The inductively coupled plasma (ICP) is a key energy source for efficient atomization, excitation, and ionization in atomic spectrometry. Plasma robustness, often represented as the Mg II/I line intensity ratio, is a well-known and commonly used diagnostic probe of energy transfer in the ICP. Typical ICP parameters are set to maximize plasma robustness with relatively large injection tube diameters, decreased nebulizer (i.e., carrier gas) flow rates, and increased radiofrequency powers. ICP optical emission spectrometry is more resistant to matrix effects at higher values of Mg II/I. We describe a strategy featuring machine learning to determine plasma robustness from non-analyte, plasmabased species of Ar, H, and O. We collected a representative dataset (n = 4450) of plasma robustness and nonanalyte signals at varying instrumental conditions and plasma environments. Tuned tree-based ensemble and neural network models yielded accurate predictions of Mg II/I robustness with root mean squared errors as low as 0.36 across the training and testing data. The trained models may be used to predict plasma robustness, given model imperfections for predictions in relatively extreme matrices. Once trained, the models do not require any physical modification to commercial instrumentation nor the addition of diagnostic elements to the plasma. This machine learning strategy with plasma-based species can be adapted to train predictive models for additional plasma characteristics.

Accurate technologies and methods are needed to monitor both total and methylmercury in the marine food supply. Thermal decomposition gold amalgamation atomic absorption spectrophotometry (TDA-AAS) is an efficient and cost-effective technique for measuring low levels of total mercury requiring no sample preparation. Measuring methylmercury with TDA-AAS requires isolating methylmercury from the matrix and other mercury species prior to detection. We developed a method that uses ethyl acetate instead of a legacy non-polar solvent, toluene. Toluene is a potentially hazardous and problematic solvent whereas ethyl acetate is greener and safer. Additionally, the salting-out assisted liquid-liquid extraction (SALLE) approach with ethyl acetate avoids emulsion formation throughout extraction. We describe method development and validation of a SALLE and TDA-AAS detection for methylmercury in finfish. From 10 reference materials, our method recovered 80-118% of total or methylmercury with Z scores ranging from -1.98 to 2.75 (n = 184). The LOD and LOQ of the method for methylmercury were 3.8 and 27 ng/g, respectively. From extraction to detection, accurate results were obtained from a sample in less than 2 h for both total mercury and methylmercury.

A non-targeted convenience survey consisting of 566 ready-to-eat baby foods was conducted in 2023 to determine the levels of total arsenic, cadmium, total mercury, lead and thallium. Data collection expanded the scope of food categories tested by the U.S. Food and Drug Administration in 2021, prioritising foods commonly eaten by babies and young children, while also including selected foods consumed by pregnant women and nursing mothers. Quality control was performed according to the specific food matrix category and target analyte. Arsenic speciation analysis was completed on a subset of foods and products containing fish were analysed for both inorganic arsenic and methylmercury. Arsenic levels were associated with rice-containing foods, lead with root vegetable ingredients such as sweet potatoes and thallium with brassica vegetables such as kale. The predictor model indicated no association between cadmium and any of the individual ingredients. Also, additional data are needed to support predictors for mercury.

We evaluated the co-occurrence of arsenic (As), cadmium (Cd), and lead (Pb) in 10 categories of processed foods intended for infants and young children (<2 years old) and adapted methodology to characterise and evaluate the impact of correlations on toxic element (TE) concentrations in these foods. Co-occurrence was assessed by calculating the frequency of samples having concentrations above the limit of detection (LOD) among TE sets (i.e. As-Cd, As-Pb, Cd-Pb, and As-Cd-Pb). Pairwise correlations were evaluated using two statistical approaches adapted to censored data: (i) non-parametric Kendall's tau and (ii) parametric Bayesian modelling. Nonparametric and parametric correlation analyses showed similar results. We found positive correlations among one or more pairs of the TEs (As, Pb, and Cd) in 9 of the 10 categories of foods intended for infants and young children and a negative correlation for one TE pair for a single food category. Where positive correlations are observed, removing samples with high concentrations of a given TE reduces the mean of the other TEs in that food. We also explored the impact of correlations among TEs on the fraction of the supply below maximum levels. Positive correlations among TEs have the potential to reduce the impact on the supply when setting multiple maximum levels.

