Nanosilver-based materials as feed additives: Evaluation of their transformations along in vitro gastrointestinal digestion in pigs and chickens by using an ICP-MS based analytical platform.

The use of a new nanomaterial in the feed chain requires a risk assessment that involves in vitro gastrointestinal digestions to predict its degradation and oral exposure to nanoparticles. In this study, a nanosilver-based material was incorporated into pig and chicken feed as a growth-promoting additive and subjected to the corresponding in vitro gastrointestinal digestions. An inductively coupled plasma mass spectroscopy (ICP-MS) analytical platform was used to obtain information about the silver released in the different digestion phases. It included conventional ICP-MS for total silver determination, but also single particle ICP-MS and coupling to hydrodynamic chromatography for detection of dissolved and particulate silver. The bioaccessible fraction in the intestinal phase accounted for 8-13% of the total silver, mainly in the form of dissolved Ag(I) species, with less than 0.1% as silver-containing particles. Despite the additive behaving differently in pig and chicken digestions, the feed matrix played a relevant role in the fate of the silver.

How to trust size distributions obtained by single particle inductively coupled plasma mass spectrometry analysis.

Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is a technique widely used to obtain direct information about the number concentration and the size distribution of nanoparticles in liquid suspensions. However, its methods still lack clear quality control strategies to confirm the validity of the information derived from them. Only the detection of the complete size distribution of the nanoparticles in a sample over the size critical value ensures obtaining unbiased quantitative information, otherwise information should be restricted to report the presence of nanoparticles over a certain size and number concentration since their actual total number concentration is underestimated and the size overestimated. Under the latter conditions, data processing produces histograms showing the tails of the incomplete size distributions, although apparently, complete distributions can also be obtained when particle events are recorded as peaks, as reported here for the first time. The occurrence of these misleading situations must be critically evaluated for each SP-ICP-MS analysis. An approach, based on estimation of size critical values and successive dilutions, is proposed for the assessment of the validity of the quantitative information obtained, together with specific criteria for reconsidering the information that can be derived from those measurements. The approach was verified with different case studies and applied to the analysis of complex nanomaterials, confirming the validity of the reported information by comparison with other techniques. A calculation tool is also included to facilitate the estimation of size critical values under experimental conditions.

Dissolved metal ion removal by online hollow fiber ultrafiltration for enhanced size characterization of metal-containing nanoparticles with single-particle ICP-MS.

Single particle-inductively coupled plasma mass spectrometry (SP-ICP-MS) is a powerful tool for size-characterization of metal-containing nanoparticles (MCNs) at environmentally relevant concentrations, however, coexisting dissolved metal ions greatly interfere with the accuracy of particle size analysis. The purpose of this study is to develop an online technique that couples hollow fiber ultrafiltration (HFUF) with SP-ICP-MS to improve the accuracy and size detection limit of MCNs by removing metal ions from suspensions of MCNs. Through systematic optimization of conditions including the type and concentration of surfactant and complexing agent, carrier pH, and ion cleaning time, HFUF completely removes metal ions but retains the MCNs in suspension. The optimal conditions include using a mixture of 0.05 vol.% FL-70 and 0.5 mmol/L Na2S2O3 (pH = 8.0) as the carrier and 4 min as the ion cleaning time. At these conditions, HFUF-SP-ICP-MS accurately determines the sizes of MCNs, and the results agree with the size distribution determined by transmission electron microscopy, even when metal ions also are present in the sample. In addition, reducing the ionic background through HFUF also lowers the particle size detection limit with SP-ICP-MS (e.g., from 28.3 to 14.2 nm for gold nanoparticles). This size-based ion-removal principle provided by HFUF is suitable for both cations (e.g., Ag+) and anions (e.g., AuCl4-) and thus has good versatility compared to ion exchange purification and promising prospects for the removal of salts and macromolecules before single particle analysis.

Evaluation of collision/reaction gases in single-particle ICP-MS for sizing selenium nanoparticles and assessment of their antibacterial activity.

