Sample Preparation System Research Articles

Infrared radiation as a heat source in sample preparation of shrimp for trace element analysis

An open sample preparation system based on use of infrared radiation (IR) for heating was used to accelerate the mineralization of shrimp samples to quantify their As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, Sn and V content by ICP-OES. The method presented good accuracy, as verified by analysis of NIST SRM 1566b oyster tissue, acceptable precision (<20% RSD) and low RCC in the solutions (<3 % w w−1). Optimal experimental conditions (1.0 g sample, 8 mL of HNO3, 8 min heating with a 500 W of lamp) were obtained using a full factorial design. The method was applied to whole harvested shrimp samples (with head, exoskeleton and viscera), which revealed levels of As (4.84 ± 0.23 mg kg−1) and Cd (0.80 ± 0.01 mg kg−1) above those allowed by Brazilian law. Sample preparation based on IR-assisted digestion provides a quick, simple and inexpensive alternative to conventional sample preparation techniques.

Dimethyl 3,3′-dithiobispropionimidate (DTBP) as a cleavable disulfide-based polymer to encapsulate nucleic acids in biological sample preparation

Cleavable disulfide bonds are extremely valuable functional groups for numerous biological applications, including applications as antitumor treatments, gene delivery, and diagnosis. Herein, we demonstrate the use of dimethyl 3,3′-dithiobispropionimidate (DTBP) as a disulfide cleavable bond based cross-linker in nano-composites that encapsulate and release nucleic acids in sample preparation systems for disease diagnoses. We conjugated DTBP with nano-composites, such as amine group-modified diatomaceous earth (DA), which is a solid substrate, and a zinc oxide nanomultigonal shuttle (ZnO NMS) that disrupts cell membranes without chaotropic detergents and improved the quantity and purity of nucleic acids from various biological samples. After encapsulating nucleic acids, the cleavable disulfide bond of DTBP was used to release nucleic acids by breaking disulfide bonds using dithiothreitol (DTT), resulting in highly enhanced efficiency of downstream analyses without PCR inhibitors such as high salt concentrations and SDS. Therefore, nano-composites with cleavable disulfide linkages have potential for various biological applications, including disease diagnostics and therapies.

Abstract P3-01-11: A novel six-parameter assay for comprehensive phenotyping of circulating tumor cells

Abstract Background. The presence and number of circulating tumor cells (CTCs) are prognostic for breast cancer treatment outcome. Direct imaging assays traditionally employ four markers to identify canonical epithelial CTCs: nucleus, exclusion (CD45), and inclusion (EpCAM and cytokeratin). There is intense interest in the ability to phenotype CTCs in order to provide a noninvasive means by which to predict treatment benefit from endocrine therapy and/or HER2-directed therapy in breast cancer. To address this, a 6-parameter assay for detection of ER and HER2 expression on CTCs was developed. We applied this assay to four well characterized breast cancer cell lines representative of various ER and HER2 phenotypes. Methods. BT474, MCF-7, SKBR3, or MDA-MB-231 cells were spiked into peripheral blood from healthy donors and processed using the AccuCyte® sample preparation system; nucleated cells, including CTCs, are captured onto glass slides (8 slides per 7.5 mL blood sample) for subsequent immunofluorescent staining. Slides were stained using the combined epithelial marker and ER/HER2 CTC assay and then analyzed with the CyteFinder® imaging system. CTCs were identified as nucleated cells with positive EpCAM and/or cytokeratin staining, and negative CD45 staining. ER and HER2 expression were assessed as present or absent. Results. All cell lines expressed both cytokeratin and EpCAM, except for MDA-MB-231 which was EpCAM-negative. The ER / HER2 expression patterns observed were consistent with reported phenotype: BT474 (+/+), MCF-7 (+/–), SKBR3 (–/+), and MDA-MB-231 (–/–). Conclusions. Identification of epithelial CTCs and phenotypic characterization of ER and HER2 status are feasible in a combined assay applied to a single blood sample. This approach has implications for efficiency and cost effectiveness, which are of particular importance given the interest in longitudinal testing. Assay evaluation is currently underway using blood samples from breast cancer patients with known receptor status, treatment history, and clinical outcomes. Results will be available for presentation at the meeting. Citation Format: Liu MC, Sun Y, Ramirez A, Campton D, George T, Haselkorn KE, Clein A, Gadi V, Sabath D, Kaldjian E. A novel six-parameter assay for comprehensive phenotyping of circulating tumor cells [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-11.

