毛细管电泳-电喷雾质谱联用中缓冲液pH对质谱检测灵敏度的影响

Evaluation of the Effects of the pH Value of Buffer on Capillary Electrophoresis-Electrospray Ionization-Mass Spectrometry Signal Intensity

毛细管电泳 电喷雾质谱联用以其高效及高准确性被广泛应用于很多领域。联用过程中,质谱信号强度受多种因素的影响,缓冲溶液pH是其中之一。以两种小肽(组氨酸 脯氨酸 亮氨酸(His Pro Leu)和丙氨酸 色氨酸(Ala Trp))为例从理论上探讨了分离的缓冲溶液和包层液形成的混合液中H+浓度对质谱信号的影响。结果表明,缓冲液和包层液对质谱信号的影响不是独立的,而是两者的相互耦合。

In recent years, the hyphenation of capillary electrophoresis (CE) and electrospray ionization mass spectrometry (ESIMS) has been widely applied to some research fields with high efficiency and high accuracy. The effects of pH of the mixed solution consisting the running buffer and the sheath flow on the ESIMS signal intensity were investigated experimentally and theoretically with a mixture of two model peptides, histidineprolineleucine (HisProLeu) and alaninetryptophan (AlaTrp). The running buffer and the sheath flow were found to affect the signal intensity in a synergistic fashion. The ESIMS signal intensity of HisProLeu increased with the H+ concentration of the mixed solution ranging from 0.5 to 2.3 mmol/L, but decreased with the H+ concentration range of 2.3 to 3.09 mmol/L. It is concluded that the ESIMS signal intensity of these peptides increases at first and then decreases subsequently with the increase of the concentration of H+ of the mixed solution, and therefore, there exist an optimal pH value of the mixed solution to maximize the MS response.