BACKGROUND:An interlaboratory study was conducted at the U.S. Food and Drug Administration's (FDA) Northeast Food and Feed Laboratory (NFFL) and the Center for Food Safety and Applied Nutrition (CFSAN) with the purpose to expand FDA Elemental Analysis Manual (EAM) method 4.7 (Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion) to include new analytes. OBJECTIVE:The goal of the study was to demonstrate the performance of FDA EAM method 4.7 when analyzing new analytes cobalt (Co), strontium (Sr), thallium (Tl), tin (Sn), uranium (U), and vanadium (V). This analyte extension method validation of EAM 4.7 for six additional elements, Co, Sr, Tl, Sn, U, and V, followed all guidelines for a Level 2 or single-laboratory validation and met all acceptance criteria for analyte extensions as per the Guidelines for the Validation of Chemical Methods. METHOD:As per EAM 4.7, this study followed the procedures and used specified equipment operated under recommended conditions. The analyte extension method validation was performed in accordance with protocol and with no deviations. RESULTS:All quality control (QC) requirements for this analyte extension method validation of EAM 4.7 passed as evidenced by the analytical data. The results presented demonstrate accuracy, linearity, and precision by successful analyses of method blanks, matrix spikes, unfortified test samples, and reference materials. The data analyzed met each of the validation requirements for each analyte in all representative matrixes. CONCLUSIONS:The study showed that the new analytes performed satisfactorily using EAM 4.7 for total acidic extractable elemental analysis of food according to FDA's guidelines. HIGHLIGHTS:The method met or exceeded the performance criteria.

BACKGROUND:The National Institute of Standards and Technology (NIST) has produced over 40 botanical dietary supplement Standard Reference Materials (SRMs) and reference materials (RMs) with values assigned for chemical markers and/or active compounds. Although environmental accumulation or inadvertent introduction of toxic elements (arsenic, cadmium, lead, and mercury) is a potential source of exposure in botanical dietary supplement products, the majority of the dietary supplement SRMs/RMs do not have values assigned for the four major toxic elements. OBJECTIVE:To determine As, Cd, Pb, and Hg content in the current inventory of NIST botanical dietary supplement SRMs/RMs. METHODS:Fifteen SRMs/RMs suites of plant part, extract, and finished products (i.e., solid oral dosage form [SODF]) were analyzed for As, Cd, Pb, and Hg using nitric acid microwave-assisted digestion followed by quantification using inductively coupled plasma-mass spectrometry. RESULTS:Results for control samples were in good agreement with certified values indicating that the analyses of 38 individual botanical SRMs/RMs were in control. Characterization of linked plant/extract SRMs/RMs derived from the same source materials demonstrated that while extraction processes can often yield extracts with lower toxic element content for Hg or As, it is also possible for mass fraction levels to remain unchanged or even to increase after extraction. CONCLUSIONS:The results fill significant knowledge gaps in toxic element content ranges for SRMs/RMs where no NIST assigned values existed, in particular for Hg content and for extract and SODF matrixes. With comprehensive toxic element content now available, researchers can better select appropriate dietary supplement SRMs/RMs for use as controls in the analysis of dietary supplement ingredients and products. HIGHLIGHTS:Results for As, Cd, Pb, and Hg are reported for 38 dietary supplement SRMs/RMs including six suites of plant, extract, and SODF and nine pairs of plant and extract from the same batch of plant material.

Accurate results with analytical solution to standard concentration ratios less than 10.

