title: Monitoring of fluoride in water samples using a smartphone.
abstract: In several parts of India, groundwater is the only reliable, year round source for drinking water. Prevention of fluorosis, a chronic disease resulting from excess intake of fluoride, requires the screening of all groundwater sources for fluoride in endemic areas. In this paper, the authors present a field deployable colorimetric analyzer based on an inexpensive smartphone embedded with digital camera for taking photograph of the colored solution as well as an easy-fit, and compact sample chamber (Akvo Caddisfly). Phones marketed by different smartphone makers were used. Commercially available zirconium xylenol orange reagent was used for determining fluoride concentration. A software program was developed to use with the phone for recording and analyzing the RGB color of the picture. Linear range for fluoride estimation was 0-2mgl(-1). Around 200 samples, which consisted of laboratory prepared as well as field samples collected from different locations in Karnataka, India, were tested with Akvo Caddisfly. The results showed a significant positive correlation between Ion Selective Electrode (ISE) method and Akvo Caddisfly (Phones A, B and C), with correlation coefficient ranging between 0.9952 and 1.000. In addition, there was no significant difference in the mean fluoride content values between ISE and Phone B and C except for Phone A. Thus the smartphone method is economical and suited for groundwater fluoride analysis in the field.
authors.affiliation: Akvo Foundation, Netherlands.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Levin
authors.affiliation: INREM Foundation, India.
authors.forename: Sunderrajan
authors.initials: S
authors.lastname: Krishnan
authors.affiliation: Akvo Foundation, Netherlands.
authors.forename: Samuel
authors.initials: S
authors.lastname: Rajkumar
authors.affiliation: Akvo Foundation, Netherlands.
authors.forename: Nischal
authors.initials: N
authors.lastname: Halery
authors.affiliation: Akvo Foundation, Netherlands.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Balkunde
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D005459:Fluorides / Q000032:analysis*; D000068997:Smartphone; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D005459:Fluorides
keywords: Colorimeter; Drinking water; Fluoride; Fluorosis; Smartphone; Zirconium Xylenol Orange