Radiocarbon measurement using a gas/solid hybrid ion source and an automated sample preparation system at the University of Tsukuba

The first preliminary test of the 14C-accelerator mass spectrometry (AMS) system at the University of Tsukuba was successfully performed using a gas/solid hybrid ion source and an automated sample preparation system with an elemental analyzer (EA). The maximum 12C− current of ∼11 µA was achieved using the optimized CO2 flow rate to the hybrid ion source. The machine background of 14C/12C for the AMS system reached to ∼2.4 × 10−16 (∼0.02 percent modern carbon, pMC) using unprocessed mineral graphite. Moreover, the blank level of 14C/12C including the combustion process for an IAEA-C1 graphite sample was 4.6 × 10−16 (0.05 pMC), demonstrating the low blank level of the automatic sample preparation system. In contrast, the blank level of 14C/12C including the combustion process for an IAEA-C1 CO2 sample was 5.0 × 10−15 (0.49 pMC), an order of magnitude worse than that for the graphite sample. The measurement uncertainty for the gas ion source was 0.6%, 2–3 times worse than that for the solid ion source (0.2%–0.3%).

Determination of 34 pesticide residues in plant-derived foods by automated QuEChERS sample preparation system combined with high performance liquid chromatography-tandem mass spectrometry

An analytical method for the determination of 34 pesticide residues in plant-derived foods was established using an automated QuEChERS sample preparation system combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample extraction and dispersive solid-phase extraction in the manual QuEChERS method were combined using the vortex vibration and centrifugation functions of the automated QuEChERS sample preparation system. The operating parameters and pretreatment steps were optimized, and the analytes were detected in the multiple reaction monitoring (MRM) mode. The quantification analysis was performed by the matrix-matched external standard method. The automated and the manual QuEChERS methods were compared from the methodological verification standpoint. The calibration curves showed good linearity in a certain range, and the correlation coefficients (R2) were greater than 0.99. The limits of detection and limits of quantification were 0.76-3.60 μg/kg and 2.28-10.80 μg/kg, respectively. Moreover, the recoveries ranged from 53.0% to 125.2%, and the relative standard deviations (RSDs) were less than 1.59% (n=5). The results obtained by the manual QuEChERS method were not significantly different from those obtained by the automated QuEChERS method. This method can effectively reduce the labor intensity and probability of error in the determination of pesticide residues.

Nanotracing and cavity-ring down spectroscopy: A new ultrasensitive approach in large molecule drug disposition studies.

New therapeutic biological entities such as bispecific antibodies targeting tissue or specific cell populations form an increasingly important part of the drug development portfolio. However, these biopharmaceutical agents bear the risk of extensive target-mediated drug disposition or atypical pharmacokinetic properties as compared to canonical antibodies. Pharmacokinetics and bio-distribution studies become therefore more and more important during lead optimization. Biologics present, however, greater analytical challenges than small molecule drugs due to the mass and selectivity limitation of mass spectrometry and ligand-binding assay, respectively. Radiocarbon (14C) and its detection methods, such as the emerging 14C cavity ring down spectroscopy (CRDS), thus can play an important role in the large molecule quantitation where a 14C-tag is covalently bound through a stable linker. CRDS has the advantage of a simplified sample preparation and introduction system as compared to accelerator mass spectrometry (AMS) and can be accommodated within an ordinary research laboratory. In this study, we report on the labeling of an anti-IL17 IgG1 model antibody with 14C propionate tag and its detection by CRDS using it as nanotracer (2.1 nCi or 77.7 Bq blended with the therapeutic dose) in a pharmacokinetics study in a preclinical species. We compare these data to data generated by AMS in parallel processed samples. The derived concentration time profiles for anti-IL17 by CRDS were in concordance with the ones derived by AMS and γ-counting of an 125I-labeled anti-IL17 radiotracer and were well described by a 2-compartment population pharmacokinetic model. In addition, antibody tissue distribution coefficients for anti-IL17 were determined by CRDS, which proved to be a direct and sensitive measurement of the extravascular tissue concentration of the antibody when tissue perfusion was applied. Thus, this proof-of-concept study demonstrates that trace 14C-radiolabels and CRDS are an ultrasensitive approach in (pre)clinical pharmacokinetics and bio-distribution studies of new therapeutic entities.

