Compared to many sophisticated analytical instruments in the laboratory, vials may be small, but their proper selection and usage play a crucial role in experiment efficiency, processes, and data accuracy. Incorrect choices of vials can lead to various issues, including poor sealing causing analyte volatilization, chromatographic peaks due to solvent-septa interaction, damage to automatic samplers, poor injection repeatability, sample degradation, and sample adsorption. Therefore, when selecting the right vials for your application, you must carefully consider three key factors: septa, caps, and the vial itself.

Septa Selection:

1. PTFE:

   • Recommended for single injections.
   • Excellent solvent resistance and chemical compatibility.
   • Does not reseal after piercing.
   • Not suitable for long-term sample storage.

2. PTFE/Silicone:

   • Recommended for multiple injections and sample storage.
   • Exhibits excellent resealing properties.
   • Prior to piercing, has chemical resistance of PTFE, post-piercing exhibits chemical compatibility of silicone.
   • Operating temperature range: -40 ℃ to 200 ℃.

3. PTFE/Silicone Pre-slit:

   • Provides excellent ventilation to prevent vacuum formation in the vial, ensuring outstanding sampling reproducibility.
   • Eliminates needle clogging at the bottom after sampling.
   • Good resealing capability.
   • Recommended for multiple injections.
   • Operating temperature range: -40 ℃ to 200 ℃.

4. Non-sealed PE (Polyethylene):

   • Possesses similar advantages as PTFE.

Cap Selection:

1. Screw Cap:

   • Excellent sealing without the need for any tools.

2. Crimp Cap:

   • Aluminum crimp cap provides excellent sealing, reducing the risk of sample volatilization.
   • More heat-resistant in high-temperature experimental environments.
   • Requires a crimping tool for application.

3. Snap Cap:

   • Sealing effectiveness is inferior to screw caps and crimp caps.
   • Press-on snap caps are suitable for storing powdered samples and are not ideal for transporting liquids.
   • Tight-fitting caps may be challenging to place and could potentially break.

4. One-piece Cap/Septum:

   • Ensures that the septum and cap stay together during transport and when the cap is applied to the vial.
   • Prevents the septum from falling off during use.
   • Mitigates excessive evaporation, maintaining proper vial sealing.

Vial Material Selection:

1. Type I, 33-Expansion Borosilicate Glass:

   • Exhibits high chemical inertness and is commonly used in analytical laboratories for high-quality experimental results.

2. Type I, 51-Expansion Glass:

   • More alkaline than 33-expansion glass and suitable for various laboratory purposes.

3. Deactivated Glass (DV):

   • Ideal for analytes strongly polar and prone to binding to the polar glass surface.
   • Surface treated with organosilane for hydrophobicity.
   • Can be stored indefinitely under dry conditions.

4. Polypropylene (PP):

   • Non-reactive plastic suitable for situations where glass is not preferred.
   • Maintains good sealing even when exposed to flames during sealing.
   • Maximum use temperature: 135 ℃.

By considering these factors, you can make informed choices in selecting chromatography vial accessories, ensuring the success of your experiments with enhanced safety and accuracy.