how long can biological samples be stored before testing?

What You’ll Learn:

• How long biological samples—tissue, urine, and blood—can be safely stored before testing.
• Which factors most affect sample stability.
• Why temperature, preservatives, and storage duration are critical for reliable test results.
• How modern microsampling techniques may improve sample preservation and logistics.

What Determines How Long Biological Samples Can Be Stored?

The stability of biological specimens depends on multiple factors, sample type, temperature, storage conditions, and intended analysis. Each biospecimen (tissue, urine, or blood) contains unique molecular components that degrade at different rates. Understanding these differences ensures reliable results and preserves the scientific value of each sample.

1. Human Tissue Samples: How Long Can They Be Stored?

Tissue samples are widely used in genomics, toxicology, and pathology research. Their stability depends on how quickly they are preserved after collection and how they are stored.

• Frozen storage stability: Studies on adrenal, liver, and brain tissue show that mRNA and protein integrity can remain stable for several years when stored at –80°C.
• Chernobyl biobank example: Decades-old tissue samples stored under cryogenic conditions retained measurable RNA integrity, proving long-term viability when preserved appropriately.
• Formalin-fixed paraffin-embedded (FFPE) tissues are another standard for long-term histological analysis. However, FFPE can cause cross-linking that complicates downstream molecular assays.

Takeaway: Proper cryopreservation techniques and temperature control are key to maintaining tissue integrity for long-term biobanking and molecular testing.

2. Urine Samples: Storage Conditions and Longevity

Urine samples are commonly analyzed for metabolic and toxicological studies. However, they are highly sensitive to environmental changes.

• Temperature control: Urine samples stored at 4°C can remain stable for up to 24–48 hours, but freezing at –20°C or –80°C extends stability to weeks or months.
• Preservatives: Adding stabilizing agents can prevent bacterial growth and analyte degradation during transport or delayed analysis.
• Freezing and thawing cycles: These can affect certain metabolites, particularly amino acids and hormones; therefore, minimizing freeze–thaw events is recommended.

Implications: For biobanking and population studies, it’s best to aliquot and freeze samples immediately after collection to maintain consistency in results.

3. Blood Samples: Stability Across Analytes

Blood is one of the most complex and commonly used biological matrices. Different analytes within blood have different stability profiles, depending on storage conditions and collection methods.

DNA and miRNA Stability

• DNA and miRNA – A study of serum samples from the Janus Serumbank revealed that even after 40 years, serum samples stored at -25°C are viable for whole-genome sequencing and SNP calling, as well as qPCR and small RNA sequencing, with 650 unique miRNAs detected, on average, in each sample.

Protein Stability

• Proteins – Stability of proteins in plasma varies from molecule to molecule; however, available evidence suggests that, when stored at -80°C for up to 6 years, proteins and other molecules in plasma samples do not degrade over time.
• However, at room temperature, protein degradation increases rapidly after 48 hours.

Small Molecules and Metabolites

• Small molecules – Another study of the serum samples at Janus Serumbank revealed that sodium, calcium, iron, and creatinine levels do not significantly change over time if the serum is stored at -25°C.
• Metabolites like glucose, lactate, and amino acids show variability depending on anticoagulant use and temperature.
• Immediate processing or freezing minimizes post-collection shifts in concentration.

Serum levels of other analytes, however, may be substantially altered over time; the study revealed a 26.4% increase in potassium levels and a 59.4% decrease in bilirubin levels after storage for 25 years.

Microsampling Applications

Recent studies highlight that dried blood microsamples, collected via devices like the Mitra® microsampler, can maintain analyte stability for weeks at ambient temperature. This eliminates the need for cold-chain logistics while maintaining data integrity, especially in remote sampling and decentralized research.

Best Practices for Biological Sample Storage

Smarter, Longer-Term Blood Sample Preservation

Biological sample stability is critical for reliable research outcomes. With proper protocols, tissues can last for years, urine for months, and blood for weeks to years depending on the analyte.

Innovations like Volumetric Absorptive Microsampling (VAMS®) are redefining how scientists store and transport blood samples, allowing ambient, stable storage without freezing. These advances make global studies more accessible, cost-effective, and environmentally sustainable.