Antonio Bazo Sánchez

@article{MATALONI2027130379,

title = {Determining Si/Al atomic ratios in particulate matter via quadrupole single-particle ICP-MS with combined unit-mass and bandpass resolution modes: a proof-of-concept study on Antarctic snow},

author = {Matilde Mataloni and Antonio Bazo and Eduardo Bolea-Fernandez and Ana Rua-Ibarz and Maite Aramendía and Lucas Güemes and Carlos Téllez and Joaquín Coronas and Marco Grotti and Martín Resano},

url = {https://www.sciencedirect.com/science/article/pii/S0039914026010350},

doi = {https://doi.org/10.1016/j.talanta.2026.130379},

issn = {0039-9140},

year  = {2027},

date = {2027-01-01},

urldate = {2027-01-01},

journal = {Talanta},

volume = {312},

pages = {130379},

abstract = {Micrometer-scale mineral dust deposited in Antarctica represents a valuable archive for reconstructing atmospheric variability and for improving our understanding of dust-climate interactions. Among the various types of particle-specific information available, elemental ratios, such as the Si/Al atomic ratio, are especially useful as geochemical indicators of particle composition and provenance. However, the nature of these samples, characterized by coexisting particle populations and limited particle numbers, makes this determination particularly challenging. In this work, a novel quadrupole-based single-particle ICP-mass spectrometry (SP-ICP-QMS) approach to determine population-specific Si/Al atomic ratios containing chemically heterogeneous particle populations is presented. To overcome the sequential acquisition inherent to ICP-QMS instrumentation, Al and Si measurements at unit-mass resolution (m/z 27 and 28, respectively) were combined with bandpass acquisition centered at m/z 27 (2.47 ± 0.06 amu resolution at 10% peak height), enabling simultaneous collection of 27Al+ and 28Si + signals. This strategy was first used to identify the Al and Si distributions belonging to the same particle population and, consequently, to determine the corresponding atomic ratios in a suspension containing SiO2 microparticles (MPs) and two different types of synthesized zeolite MPs with different Si/Al atomic ratios. The reliability and accuracy of the method were confirmed by comparing the results with those obtained from individual Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX) and SP-ICP-MS characterization of the zeolite samples. As a proof-of-concept, the analysis of an Antarctic snow sample demonstrated the potential of the developed method to provide population-specific information – Si/Al atomic ratios – essential for environmental assessments based on high-resolution short-term records.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Direct Characterization of Halogen-Based Microplastics via Single-Event ICP-Mass Spectrometry in Negative-Ion Mode},

author = {Antonio Bazo and Eduardo Bolea-Fernandez and Ana Rua-Ibarz and Martín Resano and Hamid Badiei and David Clases and Andrea Raab and Jörg Feldmann and Raquel Gonzalez de Vega},

url = {https://pubs.acs.org/ancham/article/98/31/22977/5236192/Direct-Characterization-of-Halogen-Based},

doi = {10.1021/acs.analchem.6c02321},

year  = {2026},

date = {2026-07-28},

urldate = {2026-07-28},

journal = {Anal. Chem.},

volume = {98},

issue = {31},

pages = {22977-22987},

abstract = {Halogen-containing microplastics such as polytetrafluoroethylene (PTFE) and poly(vinyl chloride) (PVC) are analytically relevant targets, yet their selective characterization by ICP-MS remains challenging, particularly for fluoropolymers due to the limited formation of F+ in conventional positive-ion mode. Here we introduce negative-ion single-event ICP-MS as a direct strategy for particle-resolved characterization of halogen-containing microplastics by monitoring F– and Cl– on a quadrupole ICP-MS without plasma modifiers or proxy-ion chemistry. PTFE and PVC particle standards were used as well-defined model systems, with scanning electron microscopy (SEM) confirming particle morphology and size distributions. Key acquisition and instrumental conditions governing event detectability were systematically optimized, enabling reliable transient detection at a dwell time of 100 μs. Using a conventional spray-chamber configuration, size detection limits of 1.18 μm (PTFE) and 0.73 μm (PVC) were achieved, improving to 0.68 μm (PTFE) and 0.45 μm (PVC) with a high-efficiency sample introduction system. Quantification strategies for negative-mode operation, including external calibration and transport-efficiency-based workflows, were further assessed. Overall, this work establishes negative-ion mode single-event ICP-MS as a direct platform for fluorine- and chlorine-selective microplastic detection and sizing, expanding the analytical scope of particle-resolved microplastic analysis beyond indirect fluorine detection or carbon-based approaches.},

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 = {97},

pages = {24065-24072},

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{,

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 = {Analytical Chemistry},

volume = {97},

pages = {13922-13929},

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{BAZO2025344694,

title = {Improving detection and figures of merit in single-particle inductively coupled plasma-mass spectrometry via transient event heights},

author = {Antonio Bazo and Lorién López-Villellas and Matilde Mataloni and Eduardo Bolea-Fernandez and Ana Rua-Ibarz and Marco Grotti and Maite Aramendía and Martín Resano},

url = {https://www.sciencedirect.com/science/article/pii/S0003267025010888},

doi = {https://doi.org/10.1016/j.aca.2025.344694},

issn = {0003-2670},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

journal = {Analytica Chimica Acta},

volume = {1378},

pages = {344694},

abstract = {Background 

Single-particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) is a powerful method for characterizing micro- and nanoparticulate materials. The technique primarily relies on the linear relationship between the integrated intensities of individual events (peak areas) and the analyte mass, though transit times (peak widths) have also been used for quantitative purposes. This work (1) evaluates the potential of using peak heights as analytical signals in SP-ICP-MS, (2) introduces a new method for determining peak heights, and (3) explores scenarios in which peak height offers added value over the commonly used SP-ICP-MS signals. 

Results 

A new method was proposed to estimate peak height values in SP-ICP-MS accurately. The cumulative intensity across consecutive dwell times was modeled using a third-degree polynomial, from which the adjusted peak height was derived. This approach reduces the uncertainty associated with using raw maximum intensity values, yielding NP distributions comparable to those obtained via integrated intensities. The effect of dwell time on peak height was also evaluated. An optimal range (50 μs–200 μs) was identified, where a linear relationship was observed between the peak height and the square of the NP diameter. Within this range, peak height showed the lowest bias when characterizing smaller NPs, indicating the potential to improve the limit of quantification (LoQ). Additionally, peak heights proved helpful in determining the limit of detection (LoD) and setting appropriate threshold values for data processing, thereby helping to flag incorrect resultsand addressing a challenge in SP-ICP-MS analysis. 

Significance 

This is the first study to evaluate peak height as an analytical signal in SP-ICP-MS. The results highlight its advantages in specific applications, such as sizing NPs near the LoD, and in supporting the more reliable use of other signals, such as peak areas, by helping to identify incorrect threshold selection that could lead to biased distributions. Finally, monitoring peak heights allows for a more realistic and assumption-free determination of the LoD.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}