Abstract
A flow-injection analysis (FIA) system is presented for the determination of phosphorus in cement, which is based on the formation and spectrophotometric detection of molybdenum blue under coexistence of potassium antimonyl tartrate in a FIA system, the sample was dissolved in perchloric and hydrochloric acids solution, and then silica was removed by filtration. The dissolved solution was diluted twice and injected to FIA system. The sample solution injected into the carrier stream (0.18 M perchloric acid and 0.06 M hydrochloric acid) is mixed with a reagent stream (0.8 M sulfic acid, 4 mM ammonium molybdate, 0.3 mM antimonyl potassium tartrate and 0.3% ascorbic acid) at a confluence point. Then the molybdenum blue was developed in the reaction coil which was immersed in a temperature controlled bath (65°C) and the absorbance was measured at 880 nm. The recommended concentration range of phosphorus was 0.2-3.0, μg/ml and the limit of detection was 0.05, μg/ml of phosphorus. It has proved that the FIA system allows simple and rapid analysis without complicated manual operations; only 2 min is required for analytical measurement after sample injection.
