Decoration of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) with N-oxides increases the T1 relaxivity of Gd-complexes.

High complex stability and longitudinal relaxivity of Gd-based contrast agents are important requirements for magnetic resonance imaging (MRI) because they ensure patient safety and contribute to measurement sensitivity. Charged and zwitterionic Gd3+-complexes of the well-known chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) provide an excellent basis for the development of safe and sensitive contrast agents. In this report, we describe the synthesis of DOTA-NOx, a DOTA derivative with four N-oxide functionalities via "click" functionalization of the tetraazide DOTAZA. The resulting complexes Gd-DOTA-NOx and Eu-DOTA-NOx are stable compounds in aqueous solution. NMR-spectroscopic characterization revealed a high excess of the twisted square antiprismatic (TSAP) coordination geometry over square antiprismatic (SAP). The longitudinal relaxivity of Gd-DOTA-NOx was found to be r1=7.7 mm-1 s-1 (1.41 T, 37 °C), an unusually high value for DOTA complexes of comparable weight. We attribute this high relaxivity to the steric influence and an ordering effect on outer sphere water molecules surrounding the complex generated by the strongly hydrated N-oxide groups. Moreover, Gd-DOTA-NOx was found to be stable against transchelation with high excess of EDTA (200 eq) over a period of 36 h, and it has a similar in vitro cell toxicity as clinically used DOTA-based GBCAs.

Rapid determination of the shell content in cocoa products using FT-NIR spectroscopy and chemometrics.

The determination of the cocoa shell content is of interest because a high shell content causes a reduction in the quality of cocoa products. Consequently, the aim of the present study was the development of a routinely applicable method for the quantitation of shell material in cocoa nibs. For this, 51 fermented cocoa samples of different varieties from 14 cocoa growing countries covering the crop years 2012-2017 were acquired. Admixtures of cocoa nibs with shell material were prepared in a range of 0-20% cocoa shell and subsequently analysed by Fourier transform near-infrared spectroscopy (FT-NIRS). Support vector machine regression models were created, which enabled the prediction of the cocoa shell content in a mixing ratio range of 0-20% with an RMSE of 2.05% and a R2 of 0.88 and in a range of 0-10% with an RMSE of 1.70% and a R2 of 0.72. This predictive capability suggests that the presented method is suitable for rapid determination of cocoa shell content in cocoa nibs. In addition, it was demonstrated that the method is applicable to other relevant cocoa matrices, as the prediction of the shell content of several industrial cocoa masses by the FT-NIRS-based model showed good consistency with the prediction by liquid chromatography-mass spectrometry. This emphasizes that FT-NIRS combined with chemometrics has great potential for the determination of cocoa shell content in cocoa nibs and cocoa masses in routine analysis, such as incoming inspection.

Food Authentication of Almonds (Prunus dulcis Mill.). Fast Origin Analysis with Laser Ablation Inductively Coupled Plasma Mass Spectrometry and Chemometrics.

Food fraud is a growing problem, especially misdeclaration due to regional price differences offering a wide field. Fast, powerful, and cost-effective analytical methods are therefore essential to counteract food fraud. The isotopolome is suitable for origin discrimination and was analyzed in this study using laser ablation inductively coupled plasma mass spectrometry (ICP-MS). A total of 250 almond samples from six countries and four crop years were analyzed and evaluated by chemometric methods. By using a ratio-based assessment, calibration problems were avoided and an origin predictive accuracy of 85.2 ± 1.2% was achieved. Compared to ICP-MS with solution nebulization, the analysis time could be reduced to about one-fifth.

Determination of Isothiocyanate-Protein Conjugates in a Vegetable-Enriched Bread.

Vegetables of the plant order Brassicales are believed to have health-promoting properties, as they provide high contents of glucosinolates (GLS) and deriving from these, enzymatically and heat-induced breakdown products, such as isothiocyanates (ITC). Besides their positive physiological effects, ITC are electrophilic and can undergo reactions with food components such as proteins. Following the trend of improving traditional food products with GLS-rich ingredients, interactions of ITC with proteins can diminish the properties of both components-protein's value and functionality as well as ITC's bioactivity. In vegetable-enriched bread, where cresses (Lepidium sativum L. or Tropaeolum majus L.) are added to the initial dough, together with benzyl cyanide, benzyl isothiocyanate (BITC) is formed during the baking process. The aim of the present study was to investigate the possible migration behavior of the GLS breakdown products and the formation of ITC-wheat protein conjugates. After the baking process, the breads' proteins were enzymatically hydrolyzed, and the ITC-amino acid conjugates analyzed using a LC-ESI-MS/MS methodology. In all samples, BITC-protein conjugates were detected as thiourea derivatives, while formation of dithiocarbamates could not be detected. The study showed that GLS and their breakdown products such as ITC migrate into the surrounding food matrix and undergo reactions with proteins, which could in turn lead to modified protein properties and reduce the bioavailability of ITC and lysine.