Spatially Resolved Proteome Mapping of Laser Capture Microdissected Tissue with Automated Sample Transfer to Nanodroplets

Current mass spectrometry (MS)-based proteomics approaches are ineffective for mapping protein expression in tissue sections with high spatial resolution because of the limited overall sensitivity of conventional workflows. Here we report an integrated and automated method to advance spatially resolved proteomics by seamlessly coupling laser capture microdissection (LCM) with a recently developed nanoliter-scale sample preparation system termed nanoPOTS (Nanodroplet Processing in One pot for Trace Samples). The workflow is enabled by prepopulating nanowells with DMSO, which serves as a sacrificial capture liquid for microdissected tissues. The DMSO droplets efficiently collect laser-pressure catapulted LCM tissues as small as 20 μm in diameter with success rates >87%. We also demonstrate that tissue treatment with DMSO can significantly improve proteome coverage, likely due to its ability to dissolve lipids from tissue and enhance protein extraction efficiency. The LCM-nanoPOTS platform was able to identify 180, 695, and 1827 protein groups on average from 12-μm-thick rat brain cortex tissue sections having diameters of 50, 100, and 200 μm, respectively. We also analyzed 100-μm-diameter sections corresponding to 10-18 cells from three different regions of rat brain and comparatively quantified ∼1000 proteins, demonstrating the potential utility for high-resolution spatially resolved mapping of protein expression in tissues.

Spatially Resolved Proteome Profiling of

Due to sensitivity limitations, global proteome measurements generally require large amounts of biological starting material, which masks heterogeneity within the samples and differential protein expression among constituent cell types. Methods for spatially resolved proteomics are being developed to resolve protein expression for distinct cell types among highly heterogeneous tissues, but have primarily been applied to mammalian systems. Here we evaluate the performance of cell-type-specific proteome analysis of tomato fruit pericarp tissues by a platform integrating laser-capture microdissection (LCM) and a recently developed automated sample preparation system (nanoPOTS, nanodroplet processing in one pot for trace samples). Tomato fruits were cryosectioned prior to LCM and tissues were dissected and captured directly into nanoPOTS chips for processing. Following processing, samples were analyzed by nanoLC-MS/MS. Approximately 1900 unique peptides and 422 proteins were identified on average from ∼0.04 mm2 tissues comprising ∼8-15 parenchyma cells. Spatially resolved proteome analyses were performed using cells of outer epidermis, collenchyma, and parenchyma. Using ≤200 cells, a total of 1,870 protein groups were identified and the various tissues were easily resolved. The results provide spatial and tissue-specific insights into key enzymes and pathways involved in carbohydrate transport and source-sink relationships in tomato fruit. Of note, at the time of fruit ripening studied here, we identified differentially abundant proteins throughout the pericarp related to chlorophyll biogenesis, photosynthesis, and especially transport.

Validation of a sample preparation system (eFlow) for semen analysis in the AndroVision® CASA-System

Objective was to evaluate the echotexture and characteristics during terminal development of canine foetal respiratory and hepatic systems through elastographic examinations. Fifteen pregnant bitches were evaluated by ultrasonography twice daily, from the 53rd gestational day until whelping, and images obtained from 120 to 0 h before parturition were analysed. Images of foetal lungs and liver were recorded and then used for computer-assisted analyses to determine quantitative attributes. Acoustic Radiation Force Impulse (ARFI) elastographic of internal organs were classified as ‘soft’ (white areas) or ‘hard’ (dark areas) and quantitative analyses determined the mean shear wave velocities (SWV) of foetal lungs and liver. After delivery, canine neonates were clinically evaluated, and their health status was monitored weekly until 60 days post-partum. Sonographic parameters over time were compared by ANOVA and Pearson’s correlations were used to determine associations between SWVs and echotextural variables. Foetal lungs and liver had a homogeneous echotexture and pulmonary parenchyma appeared hyperechoic when compared with that of the liver. Mean numerical pixel values (NPVs) of lungs decreased from 120 to 24 h and subsequently increased until parturition (P = 0.04). Lungs and liver mean (± SD) SWVs (0.98 ± 0.12 and 0.84 ± 0.11 m/s, respectively) didn’t vary (P > 0.05) over time. Fluctuations in pulmonary NPVs indicated there was a pattern corresponding to structural and functional changes that occur during the terminal stage of pre-natal canine development and hence can be a useful diagnostic tool in veterinary. Foetal lung and liver SWVs were relatively consistent and there was no detectable changes during the pre-partum period for this variable or in echotexture.

