Stopped-flow injection method for determination of phosphate in soils and fertilisers

Maejo International Journal of Science and Technology

关键词: phosphate;    stopped-flow injection;    molybdenum blue;    fertiliser;    soil;   

DOI  :  

来源: DOAJ

【 摘 要 】

A stopped-flow injection system for the determination of phosphate has been developed.It involves the phosphate-molybdate-ascorbic acid reactions in the molybdenum blue method. The system is controlled by a semi-automatic stopped-FI analyser with a light emitting diode (LED)-colorimeter for monitoring the absorbance change relating to the concentration of a reaction product formed during the stopping period while the injected zone of a standard or sample is being in the flow cell. The slope of the FIAgram obtained is linearly proportional to the reaction rate, which depends on the phosphate concentration.Effects of concentration of reagents, viz. sodium molybdate, ascorbic acid and nitric acid, on the slope of the FIAgram were studied.The suitable concentration is 0.02 M, 0.25 %w/v and 0.15 M, respectively.A linear calibration graph in the range of 0.3-6.0 mg P L-1 was employed for thedetermination of phosphate in soil and fertiliser samples. The results obtained agree well with those from a standard spectrophotometric method.

【 授权许可】

Unknown