This experiment used in the Instrumental Analysis course at Missouri Western State University requires students to perform a study of visible absorption calibration curves to illustrate effects of using a single beam versus double beam instrument, as well as using a wavelength of maximum absorption, ‘λmax’, versus another wavelength of significant, but not maximum, absorption. Students produce their own standard solutions from a given stock solution and then obtain absorption data using Spectronic 200’s and a Cary BIO100 UV Vis instrument. Typically stocks of aqueous Co2+, Cr3+, or Cu2+ are used. Once calibration curves are obtained, students use F-tests to determine if there is a significant difference in the standard deviations of the slopes obtained from the two instruments at similar wavelengths. They then use t-tests to determine if the slopes are statistically different at the same wavelengths. Students also use F tests to determine if there is a significant difference in the standard deviations of the slopes of the slopes obtained for two different wavelengths on the same instrument. This exercise has overall objectives of showing students the effects that their choice of instrument type or absorption wavelength may have on their overall results, introducing them to the general use of the instruments, and reinforcing their previous knowledge with statistical analysis. Typical student results will be shown.

Slope statistics: An Instrumental Analysis experiment to study the reliability of calibration curves obtained from different visible absorption methods

251st National Meeting (2016)

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