Non-targeted screening for contaminants in paper and board food-contact materials using effect-directed analysis and accurate mass spectrometry

Due to large knowledge gaps in chemical composition and toxicological data for substances involved, paper and board food-contact materials (P&B FCM) have been emerging as a FCM type of particular concern for consumer safety. This study describes the development of a step-by-step strategy, including extraction, high-performance liquid chromatography (HPLC) fractionation, tentative identification of relevant substances and in vitro testing of selected tentatively identified substances. As a case study, we used two fractions from a recycled pizza box sample which exhibited aryl hydrocarbon receptor (AhR) activity. These fractions were analysed by gas chromatography (GC) and ultra-HPLC (UHPLC) coupled to quadrupole time-of-flight mass spectrometers (QTOF MS) in order tentatively to identify substances. The elemental composition was determined for peaks above a threshold, and compared with entries in a commercial mass spectral library for GC-MS (GC-EI-QTOF MS) analysis and an in-house built library of accurate masses for substances known to be used in P&B packaging for UHPLC-QTOF analysis. Of 75 tentatively identified substances, 15 were initially selected for further testing in vitro; however, only seven were commercially available and subsequently tested in vitro and quantified. Of these seven, the identities of three pigments found in printing inks were confirmed by UHPLC tandem mass spectrometry (QqQ MS/MS). Two pigments had entries in the database, meaning that a material relevant accurate mass database can provide a fast tentative identification. Pure standards of the seven tentatively identified substances were tested in vitro but could not explain a significant proportion of the AhR-response in the extract. Targeted analyses of dioxins and PCBs, both well-known AhR agonists, was performed. However, the dioxins could explain approximately 3% of the activity observed in the pizza box extract indicating that some very AhR active substance(s) still remain to be identified in recycled low quality P&B.     

Decision tree based control chart pattern recognition

This paper presents a new approach to classify six anomaly types of control chart patterns (CCP), of systematic pattern, cyclic pattern, upward shift, downward shift, upward trend, and downward trend. Current CCP recognition methods use either unprocessed raw data or complex transformed features (via principal component analysis or discrete wavelet transform) as the input representation for the classifier. The objective of using selected features is not only for dimension reduction of input representation, but also implies the process of data compression. In contrast, using raw data is often computationally inefficient while using transformed features is very tedious in most cases. Therefore, owing to its computational advantage, using appropriate features of CCP to achieve good classification accuracy becomes more promising in real process implementation. In this study, using three features of CCP shows quite a competitive performance in terms of classification accuracy and computational loading. More importantly, the proposed method presented here has potential to be generalized to medical, financial, and other application of temporal data.     

Phenylamine Analogous Adducts of C60

Abstract

Reaction conditions leading to efficient nitration of the C₆₀ molecules for the production of nearly pure hexanitro[60]fullerenes using gaseous nitrogen dioxide as the nitration agent were developed. Approach of utilizing hexanitrofullerene as a reactive precursor molecule in the preparation of organic derivatives of C₆₀ demonstrated a versatile alternative synthetic method for indirect fullerene functionalization. Fullerenic nitro functions were found to be excellent leaving groups opt for replacement by nucleophilic substituents, such as phenylamine and oligophenylamines.     

Effects of Hexasulfobutylated C60 on the Thalamic Neurons in Neonatal Rat in vitro

Abstract

The effects of hexasulfobutylated C₆₀ (FC₄S) on membrane potentials and currents were studied by tight-seal, whole-cell recording in thin slices of the neonatal rat thalamus. Silent neuron with resting membrane potentials of around -62.4 ± 0.7 mV was found in whole-cell current clamp recordings. Hexasulfobutylated C₆₀ depolarized the neuron by a concentration dependent manner. It also (1) prolonged the decay time constant of action potential and (2) decreased the threshold of the directly elicited action potentials of the neuron. Hexasulfobutylated C₆₀ did not alter the input resistance of the excitable membrane. In whole-cell voltage clamp studies, depolarizing command pulses from a holding potential of about -70 mV evoked a fast inward current followed by an outward current in the thalamic neurons. Hexasulfobutylated C₆₀ (30 - 100 μM) increased the total inward sodium current of the neuron, while hexasulfobutylated C₆₀ did not alter the outward potassium currents in all voltage steps tested. It was concluded that hexasulfobutylated C₆₀ (1) decreased the threshold of the action potential and (2) prolonged the decay time constant of the directly elicited action potential of the neonatal rat thalamic neurons. The effect may be closely associated with the Na⁺ current in thalamic neurons.     

