Laser ablation inductively coupled plasma mass spectrometry for direct analysis of the spatial distribution of trace elements in metallurgical-grade silicon

The spatial distribution and concentration of impurities in metallurgical-grade silicon (MG-Si) samples (97-99% w/w Si) were investigated by use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The spatial resolution (120μm) and low limits of detection (mg kg−1) for quality assurance of such materials were studied in detail. The volume-dependent precision and accuracy of non-matrix-matched calibration for quantification of minor elements, using NIST SRM 610 (silicate standard), indicates that LA-ICP-MS is well suited to rapid process control of such materials. Quantitative results from LA-ICP-MS were compared with previously reported literature data obtained by use of ICP-OES and rf-GD-OES. In particular, the distribution of element impurities and their relationship to their different segregation coefficients in silicon is demonstrate

Differentiation of degrees of ripeness of catuai and tipica green coffee by chromatographical and statistical techniques

The quality of green coffee is influenced by the degree of ripeness of the fruit at harvest. The aim of this study was to identify chemical markers differentiating between degrees of ripeness. Two coffee varieties, Catuai and Tipica, from the same farm were analysed using the following parameters and methods: caffeine and chlorogenic acid content using high-performance liquid chromatography (HPLC), sucrose content using hydrophilic interaction chromatography, high-molecular weight fraction (HMW) using high-performance size-exclusion chromatography (HPSEC) and volatile compounds using headspace solid phase micro extraction gas chromatography/mass spectrometry. The best method for differentiating between degrees of ripeness was found to be principal component analysis (PCA) based on HPLC data. HPSEC showed differences in the HMW fraction for different degrees of ripeness and both coffee varieties. Volatile profiles allowed separation of both varieties; yet, except for ripe Catuai, no separation was achieved for the degree of ripeness

Analytical evidence of amorphous microdomains within nitridosilicate and nitridoaluminosilicate single crystals

Single crystals of new nitridosilicates and nitridoaluminosilicates with excellent R values in X-ray investigations were analysed quantitatively using 30 to 60μm single-spot LA-ICP-MS. Significant discrepancies between expected and measured chemical composition could not be explained by the crystallographic data. High spatial resolution analysis using electron probe microanalysis (EPMA, 10μm) leads to the discovery of inhomogeneities in the crystalline material. The application of standard single-spot LA-ICP-MS with a spatial resolution of 30 to 60μm is not suitable for the analysis of these crystals as the existing inhomogeneities dominate and alter the determined concentrations. However, owing to the better detection capabilities, a scanning LA-ICP-MS procedure enables a more representative analysis of single crystals of Ca5Si2Al2N8 than single-spot LA-ICP-MS as a result of a larger sampling volume. It is highly likely that these impurities consist of amorphous, vitreous phases as powder diffraction X-ray data indicates the existence of a significant fraction of an X-ray amorphous material besides crystalline silicates. These microdomains contain less aluminium, silicon and calcium or are nearly free of aluminium, which explains the detected discrepancies in the chemical compositio

Characterization of Pinus nigra var. laricio Maire bark extracts at the analytical and pilot scale

Pinus nigra var. laricio bark and its hot-water extracts (HWE) obtained at an analytical and pilot plant scale have been characterized in terms of phenolic extractives, condensed tannins (CTs), carbohydrates and inorganic compounds. Analytical extractions with aqueous acetone were also performed for comparison with HWE. The bark contains 35.5 g kg−1 CT, and two-thirds of it could be extracted. Analytical HWE at 75°C led to a total yield of 56.4 g kg−1. The extracts are mainly composed of phenolic compounds (50.7%) and pectins (19.7%). CTs amount to 17.9% of the extracts and are procyanidins with a mean degree of polymerization (DP) of about 9. Non-tannin phenolic oligomers also occurred in the extracts, which could be identified by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) as lignin fragments. Matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry (MALDI-TOF MS) revealed that the CT is a flavanol derivative in methylated form. Further characterization and tailoring of the HWE properties is needed in the context of their specific application

Isolation and identification of actinomycetes strains from Switzerland and their biotechnological potential

Actinomycetes strains isolated from different habitats in Switzerland were investigated for production of antibacterial and antitumoral compounds. Based on partial 16S rRNA gene sequences, the isolated strains were identified to genus level. Streptomyces as the largest genus of Actinobacteriawas isolated the most frequently. A screening assay using the OmniLog instrument was established to facilitate the detection of active compounds from actinomycetes. Extracts prepared from the cultivated strains able to inhibit Staphylococcus aureusand Escherichia coliwere further analysed by HPLC and MALDI-TOF MS to identify the produced antibiotics. In this study, the bioactive compound echinomycin was identified from two isolated Streptomycesstrains. Natural compounds similar to TPU-0037-C, azalomycin F4a 2-ethylpentyl ester, a derivative of bafilomycin A1, milbemycin-α8 and dihydropicromycin were detected from different isolated Streptomyces strains. Milbemycin-α8 showed cytotoxic activity against HT-29 colon cancer cells. The rare actinomycete,Micromonospora sp. Stup16_C148 produced a compound that matches with the antibiotic bottromycin A2. The draft genome sequence from Actinokineospora strain B136.1 was determined using Illumina and nanopore-based technologies. The isolated strain was not able to produce antibacterial compounds under standard cultivation conditions. The antiSMASH bioinformatics analyses of the genome from strain B136.1 identified biosynthetic gene clusters with identity values between 4% to 90% to known gene clusters encoding antibiotics. The combinations of cultivation conditions, screening assays, analytical methods and genome mining are important tools to characterize strains of actinomycetes for the identification of their potential to produce natural compounds with antimicrobial activity

Determination of Molecular Structures of Condensed Tannins from Plant Tissues Using HPLC-UV Combined with Thiolysis and MALDI-TOF Mass Spectrometry.

