Enhancing Transport Efficiency Using an Optimized Infrared-Heated Sample Introduction System for Yeast Cell Analysis by Single Cell Inductively Coupled Plasma Mass Spectrometry

Single cell inductively coupled plasma mass spectrometry (scICPMS) enables quantitative determination of elemental content in individual cells, providing access to cellular heterogeneity that is obscured in bulk analyses. However, its analytical performance is strongly constrained by sample introduction efficiency, particularly for biological cells whose transport behaviour differs markedly from dissolved standards and nanoparticles. In this work, an infrared (IR)–heated pneumatic sample introduction system based on a modified cyclonic spray chamber was systematically optimized for scICPMS analysis of Saccharomyces cerevisiae for Se. Multivariate optimization was performed using a Se-enriched yeast certified reference material (SELM-1), with the number of detected cell events serving as a practical proxy for transport efficiency. The effects of IR-heating temperature, nebulizer gas flow rate, sample uptake rate, and sampling position were studied using cell suspensions rather than standard solutions to better reflect cell transport and detection behaviour. Under optimized conditions (150 °C, 5 µL min⁻¹ uptake rate), the IR-heated system achieved a cell transport efficiency of 47 ± 6%, representing a substantial improvement compared with a conventional cyclonic spray chamber (1.1 ± 0.4%) and exceeding that of a commercial single cell introduction system (30 ± 3%). Detection limits of 100–120 ag per cell were obtained for both ⁷⁸Se and ⁸²Se. The Se mass per cell determined by scICPMS (65–68 fg cell⁻¹) was consistent with independent estimates derived from certified total Selenium concentration and bulk digestion measurements, confirming analytical accuracy. Temperature-dependent experiments revealed an upper heating threshold beyond which cell lysis occurred, emphasizing the necessity of optimization using cell-based matrices. Overall, this study demonstrates that controlled IR-heated sample introduction significantly enhances transport efficiency and enables reliable single cell Se quantification without requiring independent transport efficiency calibration.