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Key points the analyst must know

Reagents are substances used in methods to cause a change or to observe a change (e.g. an indicator used in determining the end point of a titration). In general, the concentration of reagents does not need to be known as accurately as for standard solutions, so they can normally be prepared using laboratory equipment such as measuring cylinders and top pan balances.

The analyst should know the following:

• how to prepare a reagent solution quickly but with the required accuracy;
• how to plan the preparation of reagents of suitable concentrations involving a minimum of dilution steps and with satisfactory uncertainty for the task in hand;
• the relative merits (e.g. measurement uncertainties) of using syringes, pipettes, burettes, measuring cylinders, volumetric flasks, beakers and different types of balances when preparing reagent solution
• whether to use class A or class B glassware;
• whether to use a pipette or measuring cylinder, etc., to prepare dilutions;
• how to prepare reagents which require specialist skills such as handling hazardous materials in controlled environments;
• the appropriate type of vessel to store the reagent, e.g. amber glass bottle;
• common mistakes made by trainee analysts, e.g. not mixing the prepared reagent before use.