Sep. 11th, 2023
Sample preparation is a crucial step in many analytical and scientific processes, and selecting an appropriate vial for sample storage can have a major effect on its quality and accuracy. Vials are small containers designed to store samples safely; selecting an ideal vial ensures sample integrity as well as reliable analyses. In this article we'll give an overview of selecting vials for sample preparation purposes, discussing key factors when making this choice.
1. Vial Materials
The primary factor to keep in mind when selecting a vial is its composition; usually made of either glass or various types of plastics, each type offers distinct advantages and disadvantages.
Glass Vials: These inert and chemical-resistant vials make for ideal containers to store volatile and reactive samples, including volatile solvents and reactive materials. Their transparency allows easy visual inspection as well as optical detection methods.
Glass vials come in different varieties, such as borosilicate or clear glass, depending on your individual requirements.
Curious about the advantages of glass chromatography vials over plastic ones? Find out in this informative article! Top 3 Reasons Why Glass Chromatography Vials are Better Than Plastic Vials
Plastic Vials:Plastic vials offer lightweight convenience without risk of breakage for some applications, making them safer options in certain instances.
Plastic vials come in various plastic materials, such as polypropylene (PP), polyethylene (PE) and polytetrafluoroethylene (PTFE), each offering specific chemical compatibility characteristics.
They may be preferable when working with samples containing acids or bases.
Curious about the advantages of plastic chromatography vials? Explore our comprehensive article for all the insights you need:4 Benefits of Using Plastic Chromatography Vials
2. Vial Size and Volume
To meet sample volume and analytical method specifications, vial sizes should correspond with sample volumes as well as be compatible with analytical methodology requirements. Among many factors that need to be taken into consideration for selecting an ideal vial are:
Sample Volume: Select a vial capable of accommodating the full volume of your sample without overfilling or underfilling; overfilling may lead to contamination and result in inconsistent analysis, while underfilling can impair its precision.
Analytical Technique: Different analytical techniques may require different vial sizes. For instance, gas chromatography (GC) typically utilizes smaller vials while liquid chromatography (LC) requires larger ones - so be sure to consult your method's instructions beforehand.
3. Closure Type
Vial closures come in various forms, such as screw caps, crimp caps, snap caps and septa. Your choice should meet the specific needs of your application:
Screw Caps: Screw caps provide a secure, leakproof seal suitable for long-term storage and preventing the loss of volatile samples due to evaporation.
Crimp Caps: Crimp caps require special tools to secure them securely onto vials and ensure a tight and tamper-evident seal, often found in gas chromatography applications.
Snap Caps: Snap caps provide an efficient means of sealing vials without the use of tools, making them popularly utilized in HPLC applications.
Septa: Septa are commonly used with screw caps and crimp caps to create an airtight but penetrable closure for applications that require sample injection via syringe.
Interested in choosing between Crimp Vial, Snap Vial, and Screw Cap Vial? Dive into this article for expert guidance:Crimp Vial vs. Snap Vial vs. Screw Cap Vial, How to Choose?
4. Specialized Vials
Securing your application may necessitate special vials designed for specific sample types or analytical techniques, including vials that accommodate unconventional sample forms or techniques. A few examples include:
Headspace Vials: These vials have been specially designed to facilitate gas chromatographic analyses of volatile compounds by collecting samples from the headspace above liquid or solid samples and analyzing their volatile components.
Microvials: Microvials are miniature vials used when sample volumes are extremely limited - typically in the microliter range - making them popular choices in mass spectrometry and other highly sensitive analytical processes.
CryoVials: These vials are specially-made to store samples at extremely low temperatures - such as for cryogenic applications - for long-term storage purposes.
5. Compatibility between Sample and Analysis
To ensure proper sampling results and analyses, it is crucial that both the material and closure type chosen match your sample as well as your analytical method of choice. Factors like pH levels, temperature variations and chemical reactivity should all be taken into account to prevent contamination or degradation of samples.
6. Sample Containment and Preservation
Ensuring that your sample remains undamaged is of paramount importance. When choosing a vial for its protection, keep these things in mind:
Airtight Sealing: To prevent contamination or sample degradation, ensure the vial and closure provide an airtight seal against its environment. For volatile or sensitive compounds, this is of particular significance.
Amber or Colored Vials: For samples that are light sensitive, amber or colored vials could provide additional protection from photodegradation.
Inserts: When working with small sample volumes or autosamplers, inserts can help minimize exposure of sample surfaces to atmospheric conditions and thus decrease risks such as evaporation or contamination.
7. Vial Cleanliness
Contaminants can have an adverse impact on your results, here are some strategies for maintaining vial cleanliness:
Pre-Cleaned Vials: Certain applications require vials that have been certified to be free from particulates or trace contaminants, particularly for trace-level analyses. This is especially essential when working at low concentrations of particulate matter.
Washing and Drying: If you plan on reusing vials, be sure to ensure they have been carefully washed, rinsed, and dried to reduce cross-contamination risk.
Quality Septum: For vials using septa, ensure it meets your sample type to avoid septum-related contamination and ensure compatibility.
8. Sample Access I/II
This factor refers to how easily you can gain access to the sample in its vial:
Screw Vials Vs Snap Vials: Screw vials provide more secure seals but may take more time and effort to open and close than snap vials, which offer quicker opening/closing action.
Easy Sample Retrieval: Make sure that the vial design allows for straightforward sample retrieval if you plan on performing multiple injections or transfers.
9. Vials With Specialized Coatings or Treatments
Some vials offer enhanced performance by including special coatings or treatments to increase performance:
Silanized Vials: Silanization involves treating the inner surface of a vial with a silane compound to decrease sample adsorption to its walls, making this technique particularly suitable for trace analysis where sample loss may be an issue.
Low-Binding Vials: Low-binding vials are designed to minimize interactions between samples and surfaces in vials, thus minimizing analyte loss risks.
10.Consider Environmental Considerations
Being environmentally responsible is becoming ever more essential, so be sure to assess how your vial selection could have an effect on our planet.
Recyclability: Plastic vials tend to be easier for recycling than glass vials, so check your local recycling guidelines when selecting vials.
Reusable Vials: Certain vials are designed for multiple uses, reducing waste. Be sure to clean and sterilize them between uses in order to extend their shelf life.
11. Cost and Budget
Laboratories often face financial constraints that force them to strike a delicate balance between quality and cost-effectiveness; sometimes higher-grade vials may yield savings by preventing sample loss or subsequent reanalysis costs in the future.
Vial selection is a critical step in sample preparation and requires careful consideration of many factors, including material, size, closure type and compatibility with analytical methods used. By carefully considering all these considerations in relation to your specific application and analytical method you can ensure an efficient, reliable process with accurate results. Always consult colleagues, experts or suppliers should any doubts or special requirements arise with regard to sample preparation vials.
5 Points Need to Consider When Choosing An Autosampler Vial,please check this article.
Get comprehensive insights into HPLC vials with answers to the top 50 FAQs in this informative article: 50 Most Frequently Asked Questions on HPLC Vials