Theoretical study of general principle of high-resolution MALDI-linear time-of-flight mass spectrometry in middle to high m/z ranges

Abstract

This work discusses general principles of high-resolution linear time-of-flight (TOF) mass spectrometers across a wide m/z range. Conventional instrument designs are unable to offer adequate performance across a wide m/z range due to inappropriate calculation. Based on big data analyses conducted using comprehensive flight-time topological calculations, high mass resolving power (Rm) is available when instrument dimensions and extraction parameters satisfy several preconditions. The result indicates that a longer flight distance does not necessarily provide higher Rm. The possibility to achieve high Rm for ions of m/z range 100–100,000 are high when the relative length of extraction and acceleration regions to overall instrument length satisfies specific ratios that distinct from conventional designs. With adequate instrument dimensions, achieving optimal Rm needs to optimize the voltages and extraction delay in the ion source. Simulation shows that a 900 mm-long instrument of ideal design can enhance Rm by more than 250 times (to the order of >100,000) in comparison to the extreme condition of conventional design for ions of m/z 100,000. This general principle can be applied to other TOF instruments of different sizes. The method to finding the ultimate parameters is thoroughly described.