MEASUREMENT OF NONRADIOACTIVE ISOTOPES OF COPPER IN HAIR WITH INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY

A method is reported for tracing dietary enriched (99.61 atom %) nonradioactive 65CU in rat hair. The method is based on the measurement of the two nonradioactive isotopes of copper (i.e., 63Cu and 65Cu) in rat hair by using inductively coupled plasma mass spectrometry (ICP-MS). Sodium, known to cause interferences in ICP-MS analyses, was removed by using an ion-exchange procedure. Correlation between the diet and hair element concentration levels have been reported. Controversy in the literature exists about the validity of elemental analyses of hair because elements may be incorporated in hair from the diet and body stores during growth, as well as from environmental sources. Tracing dietary elements in hair during growth would eliminate the uncertainness of this procedure. In nature, copper exists as 69.174 atom % 63Cu and 30.826 atom % 65Cu expressed as the 63Cu/65Cu ratio of 2.2400. Enriched (99.61 atom %) 65Cu was obtained and used to label the dietary source of copper. Data showed that 50% of the copper in the rat hair of rats gavaged with the enriched 65Cu isotope was due to 65Cu and 50% was natural isotope-abundant copper. © 1990.