Journal of the Indian Society of Soil Science

This study, aimed to evaluate the effect of sample solution temperature during and after colour development on precision and accuracy of B determination by azomethine-H method, revealed that value of absorbance of a given standard was highly dependent on temperature of solution during colour development. Absorbance values were unstable with respect to temperature even after the colour detorelopment period of one hour. Concentrations of B determined in the extracts obtained by hot 0.02M CaCl₂ and hot water for ten medium Typic Haplusterts were higher when colour was developed at 30 and 40°C as compared to concentrations of the same solutions determined at 15°C. The magnitude of increase depended upon the non-clarity of the extracts. This study indicates that temperature of the sample solutions should be maintained constant between 15 and 20°C throughout the period of colour development and absorbance measurement for higher sensitivity and accuracy of B determination.