Padley H R, Bashir S, Wood T D
Department of Chemistry, Natural Sciences and Mathematics Complex, State University of New York at Buffalo 14260-3000, USA.
Anal Chem. 1997 Aug 1;69(15):2914-8. doi: 10.1021/ac9700235.
Fourier transform mass spectrometry (FTMS) is well-known for its capabilities in structural characterization of molecules. Recent developments in radio frequency excitation, linearized trapping, and accumulation of ions generated from external sources have improved the potential of FTMS for quantitative analysis. Here, a commercial external electrospray ionization FTMS, employing a linearized ion trap (the Infinity Cell) and an ion accumulation procedure in which ions are deflected off-axis and injected into the trap, is evaluated as an analytical method for quantifying amino acids, peptides, and proteins. Linear response over approximately 2-3 orders of magnitude is observed for singly-charged ions with low coefficients of variation (generally < 10%), and the calibration curves generated can be used to quantify structurally similar analytes with < 4% relative error, as shown here for quantification of leucine enkephalin from curves generated by methionine enkephalin. Similar precision is obtained for multiply-charged lysozyme, but over only 1.5 orders of magnitude. Some m/z discrimination is observed as a function of trap accumulation potential for a two-component cytochrome c/lysozyme mixture. The results are promising because they suggest that quantification using liquid chromatography coupled to electrospray FTMS is possible.
傅里叶变换质谱（FTMS）以其在分子结构表征方面的能力而闻名。射频激发、线性化阱捕集以及外部源产生离子的累积等方面的最新进展，提升了FTMS进行定量分析的潜力。在此，对一种商用外部电喷雾电离FTMS进行评估，该仪器采用线性化离子阱（Infinity Cell）以及离子累积程序，其中离子被偏转到离轴方向并注入阱中，以此作为定量分析氨基酸、肽和蛋白质的一种分析方法。对于单电荷离子，观察到在大约2至3个数量级范围内呈线性响应，变异系数较低（通常<10%），并且生成的校准曲线可用于定量结构相似的分析物，相对误差<4%，此处以由甲硫氨酸脑啡肽生成的曲线对亮氨酸脑啡肽进行定量为例予以说明。对于多电荷溶菌酶也获得了类似的精密度，但范围仅为1.5个数量级。对于细胞色素c/溶菌酶两组分混合物，观察到一些质荷比歧视现象，它是阱累积电位的函数。这些结果很有前景，因为它们表明使用液相色谱与电喷雾FTMS联用进行定量分析是可行的。
