In high performance liquid chromatography (HPLC), the quality and performance of your autosampler vials can have a significant impact on the reliability and reproducibility of your analytical results. Selecting the right vials is a critical but often overlooked part of optimising an HPLC workflow.
So how can you evaluate and ensure the quality of the HPLC autosampler vials you’re using? Here are some of the key factors to consider:
The material used to manufacture the vials is a critical factor in their suitability for your HPLC application. The most common vial materials are glass and plastic.
Glass vials are favoured for their excellent chemical compatibility and inertness, making them a good choice for a wide range of sample types. However, glass vials can be more fragile and prone to breakage than plastic vials.
Plastic vials, on the other hand, tend to be more durable and shatter resistant. However, they have limited compatibility with certain aggressive solvents and samples. Common plastic materials used for HPLC vials include polypropylene (PP) and polyethylene terephthalate (PET).
When evaluating vial materials, consider the chemical properties of your samples and mobile phases to ensure compatibility and prevent analyte adsorption or leaching.
The physical dimensions of HPLC vials must be accurately matched to your autosampler to ensure proper fit and sample introduction. Key dimensions to check include:
Vial height: Ensure that the vial fits snugly into the autosampler tray.
Neck diameter: The vial neck must form a tight seal with the autosampler septum.
Base shape: The base of the vial should be designed to minimise dead volume.
Vials that are even slightly out of specification can cause problems such as leaks, carryover and poor injection precision. Always check dimensional compatibility with your HPLC system.
The internal and external surface quality of HPLC vials can affect analytical performance. Look for vials with a uniform, scratch-free surface to prevent sample adsorption or carryover.
Some vials may also have special surface treatments, such as silanisation, to improve inertness and minimise analyte interactions. Evaluate whether these special coatings are required for your application.
The caps and septa used to seal HPLC vials play a critical role in preventing evaporation, contamination and leakage. Evaluate the quality and durability of vial closures to ensure they provide a tight, consistent seal.
Look for features such as compatible sealing materials, easy-to-pierce septa and tamper-evident closures. It is also recommended to test closure integrity under expected conditions of use.
When sourcing HPLC vials, always request comprehensive quality control documentation from the manufacturer. This should include information on
Lot-to-lot consistency
Compliance with industry standards
Detailed analysis of material composition and physical properties
Thorough QC data allows you to make an informed decision and ensures that the vials will perform reliably in your HPLC system.
By carefully evaluating these key quality factors, you can select HPLC autosampler vials that deliver the precision, compatibility and durability you need for your analytical workflows. Taking the time to evaluate your vial supplier can pay dividends in terms of improved data quality and instrument performance.