Martín Resano Ezcaray

@article{D6JA00062B,

title = {Single- and dual-isotopic analysis using high-resolution continuum-source graphite-furnace molecular absorption. Strategies for data selection, processing, and modeling},

author = {André L. M. Souza and Maite Aramendía and Esperanza García-Ruiz and Flávio V. Nakadi and Javier Resano and Martín Resano},

url = {http://dx.doi.org/10.1039/D6JA00062B},

doi = {10.1039/D6JA00062B},

year  = {2026},

date = {2026-01-01},

journal = {J. Anal. At. Spectrom.},

pages = {-},

publisher = {The Royal Society of Chemistry},

abstract = {This work evaluates different strategies for data processing, aiming at achieving isotopic information via high-resolution continuum-source graphite-furnace molecular absorption. For this purpose, two different molecules are investigated: CaF and CaCl. In the first case, only the measurement of 44Ca and 40Ca is pursued, whereas in the second case, isotopic variations affect both elements present in the molecule (44Ca and 40Ca, but also 37Cl and 35Cl). Thus, two different approaches are proposed. For Ca isotopic analysis through the monitoring of CaF, the effects of selecting the number of detection pixels and the number of molecular spectra, as well as of using a regression approach for temporal data, are discussed. Overall, using three detector pixels and using this regression approach tend to produce the best results (0.5–1.0% RSD) for isotopic analysis via HR CS GFMAS in those situations in which the signal can be derived from two separate peaks. On the other hand, to perform simultaneous Ca and Cl isotopic analysis by monitoring CaCl, a machine-learning strategy is proposed. The performance of such a model is promising for isotopic abundances of at least 10% (median absolute percentage error of 1.21%), while the error escalates when one of the isotopes shows a lower abundance. To detect such underperforming situations in real-world settings, it is recommended to monitor the prediction uncertainty to set thresholds and flag results with poor reliability.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Discrete Entity Analysis via Microwave-Induced Nitrogen Plasma–Mass Spectrometry in Single-Event Mode},

author = {Ana Rua-Ibarz and Flávio V. Nakadi and Eduardo Bolea-Fernandez and Antonio Bazo and Beatrice Battistella and Anna Matiushkina and Ute Resch-Genger and Carlos Abad and Martín Resano},

url = {https://doi.org/10.1021/acs.analchem.5c04341},

doi = {10.1021/acs.analchem.5c04341},

year  = {2025},

date = {2025-10-14},

urldate = {2025-10-14},

journal = {Analytical Chemistry},

volume = {0},

number = {0},

pages = {null},

abstract = {In this work, single-event microwave-induced nitrogen plasma–mass spectrometry (single-event MINP-MS) was evaluated for the first time for the analysis of discrete entities such as nanoparticles, biological cells, and microplastics. Nitrogen (N2) effectively overcomes Ar-based polyatomic interferences, enabling (ultra)trace element determination of Fe and Se using their most abundant isotopes, 56Fe (91.66%) and 80Se (49.82%). Iron oxide nanoparticles (Fe2O3 NPs) ranging from 20 to 70 nm were accurately characterized, with excellent agreement with established sizing techniques, such as transmission electron microscopy (TEM) and dynamic light scattering (DLS). A limit of detection (LoD) of 8.6 ag for Fe─equivalent to an LoDsize of 19 nm for Fe2O3─was achieved, which is significantly lower than recent values reported for high-end quadrupole-based ICP-MS. Selenium nanoparticles (SeNPs) of 150 and 250 nm were also accurately characterized, without the N2-based plasma experiencing issues handling relatively large metallic NPs (linearity, R2 = 0.9994). Se-enriched yeast cells (SELM-1 certified reference material) were successfully analyzed via single-cell MINP-MS using external calibration based on SeNPs and a transport efficiency-independent approach. In addition, 2–3 μm polystyrene (PS) and polytetrafluoroethylene (PTFE) were accurately sized by monitoring 12C+, confirming the method’s suitability for handling micrometer-sized polymeric materials (microplastics). The average duration of individual events (680 ± 160 μs) suggests that the digestion of individual entities in N2-based plasmas is comparable to that in Ar-based plasmas. These results open new avenues for this instrumentation as an alternative to ICP ionization sources, also in the context of discrete entity analysis.},

note = {PMID: 41084806},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ions with Ions, Entities with Entities: A Proof-of-Concept Study Using the SELM-1 Yeast Certified Reference Material for Intra- and Extracellular Se Quantification via Single-Cell ICP-Mass Spectrometry},

author = {Antonio Bazo and Eduardo Bolea-Fernandez and Ana Rua-Ibarz and Maite Aramendía and Martín Resano},

