María Carmen Barciela-Alonso

Speciation and bioavailability studies have become essential tools for understanding the environmental behaviour, toxicity, and health risks associated with chemical contaminants. Unlike total elemental concentrations, speciation analysis provides detailed information on the chemical forms of elements, which largely determine their mobility, persistence, bioavailability, and toxicological impact. This chapter reviews recent advances in speciation and bioavailability research, with particular emphasis on chemically and regulatory relevant contaminants, including As, Cr, Hg, Pb, organotin compounds, polyfluoroalkyl substances (PFAS), and engineered nanomaterials. The relationships between chemical form, exposure pathways, and adverse health effects are discussed alongside current European and international regulatory frameworks. Advances in analytical methodologies, particularly hyphenated techniques combining separation and element-specific detection, have improved the characterization of chemical species in complex environmental, food, and biological matrices. The chapter highlights how speciation data support risk assessment and regulatory decision-making, while identifying remaining challenges related to standardization, analytical complexity, and future implementation.

The increasing industrial use of silver nanoparticles (AgNPs) has led to interest in their determination in different types of environmental complex samples, including saline matrices such as aquaculture waters. A simple, reliable, and green analytical method using instrumentation available in most of the laboratories has been developed for the determination of silver as nanoparticles in saline samples. Cloud point extraction (CPE) was used for the separation of AgNPs from seawater, and silver was then determined in the surfactant-rich extracts by electrothermal atomic absorption spectrometry (ETAAS). Parameters related to ETAAS and the cloud point extraction procedure (Triton X-114 concentration, volume of complexing agent (EDTA), pH and type of buffer, effect of repetitive extraction, matrix modifier, etc) were evaluated. A concentration of Triton X-114 of 12% (v/v), a volume of 750 μL of saturated EDTA, and a pH of 7.0 were selected as the optimum conditions for the separation of AgNPs. Standard addition calibration solutions in a concentration range from 0 to 3.0 μg L⁻¹ of AgNPs were subjected to the CPE procedure and used for silver determination by ETAAS. The LOD and LOQ were 0.038 and 0.125 μg L⁻¹ of silver (as AgNPs), respectively. The method is precise (whole procedure 9.7%) and accurate (recovery percentages 99±4%), showing a good selectivity for the extraction of AgNPs, while ionic Ag remains in the aqueous phase. Moreover, the results of size analysis of the nanoparticles in the surfactant extracts of seawater samples spiked with AgNPs (40 and 60 nm) by SP-ICP-MS and TEM were in good agreement. Graphical Abstract

Bioavailability studies on pollution pre-concentrator organisms such as algae and mussels are necessary to ensure food safety, particularly in the case of nanomaterials whose industrial applications have increased in recent years. Thus, the bioaccessibility and the bioavailability of total Ag and Ti and AgNPs and TiO₂NPs from raw and cooked seaweed (Palmaria palmata and Ulva sp.) and cooked mussels (Mytilus edulis) exposed to 1.0 mg L⁻¹ of 15 nm PVP-AgNPs, 1.0 mg L⁻¹ of 25 nm citrate-TiO₂NPs, or 1.0 mg L⁻¹ 5 nm citrate-TiO₂NPs, for 28 days, were evaluated. Samples were subjected to an in vitro process simulating human gastrointestinal digestion while cell transport from the intestinal lumen to the bloodstream was mimicked using Caco-2 cell cultures. Total Ag and Ti in the digest samples, the bioaccessible fractions, the apical, and basolateral fractions were determined by ICP-MS, while AgNPs and TiO₂NPs were determined by single-particle-ICP-MS (SP-ICP-MS). Finally, the presence of nanoparticles in the Caco-2 cells was verified by single-cell-ICP-MS (SC-ICP-MS). AgNP bioaccessibility ratios were between 22% and 97% for seaweed and 18% for mussels, while for TiO₂NPs were between 17% and 81% (seaweed) and 76% and 100% (mussels). Nanoparticle cellular transports were in all cases less than 1%. However, the mass percentages of Ag as NPs and Ti as NPs in the Caco-2 cells for raw and cooked seaweed were 9% and 7% and 20% and 6%, respectively. These results confirm a small transport of the nanoparticles through the Caco-2 cells under the proposed experimental conditions. Graphical abstract

