Spectrophotometric Determination of Exchangeable (Mobile) Aluminum in Soil Using Arsenazo I

The possibility of using arsenazo I as a reagent for the spectrophotometric determination of the content of exchangeable (mobile) aluminum in soils of various types (clay, loamy, sandy, and sandy loam) is considered. An algorithm of analysis has been developed, taking into account the methodological guidelines MGU 4.1.2466, calibration dependencies have been established, and soil samples have been analyzed according to certified and proposed experimental methods. As a certified methodology, the methodology for performing measurements of GOST 26485 "Soils. Determination of exchangeable [mobile] aluminum by the SICAA method", in which one of the reagents is xylene orange has been used. To determine the effect of soil type on the results of aluminum determination, samples with different humus content and metabolic acidity were analyzed, and an artificial soil humification Al(III) reagent was used to study the effect of organic compounds on the analytical signal. It was determined that humus affects the measurement results only when its content is significant. It has been established that the use of arsenazo I for the spectrophotometric determination of exchangeable (mobile) aluminum in soil is possible along with the reagents provided by a certified measurement technique-xylene orange and chromazurol C. A number of advantages of using arsenazo I to determine the content of mobile aluminum have been established.