Selection of optimal conditions for the spectrophotometric determination of phosphorus in archaeological finds made of cast Iron using reducing agents - ascorbic acid and Mohr salt

Purpose of research . The aim of the work was to select conditions for the quantitative spectrophotometric determination of phosphorus in archaeological finds made of Iron using reducing agents - ascorbic acid and Mohr salt. Methods . A fragment of a cast-iron object discovered during archaeological excavations in the Salovsky settlement on the territory of the Penza region was chosen as the object of research. Reagent preparation and spectrophotometric analysis of phosphorus content were carried out in accordance with GOST 2604.4-87 Alloyed cast iron. Methods for the determination of phosphorus. To assess the reliability of the results, errors were identified according to the Smirnov criterion, and to assess the accuracy of the results, the variance, standard deviation and relative standard deviation of the determination of phosphorus content were calculated. To identify the effect of the reducing agent on the results of phosphorus determination, a one-factor analysis of variance was performed. Results . In the course of the work, the conditions for dissolving the samples were selected: the weight of the sample, the required volume of nitric acid, dilution of the samples, the volume of reagents for analysis. An experiment aimed at searching for a reducing agent of the yellow phosphorous-molybdenum complex has demonstrated satisfactory results when using the Mohr salt. The adequacy of replacing ascorbic acid with Mohr salt is proved by the close values of the phosphorus content in the studied samples: using the ascorbic acid reducing agent, the phosphorus content was (1.74.0.15)%, and using Mohr salt (1.72.0.24)%. Conclusion . The results obtained during the study allow us to conclude that the Mohr salt can be used as a reducing agent in the determination of phosphorus in the form of blue heteropolycomplex in iron alloys.