Investigating salicylic acid impurity alongside aspirin storage history

Set up the comparison

Retain sealed and in-use aspirin from the same lot. Record storage, opening and sample preparation times, then compare related substances using the applicable method.

Measurements to record

Principal component assay (% on a dry basis). Provide the batch assay and conversion basis. Limits from a different edition may differ. Free salicylic acid (%). Record the method and sample preparation time, then compare with the retained sample from the same lot. Record the sample ID and method revision for repeat testing.

Interpreting the results

Check seals, transport and sampling history and test the unopened control. Record deviations under the quality agreement rather than judging the lot by odour alone.

What to record

• Batch
• Seal
• Time opened
• Related substances method
• Retained sample result

Technical references

• USP: aspirin raw material monograph and salicylic acid reference standards ↗

Products and processes