Perfluoroalkyl Acid Concentrations in Blood Samples Subjected to Transportation and Processing Delay

BackgroundIn studies of perfluoroalkyl acids, the validity and comparability of measured concentrations may be affected by differences in the handling of biospecimens. We aimed to investigate whether measured plasma levels of perfluoroalkyl acids differed between blood samples subjected to delay and transportation prior to processing and samples with immediate processing and freezing.MethodsPregnant women recruited at Aarhus University Hospital, Denmark, (n = 88) provided paired blood samples. For each pair of samples, one was immediately processed and plasma was frozen, and the other was delayed and transported as whole blood before processing and freezing of plasma (similar to the Danish National Birth Cohort). We measured 12 perfluoroalkyl acids and present results for compounds with more than 50% of samples above the lower limit of quantification.ResultsFor samples taken in the winter, relative differences between the paired samples ranged between -77 and +38% for individual perfluoroalkyl acids. In most cases concentrations were lower in the delayed and transported samples, e.g. the relative difference was -29% (95% confidence interval -30; -27) for perfluorooctane sulfonate. For perfluorooctanoate there was no difference between the two setups [corresponding estimate 1% (0, 3)]. Differences were negligible in the summer for all compounds.ConclusionsTransport of blood samples and processing delay, similar to conditions applied in some large, population-based studies, may affect measured perfluoroalkyl acid concentrations, mainly when outdoor temperatures are low. Attention to processing conditions is needed in studies of perfluoroalkyl acid exposure in humans.

**背景**：全氟烷基酸（perfluoroalkyl acids）相关研究中，生物样本处理方式的差异可能影响检测浓度的有效性与可比性。本研究旨在探讨：血液样本在处理前经历延迟运输，与即刻处理并冻存的样本之间，所测得的全氟烷基酸血浆水平是否存在差异。

**方法**：本研究招募了丹麦奥胡斯大学医院的88名孕妇（n=88），采集其配对血液样本。每对样本中，一份即刻处理并冻存血浆；另一份以全血形式延迟运输，待后续处理并冻存血浆，操作流程与丹麦国家出生队列一致。本研究检测了12种全氟烷基酸，仅呈现定量下限（lower limit of quantification）以上样本占比超过50%的化合物的研究结果。

**结果**：冬季采集的样本中，各全氟烷基酸的配对样本相对差异介于-77%至+38%之间。多数情况下，延迟运输的样本浓度更低：例如全氟辛烷磺酸（perfluorooctane sulfonate）的相对差异为-29%（95%置信区间：-30，-27）；而全氟辛酸（perfluorooctanoate）在两种处理方式下无显著差异，对应估计值为1%（0，3）。夏季采集的所有化合物样本间差异均可忽略不计。

**结论**：与部分大型人群队列研究的操作条件类似，血液样本运输与处理延迟可能影响全氟烷基酸的检测浓度，该效应在室外温度较低时尤为显著。在人类全氟烷基酸暴露相关研究中，需重视样本处理条件的标准化。