A microcomputer automated anodic stripping voltammetric analyzer for trace heavy metal speciation Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/mw22v934w

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  • An automated instrument based on a single-board microcomputer was developed for use in voltammetric analyses. Operator input of numerous experiment parameters allows any type of voltammetric analysis to be implemented and multiple scans to be run unattended. A three operational amplifier potentiostat is used to control the cell voltage and convert the cell current to a voltage signal. A 16-bit digital-to-analog converter allows the computer to determine the cell voltage. A 12-bit analog-to-digital converter converts the signal to digital form for the computer to manipulate, store and display. The potentiostat is isolated electrically from the computer through the use of opto-isolators. The computer is interfaced to solid state switches, 3-way valves and pumps for control of electrode rotation, outgassing of 0₂. filling of the cell with a buffer solution, and evacuation of cell solution. Injection of spike solutions and rapid washing of the cell is also under computer control. Data manipulation handled by the microcomputer includes waveform generation, data acquisition, automatic background acquisition and subtraction, polynomial fitting of the baseline, and peak potential and peak current calculations. Instrument parameters were optimized in the differential pulse anodic stripping voltammetry mode with a rotating thin mercury film electrode on a glassy carbon disc support. With this system the heavy metals, Zn, Cd, Pb and Cu, were quantitated at 1 μg/L levels with five minute deposition periods and at 0.1 μg / L levels with thirty minute deposition. Metal speciation studies were carried out to evaluate the automation abilities of the instrument and to observe and demonstrate important problems in metal speciation studies with ASV. Pseudopol arography was used to confirm that EDTA formed a quasi-labile complex with Cu. Humic acid was adsorbed by the mercury electrode and reduced the response to metals. The ASV determinable Zn, Cd, Pb and Cu concentrations in a river water sample were found to be 4.0, 0.32, 0.15 and 0.40 μg/L, respectively. Some complexation capacity was observed as was adsorption of organics onto the electrode.
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  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0 on a Canon DR-9050C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
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  • description.provenance : Approved for entry into archive by Deborah Campbell(deborah.campbell@oregonstate.edu) on 2013-07-30T14:51:44Z (GMT) No. of bitstreams: 1 DewaldLamarRobert1984.pdf: 2175288 bytes, checksum: 7161f506e85b5674b1e6df393b05f51d (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-07-29T15:58:42Z (GMT) No. of bitstreams: 1 DewaldLamarRobert1984.pdf: 2175288 bytes, checksum: 7161f506e85b5674b1e6df393b05f51d (MD5)
  • description.provenance : Made available in DSpace on 2013-07-30T14:51:44Z (GMT). No. of bitstreams: 1 DewaldLamarRobert1984.pdf: 2175288 bytes, checksum: 7161f506e85b5674b1e6df393b05f51d (MD5) Previous issue date: 1984-03-09
  • description.provenance : Submitted by Kirsten Clark (kcscannerosu@gmail.com) on 2013-07-25T17:33:54Z No. of bitstreams: 1 DewaldLamarRobert1984.pdf: 2175288 bytes, checksum: 7161f506e85b5674b1e6df393b05f51d (MD5)

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