Sorting the Wheat from the Chaff: Simple Assays to Monitor Serum and Plasma Sample Quality

Biological samples are the heart of many preclinical and clinical research programs and sample quality has a large impact on final experimental results1. Something as simple as leaving a biological sample on the bench for an extra few hours before processing can affect the quality of that sample. Variations in collection methods, pre-processing time and temperature, processing methods and storage conditions can all affect the quality and integrity of biological samples1,2. If samples of differing quality are used in a study, it can be very difficult to know whether the experimental results are due to real biological changes or were caused by variations in preanalytical handling and thus in sample integrity.

The International Society of Biological and Environmental Repositories (ISBER) has a Biospecimen Science Working Group that identifies critical points in biological sample handling, validates biological sample processing and QC methods, and standardizes biological sample research protocols3. The group is co-chaired by Kathi Shea, who is also Biobank Business Lead at Brooks Life Sciences and Dr. Fay Betsou, Chief Scientific Officer at the Integrated BioBank of Luxembourg (IBBL).

The Biospecimen Science Working Group conducts peer-reviewed research as part of their work to determine best practice methods of biological sample handling and storage. They recently published a paper showing that researchers can measure the levels of 2 interleukins, IL8 and IL16, to assess the quality of serum and plasma samples4.

Plasma samples treated with EDTA to prevent coagulation are often used to isolate cell free DNA, metabolites or peptides for preclinical or clinical research studies. The industry standard is to process EDTA plasma samples within 3 hours of collection4. For studies looking at protein levels in either plasma or serum, the industry standard is to process the samples within 24 hours4.

The ISBER Biospecimen Science Working Group wanted to see whether cytokine levels changed in samples left at room temperature for 24 hours or more. They reasoned that cytokine levels could serve as a marker for overall biological sample quality. The group compared the level of 20 cytokines in serum, EDTA plasma and in plasma treated with citrate, another anticoagulant commonly used in blood collection tubes. They found higher IL8 and IL16 levels in serum and EDTA plasma samples respectively, when samples were left at room temperature for 24 hours or longer before centrifuging, compared with samples left at room temperature for less than 3 hours. Likewise, IL8 levels were up in citrate plasma samples left at room temperature for 48 hours or more. In contrast, IL8 and IL16 levels did not increase in samples kept at 4°C for up to 53 hours before analysis. The ISBER Biospecimen Science Working Group validated these results in 7 independent cohorts.

The authors concluded that commercially available ELISA assays can be used to measure IL8 and IL16 levels in serum and plasma samples. These tools provide a sensitive and specific method to screen serum and plasma samples and can help life science organizations standardize the quality of their biological samples. This approach may be particularly useful to assess the integrity of samples for which preanalytical handling processes have not been documented.

Kathi and the entire team of Brooks Life Sciences experts are committed to creating best-in-class tools and services to help life science organizations maintain the quality of their biological samples.

Contact us for more information on how we can help you manage your biological samples.



  1. NCI Best Practices for Biospecimen resources
  2. Betsou et al. Standard Preanalytical Coding for Biospecimens: Defining the Sample PREanalytical Code. Cancer Epidemiol. Biomarkers Prev. 2010.
  3. ISBER Biospecimen Science Working Group
  4. Kofanova et al. IL8 and IL16 levels indicate serum and plasma quality. Clin. Chem. Lab. Med. 2018