For chemical experiments, all results are typically stage-dependent, which involves issues of sample storage and sampling, as well as how to choose appropriate HPLC Vials based on the characteristics of the samples themselves to minimize experimental errors and save costs.
Sample Vials include HPLC vials, headspace vials, storage vials, TOC vials, etc. This time, we mainly introduce the selection method of injection vials.
01 SEALING METHODS FOR SAMPLE VIALS
Screw thread Cap: a sealing method that provides low evaporation, can be reused, causes less harm to hands compared to crimp seals, and has good sealing performance without the need for additional tools. It is currently the most widely used product on the market and saves experimental time.
Snap cap: When properly tightened, it provides good sealing and can be used for long-term storage to provide optimal sealing. Snap-on caps are not reusable and require a capper for sealing.
Crimp cap: When using a crimp cap, no tools are required, but its sealing performance is not as good as that of snap-on and screw cap vials.
02 COLORS OF SAMPLE VIALS
There are two colors: clear and amber. The color of the vials is determined by whether the chemical composition needs to be protected from light.
At Welch Materials, we use high-quality raw materials to produce HPLC vials, both amber and clear vials have excellent product quality. We can also provide HPLC vials made of PP material, which is a suitable choice if your sample reacts with silica.
03 CAP & SEPTA FOR SAMPLE VIALS
The closure of the Vials is divided into two parts: Cap and Septa, which are often used together.
Cap: It is mainly divided into solid cap and open top cap. Solid cap is mainly used for storage vials, while perforated lid is used for other types of HPLC vials, such as headspace vials, TOC vials, etc.
Non-slit septa: The most commonly used type of septa, but requires more force when inserting the needle, and sometimes produces debris or septa falling into the sample, affecting sample injection.
Pre-slit septa: These septa are easier to puncture with the syringe needle compared to the solid ones, and are less likely to produce debris or drop fragments into the sample, thus reducing the risk of contamination. However, they may lead to increased evaporation of the sample over time.
Double-layer film septa: provides a more stable physical structure compared to regular septa (double-layer film septa consists of two layers of PTFE sandwiching a layer of silicone, while regular septa consist of one layer of PTFE and one layer of silicone).
Bonded septa: The septa is connected to the cap as one piece, which can prevent the septa from falling off during use.
Sometimes we have very few samples, and in these cases, we need to use an insert.
Insert with with Polyspring: The stand can fix the insert in the center position of the sample vial, ensuring the smooth insertion of the needle. Additionally, the bottom of this type of insert has a smaller capacity, and its liquid level height is also the highest.Conical Insert: Compared to the Insert with with Polyspring, the liquid level of the conical insert is lower, but it is a more economical option due to its lower cost.
Flat Base Insert: It has a relatively large dead volume at the bottom, which results in the lowest possible sample liquid level in the insert. At the same time, its cost is also the lowest.
If you find using an insert tube to be inconvenient, you can also choose HPLC vials with welded insert tubes. The inside of the vial has a structure similar to a conical insert tube, while the outside has a normal 9mm vial structure that can use the same cap as most HPLC vials.