การตุรวจว ัดปร ิมาณฟอสีฟอรัสีทังหมดในตััวอย่างปิุยเคมี ด้วยระบบแบบไหลชุ่นิดโฟลอินเจิคชุ่ัน

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 vanado-molybdophosphate. 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).