Assessment of sample freezing as a preservation technique for analysing the molecular composition of dissolved organic matter in aquatic systems.
Assessment of sample freezing as a preservation technique for analysing the molecular composition of dissolved organic matter in aquatic systems.
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作者：
溶解性有机物（DOM）是环境和地球化学领域的重要研究对象，但在样品运输和储存过程中易发生化学和生物降解。在偏远地区、船上或大量采集的样本需要保存下来，以备以后分析，而不改变DOM的组成。在这里，我们比较了在−20 °C冷冻前后固相可提取DOM的高分辨率质谱。我们发现，当比较冷冻与未冷冻的重复时，冷冻使DOM的组成差异增加0至18.2%（7个地点的中位数= 2.7%），即，取样后立即处理，与未冷冻重复样品之间的差异进行比较。冷冻的影响主要包括较差的检测限，但小于其他样品制备和分析步骤，如固相萃取和可变电离效率。冷冻样品无论是21天或95天导致类似的，只有轻微的变化，DOM组成，虽然后者的变化更大。因此，我们的结论是，在这些时间尺度上的样品冻结不应妨碍水生DOM的科学研究，并可以使用在它具有后勤意义，如大型空间调查或研究存档的样品。我们评估样品冷冻的影响，从溶解的有机物样品通过高分辨率质谱仪收集的数据，并发现，这种保存技术是适当的，如果必要的。
Dissolved organic matter (DOM) is widely studied in environmental and biogeochemical sciences, but is susceptible to chemical and biological degradation during sample transport and storage. Samples taken in remote regions, aboard ships, or in large numbers need to be preserved for later analysis without changing DOM composition. Here we compare high-resolution mass spectra of solid phase extractable DOM before and after freezing at −20 °C. We found that freezing increases compositional dissimilarity in DOM by between 0 to 18.2% (median = 2.7% across 7 sites) when comparing replicates that were frozen versus unfrozen, i.e., processed immediately after sampling, as compared with differences between unfrozen replicates. The effects of freezing primarily consisted of a poorer detection limit, but were smaller than other sample preparation and analysis steps, such as solid phase extraction and variable ionisation efficiency. Freezing samples for either 21 or 95 days led to similar and only slight changes in DOM composition, albeit with more variation for the latter. Therefore, we conclude that sample freezing on these time scales should not impede scientific study of aquatic DOM and can be used where it makes logistical sense, such as for large spatial surveys or study of archived samples. We assess the effect of sample freezing on the data collected from dissolved organic matter samples by high resolution mass spectrometry, and find that this preservation technique is appropriate if necessary.
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影响因子：
7.4
作者：
Patriarca C;Balderrama A;Može M;Sjöberg PJR;Bergquist J;Tranvik LJ;Hawkes JA
通讯作者：
Hawkes JA
影响因子：
3
作者：
Kattner, G
通讯作者：
Kattner, G
影响因子：
7.4
作者：
Han, Limei;Kaesler, Jan;Lechtenfeld, Oliver J.
通讯作者：
Lechtenfeld, Oliver J.
影响因子：
7.4
作者：
Hertkorn, N.;Frommberger, M.;Perdue, E. M.
通讯作者：
Perdue, E. M.
影响因子：
4.5
作者：
Williams, Clayton J.;Yamashita, Youhei;Xenopoulos, Marguerite A.
通讯作者：
Xenopoulos, Marguerite A.