What is Lyophilisation?

Lyophilisation or ‘freeze drying’ is the process by which water is removed from a product after it is frozen and placed under a vacuum, allowing the ice to change directly from solid to vapor without passing through a liquid phase. The process consists of three separate processes:

1. Freezing
2. Primary Drying (Sublimation)
3. Secondary Drying (Desorption)

There are many benefits to using a lyophilised control including; improved product shelf-life and enhanced stability of volatile analytes. For example, many lyophilised controls have a shelf life of up to four years from the date of manufacture resulting in a reduction of costly new lot validation studies. Furthermore, lyophilised controls can be aliquoted and refrozen to extend the working stability of the product.

Reconstituting Lyophilised QC Material

The process of reconstitution involves adding a specified volume of distilled water to lyophilised QC material. The water should completely dissolve the lyophilised contents, giving a liquid solution, which is ready for analysis.

Reconstitution is a straightforward process, but requires a high level of precision. Small errors can have serious implications to the reconstituted material:

• If too much water is pipetted during reconstitution, the material will be heavily diluted and results will be lower than expected
• If too little water is pipetted during reconstitution, the material will not be sufficiently diluted, and results will be higher than expected
• If the correct volume of water is pipetted, but a small amount of water gets stuck in the pipette tip due to poor pipetting technique, results will be higher than expected

If a lyophilised control has been reconstituted incorrectly the contents of the vial will be wasted. It is therefore vitally important that controls are reconstituted with care.

Materials and Methods Required

The list of requirements for an accurate and consistent reconstitution technique is not extensive, but each requirement is vital. Labs should have:

• Calibrated volumetric pipettes
• Sterile, appropriately sized pipette tips
• Distilled water, or other reconstitution fluid as specified
• Technician with good pipetting technique
• Lyophilised QC stored according to manufacturer’s specifications

How to Reconstitute Lyophilised QC Material

Each different lyophilised control may require slightly different preparation, always refer to the instructions for use before reconstituting control material. The below guide provides a general overview of the reconstitution process, using the Randox Human Assayed Chemistry Premium Plus control (HN1530) as an example

1. Place the vial of lyophilised QC on a flat surface, carefully remove the lid and the rubber stopper making sure not to spill any material
2. Using a calibrated pipette and sterilised pipette tip, add exactly 5ml of distilled water directly into the QC vial, ensuring no water is left in the pipette tip, or on the rim/side of the vial
3. Place the rubber stopper and lid firmly back onto the QC vial, and leave to stand for 30 minutes
4. After 30 minutes, gently invert the QC vial 10-15 times to ensure the contents is completely dissolved, making sure to avoid the formation of foam. It is important that you DO NOT SHAKE the vial. Alternatively place the vial on a roller for 30 minutes to ensure the contents is thoroughly mixed
5. Once satisfied all material has been completely dissolved, proceed to use the QC product in accordance with the ‘Control’ section of the individual analyser application
6. Once finished, refrigerate any unused material. It is good practice to label the vial with the date of reconstitution to prevent the use of material outside of the recommended stability period
7. Prior to reusing lyophilised material, mix the contents thoroughly by gentle inversion, as highlighted in Step 4

Additional Considerations

It is important to remember that there may be slightly different reconstitution requirements for different QC material. For this reason, it is vital that the instructions provided on the QC Kit Inserts are closely followed.

Reconstituting lyophilised QC can be time-consuming. Therefore, Randox Acusera offer convenient 5ml distilled water serum diluent to assist laboratories with reconstitution of lyophilised controls. These user-friendly pour over vials streamline the reconstitution process and eliminate the risk of pipetting errors.

If you have any further questions regarding lyophilised controls or would like to contact us, please do so by emailing us at acusera@randox.com or use the contact us button provided.