Precise determination of small amounts of phosphorus in steel by a computer data processed automatic spectrophotometric analyser

A computer data processed spectrophotometric analyser has been developed for determination of small amounts of phosphorus (less than 100 ppm) in steel samples. The analyser performs automatically and continuously all the photometric procedures after sample preparation by acid dissolution. The spectrophotometric absorbances are automatically measured and are corrected by smoothing drift, discard of abnormal signal by Grubbs and Dixon verification using a data processing computer system. Certificated steel samples containing 2 ppm and 11 ppm of phosphorus were determined for 6 min with a relative standard deviation of 9% and 2%, respectively