Infrared Lightbox and iPhone App for Improving Detection Limit of Phosphate Detecting Dip Strips
In this paper, we report the development of a portable and inexpensive infrared lightbox for improving the detection limits of paper-based phosphate devices. Commercial paper-based devices utilize the molybdenum blue protocol to detect phosphate in the environment. Although these devices are easy to use and have a long shelf life, their main deficiency is their low sensitivity based on the qualitative results obtained via a color chart. To improve the results, we constructed a compact infrared lightbox that communicates wirelessly with a smartphone. The system measures the absorbance of radiation for the molybdenum blue reaction in the infrared region of the spectrum. It consists of a lightbox illuminated by four infrared light-emitting diodes, an infrared digital camera, a Raspberry Pi microcontroller, a mini-router, and an iPhone to control the microcontroller. An iPhone application was also developed to analyze images captured by the infrared camera in order to quantify phosphate concentrations. Additionally, the app connects to an online data center to present a highly scalable worldwide system for tracking and analyzing field measurements. In this study, the detection limits for two popular commercial devices were improved by a factor of 4 for the Quantofix devices (from 1.3 ppm using visible light to 300 ppb using infrared illumination) and a factor of 6 for the Indigo units (from 9.2 ppm to 1.4 ppm) with repeatability of less than or equal to 1.2% relative standard deviation (RSD). The system also provides more granular concentration information compared to the discrete color chart used by commercial devices and it can be easily adapted for use in other applications.Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 192
 S. Ganesh, Fahmida Khan, M. K. Ahmed, P. Velavendan, N. K. Pandey and U. Kamachi Mudali, "Spectrophotometric determination of trace amounts of phosphate in water and soil," Water Science & Technology, pp. 2653-2658, 2012.
 A. T. Lawal, S. B. Adeloju, "Polypyrrole based amperometric and potentiometric phosphate biosensors: A comparative study B," Biosensors and Bioelectronics, vol. 40, no. 1, pp. 377-384, 2012.
 S. Islam, M. N. Reza, J. T. Jeong, K. H. Lee, "Sensing Technology for Rapid Detection of Phosphorus in Water: A Review," Journal of Biosystems Engineering, vol. 41, no. 2, pp. 138-144, 2016.
 J. Murphy, J. P. Riley, "A modified single solution method for the deter- mination of phosphate in natural waters," Analytica Chimica Acta, vol. 27, pp. 31-36, 1962.
 M. Jayawardane, W. Wongwilai, K. Grudpan, S. D. Kolev, M. W. Heaven, D. M. Nash, I. D. McKelvie, "Evaluation and Application of a Paper-Based Device for the Determination of Reactive Phosphate in Soil Solution," Journal of Environmental Quality, vol. 43, p. 1081–1085, 2014.
 L. Drummond, W. Maher, "Determination of phosphorus in aqueous solution via formation of the phosphoantimonylmolybdenum blue complex Re-examination of optimum conditions for the analysis of phosphate," Analytica Chimica Acta, vol. 302, pp. 6Y-74, 1995.
 S. J. Eisenreich and J. E. Going, "Extraction of reduced molybdophosphoric and molybdoantimonylphosphoric acids with oxygenated solvents," Analytica Chemica Acta, vol. 71, pp. 393-403, 1974.
 W. A. Dick, M. A. Tabatabai, "Kinetic parameters of phosphatases in soils and organic waste materials," Soil Science, vol. 137, p. 7–15, 1984.
 J. Zhang, J. Chi, "Automated Analysis of Nanomolar Concentrations of phosphate in natural waters with liquid waveguide," Environ. Sci. Technol., vol. 36, pp. 1048-1053, 2002.
 E. A. Nagul, I. D. McKelvie, P. Worsfold, S. D. Kolev, "The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box," Analytica Chimica Acta, vol. 890, pp. 60- 82, 2015.
 M. Jayawardane, I. D. McKelvie, S. D. Kolev, "A paper-based device for measurement of reactive phosphate in water," Talanta, vol. 100, pp. 454-460, 2012.
 T. Kaneta, W. Alahmad, P. Varanusupakul, "Microfluidic paper-based analytical devices with instrument- free detection and miniaturized portable detectors," applied spectroscopy reviews, vol. 54, no. 2, pp. 117-141, 2019.
 B. Ribeiro, "Development of a paper-based microfluidic device for the detection of orthophosphate in water," Master dissertation, Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, RI, 2019.
 B. Waghwani, S. Balpande, J. kalambe, "Development of Microfluidic Paper Based Analytical Device for Detection of Phosphate in Water," International Journal of Innovative Technology and Exploring Engineering, vol. 8, no. 6S, pp. 592-595, 2019.
