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Silicon dioxide (silica, SiO2, SAS) and titanium dioxide (TiO2) are produced in high volumes and applied in many consumer and food products. As a consequence, there is a potential human exposure and subsequent systemic uptake of these particles. In this study we show the characterization and quantification of both total silicon (Si) and titanium (Ti), and particulate SiO2 and TiO2 in postmortem tissue samples from 15 deceased persons. Included tissues are liver, spleen, kidney and the intestinal tissues jejunum and ileum. Low-level analysis was enabled by the use of fully validated sample digestion methods combined with (single particle) inductively coupled plasma high resolution mass spectrometry techniques (spICP-HRMS). The results show a total-Si concentration ranging from <2 to 191 mg Si/kg (median values of 5.8 (liver), 9.5 (spleen), 7.7 (kidney), 6.8 (jejunum), 7.6 (ileum) mg Si/kg) while the particulate SiO2 ranged from <0.2 to 25 mg Si/kg (median values of 0.4 (liver), 1.0 (spleen), 0.4 (kidney), 0.7 (jejunum, 0.6 (ileum) mg Si/kg), explaining about 10% of the total-Si concentration. Particle sizes ranged from 150 to 850 nm with a mode of 270 nm. For total-Ti the results show concentrations ranging from <0.01 to 2.0 mg Ti/kg (median values of 0.02 (liver), 0.04 (spleen), 0.05 (kidney), 0.13 (jejunum), 0.26 (ileum) mg Ti/kg) while particulate TiO2 concentrations ranged from 0.01 to 1.8 mg Ti/kg (median values of 0.02 (liver), 0.02 (spleen), 0.03 (kidney), 0.08 (jejunum), 0.25 (ileum) mg Ti/kg). In general, the particulate TiO2 explained 80% of the total-Ti concentration. This indicates that most Ti in these organ tissues is particulate material. The detected particles comprise primary particles, aggregates and agglomerates, and were in the range of 50–500 nm with a mode in the range of 100–160 nm. About 17% of the detected TiO2 particles had a size <100 nm. The presence of SiO2 and TiO2 particles in liver tissue was confirmed by scanning electron microscopy with energy dispersive X-ray spectrometry. [ABSTRACT FROM AUTHOR]

Detection and characterization of nanoparticles (NPs) in complex media as consumer products, food and toxicological test media is an essential part of understanding the potential benefits and risks of the application of nanoparticles. Single particle ICP-MS (spICP-MS) was studied as a screening tool for the detection and characterization of nanoparticles in complex matrices such as food and biological tissues. A data evaluation tool was created for the calculation of particle size, concentration and size distribution from the raw data. spICP-MS measurements were carried out on a standard quadrupole instrument as well as on a sector-field instrument. Performance characteristics were determined for four types of NPs. For the quadrupole instrument the size detection limits were 20 nm (Au and Ag), 50 (TiO2) and 200 nm (SiO2). For the sector-field instrument size detection limits are lower, 10 nm (Au). Concentration detection limits ranged from 1 ng L−1 for 60 nm Au NPs to 0.1 μg L−1 for 500 nm SiO2 particles. The dynamic range of spICP-MS is limited to two orders of magnitude and as a consequence sample dilution is often required. The precision of the method was found to be ＜5% and ＜10% for the determination of particle size and concentration, respectively while the accuracy for particle size (Au NP only) was ＜10%. The robustness against potential sample matrix components was investigated. The applicability to routine samples was demonstrated by four examples (food, waste water, culture media and biological tissues). The presented combination of spICP-MS measurements with a powerful data evaluation tool enables the use of this technique as a fast, cost efficient and easy to use screening tool for metal and metal oxide NPs that can be widely implemented in the statutory monitoring of food and consumer products for the presence of NPs, as well as in the analytical evaluation of toxicological studies. [ABSTRACT FROM AUTHOR]

Polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs), dioxin-like and non-dioxin-like (indicator) polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs) were monitored in butterfat obtained from 18 different areas in Turkey, both rural and industrial. The results obtained both at RIKILT in the Netherlands and in a food control laboratory in Turkey for PCDD/Fs and PCBs were in good agreement. The sum of PCDD/Fs+dl-PCBs, total indicator PCBs and PBDEs were in the range 0.26-3.82 pg TEQ g-1 fat, 0.20-3.04 ng g-1 fat and 0.18-5.00 ng g-1 fat, respectively. Despite the very low levels measured, slightly elevated PCDD/F and PCB levels were found in Izmir-Aliağa, Kocaeli, Denizli, and Zonguldak. The only result exceeding the EU action level was the dl-PCB concentration in Izmir-Aliağa. Ratios of PCDD/Fs and PCBs indicate that contamination in the elevated areas originated from different sources. High BDE 209 levels were detected in Mersin and Bursa. For the 18 regions analysed, the average total daily intake of total TEQ (dioxins and dl-PCBs) from butterfat was 0.09 pg TEQ(1998) (0.08 pg TEQ(2005)) kg-1 body weight, while those for indicator PCBs and PBDEs were 58.8 and 35.1 pg kg-1 body weight, respectively. The average total daily intake from dairy products were 0.26 pg TEQ(1998) (0.20 pg TEQ(2005)), 183 and 103 pg kg-1 body weight, respectively. [ABSTRACT FROM AUTHOR]

Generic methods based on chromatography with full scan MS detection are maturing. Progress has been made in the development of software for automated detection or identification of the analytes, but this still is the bottleneck inhibiting implementation for routine analysis. Validation of qualitative wide-scope screening is another hurdle to be taken before application. An overview of current chromatography-based food toxicant screening is presented. [ABSTRACT FROM AUTHOR]

Deposition precipitation of nickel hydroxide onto modified carbon nanofibers has been studied and compared to deposition onto silica. The carbon nanofiber support materials consisted of graphite-like material of the fishbone-type with a diameter of 20-50 nm and a specific surface area of 150 m²/g. Modification involved surface oxidation (CNF-O) optionally followed by partial reduction (CNF-OR) or thermal treatment (CNF-OT). Titration of the support materials showed the presence of 0.17 and 0.03 mmol/g carboxylic acid groups for CNF-O and CNF-OR, respectively. For the CNF-OT only basic groups were present. The deposition precipitation of 20 wt % nickel onto these supports has been studied by time dependent pH and nickel loading studies. With silica, nickel ion adsorption did not occur prior to nucleation of the nickel hydroxide phase at pH = 5.6. With CNF-O, nickel ion adsorption took place right from the start of the deposition process at pH = 3.5, and at pH = 5.6 already 4 wt % nickel was adsorbed. Nucleation of nickel hydroxide onto adsorbed nickel ion clusters proceeded subsequently. Characterization of the dried Ni/CNF-O samples with TEM and XRD showed well dispersed and thin (5 nm) platelets of nickel hydroxide adhering to the carbon nanofibers. After reduction at 773 K in hydrogen the Ni/CNF-O contained metallic nickel particles of 8 nm homogeneously distributed over the fibers. With CNF-OR and CNF-OT, precipitation of large platelets (> 500 nm) separate from the support took place. Clearly, the presence of carboxylic acid groups is essential to successfully deposit nickel hydroxide onto modified carbon nanofibers. [ABSTRACT FROM AUTHOR]