Determination of Total Phosphorus Content in Chemical Fertilizer Samples Using Flow Injection Analysis System

Piyawan Phansi; Jirayu Chumkate; Duangjai Nacapricha

Authors

Piyawan Phansi Department of Chemistry, Faculty of Science and Technology, Thepsatri Rajabhat University, Lopburi, Thailand
Jirayu Chumkate Department of Chemistry, Faculty of Science and Technology, Thepsatri Rajabhat University, Lopburi, Thailand
Duangjai Nacapricha Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok, Thailand

Keywords:

Chemical Fertilizer, Phosphorus, Flow Injection, Vanadomolybdate, Spectrophotometer

Abstract

The aim of this work was to propose a flow injection analysis system for total phosphorus content determination in chemical fertilizers using the vanadomolybdate method. The fertilizer samples were digested in an acid solution and then injected into the flow-injection system. The sample zone was merged with the reagent, thus producing a yellow complex of vanadomolybdophosphate. The colour product was spectrophotometrically detected at 420 nm. The proposed system could be applied to determine the total phosphorus content in chemical fertilizer samples purchased in Lopburi province. Results obtained from the developed system agreed well with the standard method by using pair t-test (t_stat 0.19 < t_crit 2.45). Furthermore, there are many advantages of the developed system; the system is highly sensitive with a detection limit of 0.04 mg P/L, has high sample throughput of 23 samples per hour, requires low reagent and sample consumption, and exhibits high precision (%RSD=1.77) as calculated from the injection of a standard solution 5 mg P/L (n=10).

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