Development of an automated high-throughput sample preparation protocol for LC-MS/MS analysis of glycated peptides

Advanced glycation end products (AGEs) are known to play a leading part in the pathogenesis of human diseases, such as diabetes, Alzheimer's disease, lateral sclerosis, and atherosclerosis. It is for this reason that research on AGEs is crucial and large-scale studies are needed for the treatment of diseases. The aim of this study was to develop a reproducible method to analyze Amadori compounds using an automated enrichment protocol for high-throughput analysis of clinical samples. The developed method enabled the enrichment of Amadori compounds simultaneously from 96 samples, and it was applied to the discovery of biomarkers in AGEs related diseases. In this study, ten human serum samples were processed using automated filter-aided sample preparation (aFASP) in a 96-well filter plate, and the eluted peptide mixtures were enriched by Affinity Cellufine PB in a fritted 96-well filter plate using a liquid handling robotic system. The eluted glycated peptides were analyzed by a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. A total of 982 unique glycated peptides, corresponding to 524 unique glycated proteins, were identified from the analysis of ten human samples. The advantages and potentials of the automated sample preparation system were demonstrated through label free quantification of the glycated peptides.

Simultaneous determination of arsenic, cadmium and lead in plant foods by ICP-MS combined with automated focused infrared ashing and cold trap

A fully automated focused infrared lightwave ashing sample preparation system was proposed and applied to the pretreatment of volatile arsenic, cadmium and lead in plant foods prior to inductively coupled plasma mass spectrometry (ICP-MS) determination. All the steps of ashing pretreatment were automatically accomplished within forty minutes. Gold-plated infrared quartz tubes produced focused infrared to supply a rapid heating. Ozone was used to accelerate sample carbonization. A cool trap was used to capture volatile arsenic, cadmium and lead. Three certified plant food reference materials were determined. The recoveries of the three elements were between 90% and 107%. Five real plant foods were analyzed by the proposed method and microwave digestion. The results showed no significant difference.

A simple and automated sample preparation system for subsequent halogens determination: Combustion followed by pyrohydrolysis

A simple and automated system based on combustion followed by a pyrohydrolysis reaction was proposed for further halogens determination. This system was applied for digestion of soils containing high (90%) and also low (10%) organic matter content for further halogens determination. The following parameters were evaluated: sample mass, use of microcrystalline cellulose and heating time. For analytes absorption, a diluted alkaline solution (6 mL of 25 mmol L−1 NH4OH) was used in all experiments. Up to 400 mg of soil with high organic matter content and 100 mg of soil with low organic matter content (mixed with 400 mg of cellulose) could be completely digested using the proposed system. Quantitative results for all halogens were obtained using less than 12 min of sample preparation step (about 1.8 min for sample combustion and 10 min for pyrohydrolysis). The accuracy was evaluated using a certified reference material of coal and spiked samples. No statistical difference was observed between the certified values and results obtained by the proposed method. Additionally, the recoveries obtained using spiked samples were in the range of 98–103% with relative standard deviation values lower than 5%. The limits of quantification obtained for F, Cl, Br and I for soil with high (400 mg of soil) and low (100 mg of soil) organic matter were in the range of 0.01–2 μg g−1 and 0.07–59 μg g−1, respectively. The proposed system was considered as a simple and suitable alternative for soils digestion for further halogens determination by ion chromatography and inductively coupled plasma mass spectrometry techniques.

Blood Collection and Cell-Free DNA Isolation Methods Influence the Sensitivity of Liquid Biopsy Analysis for Colorectal Cancer Detection.

