Analysis of Heme Using a Combination of Total Reflection X‐Ray Fluorescence Analysis and Solid‐Phase Extraction

ABSTRACT In this study, a method to analyze iron originating from heme using a combination of total reflection X‐ray fluorescence (TXRF) analysis and solid‐phase extraction is presented. In this method, heme in a sample solution was collected on a reverse‐phase solid‐phase extraction column filled with octadecyl bonded silica, and then the collected heme was eluted with an eluent. Finally, the dry residue of a 10 μL droplet of the eluate diluted with ultrapure water was measured by a portable TXRF spectrometer. The Fe Kα peak originating from heme was observed by using this combination, and the detection limit for heme was estimated to be about 1 μmol L −1 .