Selenium nanoparticles (SeNPs) have recently attracted attention because they combine the benefits of Se and lower toxicity compared to other chemical forms of this element. In this study, SeNPs were synthesized by a green method using ascorbic acid as the reducing agent and polyvinyl alcohol as stabilizer. The nanoparticles were widely characterized. To determine the total concentration of Se by ICP-MS, several isotopes and the use of He as collision gas were evaluated, which was effective in minimizing interferences. A method for sizing SeNPs by single particle ICP-MS (SP-ICP-MS) was developed. For this purpose, He and H2were evaluated as collision/reaction gases, and the second one showed promising results, providing an average diameter of 48 nm for the SeNPs. These results agree with those obtained by TEM (50.1 nm). Therefore, the SP-ICP-MS can be implemented for characterizing SeNPs in terms of size and size distribution, being an important analytical tool for Se and other widely studied nanoparticles (e.g. Ag, Au, Ce, Cu, Fe, Zn). Finally, the antibacterial activity of SeNPs was assessed. The SeNPs showed bacteriostatic activity against three strains of Gram-positive bacteria and were particularly efficient in inhibiting the growthE. faecaliseven at very low concentrations (MIC < 1.4 mg l-1). In addition, a bactericidal activity of SeNPs againstS. aureuswas observed. These nanoparticles may have potential application in pharmaceutical industry, biomedicine and agriculture.

Analysis of Ti- and Pb-based particles in the aqueous environment of Melbourne (Australia) via single particle ICP-MS.

The analysis of natural and anthropogenic nanomaterials (NMs) in the environment is challenging and requires methods capable to identify and characterise structures on the nanoscale regarding particle number concentrations (PNCs), elemental composition, size, and mass distributions. In this study, we employed single particle inductively coupled plasma-mass spectrometry (SP ICP-MS) to investigate the occurrence of NMs in the Melbourne area (Australia) across 63 locations. Poisson statistics were used to discriminate between signals from nanoparticulate matter and ionic background. TiO2-based NMs were frequently detected and corresponding NM signals were calibated with an automated data processing platform. Additionally, a method utilising a larger mass bandpass was developed to screen for particulate high-mass elements. This procedure identified Pb-based NMs in various samples. The effects of different environmental matrices consisting of fresh, brackish, or seawater were mitigated with an aerosol dilution method reducing the introduction of salt into the plasma and avoiding signal drift. Signals from TiO2- and Pb-based NMs were counted, integrated, and subsequently calibrated to determine PNCs as well as mass and size distributions. PNCs, mean sizes, particulate masses, and ionic background levels were compared across different locations and environments.

Detection, Identification and Size Distribution of Silver Nanoparticles (AgNPs) in Milk and Migration Study for Breast Milk Storage Bags.

The engineered silver nanoparticles (AgNPs) have been widely used in various food contact materials (FCMs) based on their antibacterial properties. This widespread use of nanosilver has, however, increased the risk of exposure of AgNPs to human due to their migration from FCMs causing a potential hazard present in foods. Therefore, it is important to establish a reliable and practical method for the detection of AgNPs in food matrices to support risk assessment on AgNPs exposure. Taking the examples of milk and AgNPs-containing breast milk storage bags, this study established an approach for size characterization and quantification of AgNPs in milk and evaluated the relevant silver migration, based on enzymatic digestion and the analysis by asymmetric flow field-flow fractionation (AF4) hyphenated with inductively coupled plasma mass spectrometry (ICP-MS) and single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). No migration of AgNPs was found from breast milk storage bags under various simulated storage conditions as well as extreme scenarios. The suitability and reliability of this method were also validated by the determination of multiple parameters, including accuracy, repeatability, limit of detection (LOD), limit of quantification (LOQ), and recovery, for AF4-ICP-MS and SP-ICP-MS, respectively, with good and overall acceptable evaluation results obtained for all. The established and validated approach was demonstrated to be suitable for the characterization and quantitation of AgNPs in milk as well as the analysis of their migration from breast milk storage bags.

Simple Method for the Extraction and Determination of Ti-, Zn-, Ag-, and Au-Containing Nanoparticles in Sediments Using Single-Particle Inductively Coupled Plasma Mass Spectrometry.

The quantitative analysis of nanoparticles (NPs) in the environment is significantly important for the exploration of the occurrence, fate, and toxicological behaviors of NPs and their subsequent environmental risks. Some protocols have been recommended for the separation and extraction of NPs that are potentially dispersed in complex environmental matrixes, e.g. sediments and soils, but they remain limited. However, certain factors that may significantly affect extraction efficiency have not been comprehensively explored. In this study, on the basis of the single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) technique, a simple standardized protocol for separating and analyzing metal-containing NPs in sediment samples was developed. On consideration of the extraction efficiencies of indigenous NPs (Ti- and Zn-NPs) and spiked NPs (Ag- and Au-NPs) in sediments, sedimentation with a settling time of 6 h is recommended for the separation of NPs and large particles, and the optimal sediment to water ratio, ultrasonication power, time, and temperature are 0.4 mg/mL, 285 W, 20 min, and 15-25 °C, respectively. On the basis of the optimized method, the recoveries of spiked Ag and Au-NPs were 71.4% and 81.1%, respectively. The applicability of the optimal protocols was verified, and TOC was proved to be an important factor controlling the separation and extraction of NPs in environmental samples. The separation and extraction of NPs in elevated TOC samples can be improved by increasing the ultrasonication power, time, and temperature.