 B. A. Faber, A. J. Downer, D. Holstege, M. J. Mochizuki, "Accuracy Varies for Commercially Available Soil Test Kits Analyzing Nitrate–Nitrogen, Phosphorus, Potassium, and pH," HortTechnology, vol. 17, no. 3, p. 358–362, 2007.
 S. C. Kima, U. M. Jalala, S. B. Ima, S. Kob, J. S. Shima, "A smartphone-based optical platform for colorimetric analysis of microfluidic device," Sensors and Actuators B: Chemical, vol. 239, pp. 52-59, 2017.
 T. Salafi, K. K. Zeming, J. W. Lim, R. Raman, A. W. Ren Seah, M. P. Tan, Y. Zhang, "Portable Smartphone-Based Platform for Real-Time Particle Detection in Microfluidics," Adavnced materials technology, vol. 4, no. 3, pp. 1-12, 2018.
 Q. Fu, C. Zhang, J. Xie, Z. Li, L. Qu, X. Cai, H. Ouyang, Y. Song, D. Du, Y. Lin, Y. Tang, "Ambient light sensor based colorimetric dipstick reader for rapid monitoring organophosphate pesticides on a smart phone," Analytica Chimica Acta, vol. 1092, pp. 126-131, 2019.
 A. Shahvar, D. Shamsaei, M. Saraji, "A portable smartphone-based colorimetric sensor for rapid determination of water content in ethanol," Measurement, vol. 150, p. 107068, 2020.
 Z. Xua, Z. Liua, M. Xiaoa, L. Jianga, C. Yi, "A smartphone-based quantitative point-of-care testing (POCT) system for T simultaneous detection of multiple heavy metal ions," Chemical Engineering Journal, vol. 394, p. 124966, 2020.
 A. Shahvar, M. Saraji, H. Gordan, D. Shamsaei, "Combination of paper-based thin film microextraction with smartphone- based sensing for sulfite assay in food samples," Talanta, vol. 197, pp. 578-583, 2019.
 N. Moonrungsee, S. Pencharee, J. Jakmunee, "Colorimetric analyzer based on mobile phone camera for determination of available phosphorus in soil," Talanta, vol. 136, pp. 204-209, 2015.
 M. Xiao, Z. Liu, N. Xu, L. Jiang, M. Yang, C.Yi, "A Smartphone-Based Sensing System for On-Site Quantitation of Multiple Heavy Metal Ions Using Fluorescent Carbon Nanodots- Based Microarrays," ACS Semsors, vol. 5, pp. 870-878, 2020.
 D. Hatiboruah, T. Das, N. Chamuah, D. Rabha, B. Talukdar, U. Bora, K. U. Ahamad, P. Nath, "Estimation of trace-mercury concentration in water using a smartphone," Measurement, vol. 154, p. 107507, 2020.
 Z. He, C. W. Honeycutt, "A Modified Molybdenum Blue Method for Orthophosphate Determination Suitable for Investigating Enzymatic Hydrolysis of Organic Phosphates," Communications in Soil Science and Plant Analysis, vol. 36, p. 1373–1383, 2005.
 W. A. Dick, M. A. Tabatabai, "Determination of orthophosphate in aqueous solutions containing labile organic and inorganic phosphorus compounds," Journal of Environmental Quality, vol. 6, p. 82–85, 1977.
 A. O’Reilly, R. Coffey, A. Gowen, E. Cummins, "Evaluation of near-infrared chemical imaging for the prediction of surfacewater quality parameters," International Journal of Environmental Analytical Chemistry, vol. 95, no. 5, p. 403–418, 2015.
 L. Zhang, R. Zhang, "Effect of Soil Moisture and Particle Size on Soil Total Phosphorus Estimation by Near-Infrared Spectroscopy," Polish Journal of Environmental Studies, vol. 26, no. 1, pp. 395-401, 2017.
 M. Grossi, "A sensor-centric survey on the development of smartphone measurement and sensing systems," Measurement, vol. 135, pp. 572-592, 2019.
 H. J. Motulsky, A. Christopoulos, Fitting models to biological data using linear and nonlinear regression. A practical guide to curve fitting, San Diego, CA: GraphPad Software Inc., 2003.
 P. Cao, Y. Zhu, W. Zhao, S. Liu, H. Gao, "Chromaticity Measurement Based on the Image Method and Its Application in Water Quality Detection," water, vol. 11, no. 11, p. 2339, 2019.
 T. L. Mako, J. M. Racicot, M. Levine, "Ultrasensitive Detection of Nitrite through Implementation of N-(1- Naphthyl)ethylenediamine-Grafted Cellulose into a Paper-Based Device," ACS Sensors, vol. 5, no. 4, p. 1207–1215, 2020.
 J. C. Miller, J. N. Miller, Statistics and Chemometrics for Analytical Chemistry, 5th edn, Harlow, Essex England: Pearson Education Limited, 2005.