Advanced analytical methodologies for characterizing inorganic nanoparticles and assessing their impact on the aquaculture sector

Nanomaterials, mainly inorganic nanoparticles (NPs), have brought about a revolution at the scientific and industrial level due to their outstanding physicochemical properties. The widespread use of NPs has raised concerns about their potential impact into the environment and, consequently, the risk to humans. Toxicological studies are therefore required to assess the threats associated to these emerging pollutants. This doctoral thesis presents several nanometrological tools to face the challenge of improving the detection, characterization, and quantification of NPs in complex samples. The developed applications were focused on aquaculture products by assessing the potential effects from NPs on the cultured fish and shellfish species

Single-particle inductively coupled plasma mass spectrometry using ammonia reaction gas as a reliable and free-interference determination of metallic nanoparticles

Intensive production of nanomaterials, especially metallic nanoparticles (MNPs), and their release into the environment pose several risks for humans and ecosystem health. Consequently, high-efficiency analytical methodologies are required for control and characterization of these emerging pollutants. Single-particle inductively coupled plasma – mass spectrometry (SP-ICP-MS) is a promising technique which allows the determination and characterization of MNPs. However, several elements or isotopes are hampered by spectral interferences, and dynamic-reaction cell (DRC) technology is becoming a useful tool for free interference determination by ICP-MS. DRC-based SP-ICP-MS methods using ammonia as a reaction gas (either on-mass approach or mass-shift approaches) have been developed for determining titanium dioxide nanoparticles (TiO2 NPs), copper oxide nanoparticles (CuO NPs), copper nanoparticles (Cu NPs), and zinc oxide nanoparticles (ZnO NPs). The effects of parameters such as ammonia flow rate and dwell time on the peak width (NP transient signal in SP-ICP-MS) were comprehensively studied. Influence of NP size and nature were also investigateThe authors wish to acknowledge the financial support of the Ministerio de Economía y Competitividad (INNOVANANO projects, reference RT2018-099222-B-100), and the Xunta de Galicia (Grupo de Referencia Competitiva, grant number ED431C2018/19)S

Exploiting dynamic reaction cell technology for removal of spectral interferences in the assessment of Ag, Cu, Ti, and Zn by inductively coupled plasma mass spectrometry

Analytical methods based on dynamic-reaction cell (DRC) technology using ammonia as a reaction gas have been developed for the determination of ultra-trace Ti, Zn, Cu and Ag by inductively coupled plasma mass spectrometry (ICP-MS). Challenging spectral interferences from complex matrices were demonstrated to be overcome by DRC, and several DRC approaches (on-mass and mass-shift) using ammonium (NH3) as a reaction gas were assessed and compared to the standard or “vented” mode analysis. Ammonium cluster ions were generated for Ti, Cu, Zn, and Ag (mass shift approach). The on-mass approach was also explored to take advantage of collisional focusing phenomena. In addition, DRC operating conditions were optimised by modifying NH3 gas flow rate and rejection parameter q (RPq). The optimised conditions were applied to show the usefulness of either on-mass or mass-shift approaches when removing Ca and P interferences. Finally, the sensitivity of all measurement modes was studied and excellent limits of detection (at few ng L−1 levels) were assessedThe authors wish to acknowledge the financial support of the Ministerio de Economía y Competitividad, Gobierno de España (project INNOVANANO, reference RT2018-099222-B-100), and the Xunta de Galicia (Grupo de Referencia Competitiva, grant number ED431C2018/19)S

Quantitative titanium imaging in fish tissues exposed to titanium dioxide nanoparticles by laser ablation-inductively coupled plasma-mass spectrometry

