Issue Date: January 5, 2009
Quant Lab Revisited
MENTION quantitative analysis to someone who studied that subject 40 or more years ago and the name will bring to mind titrations, burettes, and chemical solutions that change colors. Raise the topic with someone taking the course today and that student will think of the very same things.
In many institutions, the topics and laboratory methods taught in "quant," as the introductory analytical chemistry course is commonly called, have changed little during the past several decades even though the practice of analytical chemistry in academia and industry—and the profile of the students taking the course—has changed considerably. That situation is prompting some academics to evaluate their quant course content to determine whether it is time to overhaul the curriculum.
Peruse university course catalogs and it becomes clear that quantitative analysis is taught widely across college campuses. "Almost all schools offer a quant course," says Peter R. Griffiths, an analytical chemist who just retired from the University of Idaho, Moscow, "but the form of the course differs greatly from place to place." The name differs, too.
The American Chemical Society Committee on Professional Training (CPT) establishes curriculum guidelines for schools that wish to offer ACS-certified degrees. CPT Vice Chair Cynthia K. Larive explains that ACS does not directly certify or set curricula and it does not specify that students must take a quant course. Instead, ACS approves the departments, and the department chairs, in turn, certify that their students have met the ACS guidelines.
CPT tries to be careful regarding the language of the guidelines, Larive points out, "in that we often do not require specific courses, but rather experiences that can be delivered in a variety of ways. A college course is the most common delivery mechanism." Larive, an analytical chemistry professor at the University of California, Riverside, notes that CPT released a new set of guidelines last spring requiring a foundation in each of the five traditional areas of chemistry: analytical, biological, inorganic, organic, and physical.
In the area of analytical chemistry education, Griffiths has kept a close eye on the way quant is taught in the U.S. He recently circulated a questionnaire to analytical chemistry faculty in universities and colleges in the western half of the U.S.
On the basis of the survey results, Griffiths says most curricula concentrate on "time-honored approaches to classical wet analytical chemistry." In the report he wrote based on these results, which was published last year, he also indicates that most students are not taught many of the principles of modern instrumental analysis during the course (Anal. Bioanal. Chem. 2008, 391, 875).
Often the techniques covered in the classes aren't inclusive enough to meet the needs of all students. The profiles of the students taking the course vary widely, explains Daniel C. Harris, a senior scientist at Naval Air Systems Command, in China Lake, Calif. Chemistry majors are usually required to take the course. But many students who major in other subjects are also required to take the course, adds Harris, author of the two most widely used quantitative analysis textbooks, "Quantitative Chemical Analysis" and "Exploring Chemical Analysis." Still other students are advised to take quant even though it may not be a requirement.
Griffiths' survey supports these contentions. His results show that chemistry majors are required to take quant at only 70% of the institutions that replied. Nonetheless, a full 15% of the schools surveyed also require biochemistry majors to take the course. And, according to Griffiths, 15% of the institutions reported that quant is required on their campuses for students majoring in a variety of subject areas outside of chemistry. Those areas include chemical engineering, microbiology, molecular biology, food science, nutrition, environmental studies, industrial hygiene, public health, geology, medical technology, and forensic anthropology.
Many of the chemistry majors who take quant follow it with a second course in analytical chemistry that focuses more heavily on instrumental analysis. But relatively few schools require nonchemistry majors to take the follow-up course—sometimes called advanced analytical chemistry.
"Biologists often only take the first course," says George S. Wilson, a professor of chemistry and pharmaceutical chemistry at the University of Kansas, Lawrence. As a result, life sciences students on many campuses often sit through a semester-long course devoted mainly to equilibrium chemistry and titrations without being exposed, for example, to the fundamentals of chromatography. "Yet separations are key to biological research," Wilson asserts. He wonders how relevant and beneficial "traditional" equilibrium-focused quant courses are to today's students, especially to life and environmental sciences majors.
