Spectrophotometric Method for Heme Iron Determination in Foods.

A simple and rapid method for the determination of heme iron in foods was investigated. A sample was weighed in a centrifuge tube and the fat in the sample was removed with diethyl ether. The residue was mixed well with 1-2 ml water, and added 10 ml of methyl isobutyl ketone (MIBK) and 5 ml of concentrated hydrochloric acid. The tube was placed in an ultrasonic water bath for 10 min. Five ml of water was added to separate the MIBK layer from the aqueous layer. After shaking for 5 min, the mixture was centrifuged for 5 min at 3000 rpm. Heme iron in the MIBK layer was determined by spectrophotometer at a wavelength of 640 nm. The calibration curve was linear from 2.5 to 15 mu g Fe/ml. The recoveries of heme iron added to foods were within the range from 80.5% to 90.0%. An interlaboratory study of this method for the determination of heme iron in cookie, liver and meat was conducted in 3 laboratories. The coefficient of variation for each sample was within the range of 6.29-7.15%. This method is simple and useful for the determination of heme iron in foods.