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Electrical asymmetric-flow field-flow fractionation (EAF4) is a new and interesting analytical technique recently proposed for the characterization of metallic nanoparticles (NPs). It has the potential to simultaneously provide relevant information about size and electrical parameters, such as electrophoretic mobility (μ) and zeta-potential (ζ), of individual NP populations in an online instrumental setup with an array of detectors. However, several chemical and instrumental conditions involved in this technique are definitely influential, and only few applications have been proposed until now. In the present work, an EAF4 system has been used with different detectors, ultraviolet-visible (UV-vis), multi-angle light scattering (MALS), and inductively coupled plasma with triple quadrupole mass spectrometry (ICP-TQ-MS) for the characterization of gold, silver, and platinum NPs with both citrate and phosphate coatings. The behavior of NPs has been studied in terms of retention time and signal intensity under both positive and negative current with results depending on the coating. Carrier composition, particularly ionic strength, was found to be critical to achieve satisfactory recoveries and a reliable measurement of electrical parameters. Dynamic light scattering (DLS) has been used as a comparative technique for these parameters. The NovaChem surfactant mix (0.01%) showed a quantitative recovery (93 ± 1%) of the membrane, but the carrier had to be modified by increasing the ionic strength with 200 μM of Na

Nanoscience and nanotechnology have emerged in recent years as revolutionary trends in almost all fields of activity. Their impact has taken place in the analytical science, too. Firstly, because the use of nanomaterials as analytical tools is more and more frequent and secondly, because the analytical control of nanomaterials in a wide variety of samples is required. In both aspects, analytical metrology for nanomaterials is involved as the scientific discipline responsible for providing reliable information (based on experimental measurements) to end users. This review presents a general view of the present achievements and the future challenges of analytical metrology for nanomaterials. Selected references and a critical discussion are reported for illustrating this important role of the metrology applied to nano-world.

Magnetic hybrid nanoparticles (MHNPs) are very interesting tools in analytical chemistry because they improve different steps of the analytical process. MHNPs contribute to sample preparation in terms of selectivity and sensitivity. They also simplify this often tedious and long step. Microextraction techniques have benefited to the point that magnetic solid phase extraction involves MHNPs as sorbents in almost all cases. In addition, they can improve resolution in chromatographic or electrophoretic separations, on which many analytical methods are based. Another critical step in which magnetic nanomaterials can be influential is detection, and new advantageous possibilities are being exploited. All these features are discussed in this chapter.

Migration of silver nanoparticles (AgNPs) from food containers (FCs) has been assessed for the first time using a screening method previously validated. Migration was evaluated using water and 3% acetic acid as food simulants (FSs), from 20 to 70 °C at contact times of 2 h and 10 days. Total and migrated Ag were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in the FCs and FSs, respectively. Then, the screening method was validated, and probability of detection (POD) curves were constructed in both FSs to characterize the response to AgNPs. The results provided by the present screening method showed no release of AgNPs. The FSs in contact with FCs were spiked at levels above, inside and below the unreliability region, with a reliability rate (RLR) of 0.90. Asymmetric flow field flow fractionation coupled to inductively coupled plasma mass-spectrometry (AF4-ICP-MS) was used for confirmative analyses.

Magnetic cellulose nanoparticles (MCNPs) coated with 1-butyl-3-methylimidazolium hexafluoro phosphate [C4MIM][PF6] ionic liquid (IL) through electrostatic interactions are proposed for the first time as sorbents in a magnetic solid phase extraction (MSPE) method for the determination of paracetamol (PAR), ibuprofen (IBU), naproxen (NAP) and diclofenac (DIC) in natural waters. The parameters that affect adsorption (dispersive solvent, amount of IL, pH and salt content) and desorption (desorption solvent, type of energy and time) were studied. The values that provided the maximum adsorption efficiency and extraction recovery were selected as optimum conditions for adsorption and desorption, respectively. Under the optimum conditions, the adsorption and desorption of all analytes was simultaneous and quantitative. High performance liquid chromatography (HPLC) with ultra violet (UV) and fluorescence (FL) detector was used after the sample preparation. The precision, expressed as relative standard deviation was between 1.4 and 7.6%. Limits of detection and quantification were in the range 3.2–7.2 μg L− 1 and 11–24 μg L− 1, respectively. Moreover, the proposed method provides enrichment factors from 29.0 to 34.2. Recovery studies on 10 mL of spiked tap, river and dam water samples at 50 and 100 μg L− 1 were carried out. The extraction recoveries were from 85 to 116%, and were in a comparable range regardless of the type of water. The method is simple, rapid, and environmentally friendly.

