X-ray fluorescence spectrometry in the analysis of trace elements in human milk.

XRF has broad applications in the quantitative analysis of trace elements in biological materials. Evaluation of its potential for the analysis of trace elements in human milk was performed. Precision of the method was demonstrated by the low (less than 3%) coefficient of variation in reproducibility of analyses performed within a given day, on different days, and by different operators. Standard curves were constructed for human milk and correlation was high (r greater than 0.98) for each of nine metals analyzed. The lower limits of determination and minimum detection limits were calculated for nine elements. Excellent correlation (r greater than 0.99) was achieved in comparison of XRF TO AA in analysis of zinc in human milk. Preliminary results of the analysis of milk zinc, copper, and iron throughout the initial 8 months of lactation disclose a decrease in trace metal concentration, most notable for zinc, during the first 60 days.