Ion-chromatographic study of the possible absorption of copper and zinc bythe skin of Rana pipiens

Frogs are known to obtain some of their nutrients (e.g., glucose and sodium ) through their skin. However, no studies have been made of the possible ab sorption of transition metals, which exist in most river water at low-ppb ( w/w) levels. Therefore, this research was undertaken to evaluate the use of ion chromatography for such an investigation. Solutions of copper and zinc (20 ppb in each) were chosen for use in a small-scale screening study. Ten live frogs were each placed in individual baths for approximately 50 h. Of interest were the net changes in the concentrations of the metals. These d ifferences were the result of any absorption and/or excretion processes tha t took place. A Dionex IonPac CS5 column was used to analyze this simulated river water, both before and after frogs had been placed in the solution. Included in this paper are: (1) methodology and calculation formulas; (2) p recautions needed to ensure sample integrity; (3) statistical analyses, whi ch indicated that ion chromatography is an accurate, precise technique for quantifying Cu and Zn in these samples; and (4) screening-study results, wh ich were used to test the null hypothesis that frogs do not absorb copper a nd zinc either onto or through their skin. (C) 2000 Elsevier Science B.V. A ll rights reserved.