Wipf Group - Required Laboratory Practices
- First and foremost, it is imperative that lab notebooks are kept in accordance to ACS guidelines and the standard of good laboratory practices. Have a look at this web link , a summary I wrote for an undergrad lab course, and the sample notebook pages (the good, the bad, and the ugly)! The ACS "Writing the Laboratory Notebook" is on file in our Group Collection. For an adequate experimental progress report, see here.
Good laboratory practice is strongly dependent on reliable and extensive records in your lab notebook. All quantitative measurements have to be clearly noted, and full, detailed sentences must be used to describe the course of the reaction. Your handwriting must be readable! TLC or other analytical measurements must be recorded accurately, including the solvent and the assignment of reference samples. Keeping a good notebook is a critical feature of your practical training. Obviously, the notebook has to be in the lab, and not anywhere else, and it always has to be up-to-date on all current experiments. If something is not in your notebook, it does not exist and cannot be reported in group meetings, presentations, or paper drafts. There is only one authentic notebook; loose pages or "drafts" are not permissible.
••••• Information about our new electronic inventory and notebook system •••••
It is crucial that everybody realizes that for every compound that you claim to have synthesized you need full experimental characterization, which includes Mp (if a solid), [a]D (if chiral and not racemic), IR, 1H NMR, 13C NMR, MS and HRMS. The 1H and 13C NMR spectra have to be clean, since they serve as criteria for compound purity in the absence of elemental analyses, which we usually don’t get. Therefore, solvent peaks or other impurities, known or unknown, are not acceptable. Since we generally submit copies of spectra to ACS journals as supplementary material, 1H and 13C NMR spectra have to be of high quality and in letter size format with clearly readable labels. In the context of a longer synthesis, you can use your judgment and partially characterize some intermediates, but fully characterize major intermediates and the final compounds, yet you should not go for more than three steps without full characterization. You will be unable to publish or submit your candidacy/MS/PhD thesis/paper if your samples are not fully characterized. With your thesis, please include a compound characterization checksheet (JOC format) for all compounds, and include copies of 1H and 13C NMRs of key compounds in your hardcopy.
I urge you to be conscientious in characterizing your compounds at all times. Postponing full characterization is a recipe for trouble.
See also: information about University and Departmental Ethical Research Conduct guidelines.
- Safety! Please check our webpage for general safety information. Inform yourselves about the hazards of any new chemical before using it! If you are not sure about any potential hazard, check with me first. The best safety net is a well-prepared and thoughtful experimental protocol - never rush into an experiment!
- Clean, Orderly Hoods reflect good experimental techniques! Your hood and bench should reflect professionalism, efficiency, and appreciation for a safe working environment. This real-life example does clearly not meet the minimally acceptable standards:
- Take Care of Our Equipment: A professional, responsible attitude mandates regular maintenance on personal as well as shared equipment. You cannot expect good performance if you abuse our instruments. Again, pictures say more than a thousand words. The first snapshot is from a pump that has seen a lot of tear and wear, but can still be salvaged. The lower two pictures are from another pump that was operated without a proper cold trap and has suffered a terrible fate in careless hands:
Furthermore, no laboratory item, especially vacuum pumps, or rotavaps, should be simply "borrowed" or switched from another lab bench!
- Chemical Inventory: In order to allow efficient access to group chemicals, please give the package slip of any chemical that you receive to Michelle. The Group Member(s) in charge of the inventory will add this information into our database, which is updated on a monthly basis. Also, please let Michelle know when you use up a chemical, so that the entry can be deleted from the index!
- Writing your Thesis/Paper: Have a look at our publications and experimental data/supplementary material posted on the ACS journals webpages. Also, consult the "ACS Style Guide" which is on file in our Group Collection. At any given time, several of you are in the process of writing a thesis, report, or a paper draft. In addition to devising an outline that raises the interest of the reader, rather than putting him or her to sleep, making sure that all the experimental data are presented and corrected (yes, proofread yourself several times and have somebody else proofread for you!), and applying logical reasoning, make sure that you give proper credit for any “borrowed” material!
- Purity of Compounds. All new compounds, whether synthesized or purchased, should normally possess a purity of at least 95%. All scientifically established methods (e.g., HPLC, LC/MS, combustion analysis) of establishing purity are acceptable. The specific analytical method used to determine purity should be included in the general part of the experimental section together with a statement confirming ≥95% purity. The experimental data supporting this statement should be uploaded in your CBIS ELN pages, but no further documentation is required for publication in an ACS journal, a formal report, or a thesis, unless specifically required. Spectral data is often not sufficient as a criterion of purity. When the purity of a particular compound is less than 95%, the percent of purity should be specified at the end of the description of its synthesis in the experimental section. If the compounds contain solvent, the quantity of solvent should be included in the experimental description.
- Avoid plagiarism! Scholarship builds on the knowledge, understanding, and creative extrapolation of the work of others, but there are strict rules for ethical scholarship and for avoding plegiarism. In this link, I have summarized a few important guidelines from the ethics websites of the University of Pittsburgh and the University of California. Please adhere strictly to these rules; otherwise you will face at least a significant delay in the correction of your work and at worst a failure in an exam (or annulation of your degree). Let me know if there are any questions!
- Browse: Overview of Lab Techniques and Useful Reagents (TLC, etc) for many useful hints and suggestions!