Metals are present in cosmetics due to deliberate addition by the manufacturers, contamination of raw materials, and/or contamination during their manufacture or storage. The objective of this work was to explore the metal content in the most-consumed moisturising creams on the Spanish market, to verify their degree of compliance with Regulation (EC) No. 1223/2009 of the European Parliament and of the Council of the European Union, regarding the presence of metals in cosmetics. The moisturisers were digested (microwave-assisted acid digestion) and analysed by inductively coupled plasma-mass spectrometry (ICP-MS), for metal assessment. The ICP-MS measurements were successfully validated (RSDs lower than 5% and analytical recoveries within the 91–110% range). Metals banned in cosmetics were found at very low concentrations in some of the moisturisers, as inevitable traces of pollutants. This was the case with beryllium (found in only two samples, at concentrations lower than 0.10 µg g⁻¹), cadmium (found at 0.075 µg g⁻¹ in one sample), mercury (found in four samples at concentrations within the 0.10–0.18 µg g⁻¹ range), and lead (also found in four samples at concentrations from 0.03 to 0.44 µg g⁻¹). Furthermore, nickel (0.16–0.56 µg g⁻¹, six samples), chromium (0.09–0.30 µg g⁻¹, three samples), and cobalt (lower than 0.13 µg g⁻¹, two samples) were also found in the analysed creams.

Metals, metallic compounds, and, recently, metallic nanoparticles appear in textiles due to impurities from raw materials, contamination during the manufacturing process, and/or their deliberate addition. However, the presence of lead, cadmium, chromium (VI), arsenic, mercury, and dioctyltin in textile products is regulated in Europe (Regulation 1907/2006). Metal determination in fabrics was performed by inductively coupled plasma-mass spectrometry (ICP-MS) after microwave-assisted acid digestion. The ICP-MS procedure has been successfully validated; relative standard deviations were up to 3% and analytical recoveries were within the 90–107% range. The developed method was applied to several commercial textiles, and special attention has been focused on textiles with nanofinishing (fabrics prepared with metallic nanoparticles for providing certain functionalities). Arsenic content (in textile T4) and lead content (in subsamples T1-1, T1-2, and T3-3) were found to exceed the maximum limits established by the European Regulation 1907/2006. Although impregnation of yarns with mercury compounds is not allowed, mercury was quantified in fabrics T1-2, T5, and T6. Further speciation studies for determining hexavalent chromium species in sample T9 are necessary (hexavalent chromium is the only species of chromium regulated). Some textile products commercialised in Europe included in this study do not comply with European regulation 1907/2006.

Fruit juices were analysed for their contents in a series of essential and toxic elements (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, V, Sb, Mo and Zn). Samples were subjected to microwave-assisted acid digestion (HNO3/H2O2), and analytes were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), in axial mode, or by inductively coupled plasma mass spectrometry (ICP-MS), with kinetic energy discrimination, using 103Rh and 89Y as internal standards. The methods were validated, showing good precision (relative standard deviations < 10%), linearity and mean analytical recovery values (89 to 103%). The ICP-OES instrumental limits of detection (LODs) were between 0.3 μg L-1 (for Mg) and 1.5 μg L-1 (for Ca), whereas ICP-MS instrumental LODs varied from 2 ng L-1 (for Co, Mo and V) to 5.7 μg L-1 (for Na). Some toxic elements (As and Sb) were not detected in the fruit juices analyzed, Cd concentrations were below the maximum permitted level established by Brazilian and European regulations and only in one sample the Pb concentration (61.7 µg L-1) exceeded current legal limits. Besides, essential elements such as Ca, Mg and Na were in high concentrations in the samples analyzed.

A sensitive, precise and selective method for the analysis of butyl benzyl phthalate (BBP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and dimethyl phthalate (DMP) in tea samples has been applied. Molecularly Imprinted Polymer-Solid Phase Extraction (MIP-SPE) has been used for the separation and preconcentration of these compounds. Phthalates extracted by SPE were analysed by high-performance liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS). The method was sensitive (LOD < 2 µg L⁻¹), precise (RSD <10%) and accurate with recovery percentages ranging from 84% to 97%. Finally, the developed method was applied for the analysis of these phthalates in several tea samples marketed in bags. Migration studies were also performed to evaluate the concentration of phthalates released from the bags into the infusions, and teabag filters were analysed by Fourier-transform infrared spectroscopy. The migration study shows that tea filter bags contribute to the total phthalates concentration in tea infusion, and this contribution varies between 1.8 to 93.5 % of the total phthalates’ concentrations. Tea filter bags release higher DBP than BBP, DMP, and DEP.