During colorectal cancer (CRC) development tumor-derived cell-free DNA (cfDNA) can be released into the bloodstream. Many different cfDNA isolation methods and specific blood collection tubes preventing the release of genomic DNA and stabilizing cfDNA with preservative reagents became available. These factors may affect greatly on the further liquid biopsy analyses. Our aim was to test different blood collection tubes and cfDNA isolation methods to determine whether these factors influence the cfDNA amount and the promoter methylation of four previously described hypermethylated biomarkers. Three manual isolation methods (High Pure Viral Nucleic Acid Large Volume Kit; Epi proColon 2.0 Kit; Quick-cfDNA™ Serum & Plasma Kit) and automated sample preparation systems (InviGenius and InviGenius PLUS) were examined. Furthermore, K3EDTA Vacuette tubes and Streck Cell-Free DNA BCT® tubes were compared. After cfDNA isolation and bisulfite conversion of samples, the methylation level of SFRP1, SFRP2, SDC2, and PRIMA1 were defined with MethyLight assays. We have ascertained that there are differences between the cfDNA amounts depending on the isolation methods. Higher cfDNA yield was observed using InviGenius system than column-based manual isolation method; however, InviGenius PLUS has produced lower cfDNA amounts. No remarkable variance could be found between K3EDTA and Streck tubes; slightly higher cfDNA quantity was detected in 60% of plasma samples using Streck tubes. In point of methylation level and frequency, manual column-based isolation produced more consistent results. Automated cfDNA extraction systems are easy-to-use and high-throughput; however, further improvements in the isolation protocols might lead to the increase of the sensitivity of furthermethylation analysis.

Electroflotation of Escherichia coli Improves Detection Rates by Loop-Mediated Isothermal Amplification

Abstract. The power of portable molecular diagnostic systems for detection of pathogenic microorganisms in food and environmental samples is largely limited by small assay volumes (typically 1 to 5 µL), making direct detection of trace contamination (i.e., &amp;lt;104 CFU mL-1) unreliable. To improve detection limits for pathogens dispersed on an ecological scale, we developed a portable point-of-care (POC) sample preparation system using electroflotation (EF) to recover small quantities of these organisms from samples of hundreds of milliliters. Electrolysis reactions, supported on platinum-coated titanium electrodes, generate hydrogen and oxygen microbubbles that impel and displace suspended cells into a recovered concentrate. Samples were prepared by inoculating 380 mL of sterilized phosphate buffer (0.1 M, pH 6.6) with stock culture of ATCC 25922 to final concentrations ranging from 102 to 104 CFU mL-1. Samples were subjected to 10, 15, and 20 min durations of EF treatment under high and low turbulence conditions. We used a loop-mediated amplification (LAMP) assay with primers targeting a single-copy gene (glycerate kinase) in generic to evaluate the effects of EF treatment on concentration and recovery of detectable cell material. LAMP failed to detect in all untreated (control) samples at concentrations below 104 CFU mL-1 but was able to detect in 102 CFU mL-1 samples subjected to various conditions of EF treatment. Two-way ANOVA showed significant differences in detection rates between EF treatment durations for both high (p = 0.0019) and low turbulence (p = 0.002). Dunnett’s multiple comparison tests identified five process conditions resulting in significant (p &amp;lt; 0.05) differences in detection between treatments and the control. Keywords: Biotechnology, Electrolysis, Food pathogens, Microbubbles, Molecular diagnostics, Pathogen detection, POC sample preparation.

Fully automated focused infrared microashing combined with use of ICP-based instruments for rapid analysis of multiple elements in biological samples.

