Dec. 3rd, 2019
For many users of chromatography vials, vials are only temporary containers for holding samples until they can be analyzed by gas chromatography (GC) or liquid chromatography (LC). However, choosing the correct vial and using it properly can greatly help ensure that the results of the sample analysis are as accurate as possible. Here are some tips for choosing the best vial for your chromatography needs.
Identify Vial Types
Many types of vials are available and it is important to be able to distinguish them according to their size and closure. The chromatography vials are available in different sizes, the most common for liquid injections being the 12 x 32 mm and 15 x 45 mm vials. Depending on the manufacturer of the vials, a 12 x 32 mm vials can also be referred to as a 1.5 mL bottle, a 1.8 mL bottle or a 2.0 mL bottle.
The vials also have different closures, including crimp/pressure or screw closures. Screw caps also come in different sizes identified by the outer diameter of the mouthpiece of the bottle. The screw caps used on chromatography bottles measure 8 mm, 9 mm or 10 mm, the most common size being 9 mm.
Select the right bottle
If you use an automatic sampler, be sure to choose a bottle designed to work with your specific instrument brand. For example, 11mm and 9mm crimping vials with screw caps will work with an Agilent automatic sampler, but the 10 mm and 8mm screw caps will not work. Indeed, the space between the cap and the shoulder of the bottle necessary for the proper functioning of the automatic sampler varies from one instrument to another.
In addition to the instrument requirements, you should also consider the effects of the colour and material of the bottle on your sample. If your sample is sensitive to light, use amber vials. If you need to visualize a color change (for example, for a Quecher cleaning), a clear bottle is the best choice. Finally, if your analysis involves an IC or ion chromatography, avoid glass vials and vial inserts and choose a polymer material bottle to prevent the ions from escaping from the glass.
Choose the right closure
The vial closure consists of a cap and a cap lining. The cap typically consists of either aluminum for crimp seals or plastic (polyethylene, polypropylene or phenolic resin) for non-crimp seals. The cap is the septum material that is pierced by the syringe needle to remove the sample from the vial. Cap-Liner sits in different configurations and also from different materials. Cap linings are typically made of rubber (natural or synthetic) or silicone.
They can also be coated with PTFE on one or both sides. Make sure you are using a closure compatible with your solvent. In most cases, bottle caps lined with PTFE on the side facing the sample are the best option.
Vial Cap Liners can also be pre-split, either as a single gap, cross gap or starburst. Pre-slitting of the vial closure facilitates the penetration of the needle, especially with the larger needles normally used in LC autosamplers. After selecting the vial closure, it is recommended to secure the closure with crimping pliers and remove it. These useful tools are designed specifically for each task and greatly simplify closing and unsealing. Crimper and Decapper are available in both electronic and manual versions.
Store valuable samples
If you have a limited sample quantity, consider using inserts for your chromatography vials. Bottle inserts are available in different shapes and sizes. A conical insert with a plastic spring on the floor is preferred, since the spring ensures a sealing with the vial cap lining. In addition, it picks up the needle of the autosampler syringe and automatically adjusts to different sample depths. Inserts usually have an outer diameter of 5 or 6 mm. Therefore, choose a vial size that can accommodate the insert.
Vials with an outer diameter of 11 mm, 10 mm or 9 mm fit both sizes. However, vials with an outer diameter of 8 mm can only be used for inserts with an outer diameter of 5 mm. Another option is to use vials into which the inserts have already melted. Due to this convenience, the vials and inserts no longer need to be assembled before use.
Aijiren carriers a full line of vials for chromatography as well as related supplies, such as crimpers and decappers. Visit www.hplcvials.com to find the right vial for your chromatographic application.