Zhichen Deng,Zihui Zhong,Li Li,Zhengquan Su,Yan Bai,Jincan He
A one-pot derivatization facilitated resonance Rayleigh scattering and absorption (abbreviated as one-pot RRS/Abs) dual-mode method was proposed for selective and rapid detection of phosphate. A one-pot derivatization reaction that takes only 5 min was introduced to generate a dual-mode spectroscopic signal and improve the selectivity. Using the derivatization agent (ammonium vanadic molybdate, AVM), spectral probe (crystal violet, CV), and sensitizing reagent (Triton X-114, TX-114), phosphate was transformed into a large supramolecular complex, resulting in a remarkable dual-mode signal response of RRS and UV–Vis absorption. The RRS signal (368 nm) and ratiometric absorption signal (A 590 nm /A 450 nm ) were linearly correlated with the phosphate concentration in the range of 0.05–1.0 µg/mL and 0.08–1.0 µg/mL, respectively. The correlation index (R 2 ) was 0.9976 and 0.9890, and the limits of detection (LOD) were 13 ng/mL and 42 ng/mL, respectively, which were lower than those obtained through most spectroscopic methods. The one-pot RRS/Abs dual-mode method was applied to detect phosphate in real food samples, with recoveries of 92.0%–110.0% and relative standard deviations (RSD) of 2.1%–6.6%. The one-pot RRS/Abs dual-mode method is rapid, selective, sensitive, convenient to operate, and capable of self-comparison, showing great promise for phosphate detection in complex samples. In addition, it offers an alternative strategy for the measurement of analytes with weak spectroscopic signals.
Aqueous binary surfactant solutions, based on the cloud point phenomenon, have been utilized to design efficient extraction of a variety of substances. In this study, the effect of the anionic surfactant sodium dodecyl sulfate (SDS) on the clouding behaviour of aqueous nonionic surfactant solutions of Triton X-114 (TX-114), in the presence of 100 mM sodium chloride (NaCl), has been studied as a function of temperature by means of turbidity, dynamic light scattering (DLS), and rheo-small angle light scattering (Rheo-SALS). It is found that the addition of 2 mM SDS lowers the phase separation temperature of the surfactant solution by about 2 °C. The hydrodynamic radius of the surfactant aggregates increases with increase of temperature and SDS concentration. The change in microstructure of the surfactant aggregates at different temperature and SDS concentrations is also reflected by the characteristic length and aspect ratio extracted from their SALS patterns, which range from 269 to 623 nm and from 1.01 to 1.40, respectively. The increasing characteristic length and aspect ratio with SDS concentration indicate the growth of the mixed surfactant aggregates is in the flow direction and these elongated aggregates can align under shear.
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