When sourcing NAC, you must ensure the product complies with international pharmacopoeia standards such as USP (United States Pharmacopeia), EP (European Pharmacopoeia), or BP (British Pharmacopoeia). Key certifications to verify include GMP (Good Manufacturing Practice), ISO 22000, and HACCP for food-grade applications. If the product is intended for specific dietary markets, request Halal and Kosher certifications. Always ask for a Certificate of Analysis (COA) for every batch to verify purity levels, which should typically be ≥99%.