Dispersive solid phase extraction (DSPE) prior to capillary electrophoresis with ultraviolet and visible detection was used for the first time for the determination of dabrafenib (DB) and trametinib (TT), the main drugs used for the treatment of metastatic melanoma, in serum. Six different magnetic and non-magnetic nanomaterials were evaluated as DSPE sorbents for the extraction and preconcentration of the analytes. The best results were obtained with 4 mg of pristine multi-walled carbon nanotubes in phosphate buffer (pH 12.5; 10 mM). The electrophoretic separation was carried out in a fused silica capillary (30 cm × 75 µm i.d.) at 22 °C in a voltage ramp (8–12 kV) with a background electrolyte consisting of borate buffer (pH 9.2; 25 mM), 37 mM sodium dodecylsulfate, 22% (v/v) acetonitrile and 3% (v/v) methanol. The preconcentration factor achieved was 4, and the limits of detection were 0.012 and 0.008 mg L−1 for DB and TT in serum, respectively. Linearity was observed up to 5 mg/L and precision (n = 7) was below 3% in migration time and 7.8% in peak areas. The present method was applied to six patients under treatment with DB and TT for metastatic melanoma. It requires a less sophisticated instrumentation and lower volume of harmful organic solvents than the methods reported up to present.

A rapid and reliable method based on magnetic solid-phase extraction (MSPE) and ultra-high performance liquid chromatography (UHPLC-FLD) analysis was developed and validated for the quantitative determination of seven polycyclic aromatic hydrocarbons (PAHs) in water samples. Hybrid composites made up of magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) were tested as adsorbent materials. The main factors influencing the extraction yields were optimized, namely the amount and type of adsorbent in the adsorption, and the solvent, the type of energy and the time in the desorption step. The selected composite was made up of Fe3O4 and multiwalled (MW)-CNTs. The desorption was carried out with sonication probe and tetrahydrofuran (THF); this solvent makes the method directly compatible with the chromatographic mobile phase and it reduces the analysis time. Under the optimized conditions, the LODs and LOQs achieved were in the range of 0.025–0.73 and 0.04–2.4 ng mL−1, respectively. The calibration curves were linear (R 2 ≥ 0.9936) over the concentration ranges from 1 to 500 ng mL−1. The recoveries of PAHs were from 76.4 ± 1.7 up to 106.5 ± 3.5%. The method was applied to synthetic and real (tap, dam, river and mineral) water samples with different characteristics to evaluate the performance under real conditions.

Magnetic cellulose nanoparticles (MCNPs) were used for the first time as sorbents for stir bar-sorptive dispersive microextraction (SBSDME). The main experimental parameters involved in the SBSDME process that affect extraction (i.e. amount of MCNPs, ionic strength, pH, extraction and back-extraction time) were investigated. The method was applied to the determination of nine polychlorinated biphenyls (PCBs) in fruit juice samples by gas chromatography–mass spectrometry (GC-MS). Under the optimized conditions, a good linearity was obtained in a concentration range of 10–1000 ng mL−1 with determination coefficients over 0.9945. Limits of detection and quantification for all target PCBs were in the range 2.1–54 ng L−1 and 7.0–180 ng L−1, respectively. Intra-day precision ranged from 1.7% to 8.8% and inter-day precision from 3.4% to 9.3% RSD. The enrichment factors of the analytes were from 74.6 to 98.2. The MCNPs can be reused up to 5 times. The method was applied to commercial orange and pineapple juices (n = 5), where concentrations were below the limits of detection. Recoveries from 70.4 to 108.0% were obtained by applying the method for the analysis of spiked fruit juice samples at 1 and 2 ng mL−1 concentration levels. The use of cellulose makes this approach environmentally friendly and the magnetism of the resulting sorbent in conjunction with SBSDME provides ease of handling and saving of time.

Magnetite (Fe3O4) nanoparticles were modified with nanocellulose and are showed to be a useful sorbent for magnetic solid-phase extraction of mercury species. Speciation analysis was performed by using gas chromatography coupled to atomic fluorescence detection (GC-pyro-AFS). The magnetic properties of the sorbent make this approach simple and rapid, and the use of a renewable and biodegradable nanomaterial (nanocellulose) makes it environmentally friendly. The factors that affect adsorption (pH value, amount of nanomaterial, time, volume of sample) and desorption (solvent, time) have been optimized. Both desorption and derivatization of mercury species were performed in a single step. This reduces considerably the sample preparation time. Under the optimized conditions, the limits of detection are 4.0 pg mL−1 for monomethylmercury and 5.6 pg mL−1 for inorganic mercury. The repeatability and reproducibility are satisfactory. The method enables inorganic mercury and monomethylmercury to be simultaneously extracted, with preconcentration factors up to 300. The potential interferences of organic matter and/or co-existing ions were also investigated using synthetic waters. The procedure was applied to the analysis of tap water and river water samples with different characteristics from a mercury polluted area (Almaden, Spain). The extraction recoveries ranged from 81 to 98% regardless of the type of water, which demonstrates the applicability of the method. This is the first time that this kind of sorbent is used for trace metal speciation.

