Capillary electrophoresis-mass spectrometry using robust poly(ether ether ketone) capillary for tolerance to high content of organic solvents.

Nonaqueous capillary electrophoresis (CE) and organic-aqueous CE using high content of organic solvents are common techniques in capillary electrophoresis-mass spectrometry (CE-MS) due to various advantages. However, the long-term stability of commonly used polyimide coated fused silica capillary remains a major problem that polyimide coating is prone to swelling in organic solvents and aminolysis in alkaline buffer, which cause serious problems like irregular electrospray, current drop or clogging event. In this work, robust PEEK capillary was used as separation capillary for tolerance to high content of organic solvents in CE-MS system. It is interesting that the high mechanical and chemical stability of PEEK capillary ensured stable CE separation and electrospray when used in CE-MS. All quantitative experiments were accomplished by single PEEK capillary. In addition, the using of organic solvents as running buffer reduced adsorption of hydrophobic compounds on PEEK capillary wall and improved the symmetry of peak shape. The PEEK-based CE-MS method showed good separation performance in analysis of several groups of active alkaloids in traditional Chinese medicines and was applied for quantitative analysis of peimine and peiminine in Bulbus Fritillariae thunbergii herb with high sensitivity. Based on the advantages like simple pretreatment, easy to cut, stable and good separation performance of PEEK column in CE-MS, this study provides an effective way for improving the stability and employment of high content of organic solvents in CE-MS analysis.