The approach I use in the laboratory with my separation science course is to have students work in groups of 2-3 on a single, semester-long project. The students in the course are usually in the second semester of their sophomore or junior year, although some first-year students and seniors are also enrolled, and this is usually their first analytical chemistry course. Because most of the students have no background in analytical chemistry, I identify for them the projects and the instrumental method that will be used to complete the analysis. The following is a list of the most common analysis projects that I have done over the years I have taught the course.
- Caffeine, theobromine and theophylline in chocolate – HPLC-UV
- Catechins (polyphenols) in green tea, wine and chocolate – HPLC-UV
- Amino acid analysis – HPLC-Fluorescence
- Volatiles in coffee – GC-MS
- Trihalomethanes in drinking water – GC-MS
- Methylbenzenes from car exhaust in air – GC-MS
- Polycyclic aromatic hydrocarbons in charred meats or creosote – GC-MS
- Nitrate and nitrite in hot dogs/cured meats – Ion Chromatography
- Chloride content of frozen foods – Ion Chromatography
- DNA restriction fragment analysis – Capillary Electrophoresis
- Additives in soft drinks – Capillary Electrophoresis
I assign the groups based on information I have collected the first day of class. I usually try to form groups that are mixed gender and mixed in terms of student experience. In the first laboratory period, we pair up groups with projects from a list I have selected for that year. My only constraint is that, if a group member has extensive experience with a particular instrument (e.g., she or he used GC-MS extensively during a summer job or research position), the group undertakes a project that uses a different instrument. Every group does a different project.
With a topic and instrumental method, each group must then write a proposal that describes how they intend to complete the project. Appendix 1 is the handout I provide to the students that describes the Project Proposal, and we go over this document in the first laboratory period. We have twelve week semesters and the proposal is due at the end of the fifth week. On the same day that the proposal is due, students also must submit an individual peer- and self-evaluation on the preparation of the proposal. Appendix 2 is the evaluation that is used.
The first step in constructing the proposal is for the students to search the scientific literature using Scifinder Scholar to find articles relevant to their analysis. The final activity I do in the first lab period is to provide instruction on the use of Scifinder Scholar. Groups are then expected to begin their literature search and to collect articles for their project.
In the second week of the semester I schedule a one-hour meeting with the groups that are using a particular instrumental method (e.g., HPLC, GC-MS, ion chromatograph). At this meeting I provide background relevant to their projects. This will include a brief discussion of the instrumental method. I introduce terms that they are likely to encounter in their literature articles. I identify items that they will need to decide on to complete the project (e.g., sample workup, mobile phase, preparation of standards, etc.) and will need to examine carefully in the articles. See Appendix 5 for lists of the items I cover for each project.
In each of the following weeks until the proposal is due, I meet individually with each group to review what they are finding in their literature search. At these meetings, which typically run about 30-45 minutes each, I end up explaining terms and concepts that they are uncertain about from their articles. We identify strategies for comparing methods (e.g., cost, time, ease of use, etc.). This gives me a chance to further identify steps that will be needed to complete the project and decisions that they must make and explain in the proposal. Also, I am often aware of a sample workup method that they may not have found yet. I point this out to them and that they will need to cast a broader net in their literature search. Even if I tell them generally what they need to be looking for, the specific details of now the implement the method requires that they find the actual article. During these weeks each group is also shown how to operate the instrument. Group members are then encouraged to come in at an off hour either individually or collectively and run the instrument on their own to become more familiar with its operation. As they begin to decide on particular procedures, they also begin to collect glassware and chemicals they will need to carry them out. If we identify items that they will need to order to complete the project, they must include these in the proposal with their cost and the supplier, but we order them in advance to have them in hand when they begin the laboratory portion of the project.
Because of these meetings, I usually have a good idea what to expect in each proposal. I read them carefully and approve the steps that have been put forward by the group. Often I will raise additional questions that still need to be addressed. Once these are resolved, the students begin experimental work in earnest. The policy is to have an open lab where students are allowed to come in at off-hours to undertake preapproved tasks. Students keep an annotated log in the lab notebook of all of the hours they spend on their project (all hours count except those that go into preparing the final Powerpoint presentation and writing their final individual laboratory reports). Students must put in a minimum of 30 hours on their project, and it is common to have a third to half the class often log in more than 60 hours. I encourage them to coordinate their activities so that they avoid situations where one student is undertaking an activity (e.g., preparing standards) while the others are watching. I stress the importance of having each student become proficient on all of the facets of the project so that they do not develop specific roles (e.g., one student prepares samples, another runs the instrument, and the third cleans up).
During the experimental phase of the work, my association with the students is comparable to the way I interact with students conducting independent research projects in my lab. I am available to consult with them as needed. I make a point to circulate through the lab whenever I see students working on the projects to inquire about how things are going.
On the last week of lab each group gives a 20-30 minute oral Powerpoint presentation on their project. Every student must give a section of the presentation, and in a three-person group they usually have one introduce the project, another describe the experimental procedures, and the third present the results and conclusions.
Each student must also submit an individual final report that takes the form of a published article. Appendix 3 provides the instructions for writing the final report. I have them write individual reports so that I can better distinguish the extent to which each student grasps the project and is able to present the project in written form. They also must submit a peer- and self-evaluation with the final report, which is included as Appendix 4.
Appendix 5 contains specific information about each of these projects that includes the topics I go over with each group in an introductory session, key items they need to find through a literature search, key things they find from the literature, and common problems or issues they often face in the lab when carrying out the project.