Effect of Gold
Nanoparticles Size on Detection of Methylphosphonic Acid Hydrolysis Product of Nerve
Agent
Pojol Fellyzra Elvya, Chieng Buong Woei, Ong Keat Khim, Abd Rashid Jahwarhar Izuan,
Osman Mohd Junaedy, Wan Yunus Wan Md Zin, Jamari Nor Laili-Azua and Teoh Chin Chuang
Res. J. Chem. Environ; Vol. 25(7); 1-7;
doi: https://doi.org/10.25303/257rjce0121; (2021)
Abstract
Citrate reduction of gold (III) chloride trihydrate (HAuCl4) is commonly used method
to synthesise citrate-capped gold nanoparticles (cit-AuNPs). In this study, the
sequence of reagents addition was modified (“inverse” method) to synthesise smaller
size of cit-AuNPs than the standard Turkevich method (“direct” method). Ultraviolet-visible
spectroscopy (UV-vis) and field emission transmission electron microscopy (FETEM)
confirmed the formation of cit-AuNPs. The cit-AuNPs synthesized using “inverse”
method are smaller in size (14.0 ± 3.03 nm) with uniform spherical shape compared
to “direct” method (23.5 ± 7.52 nm).
Smaller particles size of cit-AuNPs provide higher efficiency and sensitivity for
detection of methylphosphonic acid (MPA) via colorimetric incorporated with image
processing with a linear range from 2.5 to 12.5 mM and a low detection limit of
6.28 mM at shorter detection period (24 to 30 s).
