Determination of vanadium, manganese, silver and lead by graphite furnace atomic absorption spectrometry after preconcentration on silica-gel modified with 3-aminopropyltriethoxysilane

3-aminopropyltriethoxysilane modified silica-gel was used for the separation and preconcentration of vanadium, silver, manganese, and lead prior to their determination by graphite furnace atomic absorption spectrometry. Surface characteristics and surface area of the silica-gel before and after chemical modification were determined by elemental and surface area analysis. The retention and recovery of the analyte elements were studied by applying batch and column techniques. The experimental parameters, such as the effect of pH of the sample, shaking time in batch technique, flow rate of the eluent and the amount of silica, on retention and elution have been investigated. Vanadium, manganese, silver and lead were quantitatively (≥90%) recovered in the batch technique with R.S.D. values of 2.2, 1.9, 3.8 and 1.4%, respectively. The same recoveries were obtained in the column technique except for manganese, for which it was only 70%. Detection limits of the method for vanadium, manganese, silver and lead are 0.006, 0.002 0.0004 and 0.004 μg, respectively.