Synthesis of Polymer Sensor for Detection of Phosphate in Water

Abstract

Abstract-A colorimetric polymer sensor was successfully developed for the detection of phosphate in water. Potassium antimonyl tartrate, ammonium molybdate, ascorbic acid and sulfuric acid were entrapped within the polyvinyl alcohol (PVA) hydrogel matrix and acted as the colorimetric reagent. The PVA sensor was fabricated within a micro-PCR tube to which the sample solution could be directly added for in-tube detection. This made the developed sensor small and easy to carry on field. The optimum condition for sensor synthesis was determined in this research by using the digital image analysis. They are found at 0.6 g/L potassium antimonyl tartrate, 14.4 g/L ammonium molybdate, 5.28 g/L ascorbic acid, 0.05 mg/L sulfuric acid and 15 min reaction time.Index Terms-Hydrogel sensor, phosphate detection, polymer sensor.

Portable Colorimetric Hydrogel Test Kits and On-Mobile Digital Image Colorimetry for On-Site Determination of Nutrients in Water

“…Nitrate ions were reduced to nitrite by the zinc powder entrapped within the film, and the resulting nitrite reacted in the same manner as the above nitrite ions. During phosphate testing, phosphate ions reacted with the ammonium molybdate in the aqueous sulfuric acid medium, forming 12-molybdophosphoric acid that further reduced via ascorbic acid to form phosphomolybdate blue [ 10 , 19 , 25 ]. Potassium antimony tartrate was used to catalyze the reaction and inhibit the formation of a common interference (silicomolybdic acid).…”

“…The tube for nitrate testing thus had the nitrite-testing hydrogel at the bottom and a nitrate reduction film on its inner lid. For the in-tube hydrogel test kit for phosphate (Figure 2c), the ingredients in a previous study [19] were initially used for re-optimization in which a 1.5 mL plastic tube was used instead of a 200 μL plastic tube [19]. This can facilitate on-site testing, where smaller test kits may be unsuitable.…”

“…The detection mechanism of nutrients is shown in Scheme 1. Thus, the proposed in-tube hydrogel test kits for nitrite, nitrate, and phosphate we obtained from a combination of physical cross-linking (cryogenic treatment) and chemic cross-linking (use of EGDE as a cross-linker), as done in our previous studies [11,19] b modified to facilitate on-site detection. The detection mechanism of nutrients is shown Scheme 1.…”

“…Potassium antimony tartrate is commonly used as a source of antimony to increase the reaction rate and eliminate the need for a heating process to form a stable molybdenum blue product [ 15 , 16 ]. Polymeric test kits involving the use of polymers to stabilize and/or support colorimetric reagents have also been reported for the detection of these nutrients [ 11 , 17 , 18 , 19 , 20 ]. They are better than conventional liquid test kits because they are portable and carry less risk from hazardous chemicals.…”