A novel method is proposed for enhancing the separation power of ion mobility spectrometry (IMS) and other similar pulsed techniques, such as time-of-flight mass spectrometry. In this technique, rather than generating an ion packet, a dip is created in the ion beam. This is achieved by an inverse pulse applied to the shutter grid. The dip moves with the same velocity as the ion packet, and the detector reads an inverse peak at the same drift time as that of the normal operation. Using this technique, we achieved 30-60% higher resolution compared to the normal method. In addition, two close peaks that were not resolved via normal IMS were well resolved to the baseline using this technique. The main reason for the increased resolution is likely the absence of space charge in the dip.

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A method based on ESI ion mobility spectrometry as a detection technique after treatment with a molecularly imprinted polymer is described for the analysis of pioglitazone. In addition to the molecularly imprinted polymer separation methodology, the positive ion mobility spectrum and the reduced mobility values for pioglitazone are reported for the first time. The method was exhaustively validated in terms of sensitivity, imprinting factor, enrichment factor, and sorption capacity. A linear dynamic range of 0.10-20.00 μg/mL and an RSD below 6% were obtained for the analysis of this compound. The average recovery for the analysis of spiked samples was calculated to be about 91%. The method was also used to determine pioglitazone in cow plasma, and the results were compared with those obtained using HPLC. The satisfactory results evidence a convenient method for the analysis of the target compound in real samples without using any additional derivatization methods.

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