In this report, we present a new method for visual detection of Pb
2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb
2+ is added during the gold nanoparticle formation.
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In this report, we present a new method for visual detection of Pb
2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb
2+ is added during the gold nanoparticle formation. Analysis of Pb
2+ is conducted by a dual strategy, namely, colorimetry and spectrometry. During Au-NPs synthesis, addition of Pb
2+ would lead to formation of Pb-GA complex, which can induce the aggregation of newly-formed small unstable gold nanoclusters. Consequently, colorimetric detection of trace Pb
2+ can be realized. As the Pb
2+ concentration increases, the color turns from red-wine to purple, and finally blue. This method offers a sensitive linear correlation between the shift of the absorption band (Δλ) and logarithm of Pb
2+ concentration ranging from 5.0 × 10
−8 to 1.0 × 10
−6 M with a linear fit coefficient of 0.998, and a high selectivity for Pb
2+ detection with a low detection limit down to 2.5 × 10
−8 M.
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