Chromatography Facts & TipsA necessary first step for reliable chromatography sample analysis is choosing the correct vial and compatible closure components. With proper equipment and analytic procedures, this ensures that the results from your sample analyses are as accurate as possible. Here are a few tips for choosing the best vial for your chromatography needs. |
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Vial MaterialsBorosilicate Glass vials are the preferred choice for gas chromatography and liquid chromatography (GC/LC). These vials are generally free of potential contaminants that may interfere with analysis of the sample. Borosilicate glass is made by adding boron trioxide to silica for extreme heat resistance with a very low expansion coefficient, withstanding temperatures in excess of 500 degrees Celsius. Being made of glass, these vials are breakable, although breakage issues are uncommon. Vial TypesVials come in various sizes and finishes. The most common sizes for liquid injections are 12x32mm and 15x45mm vials. Depending upon the vial manufacturer, a 12x32mm vial may also be referred to as a 1.5mL vial, a 1.8mL vial, or a 2.0mL vial. Vials can have a standard opening (5mm) or wide-mouth opening (6mm) depending upon the cap type to be chosen. Always choose a vial that is appropriate for the specific instrument in use. For example, 11mm crimp and 9mm screw-cap vials will work with an Agilent® autosampler, but 11mm and 8mm screw caps will not. This is because the space between the cap and the shoulder of the vial needed for the autosampler to operate properly differs by instrument. Consult equipment specifications and manuals to determine the correct vial to use. ColorBoth glass and plastic vials can be either clear or amber in color. Amber vials offer protection for samples that could be degraded or affected by exposure to ultraviolet light. Clear vials are recommended if observation of the sample is necessary. Amber glass vials are made from 51 expansion glass, which can be heated at higher temperatures during the manufacturing process (1,200°C) while clear glass vials are made from 33 expansion glass (heated at 1,000°C during manufacturing). Vial Closure ComponentsThe vial closure components are the cap and the cap liner. Caps are either aluminum (for crimp seals) or plastic (polyethylene, polypropylene, or a phenolic resin), for screw caps or snap caps. Limited Volume InsertsSometimes samples to be examined can be rather small or scarce, necessitating the use of Limited Volume Vial Inserts to make the most of limited sample quantity. Vial inserts come in a variety of shapes and sizes. A conical insert with a plastic spring on the bottom is preferred because the spring assures a seal with the vial cap liner. In addition, it will accommodate the autosampler syringe needle and will automatically adjust to different sampling depths. Reliable QualityThere are many vendors offering chromatography vials and closures, however quality standards are not consistent across the market. By selecting a proven brand, such as Qromix™ Chromatography by QEC, you can be assured of consistent American-made quality, as well as vials and closures that are designed to work together for maximum efficiency and protection of your sample integrity. |
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