1.1E: Cleaning Glassware

Glassware should be dismantled and cleaned as soon as possible. Experience with home dishwashing can tell you that dishes are more difficult to clean when allowed to dry. If there is a time constraint, it's best to leave glassware in a tub of soapy water.

To clean glassware, use the following procedures:

• Use 2-3 mL solvent to rinse residual organic compounds from the glassware into a waste beaker. The compounds should be highly soluble in the solvent. The default solvent is often acetone as it is inexpensive, relatively nontoxic, and dissolves most organic compounds. Some institutions reuse their acetone ("wash acetone") as the solvation ability is not spent after a few uses.

As it will soon become second-nature for most students to use acetone as part of their cleaning ritual, it is worth reminding that the purpose of acetone rinse is to dissolve organic residue in a flask. Not everything dissolves in acetone, for example ionic salts are insoluble in acetone and are more successfully rinsed out with water.
• After a preliminary rinse, glassware should then be washed with soap and water at the bench.

Residual acetone will likely evaporate from the flask, but it is acceptable for small quantities of residual acetone to be washed down the drain. Acetone is a normal biological byproduct of some metabolic processes,$$^1$$ and has low toxicity as it can be easily excreted by most organisms.

If using undiluted detergent from the store, it is best to use small amounts during washing as they tend to form thick foams that need lots of rinsing (Figure 1.10). Some institutions instead use dilute soap solutions at their cleaning stations for this reason. For cleaning of glassware, the biodegradable detergent "Alconox" is the industry standard.
• Rinse all glassware with a few mL of distilled water, then store wet glassware in a locker atop paper towels to evaporate by the next lab period.

$$^1$$R. Boyer, Concepts in Biochemistry, 2$$^\text{nd}$$ edition, 2002, Brooks-Cole, p. 565.