Condensed tannins extracted from plant tissues are suitable substitutes for phenolic resins. Their molecular structure, which might influence their chemical reactivity, can be assessed by the use of both HPLC-UV after acid thiolysis and MALDI-TOF mass spectrometry. Thiolysis of plant extracts in acidic methanol with cysteamine hydrochloride results in the release of the monomeric units of the condensed tannin oligomers that can be further quantified by reversed-phase HPLC-UV by comparison with analytical standards. MALDI-TOF mass spectrometry using 2,5-dihydroxybenzoic acid as matrix and K+ as cationization agent highlights the molecular structural characteristics (e.g., monomeric unit sequence) of the tannin oligomers. The methodologies permit the estimation of the mean and the maximum (observable) degree of polymerization, the type of monomeric units and the presence of glycosylation and/or esterification of the tannin oligomers

Direct coupling of HPTLC with MALDI-TOF MS for qualitative detection of flavonoids on phytochemical fingerprints

Analysis of flavonoids is important for quality assessment of plant materials and products for many research fields e.g. pharma, medicine, food or dietary supplements. TLC or HPTLC fingerprint analysis is commonly used for this purpose. However, successful identification of flavonoids using this method depends on the ability to visualize separated zones with reagents, and reproducibility of Rf values. Therefore, a more reliable method of analysis of their fingerprints is needed. This study demonstrates the potential of combining HPTLC with UV-MALDI-TOF MS for analysis of flavonoids

Laser ablation inductively coupled plasma mass spectrometry for direct analysis of the spatial distribution of trace elements in metallurgical-grade silicon

ISSN:1618-2650ISSN:1618-264

Analysis of the structure of condensed tannins in water extracts from bark tissues of Norway spruce (Picea abies [Karst.]) and Silver fir (Abies alba [Mill.]) using MALDI-TOF mass spectrometry

Condensed tannins extracted from the bark of softwoods have been proven to be suitable compounds in the formulation of environmentally friendly adhesives and resins. Their chemical structure has been shown to significantly influence their properties and possible applications. Condensed tannins extracted from the bark of Norway spruce (Picea abies [Karst.]) and Silver fir (Abies alba [Mill.]) still lack a detail characterization of their chemical structure. In an effort to address this deficiency, barks from these species were collected and extracted in water at 60°C. The dried extracts were analyzed by MALDI-TOF mass spectrometry to identify the building blocks and to determine the degree of polymerization of the tannin oligomers. The condensed tannins extracted from spruce bark at the used conditions were mainly composed of procyanidins with a polymerization degree up to 13. Silver fir extracts revealed a predominance of prodelphinidins with a polymerization degree up to 9. The presence of less common building blocks such as stilbene glucosides and flavan-3-ols gallates was also hinted. Different curing times and viscosities in resin formulations are expected between the two studied species, as well as in comparison to the most known and available tannins from tropical species

Legionella in FM : Detection of Legionella pneumophila in waterlines of dental surgeries in the Canton of Zurich, Switzerland

Facility management (FM) is present in healthcare. According to the International Facility Management Association (IFMA) guidelines, an organisation is obliged to take precautions to enable continuous business operation and reduce hazards. As FM organizations or facilities services are sometimes responsible for water systems, and hence in the reduction of hazards in this area, the FM’s role is vital for maintaining hygiene. Being healthcare providers, dental surgeries are subject to strict hygienic criteria. During treatment patients are consigned to the care of dentists. The instruments of a dental chair unit (DCU) operate with drinking water from a source. In the process of an implemented hygienic concept in the dental surgeries the care instruments get disinfected systematically. But the water system of the building itself allows limited access, and its hygienic status is not always documented well. As can be seen by this example, hygiene concepts potentially contain blind spots. As a result, not only patients but also medical staff might be exposed to hygienic hazards, which are meant to be reduced to a minimum. Contaminated water lines may cause certain diseases (e.g. Legionnaire’s Disease). Inevitably, the personnel responsible have to manage the facilities appropriately to reduce the risks of a contamination. Literature on Legionella suggests an urgent need to address the issue of Legionella in dental surgeries. This paper will highlight the issue of Legionella in dental surgeries and aims to detect potential hazards from the built environments’ hygiene with a focus on water lines. It will further draw attention to additional criteria relevant for FM and duty holders. During the case study, data was collected on Legionella contamination in dental surgeries' waterlines. Building and water lines of the DCUs were tested as well, in compliance with the Swiss drinking water ordinance. Appreciating the fact, that there was no pathogen Legionella pneumophila detected in all samples of the DCUs, the questions arises on the incident of a potential contamination of the facilities (building) water line system itself as well as on the duties of the stakeholders involved