Use of a robotic station for full automation of the determination of organic matter in soil and fertilizers

Abstract

A fully automatic method for the determination of organic matter has been implemented using a robotic station. The overall process involves weighing, dilution, oxidation in very harsh working conditions (K2Cr2O7+ concentrated H2SO4) dilution, centrifugation and photometric monitoring of the Cr(III) formed. Batches of six samples are manipulated by the robot, which also calibrates and delivers the results of the sample determination, both in soil and fertilizers, as percentages of organic matter which require slightly different sample treatment. The precision and validation of the method have been established using both types of samples and the results obtained compare well with those of the method used for routine analysis in official agricultural laboratories.