If you've ever shopped for autosampler vials, you may have noticed that what looks like the same vial is sometimes labeled as 2mL, 1.8mL, or even 1.5mL. So, what’s the difference?

💡 It’s All About How the Vial Is Used

• A 2mL vial can physically hold about 2 milliliters of liquid when filled to the very top—right up to the rim.
• But in real-world use, especially with autosamplers, you shouldn’t fill it that full. Why? Because when the autosampler needle enters the vial to draw a sample, it displaces some of the liquid. If the vial is completely full, this can cause the liquid to spill or squirt out, especially if the vial is capped.

🧪 What Is “Nominal” Volume?

To avoid spills and ensure proper function, most labs only fill vials partially. That’s why you’ll often see the same vial described with a “nominal” volume—like 1.8mL or 1.5mL. This refers to the recommended usable volume, not the maximum capacity.

So:

• 2mL = Total capacity (filled to the brim)
• 1.8mL or 1.5mL = Usable volume (safe for autosampler use)

📸 Visual Comparison Available

The helpful images below show the different fill levels side by side, so you can see exactly what each volume looks like in the same vial.