The authors provided a succint review of the current guidelines for impurities as highlighted by various regulatory agencies. The overall summary of the current guidelines and how to classify impurities provides a good starting point for researcher entering the field but it does not provide much in-depth knowledge on how these impurities are commonly detected and how this process could be optimized. The conclusions are very brief and are not well related to the rest of the review. Language revisions should be made accordingly - the sentence structure is at times hard to follow.

Pharmacist