Metal-Containing Nanoparticles in Low-Rank Coal-Derived Fly Ash from China: Characterization and Implications toward Human Lung Toxicity.

Characterization of nanoparticles (NPs) in coal fly ashes (CFAs) is critical for better understanding the potential health-related risks resulting from coal combustion. Based on single-particle (SP)-inductively coupled plasma mass spectrometry (ICP-MS) coupled with transmission electron microscopy techniques, this study is the first to determine the concentrations and sizes of metal-containing NPs in low-rank coal-derived fly ashes. Despite only comprising a minor component of the studied CFAs by mass, NPs were the dominant fraction by particle number. Fe- and Ti-containing NPs were identified as the dominant NPs with their particle number concentration ranging from 2.5 × 107 to 2.5 × 108 particles/mg. In addition, the differences of Fe-/Ti-containing NPs in various CFAs were regulated by the coalification degree of feed coals and combustion conditions of all of the low-rank CFAs tested. In the cases where these NPs in CFAs become airborne and are inhaled, they can be taken up in pulmonary interstitial fluids. This study shows that in Gamble's solution (a lung fluid simulant), 51-87% of Fe and 63-89% of Ti (ratio of the mass of Fe-/Ti-containing NPs to the total mass of Fe/Ti) exist in the NP form and remain suspended in pulmonary fluid simulants. These NPs are bioavailable and may induce lung tissue damage.

Counting Nanoplastics in Environmental Waters by Single Particle Inductively Coupled Plasma Mass Spectroscopy after Cloud-Point Extraction and In Situ Labeling of Gold Nanoparticles.

The globally raising concern for nanoplastics (NPs) pollution calls for analytical methods for investigating their occurrence, fates, and effects. Counting NPs with sizes down to 50 nm in real environmental waters remains a great challenge. Herein, we developed a full method from sample pretreatment to quantitative detection for NPs in environmental waters. Various NPs of common plastic types and sizes (50-1200 nm) were successfully labeled by in situ growth of gold nanoparticles and counted by single particle inductively coupled plasma mass spectrometry. Sucrose density gradient centrifugation enables the isolation of gold-labeled NPs from homogeneously nucleated Au nanoparticles, enhancing the particle number detection limit to 4.6 × 108 NPs/L for 269 nm spherical polystyrene NPs. For real environmental water samples, the pretreatment of acid digestion with a mixture of 5 mM HNO3 and 40 mM HF eliminates the coexisting inorganic nanoparticles, while the following dual cloud-point extraction efficiently isolates NPs from various matrices and thus improves the Au-labeling efficiency. The high spiked recoveries (72.9%-92.8%) of NPs in different waters demonstrated the applicability of this method in different scenarios.

Assessment of strategies for the formation of stable suspensions of titanium dioxide nanoparticles in aqueous media suitable for the analysis of biological fluids.

Due to their omnipresence in consumer products, there is a growing concern about the potential effects of nanoparticles on human health. Toxicological assessment and NP end-product studies require proper quantification of these materials in biological fluids. However, their quantifications in these media require stable predispersed NP solutions in aqueous media to enable the fortification in the matrices of interest or the preparation of calibration standards. In this study, a sample preparation scheme was developed by studying various dispersion media (polyvinylpyrrolidone and polyethylene glycol) and sonication strategies (bath and ultrasonic probe) to ensure homogeneous dispersion of titanium dioxide nanoparticles. Optimization of the various parameters was performed using SRM NIST 1898 NP reference material, composed of rutile and anatase phases. Number-based size distribution for titanium dioxide NPs was determined by dynamic light scattering and single-particle inductively coupled plasma mass spectrometry to evaluate the procedure efficiency. Changes in mean size and most frequent size distribution were also studied to determine if the agglomeration of nanoparticles occurs at the various dispersion conditions tested. Among the different dispersion parameters tested herein, the use of polyvinylpyrrolidone combined with a sonication process generated by a probe leads to a significant improvement in terms of suspension efficiency and stability over 72 h. The dispersion efficiency of the proposed methodology was assessed by single-particle inductively coupled plasma mass spectrometry with spiked biological fluids such as urine and blood. Graphical abstract.