url = {https://pubs.acs.org/doi/10.1021/acs.analchem.5c01588},

doi = {https://doi.org/10.1021/acs.analchem.5c01588},

issn = {1520-6882},

year  = {2025},

date = {2025-06-07},

urldate = {2025-06-07},

journal = {Anal. Chem.},

abstract = {In this work, two novel nanoparticle (NP)-based calibration strategies, external calibration and a relative method, have been explored for single-cell ICP-mass spectrometry (SC-ICP-MS) analysis. The fundamental principle of these methods is to rely on individual entities (well-characterized NPs of the target analyte) for calibration rather than on ionic standard solutions. The performance of the NP-based calibration approaches has been compared to that of the reference method (particle size with AuNP standards). In addition to the intracellular Se content (mass per individual cell), the extracellular Se (dissolved fraction) was also determined directly and simultaneously using the average background from the SC-ICP-MS time-resolved signal. The figures-of-merit of the methods developed have been evaluated by relying on the analysis of the SELM-1 cell-certified reference material, consisting of Se-enriched yeast cells, and certified for its total Se content (intracellular + extracellular Se). All methods successfully determined the Se elemental contents, but an improvement in accuracy and precision was observed for the NP-based methods compared to the reference one. Furthermore, the NP-based methods were found to be less time-consuming, more straightforward, and more user-friendly in terms of calculations. These results open new avenues for calibration in quantitative SC-ICP-MS analysis and call for a fundamental change in the methodology, where the determination of ionic contents is based on the use of ionic standard solutions for calibration, while the determination of elemental contents in discrete micro/nanoentities, such as cells, should ideally be based on calibration using standard entities, thus avoiding the need to calculate a transport efficiency coefficient.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{NAKADI2025127920,

title = {LAMIS in the gas phase: A new approach for obtaining Ca elemental and isotopic information via CaF molecule formation},

author = {Flávio V. Nakadi and Alicia Garcia-Garcia and Ana Rua-Ibarz and Martín Resano},

url = {https://www.sciencedirect.com/science/article/pii/S0039914025004102},

doi = {https://doi.org/10.1016/j.talanta.2025.127920},

issn = {0039-9140},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

journal = {Talanta},

volume = {292},

pages = {127920},

abstract = {This work introduces a novel method for generating the calcium monofluoride (CaF) diatomic molecule by adding the molecule-forming reagent in the gaseous phase (a methyl fluoride-argon mixture), in order to perform laser-induced breakdown spectroscopy (LIBS) and laser ablation molecular isotopic spectrometry (LAMIS) measurements. By optimizing the instrumental parameters, CaF molecule formation was successfully achieved within the plasma plume, upon ablation of dried liquid samples. The isotopic shift for the X2Σ→A2Π (0,1) CaF vibronic transition at 583.0 nm was calculated to be 292.3 pm. The method proved capable of providing quantitative information for determining calcium concentrations in real samples, such as tap water and skimmed milk, using internal standardization (with Sr as internal standard; limit of detection, LOD, 20 mg L−1) and isotope dilution (which can be applied from 400 mg L−1on), respectively. Partial least squares regression (PLS) analysis was employed to enhance the quality of the isotopic data. The Ca concentration found in the tap water was 47 ± 16 mg L−1 (reference flame atomic absorption spectrometry, FAAS, value: 59 ± 0.2 mg L−1), and 1100 ± 140 mg L−1 for the skimmed milk (reference FAAS value: 1240 ± 120 mg L−1). No significant difference between LIBS and FAAS results could be established using a t-test at the 95% confidence level. Overall, this novel approach allows for the determination of calcium in terms of both the elemental concentration and the isotopic composition, thus broadening the applicability of LIBS (e.g., for tracer experiments, besides the already mentioned application of isotope dilution).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{D5JA00253B,

title = {A novel particle mass calibration strategy for the quantification of AuNPs in single cancer cells via laser ablation ICP-mass spectrometry. A case study},

author = {Antonio Bazo and Eduardo Bolea-Fernandez and Kharmen Billimoria and Ana Rua-Ibarz and Maite Aramendía and Paula Menero-Valdés and Jack Morley and Sara Neves and Armando Sánchez-Cachero and Heidi Goenaga-Infante and Martín Resano},

url = {http://dx.doi.org/10.1039/D5JA00253B},

doi = {10.1039/D5JA00253B},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

journal = {J. Anal. At. Spectrom.},

pages = {-},

publisher = {The Royal Society of Chemistry},

abstract = {Laser ablation ICP-mass spectrometry (LA-ICP-MS) has developed as a powerful tool for elemental quantitative analysis of individual cells, assuring that the content of each cell is analyzed individually. However, this technique is still limited by the difficulties associated with calibration using solid standards. This work proposes a particle mass calibration strategy that is independent of both the properties and thickness of the gelatin films used for calibration, overcoming a significant drawback of previously established methods. The fundamental principle of this strategy relies on the individual ablation of nanoparticles (NPs) of well-characterized size that are embedded in the films, so that their mass can be directly used for calibration without the need to calculate their exact concentration within the gelatin. The performance of the newly developed method was compared to that of the previously reported approaches (ionic and particle number calibration) in terms of linearity and homogeneity between different films prepared from the same gelatin solution. As a case study, the three calibration strategies were used for the quantitative analysis of HeLa cancer cells exposed to AuNPs. In parallel, in-suspension single-cell (SC) ICP-MS Au data were obtained and used as reference for comparison with the three LA-SC-ICP-MS strategies. The results obtained with the novel particle mass approach demonstrated better accuracy and repeatability over three different working sessions, addressing key limitations and providing a robust and reliable method for quantitative LA-SC-ICP-MS analysis. The particle mass method holds promise for quantitative LA-ICP-MS analysis of samples beyond NP-exposed cells, such as biological tissues.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}