The key thing with lab book usage is to record everything you are doing, at the point you do it. It's really easy to end up forgetting whether you did or didn't do something, so try to get into good habits where you record things immediately.

Typical things to ensure are recorded during laboratory work:

• The precise regent quantities taken (masses, volumes etc)

• Reaction observations (appearance, colour changes, efferescence etc)

• Sketches and measurements for TLC plates

• Crude and purified yields

• Details of any instrumentation measurements (values, filenames)

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 what you had planned (eg the details in the script), and the reason(s) for the change. The key thing is that your lab book must be an accurate record of what you did.

The precise style used to record your lab work is unimportant, and if you look at lab books kept by different chemists they are likely to be quite different. The style you use is likely to evolve over time, and it is helpful to view lab books from other scientists and encounter the different approaches people might have. Try to periodically reflect on your lab book entries and consider if the information recorded is sufficient for you to be able to reproduce the work you carried out.

One very effective way to use a lab book is to record the time you do something and listing what you did. This simple approach allows you to later calculate how long you spent doing a particular step of a reaction. For instance you might record:

• 0930 Hotplate set to 120 °C and begun heating reaction. Reaction mixture is a colourless clear solution.

• 0937 Reaction has reached reflux. Rection remains clear, and is becoming yellow in colour.

• 1007 Heating turned off and lab jack lowered. Solution is a bright yellow clear solution.

• 1030 Reaction has cooled to room temperature. Yellow precipitate formed.

From these timestamps, it is then easy to calculate the amount of time for various steps, such as that the reaction was refluxed for 30 minutes.

Whilst recording what you have been doing in the lab, you should also record any observations of changes or lack of changes. These could include notes on:

• Colour changes

• Exotherms or endotherms

• Evolution of gas

• Any other observations

The absence of any observable changes is also useful information to record. If you don't record that no change was observed, you may be unable to recall later whether there was any change observed or not.

When collecting data, you should record details of the data collection, such as information on:

• The instrument used

• The filename(s) of any data recorded

• Any submission numbers for samples submitted to a service

• Details for any methods used or parameters which were set

Students often ask about the relationship between lab books and lab scripts, and why a lab book needs to include steps when the lab script is jut being followed. The easiest way to consider the purpose of each is:

• The lab script is providing details of the work you should be intending to do

• Whereas the lab book records what you actually did

The use of a lab book providing a real time record of what you did becomes particularly helpful when things don't go to plan. Going back through lab book records can help to identify why something didn't work. It's not uncommon for people to think they have followed instructions in a script, but for subtle differences to arise when lab books are examined in more detail.