Screening and Sequential Experimentation: Simulations and Flame Atomic Absorption Spectrometry Experiments

Abstract

Students are introduced to screening and sequential experimentation using simulations and experimentation. The work begins with spreadsheet simulations and practice with the experimental design software. Students learn how to use the graphical output, normal quantile plots, to recognize the specific factors that affect the result of an experiment. In the laboratory, students make a preliminary investigation of the effect of six variables (flame observation height, flame stoichiometry, acetic acid, lamp current, wavelength, and slit width) on the atomic absorption signal for silver. This requires only sixteen experiments. Two or three active variables and an interaction of two variables are typically observed. Following this 26-2 fractional factorial design experiment, students investigate the effect of two active variables in more detail. This typically requires 16 to 25 experiments. The complexity of the system becomes apparent when flame observation height and percentage of acetic acid are studied. Most, but not all, of the observations are consistent with descriptive material that would be found in a typical instrumental methods text.

Simultaneous Atomic Absorption Spectrometry for Cadmium and Lead Determination in Wastewater. A Laboratory Exercise

“…A number of experiments dealing with FAAS and ETAAS can be found in the chemical education literature (2)(3)(4)(5)(6)(7)(8)(9). To our knowledge, there has not been any report on simultaneous atomic absorption spectrometry (SIMAAS).…”

Optimizing Signal-to-Noise Ratio in Flame Atomic Absorption Spectrometry Using Sequential Simplex Optimization

“…This experiment generates responses of the sort "I can't believe it-it really worked!" The notion of "automatic" design applied to the preliminary phase of an investigation is new to the students, although they have done a factorial design experiment previously (19). There are caveats, however.…”

Applications of Chemiluminescence in the Teaching of Experimental Design

“…Since 1990, when a valuable review of basic concepts in experimental design appeared in this Journal, a number of articles dealing with the teaching of FE have been regularly published. These were most often devoted to the application of FE in the optimization of analytical procedures, such as HPLC and GC separation, , atomic absorption spectroscopy (AAS) detection, spectrophotometry, , and gravimetry . Some of the published sessions were designed for organic synthesis courses. − …”