Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: Use of a chelating resin in the extraction and concentration of trace metals from shells of Mytilus edulis in conjunction with atomic absorption spectrophotometry
Student Author(s): Chang, John Sau
Faculty Advisor(s): Abbott, Donald
Pages: 24
Location: Final Papers Biology 175H
Date: June 1971
Keywords: marine pollution
Abstract: 1. Analyses of Mytilus edulis shell for the trace metals Pb, Mn, Cu, Zn, Co and Cd using atomic absorption spectrophotometry is difficult because of scattering effects at low wavelengths. To eliminate these interferences, experiments were performed with the use of an ion-exchange resin column of Chelex-100 with the result that scattering was completely elimintated from the samples of shells. 2. A method of concentrating a solution of trace metals by evaporation under suction was developed. This method resulted in a 100% recovery of all trace metals from a solution that had been concenctrated ten times. This in effect increased the detection limit of the atomic absorption spectophotometer ten times. 3. At a sample pH of 7.0, the Chelex column used had a generally higher percentage recovery for solutions of trace metals without shell material than for solutions with shell material. 4. Recovery precentage from the column for all the trace metals involved was much higher at sample pH of 7.8 than that at sample pH of 7.0. 5. Reagent contamination resulted in some inaccuracies in the values for some trace metals in the shells of Mytilys edulis, especially copper and zinc. When the concentration of some of the trace metals in the mussel shell are so low, contamination becomes an all-important consideration. Furthermore, the varying amounts of the inherently contaminated ammonium hydroxide used in the samles added an increased degreee of variance to the results.