Total Fat Analysis in Milk- and Soy-Based Infant Formula Powder by Supercritical Fluid Extraction

Abstract

A rapid method for the determination of total fat in infant formula powders using a commercially available supercritical fluid extraction (SFE) instrument was evaluated. The matrices examined were Standard Reference Material SRM 1846 Infant Formula (NIST) and commercial milk- and soy-based infant formula powders. Method verification and validation were done by linear regression analysis using the Method of Standard Additions. A Data Quality Objectives (DQO) format was used to define and evaluate the performance characteristic parameters of the instrumental total fat analysis by SFE. A peer validation study showed excellent agreement with the declared labeled percentage fat values and reproducibility among three participating laboratories. The laboratory relative SD (RSDR′ %) is within Horwitz's limits of acceptability and the HORRAT ratio criteria at the level of the analyte analyzed. Linear regression analysis of all infant formula matrices spiked with added fat showed that the SFE instrument response was due only to the added analyte. By integrating the DQO process with a readily available certified reference material, along with reproducibility indicated by two outside collaborating laboratories, we established verification and validation of the accuracy of the data obtained by SFE.