Factorial design for multivariate optimization of preconcentration system for spectrophotometric phosphorus determination

The present paper proposes a preconcentration procedure for phosphorus determination by using ultraviolet–visible spectrophotometer. It is based on the formation of phosphomolybdate and its reduction to molybdenum blue. Phosphorus extraction as phosphomolybdenum blue complex was performed onto Amberlite XAD-4. The optimization step was carried out using two-level full factorial design. Three variables (resin amount, sample volume, flow rate) were regarded as factors in the optimization. The relative standard deviation was 2% at 0.08 μg mL−1. The limit of detection was found to be 2.23 μg L−1 (N = 15). The proposed solid-phase extraction procedure was applied to phosphorus in some fruit leaves, natural waters, and a standard reference material (SRM 1515 apple leaves).