In vitro and in vivo evaluation of the ecotoxicity of nanoparticles

Nanoparticles (NPs) are ultrafine particle with lenghts in two or three dimensions > 1 nm and < 100 nm. Nanoparticles have unique properties, which make them useful for countless applications in a broad spectrum of industrial branches. However, their unique properties could present a potential hazard to the environment. The present study investigated the effects of SiO2, CeO2 and polymer coated gold NPs of various sizes towards the alga Pseudpkirchneriella subapitata and the cladoceran Daphnia magna according to standard OECD guidelines. In addition, in vitro cytotoxicity and uptake studies were performed with the rainbow trout gill cell line RTGill-W1. For all NPs tested, 72h No Observed Effect Concentrations obtained in algal growht inhibition tests ranged between 1.0 and 4.6 mg/l. Therefore, NPs were more toxic than the corresponding silica and ceria bulk materials, for which no effects were observed in algal growth inhibition tests at 1000 mg/l. The SiO2 NPs were stable under test conditions. Smaller (12.5 nm) NPs were more toxic than larger (27.0 nm) NPs when concentration was expressed as mass. However, when concentration was expressed as surface area, no difference in toxicity was observed. The latter finding suggested that toxicity of NPs was governed by surface area. A similar conclusion could be drawn for 14, 20 and 29 nm CeO2 NPs in algal growth inhibition tests, despite the strong aggregation to 4.5 µm mean diameter particles under test conditions. Natural organic matter stabilized CeO2 NPs suspensions to 100-200 nm aggregates and strongly decreased their toxicity. In addition, toxicity was pH dependent. No evidence of NP uptake in algal cells was found, but strong adsorption of SiO2 NPs to the cell wall and clustering of CeO2 around the algal cells was observed. Uptake of all types to NPs in RTGill-W1 cells was confirmed using transmission electron microscopy

Optimization of sample preparation and a quadrupole ICP-MS measurement protocol for the determination of elemental impurities in pharmaceutical substances in compliance with USP guidelines

Both new guidelines concerning elemental impurity limit concentrations and novel analytical procedures for elemental analysis of pharmaceutical substances are being adopted by the United States Pharmacopeia (USP). This paper outlines the optimization of two sample preparation procedures for organic pharmaceutical excipient products, one relying on direct dissolution in an aqueous medium and another on microwave-assisted acid digestion. Optimization particularly involved the stabilization and reliable determination of Hg, Pd and Os. Analyte concentrations and spike recoveries were determined in two organic pharmaceutical excipients using a quadrupole ICP-MS instrument equipped with a collision–reaction cell. Aqueous dissolution was achieved with 0.009mMKBrO3 in 1% (v/v) HNO3 and 1% (v/v) HCl and microwave-assisted acid digestion was performed with aqua regia. Polyatomic interferences originally hampering the accurate determination of 51V, 52Cr, 53Cr, 55Mn, 56Fe and 75As were eliminated through introduction of He/H2 collision–reaction gas at a flow rate of 4.5–5.1 ml min-1 and applying a kinetic energy barrier of 3 V between the hexapole collision–reaction cell and the quadrupole analyzer. Limits of detection were more than a factor of ten lower than the proposed limit concentrations for parenteral administration and the impurity concentrations in the products tested never exceeded the limit concentrations defined by USP. Elemental spike recoveries ranged between 93.8 and 109.9% when standard addition was used for calibration, with relative standard deviations (RSDs) < 12.7%. It is expected that the proposed procedures can be directly implemented for routine impurity analysis of a broad spectrum of pharmaceutical substances

Quantification of uranium, plutonium, neodymium and gadolinium for the characterization of spent nuclear fuel using isotope dilution HPIC-SF-ICP-MS

A method was developed for the determination of the nuclide-specific concentrations of U, Pu, Nd and Gd in two types of spent nuclear fuel (UOx and Gd-enriched). High-performance ion chromatography (HPIC) was used to separate the target elements from one another while sector-field inductively coupled plasma-mass spectrometry (SF-ICP-MS) was used for their determination relying on isotope dilution for calibration. In order to obtain the best possible precision for these isotope ratios extracted from the transient HPIC-SF-ICP-MS signals, the SF-ICP-MS data acquisition parameters were optimized and the most suitable method for calculating the isotope ratios from the transient signals was identified. The point-by-point (PbP), linear regression slope (LRS) and peak area integration (PAI) approaches were compared in the latter context. It was found that data acquisition in the flat centre of the spectral flat top peak using a mass window of 25%, a dwell time of 10 ms and 20 samples per peak, while using PAI for isotope ratio calculation, gave the best precision on the isotope ratios extracted from the HPIC-SF-ICP-MS transient signals. These parameters were used in the determination of the nuclide-specific mass fractions of Pu, Nd and Gd in two types of spent nuclear fuel using isotope dilution HPIC-SF-ICP-MS. For U, which was present at a higher concentration, the element fraction was collected and analyzed off-line after dilution. For the other target elements, an online approach was used. An uncertainty budget estimation was made using the bottom-up approach for the resulting mass fractions, and the accuracy and precision obtained when using isotope dilution HPIC-SF-ICP-MS were compared with those obtained with the routinely used techniques, isotope dilution TIMS & alpha spectrometry (an ISO 17025 accredited method)

Comparison of microsublimation and ion exchange chromatography for boron isolation preceding its isotopic analysis via multi-collector ICP-MS

Boron isotopic analysis is of interest in many research fields and for a large variety of sample types. Accurate and precise determination of boron isotope ratios using multi-collector ICP-mass spectrometry or thermal ionization mass spectrometry requires isolation of the target element prior to isotopic analysis, which is accomplished using either ion exchange chromatography or microsublimation. This study systematically compares the two methods in terms of B recovery, procedural blank, matrix removal efficiency, accuracy and precision of the resulting delta B-11 values as measured using multi-collector ICP-mass spectrometry, as well as labor intensiveness and costs. For this purpose, four types of sample matrices, i.e. 20 g L-1 Ca aqueous solution, seawater, digests of spinach (100 g L-1) and silicate glass (10 g L-1), were stripped from their original B content and spiked with B of known isotopic composition and were then subjected to both sample preparation methods and subsequent isotopic analysis of the purified B fraction via multi-collector ICP-mass spectrometry. For both methods, the highest (quantitative) B recoveries were obtained for Ca-rich aqueous solution and seawater. For spinach, accurate delta B-11 values were obtained after ion exchange chromatography. However, microsublimation was plagued by isotope fractionation, resulting in large offsets (similar to 8 parts per thousand) between the experimental results and the corresponding reference values. For glass, B recovery was incomplete, nevertheless the absence of fractionation rendered both sample preparation methods suitable. Overall, in the absence of isotope fractionation, microsublimation appears advantageous in terms of procedural blanks, matrix removal efficiency, precision (2 s) on delta B-11 values, labor intensiveness and costs