Graphite Furnace Atomic Absorption Spectrometry for the Determination of the Chromium Content of Selected U.S. Foods

A graphite furnace atomic absorption spectrometry method was used to determine the chromium content of selected foods following a modified dry ashing sample preparation procedure. Platform atomization is used and quantitation is accomplished using peak area measurements. Both direct calibration against aqueous standards and the use of method of additions provide accurate results. The method provides an instrumental detection limit of 5.6 pg chromium and a characteristic mass of 3.2 pg. This corresponds to a method detection limit of approximately 1 ng/g for a 20 μl injection of a digest of a typical 3-g sample diluted to a final volume of 10 ml. The method was validated using commercial standard reference materials. More than 40 frequently consumed foods were analyzed and the chromium content is reported. When available, data are compared with previous literature reports. There is, as expected, a reasonable amount of variability in the chromium content of some products. Those foods which are the best sources of chromium tend to be cereals and grains, vegetables, and fruits.