Chemie und Prozesstechnik
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Organisationseinheit der BAM
- 1.1 Anorganische Spurenanalytik (19) (entfernen)
In this paper, we describe the labelling of antibodies by gold nanoparticles (AuNPs) with diameters of 10 and 60 nm with detection by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Additionally, the AuNPs labelling strategy is compared with commercially available labelling reagents based on MeCAT (metal coded affinity tagging). Proof of principle experiments based on dot blot experiments were performed. The two labelling methods investigated were compared by sensitivity and limit of detection (LOD). The absolute LODs achieved were in the range of tens of picograms for AuNP labelling compared to a few hundred picograms by the MeCAT labelling.
Recent recommendations by the Food and Drug Administration1 and the European Medicines Agency2 are to limit the clinical use of linear gadolinium-based contrast agents (GBCAs) due to convincing evidence of deposition in tissues. Macrocyclic GBCA continued to be considered safe, provided that patients have normal renal function. To date, given the low sensitivity of conventional MRI, there has been a debate about the signal increase following the injections of a macrocyclic GBCA.
In the recent decade, metal pyrithione complexes have become important biocides for antifouling purposes in shipping. The analysis of metal pyrithione complexes and their degradation products/species in environmental samples is challenging because they exhibit fast UV degradation, transmetalation, and ligand substitution and are known to be prone to spontaneous species transformation within a chromatographic system. The environmental properties of the pyrithione species, e.g., toxicity to target and non-target organisms, are differing strongly, and it is therefore inevitable to identify as well as quantify all species separately. To cope with the separation of metal pyrithione species with minimum species transformation during analysis, a capillary electrophoresis (CE)–based method was developed. The hyphenation of CE with selective electrospray ionization- and inductively coupled plasma–mass spectrometry (ESI-, ICP-MS) provided complementary molecular and elemental information for the identification and quantification of pyrithione species. To study speciation of pyrithiones, a leaching experiment of several commercial antifouling paints containing zinc pyrithione in ultrapure and river water was conducted. Only the two species pyrithione (HPT) and dipyrithione ((PT)2) were found in the leaching media, in concentrations between 0.086 and 2.4 μM (HPT) and between 0.062 and 0.59 μM ((PT)2), depending on the paint and leaching medium. The limits of detection were 20 nM (HPT) and 10 nM ((PT)2). The results show that complementary CE-MS is a suitable tool for mechanistical studies concerning species transformation (e.g., degradation) and the identification of target species of metal pyrithione complexes in real surface water matrices, laying the ground for future environmental studies.
The most challenging part in performing a single cell ICP-MS (sc-ICP-MS) approach is the sample preparation, in particular the reduction of the ionic background. This step is, in many cases, time-consuming and required for each sample separately. Furthermore, sc-ICP-MS measurements are mostly carried out "manually", given the fact that present systems are not allowing for an automated change of samples. Thus, within this work, we developed an approach based on a HPLC system coupled on-line with sc-ICP-MS via a set of switching valves as well as an in-line filter for automated cell washing. This set-up enables the ionic background removal as well as analysis of single cells completely automated without any manual sample pretreatment. Our approach was applied for the analysis of the single celled diatom species Cyclotella meneghiniana, a marine diatom species, on the basis of Mg24 and facilitates testing in 11 min per sample, requiring only around 10,000 cells in a volume of 10 µL and approx. 10 mL of a 5% MeOH/95% deionized water (v/v) mixture. Even at extremely saline culturing media concentrations (up to 1000 mg L-1 magnesium) our on-line approach worked sufficiently allowing for distinction of ionic and particulate fractions. Furthermore, a set of diatom samples was analyzed completely automated without the need for changing samples manually. So, utilizing this approach enables analyzing a high quantity of samples in a short time and therefore in future the investigation of ecotoxicological effects is simplified for example in terms of metal accumulation by taking biovariability into account.
Complementarity of molecular and elemental mass spectrometric imaging of Gadovist™ in mouse tissues
(2019)
Drug biodistribution analyses can be considered a key issue in pharmaceutical discovery and development. Here, mass spectrometric imaging can be employed as a powerful tool to investigate distributions of drug compounds in biologically and medically relevant tissue sections. Both matrix-assisted laser desorption ionization–mass spectrometric imaging as molecular method and laser ablation inductively coupled plasma–mass spectrometric imaging as elemental detection method were applied to determine drug distributions in tissue thin sections. Several mouse organs including the heart, kidney, liver, and brain were analyzed with regard to distribution of Gadovist™, a gadolinium-based contrast agent already approved for clinical investigation. This work demonstrated the successful detection and localization of Gadovist™ in several organs. Furthermore, the results gave evidence that gadolinium-based contrast agents in general can be well analyzed by mass spectrometric imaging methods. In conclusion, the combined application of molecular and elemental mass spectrometry could complement each other and thus confirm analytical results or provide additional information.
