Department of Chemistry, University of Oslo, Post Box 1033, Blindern, N-0315 Oslo, Norway.
J Pharm Biomed Anal. 2014 Jan;87:120-9. doi: 10.1016/j.jpba.2013.05.006. Epub 2013 May 16.
On-line solid phase extraction (SPE)-liquid chromatography (LC) allows for automated, sensitive, precise and selective bioanalysis. It is a common feature in miniaturized- or nano LC systems, which are well suited for applications requiring high sensitivity and/or treatment of limited samples (laser micro-dissection samples, rare cancer stem cells, etc.). Traditionally, particles with reversed phase (RP) functional groups are used for the columns in SPE-LC systems. There is however an expanding diversity in SPE-LC combinations applied to meet today's bioanalytical challenges. Current online SPE-LC combinations employ, e.g. porous graphitic carbon (PGC) and hydrophilic interaction liquid chromatography (HILIC) materials for metabolomics and glycomics, restricted access media (RAM) columns coupled with nano LC for peptidomics, immunoaffinity trap columns for targeted proteomics and metal oxide affinity phases for phosphopeptide analysis. However, issues can arise when combining different phases in on-line SPE-LC, e.g. due to solvent incompatibilities between enrichment/separation principles and sample solvent requirements. Consequences can be low recovery and poor resolution, or need for additional instrumentation. On-line SPE-LC with very narrow columns (10-20 μm inner diameters) can be appropriate to obtain maximum sensitivity and information. In such highly miniaturized systems, non-particulate columns are arguably more suited (e.g. monolithic or porous layer open tubular (PLOT) columns) as e.g. hardware contributions resulting in extra column volumes are reduced. Basic SPE-LC systems can be configured/modified to perform quite complex analytical operations, and certain columns, configurations and hardware can improve robustness.
在线固相萃取（SPE）-液相色谱（LC）允许自动化、敏感、精确和选择性的生物分析。它是微型化或纳米 LC 系统的常见特征，非常适合需要高灵敏度和/或处理有限样品（激光微切割样品、稀有癌症干细胞等）的应用。传统上，用于 SPE-LC 系统的柱采用反相（RP）官能团的颗粒。然而，用于满足当今生物分析挑战的 SPE-LC 组合的多样性正在扩大。当前的在线 SPE-LC 组合采用，例如多孔石墨碳（PGC）和亲水相互作用液相色谱（HILIC）材料用于代谢组学和糖组学、受限访问介质（RAM）柱与纳米 LC 结合用于肽组学、免疫亲和捕获柱用于靶向蛋白质组学和金属氧化物亲和相用于磷酸肽分析。然而，在在线 SPE-LC 中组合不同相时可能会出现问题，例如由于富集/分离原理和样品溶剂要求之间的溶剂不相容性。结果可能是回收率低和分辨率差，或者需要额外的仪器。具有非常窄柱（10-20μm 内径）的在线 SPE-LC 可以适用于获得最大的灵敏度和信息。在这种高度微型化的系统中，无颗粒柱更适合（例如整体柱或多孔层开管（PLOT）柱），因为例如硬件贡献导致的额外柱体积减少。基本的 SPE-LC 系统可以进行配置/修改以执行相当复杂的分析操作，并且某些柱、配置和硬件可以提高稳健性。
