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Copper Ion Analysis. Cory Sennett November 15, 2006 CH EN 4903. Overview. Devices used to detect copper ion concentration in solution Analysis of copper ion concentration in an unknown sample Conclusions. Devices. Copper specific electrode Orion 96-29 Ionplus ® cupric electrode
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Copper Ion Analysis Cory Sennett November 15, 2006 CH EN 4903
Overview • Devices used to detect copper ion concentration in solution • Analysis of copper ion concentration in an unknown sample • Conclusions
Devices • Copper specific electrode • Orion 96-29 Ionplus® cupric electrode • Atomic absorption spectroscopy (AA) • Perkin-Elmer AAnalyst 300
Orion 96-29 Ionplus® Electrode • Ion Selective Electrode (ISE) • Measures electric potential across a membrane • Compares the potential to a reference, which gives a net charge • The net charge is directly proportional to the concentration
Orion 96-29 Ionplus® Electrode • Analysis of unknown sample • Standards • Solutions created using approximately 0.50 gm/L, 0.75 gm/L and 1.00 gm/L cupric standard mixed with 15 ml of water. • 0.1 ml of Ionic Strength Adjuster added to each standard. • Allows for consistent pH level and more accurate readings
Orion 96-29 Ionplus® Electrode • Procedure • Calibration curve created using standards (Figure 1) • Use of linear least squares to fit data Table 1 Calibration data for Orion Electrode Concentration (gm/L) Ion Ion Ion Average Stdev 0.40 625.3 625.2 600.2 616.9 14.5 0.75 1184.0 1201.0 1179.0 1188.0 11.5 1.06 1630.0 1588.0 1615.0 1611.0 21.3 Slope: 0.001 Intercept: -0.020 R2: 0.997 • Determine unknown concentration
Figure 1 Orion electrode calibration curve showing standard solution concentration versus ion concentrations.
Orion 96-29 Ionplus® Electrode • Results • 0.625±0.014 gm/L (confidence level 95%) • Reproducibility: ±2.2%
AAnalyst 300 • Uses absorption of light to measure concentration of gas-phase atoms • Atomizes liquid sample • Vaporizes liquid sample across slot burner • Concentration can be approximated using Beer-Lambert Law A=alc Where A is the absorbance,ais the absorption coefficient, l is the distance the light travels through the sample and c is the concentration of absorbing species.
AAnalyst 300 • Analysis of unknown sample • Standards • Solutions created using approximately 0.50 gm/L, 0.75 gm/L and 1.00 gm/L cupric standard mixed with 15 ml of water.
AAnalyst 300 • Procedure • Calibration curve created using standards (Figure 2) • Use of linear least squares to fit data Table 2 Calibration data for AA Concentration (gm/L) Absorb. Absorb. Absorb. Average Stdev 0.40 0.005 0.005 0.005 0.005 0.000 0.75 0.010 0.010 0.010 0.010 0.000 1.06 0.015 0.016 0.016 0.016 0.001 Slope: 61.899 Intercept: 0.101 R2: 0.995 • Determine unknown concentration
Figure 2 AA calibration curve showing standard solution concentrations versus absorbance.
AAnalyst 300 • Results • 0.788±0.016 gm/L (confidence level 95%) • Reproducibility: ±2.0%
Orion Electrode 0.625±0.014 gm/L (confidence level 95%) AAnalyst 300 0.788±0.016 gm/L (confidence level 95%) Comparison of Results • Actual concentration of unknown sample • 0.635 gm/L
Conclusions • The Orion Electrode gave a more accurate result for the unknown sample. • More experimentation required to determine precision and accuracy over a broad range.
References • Schwedt, Georg The Essential Guide to Analytical Chemistry, John Wiley & Sons, Inc., New York (1997). • Omega Engineering Inc. Ion Selective Electrodes: Measurement Considerations, http://www.omega.com/techref/ph-5.html(2006) • Wikimedia Foundation, Inc. http://www.wikipedia.com