Delayed extraction experiments using a repulsing potential before ion extraction:: evidence of non-covalent clusters as ion precursor in UV matrix-assisted laser desorption/ionization.: Part II -: Dynamic effects with α-cyano-4-hydroxycinnamic acid matrix
Delayed extraction experiments using a repulsing potential before ion extraction:: evidence of non-covalent clusters as ion precursor in UV matrix-assisted laser desorption/ionization.: Part II -: Dynamic effects with α-cyano-4-hydroxycinnamic acid matrix
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DOI：
10.1002/jms.772
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发表时间：
2005-01-01
影响因子：
2.3
通讯作者：
Bolbach, G
中科院分区：
文献类型：
--
作者：
Fournier, I;Brunot, A;Bolbach, G
延迟提取实验进行了更好地了解在紫外基质辅助激光解吸/电离的离子形成的动态效应。第I-1部分致力于2，5-二羟基苯甲酸（2，5-DHB）基质。结果清楚地表明，存在和作用的高质量的前体对应于一个非共价矩阵分析物协会在离子形成。在该补充研究中，使用基质α-氰基-4-羟基肉桂酸（HCCA）研究了离子飞行时间和丰度随延迟提取时间的变化。在我们的仪器条件下，其中喷射的离子在提取之前经历低排斥电场，获得两个主要结果：（i）在取决于排斥场的峰形中观察到两种离子成分，第一主要成分（1）类似于对2，5-DHB观察到的成分，第二次要成分（11）显然由延迟的提取脉冲触发，离子飞行时间变化与延迟时间的关系仍低于2，5-DHB矩阵，表明初始轴向速度较小。组分I的基质和低分子量肽离子的初始动能不足以克服延迟时间范围（200-2200 ns）内的排斥电位，并且我们必须假设离子具有非共价簇作为前体。这些簇-聚集体的完全去溶剂化将通过萃取步骤实现。离子飞行时间作为延迟时间的函数的模拟允许确定前体的平均尺寸，对于HCCA、ACTH 7-38和牛胰岛素准分子离子，通常分别为4500、40000和50000 u，假设前体是单电荷的。这些离子前体的大小大于2，5-DHB产生的离子前体的大小。对于组分II，离子可能不被溶剂化，并且它们直接从靶解吸。考虑到HCCA和2，5-DHB矩阵的结果和文献中的其他结果，提出并讨论了基于团簇作为离子前体的离子形成的一般模型。版权所有（C）2004约翰威利父子有限公司。
Delayed extraction experiments were undertaken to gain a better insight into the dynamic effects involved in the ion formation in UV matrix-assisted laser desorption/ionization. Part I-1 was devoted to a 2,5-dihydroxybenzoic (2,5-DHB) matrix. The results clearly demonstrated the existence and the role of high-mass precursors corresponding to a non-covalent matrix-analyte association in ion formation. In this complementary study, ion flight time and abundance were studied as a function of the delay extraction time using the matrix alpha-cyano-4-hydroxycinnamic acid (HCCA). Under our instrumental conditions, where ejected ions experienced a low repulsing electric field before extraction, two main results were obtained: (i) two ion components are observed in the peak profiles depending on the repulsing field, a first, major component (1) similar to that observed for 2,5-DHB and a second, minor component (11) apparently triggered by the delayed extraction pulse, and (ii) ion time-of-flight variation vs delay time remained lower than that noted with 2,5-DHB matrix, indicating that the initial axial velocity is smaller. The initial kinetic energy of matrix and low molecular mass peptide ions for the component I is not high enough to overcome the repulsing potential in the delay time range (200-2200 ns) and we have to assume that ions have non-covalent clusters as precursors. Complete desolvation of these clusters-aggregates would be achieved through the extraction step. Simulations of the ion time-of-flight as a function of the delay time allow the determination of the average size of the precursors, typically 4500, 40000 and 50000 u for HCCA, ACTH 7-38 and bovine insulin quasi-molecular ion, respectively, assuming that the precursors are singly charged. The size of these ion precursors is greater than that of those generated for 2,5-DHB. For component II, ions are probably not solvated and they are directly desorbed from the target. Taking into account the results on HCCA and 2,5-DHB matrices and other results from the literature, a general model for ion formation based on clusters as ion precursors is proposed and discussed. Copyright (C) 2004 John Wiley Sons, Ltd.