Determination and characterization of metal nanoparticles in clams and oysters.

With the extensive application of nanotechnology, metal nanoparticles (MNPs) have been widely used, thus are universally detected in the environment. This has caused increasingly concerns due to their toxicity and the potential health risks they pose to humans. In this work, the concentrations and particle size distributions of MNPs and concentrations of associated metal ionic species in shellfish seafood (clams and oysters) were investigated using single particle inductively coupled plasma mass spectrometry (sp-ICP-MS) and inductively coupled plasma mass spectrometry (ICP-MS). The MNPs in the clam and oyster tissues were extracted via an alkaline digestion method with a recovery rate of 95.9% (for gold nanoparticles (AuNPs)). Then total concentrations of 41 metal elements were measured in the two types of seafood, of which 20 were selected for sp-ICP-MS analysis. The results showed that 5 types of MNPs were detectable in clams (Y, La, Ce, Pr, Gd) and 5 types of MNPs were detectable in oysters (Y, La, Ce, Pr, Nd). Size distributions of MNPs in clams and oysters were in the range of 35-55 nm and 30-65 nm, respectively. Nanoparticle concentrations in clams and oysters ranged from 0.6 to 37.7 ng/g and 4.2-19.7 ng/g, and accounted for 3.4%-50% and 5.5%-46% of the total metal content, respectively. Based on this analysis, the health risks of metals in the two kinds of seafood were evaluated by comparing the Provisional Tolerable Weekly Intake (PTWI) with limits recommended by the World Health Organization (WHO)/Food and Agriculture Organization (FAO). These results provide important information about the presence of metal nanoparticles in seafood and, to the best of our knowledge, this is the first time that the nanoparticles of rare earth elements have been detected and reported in bivalve mollusc tissues.

Analysis of cerium oxide and copper oxide nanoparticles bioaccessibility from radish using SP-ICP-MS.

BACKGROUND: The transformation of nanoparticles (NPs) internalized in plant tissues is the human digestive system that can provide a better understanding of the impact of NPs on the human system. The presented methodology was developed to study the bioaccessibility of cerium oxide (CeO2 ) and copper oxide (CuO) NPs from radish after the in vitro simulation of gastrointestinal digestion using single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS). RESULTS: Radish plants were cultivated hydroponically in a growth medium containing: (i) CeO2 NPs and (ii) CuO NPs. Both cerium (Ce) and copper (Cu) were found in all organs of the radish plants after analysis by standalone ICP-MS. This confirms the bioaccumulation of CeO2 and CuO NPs and the translocation of their Ce and Cu to the aerial parts of the plant. Less Ce (4.095 µg g-1 ) has been detected in leaves than in roots (1.156 mg g-1 ) while Cu content in leaves was 5.245 µg g-1 and in roots was 10.41 µg g-1 . Analysis of the digestive extracts obtained after the in vitro simulation of gastro (pepsin) and gastrointestinal (pancreatin) digestion showed that Ce has easy access to human system at least by 73%. CONCLUSION: The size of CeO2 NPs in digestive extracts showed no significant changes. However, the results obtained for CuO NPs digestion were variable and suggested that CuO NPs dissolved during the digestion process. The CuO NPs were observed in roots after the gastrointestinal digestion concluding that CuO NPs recovered after the initial dissolution. © 2020 Society of Chemical Industry.

Detection and Sizing of Ti-Containing Particles in Recreational Waters Using Single Particle ICP-MS.

Single particle inductively coupled plasma mass spectrometry (spICP-MS) was used to detect Ti-containing particles in heavily-used bathing areas of a river (Salt River) and five swimming pools. Ti-containing particle concentrations in swimming pools ranged from 2.8 × 103 to 4.4 × 103 particles/mL and were an order of magnitude lower than those detected in the Salt River. Measurements from the Salt River showed an 80% increase in Ti-containing particle concentration over baseline concentration during peak recreational activity (at 16:00 h) in the river. Cloud point extraction followed by transmission electron microscopy with energy dispersive X-ray analysis confirmed presence of aggregated TiO2 particles in river samples, showing morphological similarity to particles present in an over-the-counter sunscreen product. The maximum particle mass concentration detected in a sample from the Salt River (659 ng/L) is only slightly lower than the predicted no effect concentration for TiO2 to aquatic organisms (< 1 µg/L).

