Rare earth element and yttrium characteristics of carbonates within the sediment-hosted Luiswishi and Kamoto Cu-Co deposits, Katanga Copperbelt (Democratic Republic of Congo - DRC)

The Neoproterozoic Central African Copperbelt is a world-class metallogenic province characterized by sediment-hosted stratiform Cu-Co ore deposits and polymetallic vein-type deposits. Two main mineralization phases have been recognized in the Katanga Copperbelt (Democratic Republic of Congo). The first phase occurred during early to intermediate diagenesis and the second during deep burial and the Lufilian orogeny. The Rare Earth Element and Yttrium (REY) concentrations of gangue dolomites associated with the second mineralization phase at the Kamoto and Luiswishi ore deposits were determined and compared to those of their respective host rocks. Kamoto samples exhibit convex Upper Continental Crust-normalized patterns with a pronounced light BEE depletion without significant Eu anomalies and with positive La anomalies. The Luiswishi samples exhibit either progressively increasing REY patterns or ramp-shaped patterns with minor mid BEE-heavy BEE fractionation, accompanied by pronounced negative Ce and Eu anomalies. These differences suggest that a more intense metamorphic overprint at Luiswishi contributed to the differences with the Kamoto deposit

A pre-column derivatization method allowing quantitative metabolite profiling of carboxyl and phenolic hydroxyl group containing pharmaceuticals in human plasma via liquid chromatography-inductively coupled plasma-tandem mass spectrometry (LC-ICP-MS/MS)

The development of suitable analytical methods for drug ADME (absorption, distribution, metabolism and excretion) studies is of great importance. The currently routinely applied detection techniques usually demonstrate a structure-dependent analytical response (MS-based method) or require the synthesis of a radiolabelled version of the parent drug (radiodetection) for accurate quantification. Inductively coupled plasma-(tandem) mass spectrometry (ICP-MS(/MS)) offers a promising alternative to radiolabelling followed by radiodetection due to the structure-independent nature of its analytical response. Within the context of this study, an accurate, simple and sensitive HPLC-ICP-MS/MS method for the quantitative metabolite profiling of diclofenac in human plasma based on the pre-column derivatization of the carboxylic and phenolic -OH groups present in the parent drug and its major metabolite, 4'-hydroxy-diclofenac, was developed and validated. A cost-effective and commercially available derivatization reagent, p-bromophenacyl bromide (p-BPB), was applied for the introduction of Br into the drug molecule and its major metabolite, enabling the element-selective detection and quantification based on the Br-signal. The presence of Cl in both diclofenac and 4'-hydroxy-diclofenac allowed an additional validation via simultaneous monitoring of the Cl-signal by using a state-of-art ICP-MS/MS instrument equipped with a collision/reaction cell. The reaction conditions were successfully optimized to achieve a quantitative formation of the corresponding derivatization products, while the baseline separation of the target compounds in a typical biological matrix (i.e. human plasma) was achieved using gradient reversed phase high-performance liquid chromatography (RP-HPLC). A fit-for-purpose accuracy (recovery between 85-115%) and precision (repeatability <= 7.2% RSD) were achieved. The limits of quantification (LOQ) are approximate to 50 mu g L-1 for Br and approximate to 80 mu g L-1 for Cl, corresponding to approximate to 0.2 mg L-1 and approximate to 0.4 mg L-1 of diclofenac, respectively

The cellular interactions of PEGylated gold nanoparticles : effect of PEGylation on cellular uptake and cytotoxicity

Poly(ethylene glycol) (PEG) is frequently used to coat various medical nanoparticles (NPs). As PEG is known to minimize NP interactions with biological specimens, the question remains whether PEGylated NPs are intrinsically less toxic or whether this is caused by reduced NP uptake. In the present work, the effect of gold NP PEGylation on uptake by three cell types is compared and evaluated the effect on cell viability, oxidative stress, cell morphology, and functionality using a multiparametric methodology. The data reveal that PEGylation affects cellular NP uptake in a cell-type-dependent manner and influences toxicity by different mechanisms. At similar intracellular NP numbers, PEGylated NPs are found to yield higher levels of cell death, mostly by induction of oxidative stress. These findings reveal that PEGylation significantly reduces NP uptake, but that at similar functional (= cell-associated) NP levels, non-PEGylated NPs are better tolerated by the cells

Light absorption coefficient of CsPbBr3 perovskite nanocrystals

Inductively coupled plasma mass spectrometry (ICP-MS) was combined with UV−vis absorption spectroscopy and transmission electron microscopy to determine the size, composition, and intrinsic absorption coefficient μi of 4 to 11 nm sized colloidal CsPbBr3 nanocrystals (NCs). The ICP-MS measurements demonstrate the nonstoichiometric nature of the NCs, with a systematic excess of lead for all samples studied. Rutherford backscattering measurements indicate that this enrichment in lead concurs with a relative increase in the bromide content. At high photon energies, μi is independent of the nanocrystal size. This allows the nanocrystal concentration in CsPbBr3 nanocolloids to be readily obtained by a combination of absorption spectroscopy and the CsPbBr3 sizing curve