scholarly journals A Transparency Sheet-Based Colorimetric Device for Simple Determination of Calcium Ions Using Induced Aggregation of Modified Gold Nanoparticles

2019 ◽  
Vol 20 (12) ◽  
pp. 2954
Author(s):  
Paweenar Duenchay ◽  
Orawon Chailapakul ◽  
Weena Siangproh

A simple and novel transparency sheet-based colorimetric detection device using gold nanoparticles (AuNPs) modified by 4-Amino-6-hydroxy-2-mercaptopyrimidine monohydrate (AHMP) was fabricated and developed for the determination of calcium ions (Ca2+). The detection was based on a colorimetric reaction as a result of the aggregation of modified AuNPs induced by Ca2+ due to the ability to form strong electrostatic interactions between positively charged Ca2+ and negatively charged modified AuNPs. Probe solution changes color from red to blue in the presence of Ca2+ and can be observed by the naked eyes. To verify the complete self-assembly of the AHMP onto the AuNP surface, the modified AuNPs were characterized using ultraviolet–visible spectroscopy and zeta potential measurements. Under optimal conditions, a quantitative linearity was 10 to 100 ppm (R2 = 0.9877) with a detection limit of 3.05 ppm. The results obtained by the developed method were in good agreement with standard atomic absorption spectrometry (AAS) results and demonstrated that this method could reliably measure Ca2+. Overall, this novel alternative approach presents a low-cost, simple, sensitive, rapid, and promising device for the detection of Ca2+.

2020 ◽  
Vol 18 (1) ◽  
pp. 303-313 ◽  
Author(s):  
Aamir Rasheed ◽  
Tahseen Ghous ◽  
Sumaira Mumtaz ◽  
Muhammad Nadeem Zafar ◽  
Kalsoom Akhter ◽  
...  

AbstractIn the present work, a novel continuous flow system (CFS) is developed for the preconcentration and determination of Cr (VI) using Pseudomonas aeruginosa static biomass immobilized onto an effective and low-cost solid support of powdered eggshells. A mini glass column packed with the immobilized biosorbent is incorporated in a CFS for the preconcentration and determination of Cr (VI) from aqueous solutions. The method is based on preconcentration, washing and elution steps followed by colorimetric detection with 1,5-diphenyl carbazide in sulphuric acid. The effects of several variables such as pH, retention time, flow rate, eluent concentration and loaded volume are studied. Under optimal conditions, the CFS method has a linear range between 10 and 100 μg L-1 and a detection limit of 6.25 μg L-1 for the determination of Cr (VI). The sampling frequency is 10 samples per hour with a preconcentration time of 5 mins. Furthermore, after washing with a 0.1 M buffer (pH 3.0), the activity of the biosorbent is regenerated and remained comparable for more than 200 cycles. Scanning electron microscopy reveals a successful immobilization of biomass on eggshells powder and precipitation of Cr (VI) on the bacterial cell surface. The proposed method proves highly sensitive and could be suitable for the determination of Cr (VI) at an ultra-trace level.


The Analyst ◽  
2019 ◽  
Vol 144 (4) ◽  
pp. 1205-1209 ◽  
Author(s):  
Chi Zhang ◽  
Caiyun Kong ◽  
Qingyun Liu ◽  
Zhengbo Chen

We herein present a simple, low-cost, and ultrasensitive colorimetric sensing strategy for the detection of mercury ions (Hg2+) that takes advantage of the natural pore structure in rose petals to encapsulate gold nanoparticles (AuNPs).


2020 ◽  
Vol 20 (6) ◽  
pp. 3356-3360
Author(s):  
Hao Yong Yin ◽  
Yi Fan Zheng ◽  
Ling Wang

We report the formation of gold nanoparticles on indium tin oxide conducting glass (ITO) surface via electrodeposition method at room temperature. The prepared nano-Au electrodes has been fabricated for sensitive detection of Pb2+, and showed highly selective response toward Pb2+. The electrochemical detection of Pb2+ were determined by differential pulse stripping voltammetric (DPSV). The nano-Au electrochemical sensor could detect Pb2+ from 0.5 to 10 μM with detection limits of 0.06 μM (S/N= 3) and sensitivity of 0.27996 mA μM−1. The proposed sensor is simple, reliable, sensitive, selective, and low-cost, thus holds potential for practical application in Pb2+ detection.


2019 ◽  
Vol 3 (4) ◽  
pp. 306-312
Author(s):  
Mi Zhou ◽  
Long Han ◽  
Haibo He ◽  
Dongmei Deng ◽  
Lin Zhang ◽  
...  

2014 ◽  
Vol 6 (7) ◽  
pp. 2031-2033 ◽  
Author(s):  
Li-Qing Zheng ◽  
Xiao-Dong Yu ◽  
Jing-Juan Xu ◽  
Hong-Yuan Chen

Based on the hydrophobic effect inducing the aggregation of Au NPs, a rapid and low-cost colorimetric method for detection of quaternary ammonium surfactants using citrate-stabilized AuNPs was developed.


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