Tonner D S, McMahon T B
Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.
Anal Chem. 1997 Dec 1;69(23):4735-40. doi: 10.1021/ac970727e.
Consecutive infrared multiphoton dissociations (IRMPD) may be observed in a Fourier transform ion cyclotron resonance mass spectrometer (FTICR). This is the IRMPD equivalent of previous MS(n)() experiments using CID. This work presents a versatile technique, using a bistable shutter to gate ON and OFF a continuous-wave (CW) CO(2) laser for multiple irradiation periods of 0.1-1000 s duration. Consecutive photodissociations, up to MS(4), are demonstrated for the proton-bound dimer of diethyl ether and the resulting fragment ions. The photoproducts are formed close to the center of the FTICR cell, resulting in high product ion recovery efficiency. This differs from CID products, which are formed throughout the FTICR cell causing reisolation/detection problems. The fragmentation resulting from the use of low-intensity, CW, infrared laser radiation is shown to be much more energy selective than CID. Photodissociation of C(2)H(5)OH(2)(+) ion produces the lowest energy product ion exclusively, even though the two product channels differ only by ∼5 kcal/mol. Low-energy CID, however, produces a mixture of C(2)H(5)(+) and H(3)O(+) products in the ratio of 1.3:1. Hence, the higher energy pathway (C(2)H(5)(+)) is substantially favored. The current results indicate that this IRMPD MS(n)() technique may be successfully applied to large biomolecules prepared by electrospray or MALDI.
在傅里叶变换离子回旋共振质谱仪（FTICR）中可以观察到连续红外多光子解离（IRMPD）。这相当于先前使用碰撞诱导解离（CID）进行的MS(n)实验中的IRMPD。本文介绍了一种通用技术，使用双稳态快门来控制连续波（CW）CO₂激光的开启和关闭，以进行持续时间为0.1 - 1000秒的多次照射。对于乙醚的质子键合二聚体及其产生的碎片离子，展示了高达MS(4)的连续光解离。光产物在FTICR池的中心附近形成，从而导致高的产物离子回收效率。这与CID产物不同，CID产物在整个FTICR池中形成，会导致重新分离/检测问题。结果表明，使用低强度、连续波红外激光辐射产生的碎片化比CID具有更高的能量选择性。即使两个产物通道仅相差约5千卡/摩尔，C₂H₅OH₂⁺离子的光解离也仅产生能量最低的产物离子。然而，低能量CID产生的C₂H₅⁺和H₃O⁺产物的混合物比例为1.3:1。因此，能量较高的途径（C₂H₅⁺）明显更受青睐。目前的结果表明，这种IRMPD MS(n)技术可以成功应用于通过电喷雾或基质辅助激光解吸电离（MALDI）制备的大型生物分子。
