Flávio Venâncio Nakadi

@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{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{D3JA00420A,

title = {Boron elemental and isotopic determination via the BF diatomic molecule using high-resolution continuum source graphite furnace molecular absorption spectrometry},

author = {Maite Aramendía and André L. M. Souza and Flávio V. Nakadi and Martín Resano},

url = {http://dx.doi.org/10.1039/D3JA00420A},

doi = {10.1039/D3JA00420A},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

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

volume = {39},

pages = {767-779},

publisher = {The Royal Society of Chemistry},

abstract = {Boron trace determination in biological materials is needed in different fields of application. Direct B determination by means of Graphite Furnace Atomic Absorption Spectrometry (SS-GFAAS) has been used in the past for this purpose, offering good detection limits hardly achievable by other techniques. However, such methods require the use of high atomization temperatures combined with large integration times to promote B atomization, which dramatically reduces the lifetime of the instrument's graphite parts. In this work, a new perspective for B determination by means of Graphite Furnace Molecular Absorption Spectrometry (GFMAS) is proposed. B was detected as the diatomic molecule BF (boron monofluoride), deploying a gas phase reaction with CH3F as fluorinating agent. Based on this strategy, a method for the direct determination of B in two biological certified reference materials (NIST SRM 1570a spinach leaves and NIST SRM 1573a tomato leaves) has been developed, providing similar detection capabilities to the GFAAS method (LOD of 0.24 ng) but requiring much milder furnace conditions. Moreover, the appearance of memory effects, very common in GFAAS methods, is also avoided with this method. Straightforward calibration with aqueous standard solutions was also found to be possible. To this end, a mixture of W (permanent), citric acid, and Ca as chemical modifiers was found to be essential for obtaining a reproducible and sufficiently sensitive signal for boron solutions, comparable to the signals obtained for the solid samples. With this method, accurate results were obtained for the direct analysis of both certified reference materials, provided that spectral interferences from the PO molecule were properly corrected. Precision values in the range of 15% RSD, as typically reported for direct solid sampling GFAAS, were found. Finally, and as an additional advantage of the GFMAS method, a large isotopic shift in the absorbance of the 10BF and 11BF molecules can be accurately monitored at a secondary transition for the BF molecule. This offers novel analytical possibilities for the method, which are also explored in this study. In this regard, control of the B concentration was found to be critical for obtaining accurate and precise isotope ratios for this element.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{FREIRE2024126417,

title = {Tracing isotopically labeled selenium nanoparticles in plants via single-particle ICP-mass spectrometry},

author = {Bruna Moreira Freire and Ana Rua-Ibarz and Flávio Venâncio Nakadi and Eduardo Bolea-Fernandez and Juan J. Barriuso-Vargas and Camila Neves Lange and Maite Aramendía and Bruno Lemos Batista and Martín Resano},

url = {https://www.sciencedirect.com/science/article/pii/S0039914024007963},

doi = {https://doi.org/10.1016/j.talanta.2024.126417},

issn = {0039-9140},

year  = {2024},

date = {2024-01-01},

journal = {Talanta},

volume = {277},

pages = {126417},

abstract = {Abstract 

Agronomic biofortification using selenium nanoparticles (SeNPs) shows potential for addressing selenium deficiency but further research on SeNPs-plants interaction is required before it can be effectively used to improve nutritional quality. In this work, single-particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) was used for tracing isotopically labeled SeNPs (82SeNPs) in Oryza sativa L. tissues. For this purpose, SeNPs with natural isotopic abundance and 82SeNPs were synthesized by a chemical method. The NPs characterization by transmission electron microscopy (TEM) confirmed that enriched NPs maintained the basic properties of unlabeled NPs, showing spherical shape, monodispersity, and sizes in the nano-range (82.8 ± 6.6 nm and 73.2 ± 4.4 nm for SeNPs and 82SeNPs, respectively). The use of 82SeNPs resulted in an 11-fold enhancement in the detection power for ICP-MS analysis, accompanied by an improvement in the signal-to-background ratio and a reduction of the size limits of detection from 89.9 to 39.9 nm in SP-ICP-MS analysis. This enabled 82SeNPs to be tracked in O. sativa L. plants cultivated under foliar application of 82SeNPs. Tracing studies combining SP-ICP-MS and TEM-energy-dispersive X-ray spectroscopy data confirmed the uptake of intact 82SeNPs by rice leaves, with most NPs remaining in the leaves and very few particles translocated to shoots and roots. Translocation of Se from leaves to roots and shoots was found to be lower when applied as NPs compared to selenite application. From the size distributions, as obtained by SP-ICP-MS, it can be concluded that a fraction of the 82SeNPs remained within the same size range as that of the applied NP suspension, while other fraction underwent an agglomeration process in the leaves, as confirmed by TEM images. This illustrates the potential of SP-ICP-MS analysis of isotopically enriched 82SeNPs for tracing NPs in the presence of background elements within complex plant matrices, providing important information about the uptake, accumulation, and biotransformation of SeNPs in rice plants.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nano13121838,

title = {An Approach Based on an Increased Bandpass for Enabling the Use of Internal Standards in Single Particle ICP-MS: Application to AuNPs Characterization},

author = {Antonio Bazo and Maite Aramendía and Flávio V. Nakadi and Martín Resano},

url = {https://www.mdpi.com/2079-4991/13/12/1838},

doi = {10.3390/nano13121838},

issn = {2079-4991},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {Nanomaterials},

volume = {13},

number = {12},

abstract = {This paper proposes a novel approach to implement an internal standard (IS) correction in single particle inductively coupled plasma mass spectrometry (SP ICP-MS), as exemplified for the characterization of Au nanoparticles (NPs) in complex matrices. This approach is based on the use of the mass spectrometer (quadrupole) in bandpass mode, enhancing the sensitivity for the monitoring of AuNPs while also allowing for the detection of PtNPs in the same measurement run, such that they can serve as an internal standard. The performance of the method developed was proved for three different matrices: pure water, a 5 g L−1 NaCl water solution, and another water solution containing 2.5% (m/v) tetramethylammonium hydroxide (TMAH)/0.1% Triton X-100. It was observed that matrix-effects impacted both the sensitivity of the NPs and their transport efficiencies. To circumvent this problem, two methods were used to determine the TE: the particle size method for sizing and the dynamic mass flow method for the determination of the particle number concentration (PNC). This fact, together with the use of the IS, enabled us to attain accurate results in all cases, both for sizing and for the PNC determination. Additionally, the use of the bandpass mode provides additional flexibility for this characterization, as it is possible to easily tune the sensitivity achieved for each NP type to ensure that their distributions are sufficiently resolved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}