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A new mechanism for resonance Rayleigh scattering detection of minoxidil based on catalytic oxidation of silver nanoparticles
(2022-07-05)
Teerasong, Saowapak
;
Praditweangkum, Wiboon
;
Chompoosor, Apiwat
This work presents a new method for minoxidil detection based on silver nanoparticle (AgNP) oxidation. Minoxidil, which is a pyrimidine N-oxide, can be reduced to its corresponding pyrimidine via a redox reaction. In this system, acetate buffer serves as a proton source. AgNPs act as electron donors that contribute electrons to the reaction, producing Ag+. Consequently, the sizes and numbers of AgNPs in the system decrease, which results in a decline in their resonance Rayleigh scattering (RRS). By monitoring the RRS intensity at 409 nm, a change in intensity was linearly related to the minoxidil concentration over a concentration range of 0.5 – 5.0 mM. The detection limit was 0.35 mM. This approach is simple and rapid. It is done by directly mixing the drug and AgNPs in an acidic buffer. The reaction was completed within 2 min. This proposed method was successfully utilized for quantification of minoxidil in topical hair-growth formulations.
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A simple and rapid method based on anti-aggregation of silver nanoparticles for detection of poly(diallyldimethylammonium chloride) in tap water
(2016-01-01)
Trisaranakul, Wichaya
;
Chompoosor, Apiwat
;
Maneeprakorn, Weerakanya
;
Nacapricha, Duangjai
;
Choengchan, Nathawut
A simple and rapid method was developed for the detection of poly(diallyldimethylammonium chloride) (PDADMAC) using citrate-capped silver nanoparticles (AgNPs). Detection was based on anti-aggregation of AgNPs in phosphate buffer caused by PDADMAC. Due to its positive charges, PDADMAC was adsorbed onto AgNPs via electrostatic interaction with citrate, which resulted in the charges at the particle surfaces to become positive and caused repulsion among particles. Furthermore, long-chain PDADMAC provided steric hindrance. These two effects promoted the dispersion of AgNPs in the phosphate buffer. A change in the state of dispersion influenced the surface plasmon resonance (SPR) of AgNPs. Therefore, in this work, the concentration of PDADMAC was determined by monitoring changes in absorbance (at 396 nm) caused by SPR of AgNPs. Under optimal conditions, the calibration was linear over the range of 1 to 100 mg L-1 with a detection limit of 0.7 mg L-1. Satisfactory precision was obtained (RSD = 2.8%). This method was successfully applied to the determination of PDADMAC in tap water samples. The recoveries ranged from 86.0 - 107.5%.
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Colorimetric sensor using silver nanoparticles for determination of hydrogen peroxide based on a flow injection system
(2013-09-01)
Teerasong, Saowapak
;
Sonsa-Ard, Thitaporn
;
Vimolkanjana, Chavin
;
Choengchan, Nathawut
;
Chompoosor, Apiwat
In this work, a colorimetric probe using a flow injection (FI) system and silver nanoparticles (AgNPs) was developed for determination of hydrogen peroxide (H2O2) concentration. AgNPs have catalytic ability for decomposition of H2O2, producing silver ions and superoxide. The reaction mechanism of H2O2 and AgNPs at various concentrations is described. H2O2 concentration was quantified by monitoring decrease in AgNPs surface plasmon resonance during the decomposition reaction. Under the optimum condition, the detection limit for H2O2 was 0.6 mg/l. The flow system developed in this study provided good precision of analysis (relative standard deviation = 2.97%) with high throughput (18 samples/h). This method was successfully applied to analysis of H2O2 in pharmaceutical and household products. Therefore, the method is feasible for on-line monitoring H2O2 in manufacturing process quality control. © Copyright 2013 American Scientific Publishers All rights reserved.

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