Robert Megargle

Feasibility and error in linear extrapolation titration procedures

Abstract Errors are considered for titration procedures in which a least squares linear extrapolation of data before and after the end-point is performed to estimate the end-point. The error caused by the titration reaction not proceeding to completion is considered. The effect of the formation constant, concentration of constituent, the range of the data used, the number of data points employed and the initial visual estimate of the end-point is discussed. Also, the titration error caused by error in the measurements is calculated.

A microcomputer automated circular dichroism spectropolarimeter

Introduction Circular dichroism (CD) measurements are especially useful in conformational and structural studies, and have proved to be a valuable tool in biochemical and medical investigations. The technique is also suited to the quantitative analysis of optically active substances. The value of the tool can, be improved by computer processing of results as it is useful to be able to compare one spectrum with another, subtract a background or interfering spectrum from another to highlight the differences, average several spectra, calculate the derivative of a spectrum, merge two spectra with overlapping wavelength ranges, or produce calculated optical rotatory dispersion (ORD) spectrum from the CD spectrum.

A Semiautomatic Stripping Analysis Instrument

A stripping analysis instrument was designed and constructed using relays at key points to control the operation. Each relay can be operated manually with switches on the front panel or placed under the control of a digital control circuit. The control circuit takes the instrument sequentially through five modes. In the ready mode the operator fills the cell, sets the controls, and pushes start. The instrument goes into the electrodeposition mode for a preset time where the unknown is deposited on the electrode at constant potential in a stirred cell. This is followed automatically by a wait mode for another preset time, and then by a scan mode where the metals deposited in the electrodeposition mode are stripped off and measured. When the scan mode time is over, the instrument enters the completion mode where the final voltage is held for exhaustive stripping of the electrode. The instrument goes from the completion to the ready mode when the operator intervenes.

A microcomputer automated recording spectropolarimeter.

INITIAL WAVELENGTH (NM)