Comparison Between Manual Method and Flow Injection Assay for Determination of Total Phosphorus in Water

The methods for total phosphorus measurement in water primarily involve manual method and flow injection assay. This study compared and analyzed the application characteristics of these two methods by examining their principles, reagent preparation, sample analysis, detection limits, precision, accuracy, and real sample testing. The results indicated that both methods exhibited a linear correlation coefficient of ≥0.999. The manual method had a detection limit of 0.007 mg/L, while the flow injection method had a detection limit of 0.002 mg/L. For the two methods, precision and accuracy analyses using three standard samples with different concentrations showed relative errors (REs) and relative standard deviations (RSDs) consistently below 4 and 5%, respectively. The adding standard recovery for samples for the two methods both ranged from 96.91 to 105.04%, meeting the quality requirements for water sample analysis outlined in the DZ/T0130-2006 “Quality Management Specification for Geological and Mineral Laboratories”. Overall, both methods demonstrate similar precision and accuracy, but the flow injection method exhibited higher sensitivity and simplicity, significantly enhancing the analytical efficiency in practical work.