Many Students and Only One GCIMS The faculty a t Saginaw Valley State University have long recognized the student's desire for actual "hands-on" erne rience with state-of the-art chemical instrumentation. To this end a procedure has been devised that allows one labaratom section of 16-20 students to acqure individual ex~erience~erformina real-time analvses usine our Fisons Trio 1 0 0 0 ~This ~ system ~ ~ . of multipleatudent users in limited -amaunt oftime has worked in baththe organic and instrumental laboratory sections. After synthesis of an unknown liquid compound, students are instructed to place about 5 drops in the bottom of a GCMS sample vial and attach a Teflon-faced crimp seal. Following this sample - preps. ration the students proceed in programming the gas chromatograph acquisition parameters as well as the expected mass range. mints. derivatizations, and other (IR. W etc.) measure. These parameters are based on measured bailing -. ments. One vial is placed in the autasampler and the student starts the acquisition. Since the amount of sample added to the vial is so small the needle of the syringe does not aspirate any of the liquid sample. This essentially amounts to a headspace analysis by injection of only the vapor. Since there is no solvent to separate from the solute the GC column can be maintained at an elevated temperature and the helium flow rate can be increased. Both of these steps dramatically shorten the time required for analysis. Typical run times ranee from 2 to 5 min depending on the particular compound being analyzed. students are amazed when they realize thatonly the vapor is injeeted and that sample loss due to GCMS analysis is kept to a bare minimum. An interesting observation is that the universal solvent and cleaner, acetone, frequently appears in the GC and is verified by the mass spectrum. This leads to a discussion of the sensitivity of the instrument as well as GLP (Gmd Lab Practices) involved durine samole preparation. The only drawback that we have found so far is the difficulty in getting the students off of the GCMS and back into the lab. I t is felt that this procedure is infinitely better than using the autosampler because the students reeeive actual hands-on experience in the analysis of their individually prepared compounds and are not just given several sheets of data obtained from an impersonal instrument.
a
-
.
Stephen S. Lawrence Saginaw Valley State University University Center, MI 4871 0
530
Journal of Chemical Education
