Guide to Selection of Sample Vials Septa and Cap

Although the sample vial is small, it is very learned. When something goes wrong with our results, the vial is always the last thing we think about, but it’s the first step. When choosing the right vial for your application, you need to make three decisions: the septa, the lid, and the vial itself.

1. Guide to the selection of septa
Recommended for a single injection. Excellent solvent resistance and chemical compatibility. No resealing after a puncture. Long-term sample storage is not recommended.

PTFE/silica gel
It is recommended for multiple injections and sample storage. Excellent reseal properties. Chemical resistance of PTFE before puncture, and chemical compatibility of silica gel after the puncture. The operating temperature ranges from -40°C to 200°C.

Precut PTFE/ silicone
Excellent sampling reproducibility is achieved by providing good ventilation to prevent a vacuum from forming in the sample vial. Eliminate the blockage of the needle at the bottom of the sample. Good resealing ability. It is recommended for multiple injections. The operating temperature ranges from -40 ℃ to 200 ℃. No isolation pad PE. It has the same advantages as PTFE.

2. Vial cap selection Guide
There are three types of the cap for sample vials: crimp top cap, snap cap, and screw thread top cap. Each sealing method has its own advantages.

Pliers flap
The sealing effect is very good and can prevent the sample from evaporating effectively. The position of the septa shall remain unchanged when the automatic sampler is pricking through sampling. The capping device is needed to seal the sample vial with a clamp cap. For a small number of samples, a manual gland is the best choice. For large samples, an automatic gland can be used.
Septa and Cap for Snap Vials
Bayonet cover
The bayonet cover is an extension of the clamp cover seal. The plastic cover on the edge of the sample vial creates a seal by squeezing the septa between the glass and the extended plastic cover. The tension of the plastic cap is caused by its attempt to regain its original size. This tension creates a seal between the glass, the vial cap, and the septa.

The plastic bayonet lid can be closed without any tools. The sealing effect of the bayonet cover is not as good as the other two sealing methods. If the cap fits very tightly, it can be difficult to put on and may break. If it is too loose, the sealing effect will be poor and the septum may leave the original position.

Screw cap
The screw cap is universal. Tightening the cap exerts a mechanical force that squeezes the septa between the glass vial edge and the aluminum cap. In the process of puncture sampling, the screw cap has an excellent sealing effect and supports the septa by mechanical means.No tools are needed for assembly. The PTFE/ silica gel septa of the screw cap are fixed to the polypropylene vial cap by a non-solvent bonding process. The bonding technology is designed to ensure that the septa stay with the cap during transportation and when the cap is placed on the sample vial.

This bonding helps prevent the septa from falling off during use, but the main sealing mechanism is still the mechanical force applied when the cap is tightly wound onto the sample vial. The mechanism of vial cap tightening is to form a seal and to keep the septa in the correct position during the insertion of the sampling needle. Do not screw the cap too tightly, as this will affect the seal and cause the septum to fall off and translocate. If the cap is rolled too tightly, the septa can become cupped or dented.

A small sample vial has so much exquisite knowledge, so is it clearer?
With the wide application of chromatography in detection, a large number of chromatographic sample vials need to be cleaned in the detection process, which not only wastes time and reduces working efficiency, but also results in deviation of experimental results due to the fact that the cleanness of chromatographic sample vials after cleaning does not meet the requirements. Therefore, choosing the right way to clean the sample vial is crucial!

Screw Thread Top Sample Vials

Plan 1
1. Pour dry the sample solution into the vial.
2. Soak all 95% alcohol, rinse twice with ultrasonic, and pour dry, because alcohol can easily enter into 1.5mL vials and can be inter dissolved with most organic solvents to achieve.
3. Pour in water and wash with ultrasonic twice.
4. Dry the lotion in the vial and bake it at 110 degrees Celsius for 1 to 2 hours. Never bake it at high temperatures.
5. Cool and store.

Plan 2
1. Rinse under running water several times.
2. Put it into a beaker filled with pure water and ultrasonic for 15 minutes.
3. Change the water and ultrasonic for another 15 minutes.
4. Soak in a beaker filled with or without water-ethanol.
5. Take out and air dry naturally.

Plan 3
1. Soak in methanol (pure by chromatography) for 20 minutes with ultrasonic cleaning, and then pour the methanol dry.
2. Then fill the chromatographic sample vial with water, ultrasonic cleaning for 20 minutes, and then pour the water dry.
3. After that, the chromatographic sample vial is dried.

Plan 4
1. Generally is the first rinse with clean water after drying with sulfuric acid dichromate potassium lotion immersion.
2. First, use medical alcohol to soak for more than 4 hours, then ultrasonic for half an hour, then pour out medical alcohol, use water ultrasonic for half an hour, rinse with water, and then dry.

Plan 5
1. If the cost is sufficient, it is best to use a new one every time.
2. If it is to be reused, the cleaning method is also very important. Firstly, soak in a strong oxidizing cleaning solution (potassium dichromate) for 24 hours, then clean it three times with deionized water under ultrasonic conditions, and finally clean it once with methanol and then dry it.
3. The vial pad must be replaced with a new one, especially when analyzing pesticide residues, otherwise the quantitative results will be affected.