Nutritional element analysis in infant formulas by direct dispersion and inductively coupled plasma-optical emission spectrometry

A method for direct determination of Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn in infant formulas and milkpowders was developed using a water-soluble, tertiary amine:EDTA dispersant and analysis by inductively-coupled plasma–optical emission spectrometry (ICP–OES). Samples were prepared as slurries in aqueous dispersant (10%, v/v) incorporating internal standard (Lu) compensation for potential matrix effects and determined against external calibration standards. The instrument was radially configured and incorporated a charge-transfer device detector, facilitating simultaneous acquisition of multi-element and multi-line measurements. Method performance parameters were estimated and the overall technique found to be applicable to routine quality control monitoring of infant formulas and milkpowders. Advantages of this direct protocol are discussed with respect to improvements in sample throughput and analytical confidence.