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Data from: Portable device for the detection of colorimetric assays Luka, George S.; Nowak, Ephriam; Kawchuk, Jamie; Hoorfar, Mina; Najjaran, Homayoun

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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 5 different samples, simultaneously. After mixing samples with specific reagents, a Hi-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 (HSV) 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 (R) of 0.998. The detection of nitrites is between concentrations of 0.4 to 1.6mg/L with a low detection limit of 0.2mg/L and has a mean standard deviation of 0.073 and an R-value of 0.999. The results represent the great potential of the proposed portable device as an excellent analytical tool for POC colorimetric analysis and offer broad accessibility in resource-limited settings.; Usage notes
Results presented in figure 7.The hue values as a function of pH values (ranging from 4 to 8) and the fitted polynomial curve.Results presented in figure 8 (a) and (b).(a) The sensor response to different nitrite concentrations in the sample, (b) nitrite concentration calibration curve (Line fitted to the experimental S values obtained for different nitrite concentrations using Griess reagents).Results presented in figure 9.A Linear relationship between the pH values obtained using the pH meter and those obtained using the portable device.Results presented in figure 10.A Linear relationship between the concentrations of the prepared nitrite solutions and those obtained using the portable device.Results presented in figure .11 (Top) and (Botoom)UV-vis measurements for nitrite concentrations (top) UV-vis spectrum for the determination of different nitrite concentration, (bottom) nitrite concentration calibration curve (Line fitted to the experimental absorbance values at 540 nm obtained for different nitrite concentrations using Griess reagents)Photocolorimeter algorithm

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