Determination of nanomolar concentrations of phosphate in natural waters using flow injection with a long path length liquid waveguide capillary cell and solid-state spectrophotometric detection

摘要

A flow injection manifold incorporating a1m liquid waveguide capillary cell and a miniature fibre-optic spectrometer for the determination of low phosphorus concentrations in natural waters is reported.The limit of detection(blank+ 3 S.D.)was 10 nM using the molybdenum blue chemistry with tin(II)chloride reduction.The sensitivity of the flow injection manifold was improved by 100-fold compared with a conventional 1 cm flow cell.The response was measured at 710 nm and background corrected by subtracting the absorbance at 447 nm.Interference from silicate was effectively masked by the addition of 0.1 %(m/v)tartaric acid and results were in good agreement(P = 0.05)with a segmented flow analyser reference method for freshwater samples containing 1 mu M phosphate.