News from the ACS National Meeting: Artful teaching

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  • Artful teaching Taking advantage of an extensive art col-lection on campus, Wellesley College ana-lytical chemistry professor Margaret Mer-ritt is developing a course in which stu-dents propose analytical methods to examine pigments on real art objects. The course combines art history and chemistry, and includes talks from art conservators. "I've never had students so enthusiastic about analytical chemistry," says Merritt.

    Merritt teaches the class in collaboration with Melissa Katz, assistant curator at the Davis Museum and Cultural Center at Welles-ley. Students in the class are assigned a par-ticular color pigmentyellow, for example. The color is linked to pieces in the museum collection; for example, the yellow is found in a 13th-century stained glass. Students are expected to investigate the chemistry of the color, identify likely compounds responsible for the color, and propose a "wet" and an instrumental method of analysis. "The lab extends the [course] material beyond the textbook to techniques such asXRF [X-ray fluorescence] " says Nlerritt

    The students learn how to research a problem by investigating the chemistry of the pigment, how to sample non-destruc-tively, and how to deal with heterogeneous samples (many pigments are covered with a varnish, for example). The work begins in mid-October and is completed in mid-De-cember when students turn in a paper de-scribing their results. "There are continual

    peer and faculty reviews of each part of the multisection paper during the October to December period," says Merritt.

    In addition, the lab emphasizes team-work. "I have facilitating conferences with students," says Merritt. "We get all the [students researching] blue pigments to-gether, for example." Students also consult with Katz, who is an expert on pigments.

    Merritt admits that she would like an experimental component to the course. She has redesigned die course this year so that physical chemistry is a prerequisite. This will provide her students with the back-ground to do reflectance IR measurements on selected sections of art objects with blue pigments. "There is not much in die litera-ture [on IR reflectance spectra of pigments] and we hope to contribute to the literature."

    Your job is this course Students taking instrumental analysis at the University of Kansas spend part of their first day in this course "applying" to work at one of several hypothetical jobs requiring analytical services. Fifteen weeks later, the students will describein oral and written presentations the experimental procedures they have devel-oped to solve their "company's" problem, their results and data interpretation, and the mone-tary costs they have incurred. "We have sacri-ficed comprehensive treatment of various in-strumental methods in favor of students con-centrating on perhaps one to three techniques

    that they will learn thoroughly," says George Wilson, who, along with Craig Lunte, created the course.

    Students select tiieir jobs from such op-tions as environmental sampling at a Super-fund site (which involves real samples from sites near Galena, KS), providing pharmaco-logical data on the excipient 2-amino-2-hy-droxymethyl 1,3-propanediol orTRIS (re-quiring animal studies and urine collection), and determining the source of "skunkiness" in a microbrewery beer. Students in each company are expected to work together; in fact, die team is expected to meet weekly, and half of each student's course grade is based on the group's performance.

    After an initial four-week introduction to the analytical equipment, students are given priority access to a broad range of sophisticated, research-grade instrumenta-tion for their analyses, which range from a GC/MS system, to FT-IR and Raman spec-trometers, to a scanning probe microscope. Biweekly reports of progress are given to Wilson, who, along with the teaching assis-tants, assumes the role of middle manage-ment. Students in some projects also work with an outside consultant.

    According to Wilson, students not only learn about analytical chemistry, but gain an appreciation of the role of government regulations, the actual costs of analyses, and the nature of group dynamics. "The objective is to learn analytical chemistry, but also to experience all dimensions of problem solving," says Wilson.


    David Bradley reports from York, England.

    Glow with the flow Norman Dovichi and his team at the Uni-versity of Alberta (Canada) have developed a capillary electrophoresis (CE) system tiiat can analyze all the wells in a 96-well microliter plate simultaneously. According to Dovichi, it could help speed up DNA sequencing, protein analysis, and the screening of protease inhibitors.

    Dovichi described the instrument as a two-dimensional array of 96 capillaries held in a sheath-flow cuvette. At one end, die capillary bundle is splayed so tiiat each capillary mates with an individual well on the plate. The sheath-flow cuvette serves as a chamber for postcolumn detection by laser-induced fluorescence, excited by an argon ion laser at 488 or 514.5 nm.

    According to Dovichi, this differs from the conventional approach in which the capillaries themselves act as detection chambers. His instrument instead detects fluorescence from the analytes after they have exited the capillary.

    The fluorescence is collected and colli-mated with a single camera lens, dis-persed spectrally using a large prism, and re-imaged on a high-efficiency CCD (charge-coupled device) camera feeding into a computer. "We generate 96 fluores-cence spectra simultaneously, one from each capillary," said Dovichi, "forming an 8 x 12 array that fills the CCD array."

    The instrument has been used pri-marily for analyzing DNA sequencing plates, collecting information about die fraction in each well, but it has also been

    tested with dye-labeled protein samples sep-arated initially by capillary gel electrophore-sis. The device has potential for high-throuehnut screening. "This instrument can

    Schematic of a single-capillary version of the iheath-flow cuvette CE detection strategy.

    Analytical Chemistry News & Features, October 1, 1998 641 A