When you're talking to a supplier or their rep, ask these questions directly. You're not being difficult—you're doing your job.

• Can you share the COA for this batch? If they hesitate, that's a problem.
• Is this salt or freebase nicotine? They should know without checking.
• What's the exact mg/mL strength? Not 'medium'—the number.
• How do you store these before shipping? Heat can degrade nicotine.
• What's your return policy for defective batches? You need to know before you buy.

Write down the answers. If they can't answer clearly, walk away.