Multiplex Data Acquisition in Multiple Time-dispersive Separation Dimensions

摘要

In conventional TOF experiments, duty cycle and throughput are limited to ion injection frequencies (t_D~(- -1)) slower than the analyte flight time (i.e. the "pulse and wait" approach). Analyte correlation in multiple timedispersive separations allow ion injection frequencies significantly faster (t_D~(- -1) than the frequency limit to retain time correlation in one dimension. Cross-correlation techniques are used to demodulate the ion signals for recovering time correlation (Figure 1). A signal-to-noise, or throughput, enhancement of 102 to 10~3 over conventional signal averaging techniques is demonstrated in the context of MALDI-ion mobility-^sTOFMS for the structural analysis of peptides, proteins, and protein complexes. Analyte ion separation is first accomplished on the basis of ion mobility drift time, which is proportional to ion-neutral collision cross section (or apparent surface area). Subsequently, ions are separated by orthogonal reflecton TOFMS. In the IM-dimension, the ion beam appears "pseudo-continuous" by using high pulse repetition rate MALDI (upto 20 kHz) for ion injection and ion packet encoding, which are subsequently decoded in the TOFMS dimension. High MALDI pulse repetition rates are accomplished by interleaving laser pulse-trains of multiple high repetition rate MALDI lasers (frequency-tripled Nd:YAG and Nd:YLF). Furthermore, effective MALDI repetition rates of up to 20 kHz are demonstrated and theoretical enhancements at rates of 100 to 200 kHz are described.