Imaging studies by laser ablation–inductively coupled plasma mass spectrometry have been successfully developed to obtain qualitative and quantitative information on the presence/distribution of titanium (ionic titanium and/or titanium dioxide nanoparticles) in sea bream tissues (kidney, liver, and muscle) after exposure assays with 45-nm citrate-coated titanium dioxide nanoparticles. Laboratory-produced gelatine standards containing ionic titanium were used as a calibration strategy for obtaining laser ablation–based images using quantitative (titanium concentrations) data. The best calibration strategy consisted of using gelatine-based titanium standards (from 0.1 to 2.0 μg g−1) by placing 5.0-μL drops of the liquid gelatine standards onto microscope glass sample holders. After air drying at room temperature good homogeneity of the placed drops was obtained, which led to good repeatability of measurements (calibration slope of 4.21 × 104 ± 0.39 × 104, n = 3) and good linearity (coefficient of determination higher than 0.990). Under the optimised conditions, a limit of detection of 0.087 μg g−1 titanium was assessed. This strategy allowed to locate prominent areas of titanium in the tissues as well as to quantify the bioaccumulated titanium and a better understanding of titanium dioxide nanoparticle spatial distribution in sea bream tissuesOpen Access funding provided thanks to the CRUE CSIC agreement with Springer Nature. Authors thank funding from European Union—Interreg POCTEP (ACUINANO, reference 07-12-ACUINANO_1_E); Ministerio de Economía y Competitividad (FOODNANORISK, reference PID2021-125276NB-I00); and Xunta de Galicia (Grupo de Referencia Competitiva, reference ED431C 2022/029)S

Synthetic cathinones determination by liquid chromatography-mass spectrometry after ultrasound membrane assisted extraction

The extraction time for membrane-assisted solvent extraction (MASE) when isolating synthetic cathinones from urine has been speeded up to 30 min by using ultrasounds. Separation and determination of eleven synthetic cathinones was further performed liquid chromatography-tandem mass spectrometry (LC-MS/MS). The ultrasound assisted MASE consisted of adjusting 5.0 mL of urine at pH 11.8 and performing the extractive process with 400 μL of n-hexane as an acceptor phase inside the polypropylene membrane under ultrasonication at room temperature. Synthetic cathinones exhibiting LogP values higher than 2.0, such as 3,4-dimethyl methcathinone, methylendioxypyrovalerone, and naphyrone), were efficiently extracted and pre-concentrated. Other synthetic cathinones (LogP between 2.0 and 0.7) were found to exhibit a lower mass transfer. The method was found to be matrix dependent, and a matrix-matched calibration was required for measurements. The achieved limits of detection (LOD) were between 0.03 (flephedrone) to 0.29 (ethylone) µg L-1, with relative standard deviations (RSDs) within the 6–14% and 7–19% ranges for intraday and inter-day assays, and intraday and inter-day analytical recoveries from 84 to 115% and 85 to 118%, respectively. The developed method was finally applied to urine samples from volunteers attending a music festivalThis work was supported by the Dirección Xeral de I + D – Xunta de Galicia Grupos de Referencia Competitiva (project number ED431C 2022/029)S

Single‑cell ICP‑MS for studying the association of inorganic nanoparticles with cell lines derived from aquaculture species

The current research deals with the use of single-cell inductively coupled plasma-mass spectrometry (scICP-MS) for the assessment of titanium dioxide nanoparticle (TiO2 NP) and silver nanoparticle (Ag NP) associations in cell lines derived from aquaculture species (sea bass, sea bream, and clams). The optimization studies have considered the avoidance of high dissolved background, multi-cell peak coincidence, and possible spectral interferences. Optimum operating conditions were found when using a dwell time of 50 μs for silver and 100 μs for titanium. The assessment of associated TiO2 NPs by scICP-MS required the use of ammonia as a reaction gas (flow rate at 0.75 mL min−1) for interference-free titanium determinations (measurements at an m/z ratio of 131 from the 48Ti(NH)(NH3)4 adduct). The influence of other parameters such as the number of washing cycles and the cell concentration on accurate determinations by scICP-MS was also fully investigated. Cell exposure trials were performed using PVP-Ag NPs (15 and 100 nm, nominal diameter) and citrate-TiO2 NPs (5, 25, and 45 nm, nominal diameter) at nominal concentrations of 10 and 50 μg mL−1 for citrate-TiO2 NPs and 5.0 and 50 μg mL−1 for PVP-Ag NPs. Results have shown that citrate-TiO2 NPs interact with the outer cell membranes, being quite low in the number of citrate-TiO2 NPs that enters the cells (the high degree of aggregation is the main factor which leads to the aggregates being in the extracellular medium). In contrast, PVP-Ag NPs have been found to enter the cellsOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. European Union – Interreg POCTEP (ACUINANO, reference 07-12-ACUINANO_1_E); Ministerio de Economía y Competitividad (FOODNANORISK, reference PID2021-125276NB-I00); and Xunta de Galicia (Grupo de Referencia Competitiva, reference ED431C 2022/029)S