The full characterization of nanomaterials (NMs), which requires a range of different and expensive equipment, is not always necessary to meet certain demands of information. Qualitative analytical methods are ideal alternatives when only a piece of information is required. In this work, a qualitative method for the screening of NMs has been developed and statistically validated for the first time, with silver nanoparticles (AgNPs) as a proof of concept. It is based on the generation of chemiluminescence of the luminol/Ag+ system in alkaline media in the presence of AgNPs. Measurements are obtained in a short time with a simple instrument. Probability of detection (POD) curves were constructed at three cut-off values next to the limit of detection of the chemiluminescent method. The unreliability region (UR) was from 0.50 to 1.82 μg L−1. Currently, no regulation on AgNPs exists, but the present method was successfully tested for a hypothetical threshold of 2.5 μg L−1 of 40 nm AgNPs. The method was applied to silver colored pearls, with silver (E-174) or aluminum (E-173) coating, used for decoration of pastry. Performance parameters such as false negative and positive rates as well as specificity, sensitivity and reliability rates were calculated for validation. The results of the screening method were confirmed by asymmetric flow field flow fractionation coupled to inductively coupled plasma mass spectrometry (AF4-ICP-MS). The proposed screening method is simple, fast, economic, and easy to transfer to routine laboratories in the field of food safety.

Objective We studied the effects of exercise training alone or combined with dietary supplementation of omega-3 polyunsaturated fatty acids (Ω-3PUFA) and oleate on metabolic syndrome (MSyn) components and other markers of cardiometabolic health. Methods Thirty-six patients with MSyn underwent 24 weeks of high-intensity interval training. In a double-blind randomized design, half of the group ingested 500 mL/day of semi-skim milk (8 g of fat; placebo milk) whereas the other half ingested 500 mL/day of skim milk enriched with 275 mg of Ω-3PUFA and 7.5 g of oleate (Ω-3 + OLE). Results Ω-3 + OLE treatment elevated 30% plasma Ω-3PUFA but not significantly (P = 0.286). Improvements in VO2peak (12.8%), mean blood pressure (−7.1%), waist circumference (−1.8%), body fat mass (−2.9%), and trunk fat mass (−3.3%) were similar between groups. However, insulin sensitivity (measured by intravenous glucose tolerance test), serum concentration of C-reactive protein, and high-density lipoprotein improved only in the Ω-3 + OLE group by 31.5%, 32.1%, and 10.3%, respectively (all P < 0.05). Fasting serum triacylglycerol, glucose, and plasma fibrinogen concentrations did not improve in either group after 24 weeks of intervention. Conclusions Diet supplementation with Ω-3PUFA and oleate enhanced cardiometabolic benefits of intense aerobic exercise training in patients with MSyn.

Ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) was used for the first time for the extraction and preconcentration of cortisone and cortisol from human saliva samples. This approach allows the determination of both compounds by liquid chromatography (LC) with ultra-violet/visible (UV/Vis) detection at physiological levels. The IL 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] and methanol (MeOH) were used as extraction and dispersive solvents, respectively. The parameters that affect extraction (ionic strength, pH, amount of IL, volume of dispersive solvent, vortex and centrifugation time) were optimized. Limits of detection were 0.11 (cortisone) and 0.16 μg L−1 (cortisol) and enrichment factors of 5.0 (cortisol) and 6.3 (cortisone) were achieved. Recoveries from 83.3 ± 1.6 to 115.8 ± 3.0% were obtained for the extraction of the target analytes in spiked human saliva samples. Intraday and interday precision, expressed as relative standard deviation, was below 4.2 and 7.8% for cortisone and cortisol, respectively. The method was successfully applied to the determination of cortisone and cortisol in saliva from healthy volunteers (n = 9) in the morning and in the evening. The method is simple, faster, and more environmentally friendly than the current ones.

Hybrid nanocomposites based on Fe3O4 magnetic nanoparticles (MNPs) coated with different types of carbon nanotubes (CNTs) have been studied for the first time as sorbent materials for magnetic solid phase extraction (MSPE) for mercury speciation analysis. Monomethylmercury (MMHg) was the target mercury species in water samples and the adsorption and desorption processes were optimized based on this species. Single-walled CNT-MNP showed higher adsorption capacity than double-walled or multi-walled CNTs. Then, the magnetic sorbent was retrieved with an external magnet and MMHg was selectively desorbed from it with dichloromethane (DCM) in two steps with vortex agitation. Inorganic mercury was removed during the desorption stage. The rapid adsorption and desorption equilibrium, the magnetic separation of the sorbent, and the simple and fast synthesis of CNT-MNPs without any additional modification of the CNTs simplified and shortened the extraction procedure. The extract was submitted to derivatization of the mercury species by ethylation (with an optional nitrogen stream evaporation of the organic phase) and injection into a gas chromatograph coupled to an atomic fluorescence detector (GC-pyro-AFS). The overall procedure provides the preconcentration of MMHg up to 150 times and the removal of inorganic mercury at the same time. The procedural limits of detection (LOD) and quantification (LOQ) were 5.4 and 17.9 pg mL−1, respectively. Moreover, magnetic nanocomposites can be reused at least 7 times without losing their efficiency. The methodology was validated in tap, dam and river water samples to evaluate the performance under real conditions with recoveries from 79% to 97% of spiked MMHg.