Evaluation of number concentration quantification by single-particle inductively coupled plasma mass spectrometry: microsecond vs. millisecond dwell times.

The quality of the quantitative information in single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) depends directly on the number concentration of the nanoparticles in the sample analyzed, which is proportional to the flux of nanoparticles through the plasma. Particle number concentrations must be selected in accordance with the data acquisition frequency, to control the precision from counting statistics and the bias, which is produced by the occurrence of multiple-particle events recorded as single-particle events. With quadrupole mass spectrometers, the frequency of data acquisition is directly controlled by the dwell time. The effect of dwell times from milli- to microseconds (10 ms, 5 ms, 100 µs, and 50 µs) on the quality of the quantitative data has been studied. Working with dwell times in the millisecond range, precision figures about 5 % were achieved, whereas using microsecond dwell times, the suitable fluxes of nanoparticles are higher and precision was reduced down to 1 %; this was independent of the dwell time selected. Moreover, due to the lower occurrence of multiple-nanoparticle events, linear ranges are wider when dwell times equal to or shorter than 100 µs are used. A calculation tool is provided to determine the optimal concentration for any instrument or experimental conditions selected. On the other hand, the use of dwell times in the microsecond range reduces significantly the contribution of the background and/or the presence of dissolved species, in comparison with the use of millisecond dwell times. Although the use of dwell times equal to or shorter than 100 µs offers improved performance working in single-particle mode, the use of conventional dwell times (3-10 ms) should not be discarded, once their limitations are known.

Combining single-particle inductively coupled plasma mass spectrometry and X-ray absorption spectroscopy to evaluate the release of colloidal arsenic from environmental samples.

Detection and sizing of natural colloids involved in the release and transport of toxic metals and metalloids is essential to understand and model their environmental effects. Single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) was applied for the detection of arsenic-bearing particles released from mine wastes. Arsenic-bearing particles were detected in leachates from mine wastes, with a mass-per-particle detection limit of 0.64 ng of arsenic. Conversion of the mass-per-particle information provided by SP-ICP-MS into size information requires knowledge of the nature of the particles; therefore, synchrotron-based X-ray absorption spectroscopy (XAS) was used to identify scorodite (FeAsO4·2H2O) as the main species in the colloidal particles isolated by ultrafiltration. The size of the scorodite particles detected in the leachates was below 300-350 nm, in good agreement with the values obtained by TEM. The size of the particles detected by SP-ICP-MS was determined as the average edge of scorodite crystals, which show a rhombic dipyramidal form, achieving a size detection limit of 117 nm. The combined use of SP-ICP-MS and XAS allowed detection, identification, and size determination of scorodite particles released from mine wastes, suggesting their potential to transport arsenic. Graphical abstract Analytical approach for the detection and size characterization of As-bearing particles by SP-ICP-MS and XAS in environmental samples.

Using Single-Particle Inductively Coupled Plasma Mass Spectrometry to Determine the Changes of Silver Nanoparticles in Bread Induced via Simulated Digestion.

Silver nanoparticles (AgNPs), widely used in various fields of technology as an antimicrobial agent, represent a new type of environmental pollutant. Through various routes, AgNPs might penetrate into agricultural crops and foodstuffs. It is important to know if AgNPs contained in food persist in digested food and are therefore available for entering the inner organs of the consumer's body. Using the technique of single-particle ICP-MS, we analysed the changes in the number and size distribution of AgNPs added to a sample of bread submitted to in vitro simulated gastrointestinal digestion. The majority of silver, in terms of mass, was transformed from the state of particles to the dissolved state during bread digestion, but the number of particles was reduced by 25% only. The most abundant particle size was reduced from 60 nm to 49 nm. Hence, a substantial part of transformed nanoparticles is still present in food digestate. This means that AgNPs consumed together with food can theoretically enter the inner cells of human body.

Identification and quantification of trace metal(loid)s in water-extractable road dust nanoparticles using SP-ICP-MS.

