Kinetic Studies of Reactions in Solution Using Fast Mass Spectrometry: Stopped-Flow Hadamard Transform Time-of-Flight

摘要

Many common techniques for kinetic analysis in biochemical systems depend upon distinguishing between optically labeled reactants and products. The requirement for optical detection focuses work on chromophoric model systems and limits the application of these methods to real systems. Because a mass spectrometer is able to detect a large class of chromophoric and nonchromophoric molecules, it represents a potential tool to expand the scope of systems amenable to kinetic analysis. We present a method to perform stopped-flow kinetic analysis using time-of-flight mass spectrometry, where signal from both reactants and products in a biochemical reaction can be simultaneously measured and distinguished. Hadamard transform time-of-flight mass spectrometry (HT-TOFMS) is based on pseudorandom spatial modulation of an ion beam, and, in our implementation, imaging detection. HT-TOFMS posses enhanced peak height precision, peak height divided by its own standard deviation, when compared to traditional on-axis time-of-flight mass spectrometry. Because measurements of the rate of chemical reaction depend upon the ability to detect stable proxies for concentration, this peak height precision advantage makes HT-TOFMS particularly well suited for the study of chemical kinetics.