Solid-phase extraction and spectrophotometric determination of molybdenum(VI) in soil and plant samples as a Mo(V)-thiocyanate complex

A method for the preconcentration and determination of molybdenum(VI) in soil and plant samples using Amberlite XAD-7 resin and spectrophotometry is proposed. Molybdenum was preconcentrated as its Mo(V)-thiocyanate complex using a column containing Amberlite XAD-7 resin and determined spectrophotometrically at 461.0 nm in acetone after elution. We investigated several parameters that affect the recovery of molybdenum, such as acidity, amount of reducing and complexing agents, flow rates, volume of sample solution, type and amount of eluent, and the presence of diverse ions. The limit of detection of the proposed method was 38 mug L-1 of molybdenum. The recovery of molybdenum was 98.25 +/- 0.05 at 95% confidence level. The highest preconcentration factor was 100 for 250 mL of sample volume. The proposed method was applied to soil and plant samples, and molybdenum was determined with a relative error of <3.5%.