Exploring bidirectional scanning for boosting the effective pixel acquisition rate of elemental mapping via LA-ICP-TOF-MS

In fifteen words or less, explain the significance of this contribution (Novel Aspect).: Evaluation of bidirectional scanning to enhance LA-ICP-TOF-MS elemental mapping speed and quality.

Abstract Text: Recent advancements in low-dispersion ablation cells and highly efficient aerosol transport systems have significantly enhanced the capabilities of laser ablation – inductively coupled plasma – time-of-flight – mass spectrometry (LA-ICP-TOF-MS) regarding elemental mapping, enabling pixel acquisition rates of up to 1 kHz. [1,2] However, practical limitations, such as element-specific two-phase sample transport and the constraints of unidirectional scanning, limit the effective pixel acquisition rates, thereby limiting throughput and spatial resolution in elemental mapping. [3] The single pulse response (SPR) duration, i.e. the full width of the transient signal monitored upon firing a single laser pulse defined at a given percentage of the maximum peak height (typically 10%, FW0.1M) is not only dependent on the instrumental setup, carrier gas flow rates and sample matrix, but also on the ablation yield, i.e. ablated mass per laser pulse. The pixel acquisition rate is restricted by increasing the laser energy density and beam size diameter. To further boost the pixel acquisition rate of LA-ICP-TOF-MS mapping experiments, bidirectional scanning is evaluated as an alternative to the conventional unidirectional approach. Several factors must be considered, including the reproducibility of SPR profiles across different scanning directions for different sample matrices, which has already been confirmed in previous work [2]. Additionally, slight differences in aerosol transfer delay times upon scanning in different direction will be assessed. Furthermore, the effect of element-specific two-phase sample transport, particularly upon ablation of carbon-based matrices, is investigated and approaches to mitigate the effects on the image quality will be evaluated.

[1] Becker, P., Koch, J., & Günther, D., Journal of Analytical Atomic Spectrometry, 2022, 37, 1846- 1854.
[2] Basabe-Mendizabal, I., Maeda, R., Goderis, S., Vanhaecke, F. & Van Acker, T., Analytical Chemistry, 2025, just accepted, DOI: 10.1021/acs.analchem.4c05667.
[3] Van Helden, T., Mervič, K., Nemet, I., van Elteren, J. T., Vanhaecke, F., Rončević, S., Šala, M., Vanhaecke, F. & Van Acker, T., Analytica Chimica Acta, 2024, 1287, 342089