Blood collection tube has minimal interference on the carbon and nitrogen isotope composition of plasma, red blood cells, and serum in cow blood

Authors: Jaramillo, David; Bauman, Lisa; CAMISA NOVA, CARLOS - University Of Wisconsin; LIMA, LAIS - University Of Florida; VAN SANTEN, EDZARD - University Of Florida

Submitted to: Rapid Communications in Mass Spectrometry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2025
Publication Date: 7/23/2025
Citation: Jaramillo, D.M., Bauman, L.M., Camisa Nova, C., Lima, L., Van Santen, E. 2025. Blood collection tube has minimal interference on the carbon and nitrogen isotope composition of plasma, red blood cells, and serum in cow blood. Rapid Communications in Mass Spectrometry. https://doi.org/10.1002/rcm.10109.
DOI: https://doi.org/10.1002/rcm.10109

Interpretive Summary: Stable isotopes can be useful tools for tracking dietary changes, diet composition, nutrient use, and other physiological processes in ruminants. These techniques rely on the fact that a given sampled tissue is directly affected by the diet consumed. Blood is a dynamic tissue, which can be separated into serum, plasma, and red blood cell (RBC) components, each providing inferences at various time scales due to different rates of turnover. This study compared several commercially available serum and plasma collection tubes and evaluated how they may affect the concentrations and stable isotopic signatures of carbon and nitrogen from blood in lactating dairy cattle. The results showed that, while isotopic values may differ slightly from various different blood collection tubes, these differences were often small, which may have little impact on interpretation of research results, when serum or red blood cells are analyzed. Meanwhile, the isotopic composition or concentrations of carbon and nitrogen of serum were not affected by the three collection tubes used within this study. This study is useful for researchers to understand the minor differences across blood tubes and decide on whether or not these may impact the objectives and the results of a given study.

Technical Abstract: Stable isotopes can be useful tools for tracking dietary changes, diet composition, nutrient use, and other physiological processes in ruminants. These techniques rely on the fact that the tissue samples directly reflect the animal’s diet, though the time scale represented varies by tissue. Blood is a dynamic tissue, which can be separated into serum, plasma, and red blood cell (RBC) components, each providing inferences at various time scales due to different rates of turnover. Numerous collection tubes for blood are commercially available. So far, no studies have compared the isotopic composition from cattle blood as affected by collection tube. Therefore, this study was conducted to compare several commercially available serum and plasma collection tubes and evaluate how they may affect d13C, d15N, and C and N concentrations from blood collected in lactating dairy cattle. Sixteen cows were used, eight to collect plasma and RBC and eight to collect serum samples. For plasma and RBC, treatments were five collection tubes containing different anticoagulants: dipotassium ethylenediaminetetraacetic acid (K2EDTA), tripotassium EDTA (K3EDTA), NaF, Li heparin (LiHep), and Na heparin (NaHep). For serum analysis, the three collection tubes were a RedTop (contained no coagulating agent), and TigerTop and Red+CAT, which both contained clot activator and serum separator gel, each made by two different manufacturers. All samples were collected via tail venipuncture. Following collection and centrifugation, all samples were processed, freeze dried, and analyzed in triplicate for d13C, d15N, and C and N using an isotope ratio mass spectrometer. The results from this study indicate that while mean differences exist on the d13C and d15N from plasma and red blood cells, these differences were largely minimal. Clot activator gels in the serum tubes did not affect the d13C and d15N isotopic composition. Overall, this study showed that, while isotopic values may differ slightly from various different blood collection tubes, these differences were often small, which may have little impact on interpretation of research results, when serum or RBC are analyzed. Meanwhile, the isotopic composition or C and N concentrations of serum were not affected by the three collection tubes used within this study. Researchers will have to understand these differences and decide on whether or not these may impact the objectives and the results of a given study.