Environmentally assisted cracking behavior of dissimilar metal weldments in simulated BWR coolant environments

The environmentally assisted cracking behavior of dissimilar metal (DM) welds, including Alloy 52-A 508 and Alloy 82-A508, under simulated BWR coolant conditions was studied. Effects of postweld heat treatment and sulfur content of the base metal on the corrosion fatigue and SCC growth rates of DM welds were evaluated. The crack growth rates for the DM weld heat-treated at 621 °C for 24 h were observed to be faster than those for the as-welded. But the DM weld heat-treated at 621 °C for 8 h + 400 °C for 200 h showed better SCC resistance than the as-welded. The longer the heat treatment at 621 °C, the higher the chromium carbides density along the grain boundary was observed. Sulfur could diffuse out of the base metal and segregate along the grain boundaries of the dilution zone, leading to weakening the grain boundary strength and the SCC resistance of the Alloy 52-A508 weld.     

Comparison of In vitro Nanoparticles Uptake in Various Cell Lines and In vivo Pulmonary Cellular Transport in Intratracheally Dosed Rat Model

In present study, the potential drug delivery of nanoformulations was validated via the comparison of cellular uptake of nanoparticles in various cell lines and in vivo pulmonary cellular uptake in intratracheally (IT) dosed rat model. Nanoparticles were prepared by a bench scale wet milling device and incubated with a series of cell lines, including Caco-2, RAW, MDCK and MDCK transfected MDR1 cells. IT dosed rats were examined for the pulmonary cellular uptake of nanoparticles. The processes of nanoparticle preparation did not alter the crystalline state of the material. The uptake of nanoparticles was observed most extensively in RAW cells and the least in Caco-2 cells. Efflux transporter P-gp did not prevent cell from nanoparticles uptake. The cellular uptake of nanoparticles was also confirmed in bronchoalveolar lavage (BAL) fluid cells and in bronchiolar epithelial cells, type II alveolar epithelial cells in the intratracheally administrated rats. The nanoparticles uptake in MDCK, RAW cells and in vivo lung epithelial cells indicated the potential applications of nanoformulation for poorly soluble compounds. The observed limited direct uptake of nanoparticles in Caco-2 cells suggests that the improvement in oral bioavailability by particle size reduction is via increased dissolution rate rather than direct uptake.     

Preparation and catalysis of amorphous CoNiB and polymer-stabilized CoNiB catalysts for hydrogenation of unsaturated aldehydes

CoNiB and polymer polyvinylpyrrolidone (PVP)-stabilized CoNiB (PVP-CoNiB) catalysts were prepared by chemical reduction with NaBH₄. They were characterized and examined for their catalysis in the hydrogenation of unsaturated aldehydes. CoNiB and PVP-CoNiB catalysts were characterized by X-ray diffraction as amorphous structures and by transmission electron microscopy as having particle sizes in the range 3.5–7 nm – smaller than those of NiB (7–15 nm) and CoB (5–10 nm). CoNiB catalysts were significantly more active than NiB and CoB in the hydrogenations of furfural, crotonaldehyde and citral, and the PVP-CoNiB catalysts were significantly more active than CoNiB. The catalytic properties of CoNiB and PVP-CoNiB catalysts during the selective hydrogenations of crotonaldehyde and citral were similar to those of NiB, but different from those of CoB. The conjugated CC bonds in crotonaldehyde and citral were preferentially reduced to form butyraldehyde and citronellal. PVP-CoNiB could hydrogenate citral to citronellal at a low reaction temperature of 30 °C.     

Emulsifier type,metal chelation and pH affect oxidative stability of n‐3‐enriched emulsions

Recent research has shown that the oxidative stability of oil‐in‐water emulsions is affected by the type of surfactant used as emulsifier. The aim of this study was to evaluate the effect of real food emulsifiers as well as metal chelation by EDTA and pH on the oxidative stability of a 10% n‐3‐enriched oil‐in‐water emulsion. The selected food emulsifiers were Tween 80, Citrem, sodium caseinate and lecithin. Lipid oxidation was evaluated by determination of peroxide values and secondary volatile oxidation products. Moreover, the zeta potential and the droplet sizes were determined. Tween resulted in the least oxidatively stable emulsions, followed by Citrem. When iron was present, caseinate‐stabilized emulsions oxidized slower than lecithin emulsions at pH 3, whereas the opposite was the case at pH 7. Oxidation generally progressed faster at pH 3 than at pH 7, irrespective of the addition of iron. EDTA generally reduced oxidation, as evaluated by volatiles formation in all emulsions, irrespective of pH and emulsifier type, except in the lecithin and caseinate emulsions where a pro‐oxidative effect was observed for some volatiles. The different effects of the emulsifier types could be related to their ability to chelate iron, scavenge free radicals, interfere with interactions between the lipid hydroperoxides and iron as well as to form a physical barrier around the oil droplets.