂O₄₀^3-) through molybdenum yellow derivatization reaction prior to RRS detection. The PMA can further react with cationic methyl violet (MV) to form larger PMA-MV ion association complexes, generating significant RRS signal. The concentration of phosphate was linearly related to the RRS signal in the range of 8-200 ng/mL, with the determining coefficient (R²) of 0.9973 and the detection limit of 4 ng/mL. The analytical procedure can be completed within 10 min and the RRS signal intensity can remain stable more than 4 h. The method showed good stability toward temperature and time, and good anti-interference capability. The method was applied to the determination of phosphate in real food samples with the recovery of 85-117% and RSD of 1-5.2%. With the advantages of rapidness, high sensitivity and good selectivity, the MYD-RRS method exhibits great potential to the determination of phosphate in food. It also provides an instructive strategy for detection of analytes with weak RRS signal.