Lead isotope amount ratios are commonly used in diverse fields such as archaeometry, geochemistry and forensic science. Currently, five reference materials with certified lead isotope amount ratios are available, namely NIST SRM 981, 982 and 983, GBW-04442 and NMIJ 3681-a. Only NIST SRM 981 and NMIJ 3681-a have approximately natural isotopic compositions, and NIST SRM 981 is predominantly used for correcting mass discrimination/mass fractionation in the applied mass spectrometric procedures. Consequently, there is no other certified reference material available to be used for validation and/or quality control of the analytical procedures applied to lead isotope amount ratio measurements. To fill this gap, two new reference materials have been produced and certified for their lead isotope amount ratios. For both certified reference materials, complete uncertainty budgets have been calculated and SI traceability has been established. This provides the users with independent means for validating and verifying their analytical procedures and for conducting quality control measures. ERM-EB400 is a bronze material with a nominal lead mass fraction of 45 mg kg-1 and certified lead isotope amount ratios of n(206Pb)/n(204Pb) = 18.072(17) mol mol-1, n(207Pb)/n(204Pb) = 15.578(18) mol mol-1 and n(208Pb)/n(204Pb) = 38.075(46) mol mol-1 with the associated expanded uncertainties (k = 2) given in brackets. ERM-AE142 is a high-purity solution of lead in 2% nitric acid with a nominal mass fraction of 100 mg kg-1 and certified Pb isotope amount ratios of n(206Pb)/n(204Pb) = 21.114(17) mol mol-1, n(207Pb)/n(204Pb) = 15.944(17) mol mol-1 and n(208Pb)/n(204Pb) = 39.850(44) mol mol-1 with the associated expanded uncertainties (k = 2) given in brackets. Both materials are specifically designed to fall within the natural lead isotopic variation and to assist users with the validation and verification of their analytical procedures. Note that while one of these reference materials requires the chemical separation of Pb from its matrix (ERM-EB400), the other does not (ERM-AE142). As additional information, δ208/206PbNIST SRM981 values are provided for both materials. For ERM-AE142, a delta value of δ208/206PbNIST SRM981 = -28.21(30) ‰ was obtained, and for ERM-EB400, a delta value of δ208/206PbNIST SRM981 = -129.47(38) ‰ was obtained, with the associated expanded uncertainties (k = 2) given in brackets.
Rationale: Boron (B) is an essential micronutrient in plants and its isotope variations are used to gain insights into plant metabolism, which is important for crop plant cultivation. B isotope variations were used to trace intra‐plant fractionation mechanisms in response to the B concentration in the irrigation water spanning the
range from B depletion to toxic levels.
Methods: A fully validated analytical procedure based on multi‐collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS), sample decomposition and B Matrix separation was applied to study B isotope fractionation. The Validation was accomplished by establishing a complete uncertainty budget and by applying reference materials, yielding expanded measurement uncertainties of 0.8‰ for pure boric acid solutions and ≤1.5‰ for processed samples. With this validated procedure SI traceable B isotope amount ratios were determined in plant reference materials for the first time.
Results: The B isotope compositions of Irrigation water and bell pepper samples suggest passive diffusion of the heavy 11B isotope into the roots during low to high B concentrations while uptake of the light 10B isotope was promoted during B depletion, probably by active processes. A systematic enrichment of the heavy 11B isotope in higher located plant parts was observed (average Δ11Bleaf‐roots = 20.3 ± 2.8‰ (1 SD)), possibly by a facilitated transport of the heavy 11B isotope to growing Meristems by B transporters.
Conclusions: The B isotopes can be used to identify plant metabolism in Response to the B concentration in the irrigation water and during intra‐plant B transfer. The large B isotope fractionation within the plants demonstrates the importance of
biological B cycling for the global B cycle.
Arraying of single cells for mass spectrometric analysis is a considerable bioanalytical challenge. In this study, we employ a novel single cell arraying technology for quantitative analysis and isotopic fingerprinting by laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS). The single cell arraying approach is based on a piezo-acoustic microarrayer with software for automated optical detection of cells within the piezo dispense capillary (PDC) prior to arraying. Using optimized parameters, single cell occupancy of >99%, high throughput (up to 550 cells per hour), and a high cell recovery of >66% is achieved. LA-ICP-TOF-MS is employed to detect naturally occurring isotopes in the whole mass range as fingerprints of individual cells. Moreover, precise quantitative determination of metal-containing cell dyes is possible down to contents of ∼100 ag using calibration standards which were produced using the same arrayer.
Boron (B) is an essential micronutrient for plant growth. Lack of valid methods for pretreatment and measurement of δ11B in plant restrict applications of it in the biosphere. Dry ashing, one step cation exchange and micro-sublimation were combined to separate and purify boron (B) in plant tissues. The low procedure blank, high B recovery and the accurate δ11B values of the plant reference materials demonstrate that this method is suitable and valid for B pretreatment and δ11B measurement in plant samples by MC-ICP-MS. Based on this method, the δ11B in different plants (Brassica napus, Chenopodium album L, moss, lichen, and Nostoc commune) was analyzed. For Brassica napus, δ11B increased gradually from root to leaf, and then decreased to rapeseed. For the same parts, the δ11B increased from the lower parts to the higher parts. This variation may be due to the B(OH)3 transporter of NIP6;1 and the incorporation of B into the cell. The reason for lower δ11B values in shell and rapeseed compared to those in leaves presumably is to the preferred Transport of borate in the phloem. The largest δ11B fractionation between leaf and root in Brassica napus and Chenopodium album L was +24.2‰ and +26.6‰, respectively. The large variation and fractionation of δ11B within plants indicates that δ11B is a good tracer to study the B translocation mechanisms and metabolism within plants. The δ11B in Nostoc commune, lichen, and moss showed variations of -4.1‰ to +21.5‰, −9.4‰ to +7.3‰, and −18.3‰ to +11. 9‰, respectively. In the same site, δ11B in different plants ranked Nostoc commune>moss>lichen and δ11B in mosses growing in different environment ranked soil>tree>rock. Rain and soil available B are the main B sources for these plants. The δ11B in Nostoc commune, lichen, and moss may be a useful tracer to study the atmospheric B input. In the future, plants culture experiments under certain environments and studies from molecular level are necessary to decipher the variation of δ11B and fractionation mechanisms within plants.