STRIKING a similar tone, Larive acknowledges that having a firm grasp on equilibrium chemistry is essential across the chemical sciences. But she's not convinced that after students complete one or two titrations, there is a lot of educational value in having them conduct additional titrations, even if they are based on other types of chemistry.
As to the relevance of quant, Griffiths notes that his survey shows that although the collection of topics covered in traditional quant courses is "dated and does not represent modern instrument-based analytical chemistry, the material is by no means irrelevant."
Harris agrees. "The course is as relevant as it ever was," he says. Both he and Griffiths relate separately that they have been told by their life sciences colleagues that it is important for students in those departments to take quant to learn critical scientific skills not taught in other classes. At the top of this skills list are learning how to make careful measurements, understanding complex aqueous equilibria, and learning how to evaluate the quality of data in the sort of detail needed for a career in the life sciences. "Similar arguments can be made as to why chemistry majors should continue to take the course," Griffiths says.
Designing a course that helps a diverse student pool acquire those skill sets—and one that students find relevant and interesting—is beset with challenges. For example, students may be advised to take courses in a specific order because of certain academic benefits or perhaps for logistical reasons.
At Southern Oregon University (SOU), in Ashland, students typically take a spectroscopy course in their sophomore year, so they don't take quant until two or three years after they have finished the general chemistry course. As a result, by the time they take quant, "they have a reasonable grasp of the principles and operation of NMR, FTIR, and GC/MS, but they have totally forgotten about chemical equilibria and the need for precision in the lab," SOU chemistry professor Steven C. Petrovic says. He adds that "once the students have taken quantitative analysis, however, they usually have a renewed appreciation for precision, both in laboratory procedures and in the way experimental results are reported. As an educator, I find that to be quite satisfying."
One universally recognized bump in the road to updating quant labs with modern instrumentation is finances. "It is much easier on the department budget to stock a teaching lab with burettes and pipettes for every student instead of spectrometers and chromatographs," Griffiths remarks.
Harris points to another impediment: human nature. "People tend to teach the way they were taught," he says. Years ago, many quant courses covered gravimetric analysis and precipitation reactions in detail. Harris says that in recent editions of his main text (he is now working on the eighth edition), he has "demoted that material to the back" of his book because of its decreased importance. Yet some professors still cover those chapters, he says.
As Harris sees it, analytical education is slowly moving toward teaching students "how to approach and solve problems in chemical analysis, as opposed to how to do equilibrium calculations." That move can go hand-in-hand with innovative and valuable lab exercises. For example, Larive tells of a colleague who presents students on the first day of quant lab with a business memo complaining about the accuracy of a few pieces of glassware, such as volumetric flasks and pipettes. The students are charged with assessing the validity of the complaint and responding collectively.
This unusual approach offers advantages over traditional introductory experiments, Larive says. The memo forces the students to think independently about methods for determining the accuracy of the glassware because it does not prescribe the way to make the measurements. In addition to other benefits, the exercise produces a data set that the whole class can use to perform a detailed and meaningful statistical analysis.
Students taking analytical lab courses at the University of Kansas are also educated through problem-based learning. As Wilson explains, after learning to use chromatographs, spectrometers, and a number of other lab instruments, groups of four or five students are challenged with industrial-type problems.
For example, they are asked to compare the concentrations of volatile organic compounds in two paint samples and to evaluate mouthwash by measuring the concentration of an antibacterial agent—a long-chain alkyl amine. Unlike students conducting traditional lab exercises, the Kansas students are not given a step-by-step laboratory manual to follow. "These are the kinds of problem-solving skills industry tells us they seek in their employees," Wilson says.
Academics are likely to continue debating whether their quant courses should include more lectures on buffer solutions or electrophoresis or drop lectures on redox titrations or some other topic. "I am not claiming to know all the answers," Griffiths says, "but I'd like to see the discussion continue." Ultimately, Griffiths and other analytical chemists are hoping that a reevaluation of the curriculum will lead to quant courses that are more representative of modern analytical chemistry and more interesting to the students who take them.
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