A non-targeted convenience survey was conducted in 2021 to estimate the range of total arsenic (As), cadmium (Cd), total mercury (Hg) and lead (Pb) concentrations in ready-to-eat baby foods. Four hundred samples were purchased both online and in brick-and-mortar retail. Samples included both organic and non-organic products, packaged in glass or plastic jars and foil or plastic pouches. Samples were analysed by acid assisted microwave digestion and ICP-MS with an emphasis on ultra-low detection limits. Limits of quantification were 2.26, 1.31, 0.72, and 3.14 mu g/kg (ppb) for As, Cd, Hg and Pb, respectively. The median concentrations of As, Cd, Hg, and Pb in tested products were 2.60, 1.81, 0.09, and 1.38 mu g/kg, respectively. Foods containing rice were more likely to contain arsenic. Foods with leafy greens, such as spinach and kale, were more likely to contain cadmium and foods with root vegetables had the highest concentrations of lead.

Polymers incorporating quantum dots (QDs) have attracted interest as components of next-generation consumer products, but there is uncertainty about how these potentially hazardous materials may impact human health and the environment. We investigated how the transport (migration) of QDs out of polymers and into the environment is linked to their size and surface characteristics. Cadmium selenide (CdSe) QDs with diameters ranging from 2.15 to 4.63 nm were incorporated into low-density polyethylene (LDPE). Photoluminescence was used as an indicator of QD surface defect density. Normalized migration of QDs into 3% acetic acid over 15 days ranged from 13.1 +/- 0.6-452.5 +/- 31.9 ng per cm2 of polymer surface area. Migrated QD mass was negatively correlated to QD diameter and was also higher when QDs had photoluminescence consistent with larger surface defect densities. The results imply that migration is driven by oxidative degradation of QDs originating at surface defect sites and transport of oxidation products along concentration gradients. A semi-empirical framework was developed to model the migration data. The model supports this mechanism and suggests that QD surface reactivity also drives the relationship between QD size and migration, with specific surface area playing a less important role.

Ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) have been investigated for biomedical applications, including novel contrast agents, magnetic tracers for tumor imaging, targeted drug delivery vehicles, and magneto-mechanical actuators for hyperthermia and thrombolysis. Despite significant progress, recent clinical reports have raised concerns regarding USPION safety related to endothelial cell dysfunction; however, there is limited information on factors contributing to these clinical responses. The influence of USPION surface chemistry on nanoparticle interactions with proteins may impact endothelial cell function leading to adverse responses. Therefore, the goal of this study was to assess the effects of carboxyl-functionalized USPION (CU) or amine-functionalized USPION (AU) (approximately 30 nm diameter) on biological responses in human coronary artery endothelial cells. Increased protein adsorption was observed for AU compared with CU after exposure to serum proteins. Exposure to CU, but not AU, resulted in a concentration-dependent decrease in cell viability and perinuclear accumulation inside cytoplasmic vesicles. Internalization of CU was correlated with endothelial cell functional changes under non-cytotoxic conditions, as evidenced by a marked decreased expression of endothelial-specific adhesion proteins (eg, vascular endothelial-cadherin and platelet endothelial cell adhesion molecule-1) and increased endothelial permeability. Evaluation of downstream signaling indicated endothelial permeability is associated with actin cytoskeleton remodeling, possibly elicited by intracellular events involving reactive oxygen species, calcium ions, and the nanoparticle cellular uptake pathway. This study demonstrated that USPION surface chemistry significantly impacts protein adsorption and endothelial cell uptake, viability, and barrier function. This information will advance the current toxicological profile of USPION and improve development, safety assessment, and clinical outcomes of USPION-enabled medical products.

