下表汇总了各种SPE模式,为方法开发工作的开展提供了一个良好的起点:
固相萃取选择色谱模式及吸附剂
反相 | 正相 | 离子交换 | ||
分析物 | 中-低极性 | 低-高极性/中性 | 带电荷、可电离 | |
分离机制 | 基于疏水性的分离 | 基于极性的分离 | 基于电荷的分离 | |
样品基质 | 水溶液 | 非极性有机溶剂 | 水溶液/低离子强度 | |
SPE吸附剂的活化/平衡 | 1. 用极性有机溶剂得到的溶剂化物 2. 水 |
非极性有机溶剂 | 低离子强度缓冲液 | |
初步冲洗步骤 | 水溶液/缓冲液 | 非极性有机溶剂 | 低离子强度缓冲液 | |
洗脱步骤 | 增加极性有机溶剂的含量 | 增加混合有机溶剂的洗脱强度 | 更强的缓冲液——通过调节离子强度或pH值而中和电荷 | |
AX [阴离子交换] |
CX [阳离子交换] |
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吸附剂官能团 | C18, tC18, C8, tC2, CN, NH2, HLB, RDX, Rxn RP | Silica, Alumina, Florisil, Diol, CN, NH2 | Accell Plus QMA, NH2, SAX, MAX, WAX | Accell Plus CM, SCX, MCX, WCX, Rxn CX |
吸附剂表面极性 | 低至中等 | 高至中等 | 高 | 高 |
典型溶剂的极性范围 | 高至中等 | 低至中等 | 高 | 高 |
典型的上样溶剂 | 水、低强度缓冲液 | 正己烷、氯仿、二氯甲烷 | 水、低强度缓冲液 | 水、低强度缓冲液 |
典型的洗脱溶剂 | MeOH/水、CH3CN/水 | 乙酸乙酯、丙酮、CH3CN | 缓冲液、高离子强度的盐类,提高pH | 缓冲液、高离子强度的盐类,降低pH |
样品洗脱顺序 | 最大极性样品组分最先洗脱出来 | 最弱极性样品组分最先洗脱出来 | 最弱电离样品组分最先洗脱出来 | 最弱电离样品组分最先洗脱出来 |
为洗脱化合物而做的流动相溶剂改变 | 减弱溶剂极性 | 增强溶剂极性 | 增加离子强度或提高pH值 | 增加离子强度或降低pH值 |
This has been a brief introduction to sample enrichment and purification using solid-phase extraction [SPE]. The best way to start using SPE is to first learn what others have done with analytes and/or matrices similar to those of interest to you. You will find > 7,700 references to the use of SPE in the Resource Library on waters.com. Fill in the blank with a partial compound or matrix name in the following search phrase:
“Sep-Pak” OR “Oasis” AND ______*
NOTE: Rather than risk a spelling error, use an asterisk [*] with a root name for best results. Using this same search string, even more references [> 60,000] may be found on GOOGLE Scholar.
Further reading:
J.C. Arsenault and P.D. McDonald, Beginners Guide to Liquid Chromatography, Waters [2007]; Order P/N 715001531 on waters.com
P.D. McDonald and E.S.P. Bouvier, A Sample Preparation Primer and Guide to Solid-Phase Extraction Methods Development, Waters [2001] Search for WA20300 on waters.com
Waters, Purity by SPE [2008]; Search for 720001692en on waters.com
U.D. Neue, P.D. McDonald, Topics in Solid-Phase Extraction. Part 1. Ion Suppression in LC/MS Analysis: A Review. Strategies for its elimination by well-designed, multidimensional solid-phase extraction [SPE] protocols and methods for its quantitative assessment [2005]; Search for 720001273en on waters.com
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