When you're reviewing supplier quotes and samples, treat nicotine strength like a flight check—verify everything before you board. Here's a practical checklist:

• Request a COA for each batch. This is the lab report that shows the actual nicotine concentration. Don't accept a generic COA that could apply to any batch; ask for one specific to your order.
• Ask about batch-to-batch consistency. Some manufacturers have tighter quality control than others. Ask what their tolerance is—typically ±5% is acceptable, but you want to know before you sign.
• For disposables, ask for the total nicotine content per device. A 50 mg/mL strength in a 2 mL device means 100 mg of nicotine total. If the device holds 5 mL, that's 250 mg. Make sure the label is clear so customers know what they're getting.
• Test the product yourself if possible. You can buy a nicotine test kit online, but they're not as accurate as a lab. If the order is large, consider sending a sample to an independent lab for a second opinion.
• Check the label formatting. Some markets require the strength to be printed in a certain way (e.g., mg/mL and percentage). Make sure your product's label complies before you mass-produce.