A Ratiometric and Visual Sensing of Phosphate by White Light Emitting Quantum Dot Complex

Ratiometric and visual sensing of phosphate by using a white light emitting quantum dot complex (WLE QDC) is reported herein. The WLE QDC comprised of Mn²⁺-doped ZnS quantum dot (with λ_em = 585 nm) and surface zinc quinolate (ZnQS₂) complex (with λ_em= 480 nm). The limit of detection was estimated to be of 5.9 nM in the linear range of 16.6-82.6 nM. This was accomplished by monitoring the variations in the photoluminescence color, intensity ratio (I₄₈₀/I₅₈₅), chromaticity and hue of the WLE QDC in the presence of phosphate. The high selectivity and sensitivity of WLE QDC toward phosphate was observed. The chemical interaction of ZnQS₂ (present in WLE QDC) with phosphate might have led to the observed specificity in photoluminescence changes. The presented WLE QDC was successfully employed for the quantification of phosphate in samples prepared using environmental water and commercial fertilizer.