Sample requirements

We are frequently asked how blood samples need to be collected for Nightingale’s analysis. Briefly, all blood samples that have been collected and processed with the standard clinical procedures and have been stored properly work with Nightingale’s analysis. No special procedures are needed. We have analyzed with great success even very old sample collections, which were deep-frozen for over 20 years.

Below we have summarized some general points based on our experience for optimal sample collection, processing, and storing.

Advice on sample collection

For blood-drawing practices we recommend to follow for example the official WHO guidelines on drawing blood: best practices in phlebotomy. Additionally, the Joint EFLM-COLABIOCLI Recommendation for venous blood sampling (Simundic et al., 2018) provides a clear step-by-step guide for blood sampling. If the conditions of fieldwork don’t allow for rapid sample processing (i.e., serum/plasma separation) after blood sampling, it is recommended to store the blood samples at +4°C until they are processed, as this will slow down sample degradation processes such as glycolysis. It is recommended to process the blood samples as soon as possible, optimally within the same day of sample collection. It is primarily important to follow blood collection tube manufacturer’s instructions and details such as precise clotting time and centrifugation settings.

Advice on sample storing

Once the blood samples have been processed and the separated serum/plasma has been transferred to a secondary tube, it is generally suggested to rapidly deep-freeze the separated serum/plasma for long-term storage. It would be optimal to freeze the serum/plasma samples at -80°C or colder as soon as possible, preferably on the day of collection and processing, and keep them at these temperatures for long-term storage. If the serum/plasma samples cannot be stored in a deep-freezer immediately after the separation, you can store them at +4°C for up to three days, or at -20°C for up to one month. Additionally, freeze-thaw cycles should be minimized. Based on Nightingale’s experience after three freeze-thaw cycles, the biological quality of the samples starts to deteriorate.

Advice on sample shipping

For advice on sample handling and shipping, take a look at our checklist.