Influence of Freezing and Storage Procedure on Human Urine Samples in NMR-Based Metabolomics
Influence of Freezing and Storage Procedure on Human Urine Samples in NMR-Based Metabolomics
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DOI：
10.3390/metabo3020243
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发表时间：
2013-06-01
期刊：
影响因子：
4.1
通讯作者：
Luy, Burkhard
中科院分区：
文献类型：
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作者：
Rist, Manuela J.;Muhle-Goll, Claudia;Luy, Burkhard
代谢组学领域的共识是，应遵循标准化方案进行样品处理、储存和分析，因为保持恒定的测量条件以识别细微的生物学差异至关重要。因此，这项工作的目的是系统地研究冷冻程序和储存温度的影响，以及它们对NMR光谱的影响，作为NMR代谢组学研究的一个潜在的干扰方面。从两名健康志愿者中采集尿样，离心并分成等份。将尿液等分试样在-20 ℃、干冰上、-80 ℃或液氮中冷冻，然后在NMR分析前在-20 ℃、-80 ℃或液氮气相中储存1-5周。结果显示，光谱变化取决于冷冻程序，干冰上冷冻的样品显示出最大的偏差。发现这种效果是基于pH值的差异，这是由冷冻过程中引入的CO2浓度的变化引起的。因此，我们建议尿样应在-20 ℃下冷冻，并在一周内转移到较低的储存温度，冷冻程序应成为出版协议的一部分。
It is consensus in the metabolomics community that standardized protocols should be followed for sample handling, storage and analysis, as it is of utmost importance to maintain constant measurement conditions to identify subtle biological differences. The aim of this work, therefore, was to systematically investigate the influence of freezing procedures and storage temperatures and their effect on NMR spectra as a potentially disturbing aspect for NMR-based metabolomics studies. Urine samples were collected from two healthy volunteers, centrifuged and divided into aliquots. Urine aliquots were frozen either at -20 degrees C, on dry ice, at -80 degrees C or in liquid nitrogen and then stored at -20 degrees C, -80 degrees C or in liquid nitrogen vapor phase for 1-5 weeks before NMR analysis. Results show spectral changes depending on the freezing procedure, with samples frozen on dry ice showing the largest deviations. The effect was found to be based on pH differences, which were caused by variations in CO2 concentrations introduced by the freezing procedure. Thus, we recommend that urine samples should be frozen at - 20 degrees C and transferred to lower storage temperatures within one week and that freezing procedures should be part of the publication protocol.