Resuspension of road dust is a major source of airborne particulate matter (PM) in urban environments. Inhalation of ultrafine particles (UFP; < 0.1 µm) represents a health concern due to their ability to reach the alveoli and be translocated into the blood stream. It is therefore important to characterize chemical properties of UFPs associated with vehicle emissions. We investigated the capability of Single-Particle ICP-MS (SP-ICP-MS) to quantify key metal(loid)s in nanoparticles (NPs; < 0.1 µm) isolated from road dust collected in Toronto, Canada. Water extraction was performed to separate the <1-µm fraction from two different road dust samples (local road vs. arterial road) and a multi-element SP-ICP-MS analysis was then conducted on the samples' supernatants. Based on the particle number concentrations obtained for both supernatants, the metal(loid)-containing NPs could be grouped in the following categories: high (Cu and Zn, > 1.3 × 1011 particles/L), medium (V, Cr, Ba, Pb, Sb, Ce, La), low (As, Co, Ni, < 4.6 × 109 particles/L). The limit of detection for particle number concentration was below 5.5 × 106 particles/L for most elements, except for Cu, Co, Ni, Cr, and V (between 0.9 and 7.7 × 107 particles/L). The results demonstrate that road dust contains a wide range of readily mobilizable metal(loid)-bearing NPs and that NP numbers may vary as a function of road type. These findings have important implications for human health risk assessments in urban areas. Further research is needed, however, to comprehensively assess the NP content of road dust as influenced by various factors, including traffic volume and speed, fleet composition, and street sweeping frequency. The described method can quickly characterize multiple isotopes per sample in complex matrices, and offers the advantage of rapid sample scanning for the identification of NPs containing potentially toxic transition metal(loid)s at a low detection limit.

Insights into the effect of manganese-based nanomaterials on the distribution trait and nutrition of radish (Raphanus sativus L.).

Manganese (Mn) is one of the essential elements for plant growth and is involved in the process of photosynthesis and seed germination. Herein, we applied two Mn-based nanoparticles, MnO2 and Mn3O4, to the soil to investigate their effects on radish growth, antioxidant system, and nutrients. The radish plant height after treatment with 10 mg/kg of MnO2 and Mn3O4 NPs were increased, compare to the control. In radish's shoot, MnO2 NPs at high concentrations (100 mg/kg) increased MDA activity by 58 % compared to the control group, while exposure to Mn3O4 NPs at the same concentration decreased MDA activity by 14 %. The nutrient content of radishes, such as soluble sugar and vitamin C, was improved. Moreover, single particle inductively coupled plasma mass spectrometry (SP ICP-MS) was used to understand the patterns of migration of Mn-based NPs in radish and subsequent impact on nutrients. We found that Mn-based NPs accumulated mainly in the roots of radish. Interestingly, the accumulation characteristics of MnO2 NPs and Mn3O4 NPs were different. MnO2 NPs accumulated more in radish leaves than in fruits, while the accumulation of Mn3O4 NPs gradually decreased from roots to leaves. Finally, we determined the mineral element content of the leaves, fruits, and roots of radish, and found that the uptake of main metallic mineral elements (e.g. Cu, Fe, Mg, Zn, Na, K) was inhibited by the application of Mn-based NPs. These findings underscore the importance of considering species and multifaceted impacts of Mn-based NPs as nanofertilizers for their wide application in agriculture.

Biosynthesis of nano selenium in plants.

Selenium is a non-essential element with beneficial and toxic effects on plants, whose exact role in plant physiology leaves many unanswered questions. Various species of hydroponically grown plants produce defined selenium nano particles (SeNP) with a narrow size distribution and about 2 million selenium atoms by biosynthesis when being exposed to selenite, proving that green synthesis of SeNP is not only possible in plants extracts, but also in living organisms. The detection was performed with single particle inductively coupled plasma mass spectrometry. These results require a new view of the selenium biochemistry in plants and its impact on nutrition, food sciences and medicine. To the best of our knowledge, this is the first report on the synthesis of elemental nanoparticles in general and selenium nanoparticles in particular by living plants.

Single particle ICP-MS combined with filtration membrane for accurate determination of silver nanoparticles in the real aqueous environment.

This work presents the role of commercial microfiltration membranes combined with single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) in removing environmental matrix interference for model silver nanoparticles (AgNPs) determination. The filters with different pore sizes (0.22 µm, 0.45 µm, 0.8 µm) and materials (mixed cellulose ester, polyether sulfone, and nylon) were investigated to acquire the recovery of particle concentration and size of AgNPs spiked into different real aqueous solutions, including ultrapure water, tap water, surface water, and sewage effluent. The maximum recovery of nanoparticle concentration was 70.2% through the 0.8 µm polyether sulfone membrane. The heated filters were able to improve the recovery of AgNPs particle concentration in the real aqueous environment. Hence, the pretreatment method by SP-ICP-MS combined with filtration membrane was simple, fast, and low-cost to quantify AgNPs in natural water environments.