Highly Sensitive Colorimetric Assay for Determining Fe³⁺ Based on Gold Nanoparticles Conjugated with Glycol Chitosan

Figure 2

(a) Photographic color images, (b) UV-Vis absorption spectra, and (c) absorption ratios (A₇₀₀/A₅₁₀) of GC-AuNPs with 90 μM Fe³⁺ and 900 μM metal cations (Fe²⁺, Ba²⁺, Mn²⁺, Ga³⁺, Ti⁴⁺, Al³⁺, Mg²⁺, K⁺, Ag⁺, Ge⁴⁺, Cr³⁺, Cu²⁺, Li⁺, As³⁺, Co²⁺, Sn²⁺, Na⁺, Pb²⁺, Hg²⁺, Ni²⁺, and Zn²⁺ ions) at pH 6, 70°C, and 300 mM NaCl concentration. (d) Absorption ratios (A₇₀₀/A₅₁₀) of GC-AuNPs with 900 μM metal cations (Fe³⁺, Fe²⁺, Ba²⁺, Mn²⁺, Ga³⁺, Ti⁴⁺, Al³⁺, Mg²⁺, K⁺, Ag⁺, Ge⁴⁺, Cr³⁺, Cu²⁺, Li⁺, As³⁺, Co²⁺, Sn²⁺, Na⁺, Pb²⁺, Hg²⁺, Ni²⁺, and Zn²⁺ ions) in the presence and absence of 90 μM Fe³⁺.

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