Ultrasensitive nanodrop spectrophotometric assay of Pb(II) using green fabricated gold nanoparticles

A versatile economically viable method for green fabricated gold nanoparticles (AuNPs) using almond hull has been developed. The bioactive components such as catechins, vanillic acid and other polyphenols in almond hull extract (AHE) act as reducing as well as stabilizing agents for the synthesis of AuNPs. The resulting AHE–AuNPs were examined by several confirmation tools such as nanodrop spectrophotometer (NDS), Fourier transform infrared spectroscopy, scanning electron microscopy (SEM)-energy dispersive X-ray and high-resolution transmission electron microscopy. Moreover, the futuristic application of AuNPs was described for selective and ultrasensitive assay of Pb(II) ions by using NDS. In the presence of Pb(II) (0.2–1.0 ppm), the absorbance of AuNPs drop linearly and might be prompted to aggregate with colour changes instantaneously. The absorption ratio (A664/A522) of AuNPs displayed a linear correlation coefficient (r2) of 0.9887 with 1.1% relative standard deviation and the limit of detection was 0.163 ppm. The co-existing ions do not interfere even in the absence of masking agents. Hence, the synthesized AuNPs were also used as an efficient probe for the quick and facile determination of Pb(II) in the real water samples via NDS. Graphical abstract