When a chemist or anyone in the medical field needs a container for samples or specimens, a vial is the first thing they think of. Despite their size, vials play a big role in the organization and testing of samples across fields, from the medical industry to more niche uses, like in crime scene investigation. We’re here to share information on vials that will give you a greater appreciation for this small but mighty tool.

Depending on your specific applications, you have several vials and vial caps to choose from. Your storage and handling specifications will determine the vial you need to acquire, whether you’re in the medical industry, a law enforcement agency, or with another industry altogether.

Finding the perfect vial for your application can feel like a daunting challenge, but we’re here to help. Read on to learn the role vials have in the medical industry and discover the materials and types of vials available to you.

Vial Materials

When you picture a vial, you probably picture a glass vial. While it’s true that glass vials are the most common in the medical industry, there are other materials that you should know about, too.

Glass

Glass is the ubiquitous material for vials. The use of glass dates back many centuries, and the benefits of this material are well-known. Whether you need to store liquid or dry pharmaceutical products, glass is a fantastic option. With a robust, thick glass vial, you can rest assured that the medicine within will remain safe and secure from the external environment.

People often store high-value liquids in glass, whether the liquids are dangerous or incredibly useful. The two main types of glass used in vials are soda-lime glass and borosilicate glass. Soda-lime glass is inexpensive and quite common throughout the medical field, and the United States Pharmacopeia classifies it as Type II and Type III.

Borosilicate glass, on the other hand, is a more “premium” Type 1 glass. This quality difference is due to the inclusion of a minimum of 5 percent boric oxide. Boric oxide increases a vial’s resistance to high and low temperatures while also increasing resistance to water. These factors make borosilicate glass the go-to option for use in laboratories.

Glass Vial Benefits

There are several reasons to choose a glass vial over one of the other materials, the first of which is clarity. A smooth and clear surface makes it easy to identify and inspect the contents of a vial so that you can spot degradation or contamination of the solution.

Additionally, there are very few substances that react with borosilicate glass, meaning that the container protects your samples from alterations. The nonporous surface of glass reduces the chance of contamination or evaporation, while other materials could lead to substances entering and remaining within the pores of their container.

Finally, glass is a sustainable material manufactured from raw materials we have a lot of—namely sand. You don’t need to worry about environmental impact when you use glass vials.

Silicone

Not all glass vials are exclusively glass. Some go through a siliconization process that adds a layer of silicone, creating a protective layer over the glass. This process can increase transparency while also preventing fluids with high viscosity from sticking to the vial.

Plastic

Plastic vials have a host of benefits and applications all their own. Professionals store and test crime scene evidence and chemical substances in plastic vials. Additionally, materials such as hydrofluoric acid require a plastic container for storage due to their unique chemical properties.

While there are dozens of plastic materials on the market, manufacturers usually produce vials using polyethylene or polypropylene. Polyethylene has excellent impact resistance (unlike glass) and high flexibility. Polypropylene shares these qualities but can also boast resistance to extreme temperatures.

Plastic Vial Benefits

Plastic vials are highly resistant to a wide variety of chemicals, from acids to bases to alcohols. While this is also true of glass, plastic vials are shatter-proof, which is an advantage in certain laboratories.

Additionally, plastic is notably lighter than glass, which allows you to transport plastic vials more efficiently and affordably.

Types of Vials

While materials can vary slightly, the applications and designs of vials vary drastically depending on your intended application.

Cryogenic

As the name suggests, cryogenic vials must withstand extremely cold temperatures, sometimes below negative 200 degrees Celsius. For this to work, you need a vial made of a special type of polypropylene—glass is not an option.

Autosampler

Autosampler vials function in tandem with an autosampler machine, which loads samples for examination. Because autosampler machines all differ, you need to ensure that the vials you have are compatible with your autosampler—otherwise, you risk damage to the machine or your vials.

Sample

Sample vials are perhaps the most well-known vials, as they work for the routine collection, transportation, and storage of a variety of samples. You can store anything from essential oils to DNA evidence from a crime scene in a sample vial. The sample vial you choose can vary in size and material composition, allowing you to find the ideal vial for the specific application.

Filter

Filter vials are useful when you need to remove particulates from the material in your vial. These vials include a plunger with a filter on one end and a cap on the other. The plunger pushes your sample liquid through the filter and separates any solid material from the rest—like a tea strainer.

Open-Top

Open-top vials have a screw cap made of inert polypropylene—like a plastic finishing plug, but with a hole in the center. This hole has a layer called a septum (made of polytetrafluoroethylene or silicone) that forms an airtight seal. The needle of an autosampler can quickly and easily pierce this septum to access the material within.

Now that you know the role vials have in the medical industry and the types available, you can opt for the combination that suits you. With so many specialized vials to choose from, you’re sure to find one that fits your exact specifications.