Smartphone Coupled with a Paper-Based Colorimetric Device for Sensitive and Portable Mercury Ion Sensing

Abstract

The rapid development of information and communication technology provides an opportunity for scientists to develop a quantitative analytical method that is built on a mobile gadget as a detector. In this paper, we report a low-cost, simple and portable analytical method for mercury ion quantification based on digital image colorimetry coupled with a smartphone application. A small amount of silver nanoparticles (AgNPs) was used as a colorimetric agent that is selective only to mercury ions. The yellowish brown color of AgNPs instantly changed to colorless after the addition of mercury ions due to a redox reaction. To increase the portability, we attached the AgNPs onto a medium to create a paper-based analytical device. The final data processing of the colorimetric analysis was conducted using an android application available on the Google Play Store, called "Mercury Detector". The proposed method has good sensitivity, with a detection limit of 0.86 ppb, which is comparable to those of bulk and more expensive instruments. This allows for the detection of mercury ions as low as 2 ppb (10 nM), which is also the maximum contaminant level permitted in drinking water by the US Environmental Protection Agency. The proposed method was applied to real samples that provide satisfactory results on accuracy (2.4%) and precision (2.5%).

Colorimetric and Fluorescence-Based Detection of Mercuric Ion Using a Benzothiazolinic Spiropyran

“…The change in color or fluorescence signal due to the complex formation between the metal ion and the merocyanine form can be used for the determination of low concentration of analyte with the help of UV-visible or fluorescence spectroscopy. In addition, the change in color intensity can be analyzed using the digital image based colorimetric method, which is receiving increased attention owing to easy, low cost and portable analysis of a variety of samples [36][37][38]. The method only requires a change in color upon addition of an analyte [36].…”

“…In addition, the change in color intensity can be analyzed using the digital image based colorimetric method, which is receiving increased attention owing to easy, low cost and portable analysis of a variety of samples [36][37][38]. The method only requires a change in color upon addition of an analyte [36]. Therefore, the use of the merocyanine form can further help in the detection of an analyte through the digital image analysis.…”

Quantitative Detection of Nitrite in Food Samples Based on Digital Image Colourimetry by Smartphone

“…[16] The detection range of DIC based on a smartphone is much broader than conventional colourimetry, improving the sensitivity. [17] So far, diverse colour measurement systems have been developed due to the popularity of smartphones, such as RGB (red, green, and blue), HSV (hue, saturation, and value), CIE-Lab, and CMYK (cyan, magenta, yellow, and black). [15a,18] The application of the RGB colour space has attracted increasing attention in the image analysis system of DIC.…”

Using Mobile– iPhone as New Visible Colour Detector for Determination of Pharmaceutical (Potassium Permanganate)

“…In recent years, there is an increasing attention in developing portable, low-cost optical spectroscopic devices and combine them with mobile phones to leverage the simplicity of accessing and processing data using mobile computing technology [1]. Add to more applications that take advantage of the digital cameras in mobile devices became important parts of scientific work and daily life researchers have recently used a mobile phone to determined mercury based on accurate image analysis [3]. Mobile phone taking the widest range of uses for health care for both adults and children in the field of running, falling and pulse and advising patients with signs of contraindications called e-health [4].…”

“…Add to more applications that take advantage of the digital cameras in mobile devices became important fic work and daily life [2]. Some researchers have recently used a mobile phone to determined mercury based on accurate image analysis [3]. Mobile phone taking the widest range of uses for health care for both adults and children in the field of running, falling and pulse and advising patients with signs of [4].…”