The determination of cadmium and six other heavy metals in nitrate/phosphate fertilizer solution by ion chromatography Original Research Article

An ion chromatographic (IC) method was developed for the simultaneous determination of Cu, Cd, Ni, Zn, Co, Pb, and Mn in a nitrate/phosphate fertilizer solution. This new method utilizes a mixed functionality column of anion and cation exchange to achieve the separation. Elution was carried out by a gradient concentration of oxalic acid and sodium chloride, and detection was performed by spectrophotometric post-column reaction with 4-(2-pyridylazo)resorcinol (PAR). Cross comparison of analytical data of two different motherliquor solutions with two other analytical techniques showed good agreement. Linear calibration graphs in the range 0.2–2.0 μg/ml were obtained, together with detection limits (greater than ten times the base line noise and 50 μl loop), which were found as Cu (1 ng), Cd and Ni (10 ng), Zn and Co (2 ng), Pb (30 ng), Mn (5 ng). The respective relative standard deviations were also determined. The IC method was accurate, reliable, and compared favourably with traditional analytical procedures such as atomic absorption spectroscopy (AAS) and inductively coupled plasma–atomic emission spectrometry (ICP–AES).