editorial
Honors Course in Introductory Analytical Chemistry
I
teach an honors course called “Modern Analytical Methods for Separation and Characterization”. The two-credit, one-hour lecture course (28 lectures plus 3 exams and Q&A days) is accompanied by a laboratory course, which students register for separately. There is a concurrent, standard course that roughly parallels the honors course, but there are some sharp differences in content and, of course, pace. Developing choices about what to teach to capable students is an inevitable precursor to the evolution of the standard course. One must decide what constitutes the fundamentals that enable the student to self-learn later on, how to teach them efficiently, and, for want of time, what to set aside. I wrote in November 2006 about finite class time budgets; this Editorial outlines my budget for this honors course. After an introductory lecture outlining different contexts of analysis (bulk versus surface), sensitivity versus selectivity, analytical calibration, and categories of chemical equilibria, there are six lectures on acid–base equilibria. Covered are mono- and diprotic acids, stoichiometric and equilibrium calculations (but not ad nauseum), buffers, and fractional composition versus pH (distribution) diagrams. Titrations are mentioned only in passing because distribution diagrams convey better insights. These lectures end with an “advanced topics” segment on the basics of how protonation affects 1HNMR chemical shifts and on using NMR titrations to determine microscopic acid–base constants. The separations leg of the course starts with CE (two lectures)—the notions of electroosmotic flow, separation by differential electrophoretic migration, instrument diagrams, band spreading, plate counts, and the influences of pH on amino acid charges and migration rates. Distribution diagrams are handy for the latter. Chromatographic principles (six lectures) come next, on how differential migration depends on partitioning, further elaboration on band-spreading mechanisms, parameters that affect resolution, and gradient elution. The essential details and uses of gas, liquid, ion-exchange, and size-exclusion chromatographies are presented, including MS as a detector. These lectures end with “advanced material” on electrophoresis in microchannels, the
© 2 0 0 7 A m e r i ca n C h e m i ca l S o c i e t y
introduction of miniaturization, crossed-tee injections, and high-speed separations. The advanced material is based on a set of five key papers from the research literature. The spectroscopy segment (eight lectures) starts with EMR properties and how light interacts with matter and causes various kinds of energy-level transitions. UV–vis electronic absorbance and emission spectra of molecules and atoms and relationships for quantitative analysis are emphasized. Spectrometer instrument systems (single- and doublebeam, diode array) and their components, flow injection analysis, and how the instrument system influences data quality receive emphasis. The students learn basic principles of lasers and photodiodes. Atomic adsorption and ICP emission instrument systems and the requirements imposed by narrow atomic lines are covered. Last but not least, an “advanced” segment discusses cavity ring-down spectrophotometry. The last course section (five lectures) is potentiometric electrochemistry—electrochemical cell potentials, reference and working electrodes, the Nernst equation and its mysteries, and how concentrations are measured with a variety of permselective membrane electrodes. A segment introducing voltammetry with a nanoscopic electrode constitutes the final “advanced material” offering. One informal session discusses chemistry occupations and opportunities for graduate education. It is hard to adequately convey the detailed content of these lectures. I suspect many readers will be unsurprised by the topics. What is important to imagine is the distillation required to discuss the topics at some conceptual depth within the time available. The quality of student note-taking is improved by providing electronic copies of course slides. Professors make many different choices about what and how to teach; I make no claim that mine is the best. I simply share my ideas with you.
D E C e m b e r 1 , 2 0 0 7 / A n a l y t i ca l C h e m i s t r y
8 817
