The quotas of a limited number of trace elements in the extended Redfield ratios have been determined before and thought to reflect the requirements of phytoplankton. However, these quotas are found to be quite variable under different environmental conditions, suggesting that the cellular trace metal quota is not an accurate measure of cellular trace metal requirement. Here we present a method that has been developed and optimised for direct analysis of 32 elements simultaneously in small volume of cell lysate in buffers with a high salt matrix (800 μL, up to 30% TDS). We then demonstrate the application of the method to resolve the extended Redfield ratio of cell requirement by measuring the intracellular trace element composition of six Emiliania huxleyi strains isolated from different locations. The method uses a quadrupole-ICP-MS with a collision/reaction cell to resolve polyatomic interferences. The ICP-MS is interfaced with an Elemental Scientific Flow Injection Automation System (FIAS). The accuracy of the analysis according to this new method is verified by measuring 2 certified reference materials, BCR 273 and BCR 414. This work presents a number of running parameters, optimised for multi-element analysis of samples with a high TDS sample matrix. This method allows direct measurement of protein samples in their native state: no alteration or digestion is needed, which simplifies the steps for sample preparation. In this study with 6 E. huxleyi strains isolated from the environment, our method reveals significant differences between whole cell and intracellular metal quotas for all strains. The intracellular metal composition, interpreted as a truer representation of organisms' metal requirements, shows an environmentally dependent signal. This suggests that, compared with whole cell metal quotas, the metalloproteins are a better indicator of metal requirements of phytoplankton under various environmental conditions.

中文翻译：

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流动注射ICP-MS直接测量高基质样品中的多种元素：应用于扩展的Emiliania huxleyi Redfield比率†

以前已经确定了扩展的Redfield比率中有限数量的微量元素的配额，并认为这些配额反映了浮游植物的需求。但是，发现这些配额在不同的环境条件下变化很大，这表明细胞痕量金属的配额并不是细胞痕量金属需求的准确度量。在这里，我们介绍了一种已开发和优化的方法，该方法可同时在具有高盐基质（800μL，高达30％TDS）的小体积细胞裂解物中同时直接分析32种元素。然后，我们通过测量六种Em草的细胞内微量元素组成，证明了该方法在解决扩展的Redfield细胞需求中所占的比例从不同位置分离的菌株。该方法使用具有碰撞/反应池的四极杆ICP-MS来解决多原子干扰。ICP-MS与Elemental Scientific Flow Injection Automation系统（FIAS）连接。通过测量两种认证的参考物质BCR 273和BCR 414，可以验证根据这种新方法进行分析的准确性。这项工作提出了许多运行参数，这些参数针对具有高TDS样品基质的样品的多元素分析进行​​了优化。这种方法可以直接测量天然状态下的蛋白质样品：无需更改或消化，从而简化了样品制备步骤。在这项研究中，有6株大肠杆菌从环境中分离出的菌株，我们的方法揭示了所有菌株的全细胞和细胞内金属配额之间的显着差异。细胞内金属成分被解释为生物对金属的更真实的表示，它显示了一种环境依赖性信号。这表明，与全细胞金属配额相比，在各种环境条件下，金属蛋白是浮游植物金属需求的更好指标。