Evaluation of Hadamard Transform Atmospheric Pressure Ion Mobility Time-of-Flight Mass Spectrometry for Complex Mixture Analysis

Ion mobility mass spectrometry (IMMS) has gained popularity in the analysis of complex mixtures such as those encountered in metabolomics and proteomics. However, the challenge that exists in conventional pulsed IMMS is its inherent low duty cycle. The first application of Hadamard transform (HT)-type signal coupled with atmospheric pressure IMMS to complex mixtures is presented. Performance of the prototype was assessed by the analysis of metabolite standard mixture. With 200 times increased IMS duty cycle in HT mode compared with conventional pulsed mode, the limit of detection (LOD) was decreased by ∼10 times. Evaluation for application to complex mixtures was achieved using the NIST Standard Reference Material 1950 Metabolites in Human Plasma. Approximately 180 metabolite ions were detected within 1 min with an IMS resolving power (Rp) of ∼100. Rapid chromatographic separation prior to IMMS analysis was also demonstrated for improving the response of metabolite ions in rat brain tissue extract