Silver Nanoparticles Capped with <i>p</i>-Hydroxybenzoic Acid as a Colorimetric Sensor for the Determination of Paraquat

Abstract

Highly stable silver nanoparticles capped with p-hydroxybenzoic acid were synthesized by reducing silver ion with p-hydroxybenzoic acid and used for the detection of paraquat. The synthesized silver nanoparticles, which are yellow, exhibited an absorption peak at 420 nm when measured with a UV-visible spectrophotometer due to the surface plasmon resonance. In the presence of paraquat, the color of silver nanoparticles changed from yellow to purple accompanied by the appearance of a new peak at 580 nm in addition to the peak at 420 nm. In order to obtain optimum experimental conditions, temperature, and time of reaction were optimized, and the ratio of absorbance obtained at 580 nm and 420 nm (A580/A420) were monitored. The A580/A420 is proportional to the concentration of paraquat. Under the most favorable condition, the calibration curve showed a high level of linearity ranging from 6.0 × 10–4 to 1.0 × 10–3 M, and the detection limit was found to be 8.30 × 10–6 M. Silver nanoparticles capped with p-hydroxybenzoic acid was found to be useful for the colorimetric determination of paraquat in the aqueous medium.

Synthesis and Characterization of Silver Nanoparticles Using Bioreductant Andong Leaf Extract (Cordyline fruticosa (L) A. Chev.)

“…At silver concentrations of 2×10 -4 M and 3×10 -4 M, two measured wavelengths, namely 410 and 415 nm, were observed, accompanied by a broadening of the peak towards the redshift, indicative of larger nanoparticle sizes. This finding aligns with previous research by Gusrizal et al [19], which demonstrated an increase in absorbance intensity with rising silver concentration and a consequent increase in silver nanoparticle size. Therefore, a silver concentration of 1.5×10 -4 M was chosen for further synthesis.…”

Antimicrobial activity of a silver-microfibrillated cellulose biocomposite against susceptible and resistant bacteria

“…1a). This was evidenced by the formation of the characteristic surface plasmon resonance (SPR) absorbance band centered at 407 nm, commonly reported around 420 nm [39][40][41] , the lack of a band in the cellulose spectrum and visually, via color change (light yellow to black to grey), indicative of the redox reaction between the Ag salt and ascorbic acid (Fig. 1b).…”

Fully Printed Cellulose Nanofiber–Ag Nanoparticle Composite for High-Performance Humidity Sensor

“…Figure 4 a shows the UV–vis absorption spectra of the neat CNF film and the CNF-AgNP composite film, reflecting the successful formation of a AgNP. AgNPs formed from the redox reaction between the Ag + ions of AgNO 3 and NaBH 4 were revealed from the cellulose spectrum of the characteristic UV–vis absorption band generally in the 400–450 nm range, as well as from the visible yellow color change [ 21 , 22 , 23 ]. This color persisted in the CNF-AgNP compound for 3 months, indicating that the AgNPs synthesized on cellulose exhibit excellent stability [ 24 ].…”