Certified Vials – Every Vial is Autosampler Compatible

Reporter US Volume 27.2

There is a vast difference between each manufacturer’s specifications for 12 x 32 mm autosampler vial bottom thickness and vial thread finish. For your autosampler vial to function correctly, both of these dimensions must be manufactured to very precise specifications.

The thickness of the glass on the bottom of the vial affects the distance that the autosampler needle can penetrate without making contact with the bottom of the vial. It is important for the needle to be set at the optimum depth to work properly. Ideally, the needle should withdraw the correct volume of sample without hitting the bottom of the vial.

The needle depth of the autosampler is determined by measuring an initial vial and deciding how deep the needle will go. This value becomes difficult to determine correctly when the bottom thickness varies from vial to vial. Although the standard bottom thickness of 12 x 32 mm vials is 0.8 mm, it can vary in a package of vials by as much as +/- 0.4 mm (0.15”).

Two things can happen if the bottom thickness specification varies. The autosampler needle may bend if it makes contact with the bottom of the vial. Secondly, if the technician sets the needle at a higher level to avoid hitting the bottom, much of the valuable sample will remain.

Neither outcome is acceptable in the laboratory. Consistency in analysis requires vials with consistent bottom thickness dimension in every vial. Our certified vials provide this feature. The thickness of the glass is carefully monitored to provide vials that have the same thickness every time.

Another key specification that causes problems for the lab technician is the thread finish of the vial. The interior of the cap thread must align perfectly with the exterior thread of the vial to provide a good seal. Any difference in these specifications will lead to sample evaporation and/ or leakage when the parts are used together.

Purchasing products from different sources is often done to be economical, but in many instances the products ordered will not fit together properly. We recommend that you purchase these components from the same supplier to ensure that the parts are compatible. Our glass vials are checked carefully to make sure they work with the caps for which they are intended.

Our certified vials are manufactured to the strictest specifications possible. Each lot of vials is examined to ensure that there are no inconsistencies in bottom thickness and vial thread as well as height and diameter.

Certified vials are offered in a variety of styles that include 9 mm thread, crimp top, and snap top vials. For assistance in selecting the correct vial for your autosampler, visit sigma-aldrich.com/vials

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