Determination of Trace Amount of Copper and Zinc in an Aqueous Solution by Atomic Absorbance Spectroscopy Abstract: The purpose of this experiment is to analyze a sample containing copper and zinc in trace amounts, where standard addition method was used and the instrument used is the atomic absorbance spectroscopy. The amount of copper obtained was 0.569 ppm ± 0.015 and for zinc we obtained 0.42 ppm ± 0.0027. Introduction: This method implies the excitation of particles in the solution sample and determination of the amount of radiation liberated from that particle to come back to its stable state. Thus the amount of radiation absorbed is related to the concentration of the sample. Inside the instrument, the sample is drawn into the burner nebulizer by air flow where it is mixed with acetylene, then it is exposed to a flame where the element (zinc or copper) are dissociated. This flame has a long path length and it is placed between a radiation sources, which is a cathode lamp including an electrode of element of interest, which is set to a defined wavelength corresponding to the element of interest. Also, a detector placed inside the instrument close to the flame to measure the amount of radiation given off. “The amount of resonant wavelength absorbed by the sample burning in the flame is measured” (1). When copper measurements are taken, the six element hollow cathode lamp must be changed for measuring zinc amount. Procedure: In this experiment, a cupper solution was obtained that was at 1000 ppm, this solution was diluted to have 10 ppm. For that 10 ml Copper solution was diluted to the mark to 100ml using water. Same procedure was done for zinc. In addition 3 ml’s of unknown was used for each dilution of the standard. Then the solutions were measured in the AAS. For more precision please refer to lab manual.
Data table for absorbance of Copper and Zinc using atomic abs. Spec.
| Copper Absorbance
| Zinc Absorbance
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