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* Division of Nutrition
Division of Microbiology, Food and Drug Administration (FDA), 1090 Tusculum Avenue, Cincinnati, OH 45226
Elemental Analysis Research Center, FDA, 1141 Central Parkway, Cincinnati, OH 45202
Division of Nutrition, FDA, Washington, DC 20204
The initial nutritional status of experimental animals can influence their response to subsequent dietary regimens. In the present study, we determined the variations in minerals in diet NIH-31, a breeding colony stock diet, and in tissues of weanling rats nursed by dams fed this diet. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used to determine nine elements (Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn) in diet and in liver, kidney, spleen, duodenum and femur from 22- to 26-day-old rats. Wet digestions were performed in mixtures of nitric, perchloric, and sulfuric acids (diets and soft tissues) or nitric and perchloric acids (femur). Solution concentrations ranged from <25 ng/ml for the trace elements to >100 µg/ml for the major elements. Large variations in mineral content were found between batches of commercially prepared NIH-31 diet; relative amounts of Cu, Fe, Mn and Zn varied markedly. Significant differences in concentrations of major and trace minerals in liver, kidney, spleen and duodenal tissue were found among groups of weanling rats obtained from the same supplier at different times. Mn was readily quantitated in all tissues except spleen, where it was below detection limits. The precision obtained with the ICP-AES methodology has significant advantages for establishing variations in tissue mineral levels.
KEY WORDS: maternal diets tissue mineral levels atomic emission spectrometry elemental analysis
Manuscript received 6 April 1984.