Original Articles

An automated colorimetric method for the determination of dicyandiamide in 1.0 M KCI soil extracts

Published in: South African Journal of Plant and Soil
Volume 10 , issue 1 , 1993 , pages: 22–27

DOI: 10.1080/02571862.1993.10634638

Author(s): D.C. Pretorius , Republic of South Africa , J.F. van Staden Department of Chemistry, Republic of South Africa , A. , D.P. Botha , Republic of South Africa , C. Kolver , Republic of South Africa

Keywords: Cyanoguanidine , didin , 1 M potassium chloride , segmented flow analysis

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Abstract

The nitrification inhibitor dicyandiamide (cyanoguanidine, didin or DCD) reacts with 1-naphthol and diacetyl to form a red complex which measures spectrophotometrically at 540 nm. An automated analytical procedure was developed to determine DCD in soils extracted with 1.0 M KCI. The method was optimized and evaluated between 0.2 and 30 mg dm⁻³ DCD-N. The calibration curve showed a high degree of linearity between 2 and 30 mg dm⁻³ DCD-N. Accurate and reliable readings were achieved at a sampling frequency of 30 samples h⁻¹. The transmittance between samples was less than 2.00%. A number of ions were tested for possible interference. Interference levels were reduced With the introduction of ethylene diamine tetra-acetic acid (EDTA) and mannitol.

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