Your lab book should contain records of the work you do before, during and after the lab session.

Before the lab session, you should prepare by reading the script carefully, reviewing any practical techniques that you are uncertain of, and planning your work for the lab session. Your plan should include the operations and manipulations that you will conduct, so it will involve some paraphrasing of the experimental script. You do not need to copy out every single word of the scripted procedure, although you may find it helpful to do so. It is good practice to carefully highlight any aspects of the practical work which are hazardous, and any precautions that you will take to control these hazards. You should also leave some space in your plan, as you may need to modify it after receiving the experimental briefing from the demonstrator at the start of the lab session.

As you prepare for the lab session, if you come across a technique in the script that you need to remind yourself of, you can use your lab book write these notes. For example, an experimental script may include the instructions:

“Dissolve the crude product in 20 mL ethyl acetate, extract with 20 mL of saturated sodium bicarbonate solution, and separate the layers. Acidify the aqueous layer with dilute hydrochloric acid until it is acidic to litmus paper, then extract with 20 mL of dichloromethane. Wash the organic layer successively with water (10 mL) and brine (2x10 mL), then dry over magnesium sulfate and remove the dichloromethane on a rotary evaporator.”

You might then review the technique of extraction, and make notes in your lab book to show more detail about these manipulations; you could write a step-by-step account of how to do an extraction; you might include a flow-chart of the steps you would take, or a series of diagrams of the flasks containing the different layers, and what happens to them; you could look up and record the densities of the solvents in use, which would help you work out which layer is which.

The purpose of making these notes is for you to complete the preparation that you require, in order to understand the labwork before you begin, and to improve the efficiency of your work in the laboratory. If, after this, you find that you are still unsure about something, make a note in your lab book to ask a demonstrator for clarification after the briefing.

During the lab session, you should use your lab book to take notes at the experimental briefing. The demonstrator will brief you on safety aspects, and also other relevant experimental and organisational details – your plan of work may need modification at this stage. The briefing is also a suitable time to ask for any clarifications which you may have about the experimental work.

As you conduct your labwork, you should make notes in your lab book, to record any data you collect. This might be reagent quantities, experimental yields, observations of a reaction, sketches of TLC plates, results of a titration, key spectroscopic data, or a table of measurements, or any number of other data. If something unexpected happens, you should record this, and it is good practice to make suggestions about why it happened. Essentially, any piece of information which is relevant to your experimental activities should be recorded. It is particularly important to record any situation where your actions deviated from the script, and the reason(s) for the change; remember that the lab book must be an accurate record of what you did.

In order to keep the relevant material together, it is good practice to leave some space in your lab book, to paste in any print-outs of experimental data, spectra etc. If you are collecting a significant amount of spectra, this may be impractical – in which case you should store the spectra in a separate folder. In this case, it is crucial that you can, at a later time, match up the spectra with the correct experiment, so you must label them appropriately. It is also good practice to record any details of electronic storage of data, e.g. filenames of spectra and which instrument they were recorded on etc. This data needs to be named in such a way that it can be easily identified: where filenames are not automatically generated, it is good practice to include the date & time, and your name, in any titles/filenames.

After the lab session, you will have a record of what you did in the lab, and any data that you collected. The experimental script may have questions for you to think about, or there may be further work required in order to process the data, perhaps to calculate a parameter or reach a conclusion. Your lab book is a sensible place to record this material, so that all of the information about the experiment (preparation, plans, what actually happened in the lab session, data, calculations, conclusions etc.) is in the same place. For some practical courses, you may be required to complete a report for submission and assessment; your lab book entries will be the main resource you rely on to complete this work.