Determination of phosphorus in polymeric systems using an ashing procedure and inductively coupled plasma atomic emission spectrometry

Abstract

Phosphorus in different forms is used in a variety of applications (catalysts, thermal stabilizers, flame retardants) in polymeric formulations. It is important to be able to determine its concentration in raw materials, intermediates and final products. The challenge of measuring low concentrations of P, combined with the volatility of the organic phosphorus compounds, has been solved through a novel analytical procedure with a method detection limit of 0.4 µg g⁻¹ P (10σ). The volatilization of organic P compounds was prevented by pre-oxidation with periodic acid, which allows ashing in the presence of magnesium acetate while maximizing the weight to final volume ratio. Using factorial design of experiments, experimental factors including ashing temperature, time, and the amount of the reagents were optimized with respect to accuracy and precision of the technique. The influence of Ti when present in the samples was eliminated by complexing it with H₂O₂. Additional pre-treatment with NH₄OH was found to improve recovery for some reactive samples. Comparison with other established methods was carried out and is discussed.