Determination of Phosphate in Environmental Samples by Sequential Injection Micro-sampling On-line Dilution Spectrophotometry

[Objective] The aim was to study the feasibility of using sequential injection micro-sampling on-line dilution spectrophotometry determining phosphate in environmental samples.[Method] A sequence injection analysis method for the direct determination of phosphate in environmental samples with on-line intelligent dilution and photometric detection was described.Phosphate was performed by the molybdenum blue method with detection at 720 nm.[Result] At the optimized condition,the calibration graph is a linear when PO43-concentration was in range of 1-6 and 6-50 mg/L.The relative standard deviation is 1.4 % for the determination of 2 mg/L PO43-(n=11) and 1.6% for the determination of 20 mg/L PO43-(n=11).[Conclusion] It is characterized by high automation and wide analytical working range,which meets the requirements of automatic analysis and on-line monitoring.