title: Colorimetric analyzer based on mobile phone camera for determination of available phosphorus in soil.
abstract: A field deployable colorimetric analyzer based on an "Android mobile phone" was developed for the determination of available phosphorus content in soil. An inexpensive mobile phone embedded with digital camera was used for taking photograph of the chemical solution under test. The method involved a reaction of the phosphorus (orthophosphate form), ammonium molybdate and potassium antimonyl tartrate to form phosphomolybdic acid which was reduced by ascorbic acid to produce the intense colored molybdenum blue. The software program was developed to use with the phone for recording and analyzing RGB color of the picture. A light tight box with LED light to control illumination was fabricated to improve precision and accuracy of the measurement. Under the optimum conditions, the calibration graph was created by measuring blue color intensity of a series of standard phosphorus solution (0.0-1.0mgPL(-1)), then, the calibration equation obtained was retained by the program for the analysis of sample solution. The results obtained from the proposed method agreed well with the spectrophotometric method, with a detection limit of 0.01mgPL(-1) and a sample throughput about 40h(-1) was achieved. The developed system provided good accuracy (RE<5%) and precision (RSD<2%, intra- and inter-day), fast and cheap analysis, and especially convenient to use in crop field for soil analysis of phosphorus nutrient.
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, Rambhai Barni Rajabhat University, Chanthaburi 22000, Thailand.
authors.forename: Nuntaporn
authors.initials: N
authors.lastname: Moonrungsee
authors.affiliation: Department of Physics, Faculty of Science, Ubon Ratchathani University, Ubonratchathani 34190, Thailand.
authors.forename: Somkid
authors.initials: S
authors.lastname: Pencharee
authors.affiliation: Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand. Electronic address: jaroon.jakmunee@cmu.ac.th.
authors.forename: Jaroon
authors.initials: J
authors.lastname: Jakmunee
mesh_terms: D040421:Cell Phone; D003124:Colorimetry; D010758:Phosphorus / Q000032:analysis*; D010781:Photography; D015203:Reproducibility of Results; D012984:Software; D012987:Soil / Q000737:chemistry*; D013053:Spectrophotometry
chemical_list: D012987:Soil; D010758:Phosphorus
keywords: Available phosphorus; Colorimetry; Mobile phone camera; RGB values; Soil