Derivatization reaction-based multi-spectroscopic techniques for ultrasensitive and rapid detection of phosphate in food using Nile blue A as probe

Herein, a multi-spectroscopic assay based on a derivatization reaction was proposed for phosphate detection. In this assay, the phosphate with weak spectral signals was transformed to a large ion-association complex via a derivatization reaction. The operation procedure of the assay was easily performed by physically mixing sulfuric acid, derivatization reagent, phosphate (or sample solution), and dye probe (Nile blue A) for 10 min. Consid-erable changes in three types of spectral signals, i.e., resonance Rayleigh scattering (RRS), fluorescence, and ultraviolet-visible absorption, could be achieved. Under certain conditions, good linear relationship was obtained between each of the three signal variations and the phosphate concentration. The assay shows good selectivity and high sensitivity with limits of detection (LOD) of 4.8, 4.9 and 5.2 ng/mL for the RRS method, fluoropho-tometry and spectrophotometry, respectively. The multi-spectroscopic assay was applied to detect phosphate in real food samples, achieving recoveries of 93.3 %-109.6 % and relative standard divisions of 1.8 %-7.1 %. Owing to its speediness, easy operation, high sensitivity, good selectivity, self-comparison function, the multi -spectroscopic assay exhibits great potential for determination of phosphate in complex samples and provides an instructive strategy for detecting analytes with no or weak spectral signal.

Automated summary

In this study, a multi-spectroscopic assay based on a derivatization reaction was developed for phosphate detection. The assay could transform the weak spectral signals of phosphate into a large ion-association complex, allowing for easy detection. Three types of spectral signals (resonance Rayleigh scattering, fluorescence, and ultraviolet-visible absorption) showed significant changes and had good linear relationships with the phosphate concentration. The assay demonstrated good selectivity and high sensitivity, making it suitable for phosphate determination in complex samples.