Abstract
In this work, a low-cost, portable device is developed to detect colorimetric assays for in-field and point-of-care (POC) analysis. The device can rapidly detect both pH values and nitrite concentrations of five different samples, simultaneously. After mixing samples with specific reagents, a high-resolution digital camera collects a picture of the sample, and a single-board computer processes the image in real time to identify the hue–saturation–value coordinates of the image. An internal light source reduces the effect of any ambient light so the device can accurately determine the corresponding pH values or nitrite concentrations. The device was purposefully designed to be low-cost, yet versatile, and the accuracy of the results have been compared to those from a conventional method. The results obtained for pH values have a mean standard deviation of 0.03 and a correlation coefficient R2 of 0.998. The detection of nitrites is between concentrations of 0.4–1.6 mg l−1, with a low detection limit of 0.2 mg l−1, and has a mean standard deviation of 0.073 and an R2 value of 0.999. The results represent great potential of the proposed portable device as an excellent analytical tool for POC colorimetric analysis and offer broad accessibility in resource-limited settings.
Highlights
There has been a growing demand to monitor and control all aspects of our urban environment in real time
The developed colorimetric device shows several advantages compared with the traditional method for colorimetric detection, using UV–vis spectroscopy
A new portable device is developed that has a high degree of versatility and provides a new cost-effective method for colorimetric detection compared with the traditional bulky, expensive instruments
Summary
There has been a growing demand to monitor and control all aspects of our urban environment in real time. This is brought about by increasing concerns with environmental, health, security and safety issues. There is a need to develop low-cost, versatile and portable diagnostic tools for early detection of harmful contaminants readily and accurately in remote areas [1,2]. Many analytical tools have been used in the field of medical diagnostics, environmental applications, 2017 The Authors.
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