We show that inorganic sulfides strongly influence transfer (migration) of nanoparticle mass out of polymer nanocomposites (PNCs) and into aqueous environments. We first manufactured two families of PNCs: one incorporating silver nanoparticles (AgNPs) and one incorporating CdSe quantum dots (QDs). Then, we assessed migration out of these PNCs and into aqueous media containing Na2S at concentrations ranging from 0 to 10-4 M. Results show that Na2S strongly suppressed migration of Ag from AgNP-based PNCs: the migration into water spiked with 10-6 M Na2S was 79% less than migration into water without Na2S, and no migration was detected (LOD approximate to 0.01 ng/cm2) in water spiked with Na2S at 10-5 M or 10-4 M. With CdSe QD-based PNCs, Na2S suppressed Cd migration but enhanced Se migration, resulting in only a small net effect on the total QD migration but a large shift of the leachate composition (from favoring Cd by an average of 5.8 to 1 in pure water to favoring Se 9.4 to 1 when Na2S was present at 10-4 M). These results show that common inorganic substances like sulfides may play a strong role in determining the environmental fate of polymer-dispersed nanoparticles and imply that migration tests conducted in purified water may not always accurately reflect migration into real environments.

This publication reports high resolution mass spectral data for copper chlorophyll and copper chlorophyll degradation products extracted from bright green table olives. These data support analyte identifications made in "Quantitation of copper chlorophylls in green table olives by ultra-high-performance liquid chromatography with inductively coupled plasma isotope dilution mass spectrometry" in the Journal of Chromatography A (Petigara Harp et al., 2020 [1]). Table olive pigments, divided into lipophilic and hydrophilic fractions by liquid-liquid repartition, were separated by ultra-high-performance liquid chromatography and detected by visible wavelength absorbance and high resolution mass spectrometry, using an Orbitrap HF with positive electrospray ionization. Full-scan mass spectra were acquired to assign pigment chemical formulae. Fragment-rich higher-energy collisional dissociation tandem mass spectra were acquired to facilitate structural assignments. Extracted ion chromatograms, full-scan, and tandem mass spectra obtained from representative lipophilic and hydrophilic green table olive extracts are presented in Figures 1-6. Annotated mass spectra comparing experimental and calculated isotope distributions, .raw mass spectral data files, and experimental details linking .raw data files to annotated spectra are provided as Supplementary Material. Spectra extracted from these native data files can be added to mass spectral libraries for use in other studies. Access to native data files uniquely enables rigorous data examination (e.g., molecular ion isotopic distribution, effective mass resolution, presence of overlapping ion series) and use in ways that are not possible when spectra are otherwise reported in simple tables listing mono-isotopic peaks and mass errors. Mass spectra reported here can be used to design multiple-reaction monitoring methods to detect these bright green pigments in agricultural food commodities and finished products.

Anti- and pro-oxidant activities of different manganese oxide nanoparticles and their implications in cell viability and redox balances.

Table olives, a widely consumed delicacy, are often selected by consumers based on the shade of their green color. The appealing coloration of fresh olives fades to brown or pale yellow during the industrial processing necessary for commercialization and storage, as a result of the degradation of chlorophyll a and b to their corresponding pheophytins and other chlorophyll degradation products (CDP). The regreening of table olives may be achieved by complexation of CDP with Cu2+, to form stable bright green copper CDP (Cu-CDP) complexes. To study this phenomenon, we developed a novel method to separately extract lipophilic and hydrophilic Cu-CDP and quantify Cu-CDP by UHPLC combined with inductively coupled plasma isotope dilution mass spectrometry (UHPLC-ICP-ID-MS) using post-column isotopic dilution with Cu-65. This technique does not require species-specific calibration standards and was applied to survey the Cu-CDP composition of the various types of table olives sold in the US market. The CDP and Cu-CDP extracted from table olives were identified by high resolution full-scan mass spectrometry. Total elemental Cu in table olives was measured by microwave digestion followed by ICP-MS detection and correlated with the content of Cu-CDP. Pale yellow olives contained <1 mg/kg lipophilic Cu-CDP and <3.5 mg/kg total elemental Cu. Bright green table olives contained 4-22 mg/kg lipophilic Cu-CDP and 14.4-161 mg/kg total elemental Cu in contrast to <6 mg/kg reported for natural abundance, indicating the formation of Cu-CDP was achieved by addition of copper salts. A dark green sample with 2.5 mg/kg of total copper and 0.267 mg/kg lipophilic Cu-CDP may have been processed by addition of sodium copper chlorophyllin (SCC); the higher content of Cu isochlorin e4 compared to Cu 15(2)-Me-chlorin e6 supports this conclusion. Published by Elsevier B.V.

Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100 nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.

ABSTRACT Cocoa powder and chocolate products are known to sometimes contain cadmium (Cd) and lead (Pb) from environmental origins. A convenience sample of cocoa powder, dark chocolate, milk chocolate, and cocoa nib products was purchased at retail in the US and analysed using inductively coupled plasma mass spectrometry to assess Cd and Pb concentrations. Cd and Pb were evaluated in relation to the percent cocoa solids and to the reported origin of the cocoa powder and chocolate products. Cd ranged from 0.004 to 3.15 mg/kg and Pb ranged from <LOD to 0.38 mg/kg. Cd and Pb were significantly correlated with percent cocoa, with correlations varying by product type and geographic origin. Geographic variation was observed for Cd, with higher Cd concentrations found in products reported as originating from Latin America than from Africa. The influence of percent cocoa solids and cocoa origin on Cd levels are relevant to international standards for Cd in chocolate products.

We fabricated polymer nanocomposites (PNCs) from low-density polyethylene and CdSe quantum dots (QDs) and used these materials to explore potential exposure after long-term storage in different acidic media that could be encountered in food contact applications. While the low-level release of QD-associated mass into all the food simulants was observed, exposure to dilute acetic acid resulted in more than double the mass transfer compared to that which occurred during exposure to dilute hydrochloric acid at the same pH. Conversely, exposure to citric acid resulted in a suppression of QD release. Permeation experiments and confocal microscopy were used to reveal mechanistic details underlying these mass-transfer phenomena. From this work, we conclude that the permeation of undissociated acid molecules into the polymer, limited by partitioning of the acids into the hydrophobic polymer, plays a larger role than pH in determining exposure to nanoparticles embedded in plastics. Although caution must be exercised when extrapolating these results to PNCs incorporating other nanofillers, these findings are significant because they undermine current thinking about the influence of pH on nanofiller release phenomena. From a regulatory standpoint, these results also support current guidance that 3% acetic acid is an acceptable acidic food simulant for PNCs fabricated from hydrophobic polymers because the other acids investigated resulted in significantly less exposure.

Polymer nanocomposites (PNCs), which consist of a polymer host and a nanomaterial filler, may become useful as food packaging materials due to their enhanced properties compared to neat polymers. Many studies have explored release of embedded nanomaterials or their components from PNCs into foods and food simulants. However, more studies are needed that systematically study the mechanistic role that nanoparticle (NP) and polymer characteristics play in determining mass transport from these materials. Here, noble-metal-containing nanoparticle (NP)/low density poly(ethylene) (LDPE) PNCs were used as model food contact materials to decouple the impact of nanofiller size, composition, and stability on release into two food simulants (water and 3% acetic acid). PNCs containing Ag NPs ranging in diameter from 4 to 41 nm were first evaluated. We found that similar to 1% of Ag mass was released from PNCs incorporating Ag NPs > 10 nm, but the percent of released Ag increased dramatically when the Ag NP diameter was <10 nm (52% release was measured when the NP diameter was 4 nm). By comparison, mass transfer from PNCs incorporating similarly sized, more stable Ag2S NPs and Au NPs was very low (<0.1%). We also found that the simulant chemistry and experiment time impact total mass transfer from these PNC films. These experiments are the first to show a direct link between NP size/composition and potential mass transfer to food simulants, and they support a model in which NP stability against oxidative dissolution plays a dominant role in determining consumer exposure in a food contact application. The results will help inform design strategies for PNCs that have reduced likelihood of mass transfer to aqueous environments.