A fully automated focused infrared microashing sample preparation system was proposed for preparation of biological samples with high organic matter content for the determination of multiple elements combined with inductively coupled plasma optical emission spectroscopy and inductively coupled plasma mass spectrometry. The whole ashing procedure, including sample transfer, carbonization and oxidation of the sample, dissolution of ash, constant volume control, and homogenization of the solution, was automatically controlled. Gold-plated infrared tubes were used to produce and focus infrared radiation to heat the sample. Ozone was used to accelerate the carbonization of samples at a lower temperature to avoid the production of large amounts of empyreumatic oil. In addition, the self-designed double-layer tube serves as a site for ashing and carbonization of the sample and as a container for dissolving ash, as well as for holding the solution. This is the only container in the entire system to reduce the risk of pollution. Eight biological certified reference materials were used as examples to evaluate the performance of the proposed device. A sample ashing pretreatment cycle, from solid sample to liquid solution, took only 40 min and simultaneously treated 12 samples. Except for individual results, the relative errors between the certified values and recorded values for 38 micro and trace elements, including Ca, Mg, Na, P, Li, Be, Sc, Ti, V, Mn, Co, Ni, Cu, Zn, Rb, Sr, Y, Mo, Ag, Cs, Ba, Tl, Th, U, and rare earth elements, were typically less than 30%. The relative standard deviations for five determinations were typically less than 15%. Graphical abstract Automated dry ashing sample preparation system. ICP inductively coupled plasma.

Design and validation of an automated solid phase extraction liquid chromatography coupled mass spectrometry method for the quantification of propofol in plasma

Propofol concentration in human plasma can be quantified by liquid chromatography coupled mass spectrometry. Sample preparation usually requires solid phase extraction to remove matrix components and enrich the analyte. To facilitate user-independent measurements and speed extraction, we developed and validated a fully automated high throughput in-line sample preparation system with direct injection into liquid chromatography coupled mass spectrometry. We assessed linearity of each method over the clinically relevant concentration range from 0.5μg/mL to 8μg/mL plasma concentration. R2 values were 0.99 for the automated process and 0.98 for manual sample preparation. The limit of detection was 6ng/mL and the lower limit of quantification was 18ng/mL for the automated method; for the manual process, the limit of detection was 1.58ng/mL and the lower limit of quantification was 4.79ng/mL. Intra-day precision for low, medium and high concentration range of the automated method was validated 4.14%, 9.68% and 3.04% relative standard deviation and 0.29%, 0.12% and 0.52% for the manual process. Carry over was 0.4% with the automated method, whereas there was no carry over with the manual method. Stability of plasma samples was tested with the manual method at concentrations of 1, 4, and 6μg/mL propofol and found to be stable over 150days at −20°C. The manual sample preparation method has successfully been transferred to a fully automated process with appropriate sensitivity and precision but the automatization failed with regard to trueness and working time due to lengthy sample preparation runtime. Therefore it is not suitable for daily use in a hospital laboratory e.g. for brain death diagnosis in the intensive care unit.

Bioanalytical methods for the detection of antidiabetic drugs: a review.

Type 2 diabetes mellitus, a disease which prevalence has been progressively increasing worldwide, is characterized by chronic hyperglycemia resulting from the combination of inappropriate insulin secretion and/or resistance to insulin action. If left uncontrolled, diabetes is associated with complications such as dysfunction and failure of various organs, and even premature death. Along with lifestyle-modification strategies, several classes of oral antidiabetic agents can be employed for glycemic control. Thus, therapeutic drug monitoring of these drugs is essential to maintain appropriate treatment. This review discusses the most frequently employed analytical techniques and sample preparation systems to obtain a reliable and trustworthy method to quantify antidiabetic drugs in biological matrices. An adequate choice of internal standard, ideal chromatography conditions and most suitable analytical detector are reported.

A New Sample Preparation System for Micro-14C Dating of Glacier Ice with a First Application to a High Alpine Ice Core from Colle Gnifetti (Switzerland)

AbstractRadiometric dating of glacier ice is an essential tool where stratigraphic dating methods cannot be applied. This study focuses on Alpine glacier ice and presents a new sample preparation system for dating of glacier ice samples via radiocarbon (14C) dating of the microscopic particulate organic carbon (POC) fraction incorporated in the ice matrix. An adaptable, low-cost inline filtration-oxidation-unit (REFILOX) has been developed, which for the first time unifies all sample preparation steps from ice filtration to CO2quantification in one closed setup. A systematic14C investigation of modern European aerosol samples revealed that a POC combustion temperature of 340°C provides the best representation of the real sample age. A very low process blank of maximally 0.3±0.1 µgC now enables14C dating of high Alpine ice samples, where POC concentrations are generally low (typically 10–50 µgC/kg), in an ice sample mass range of 300–500 g. In a first successful application, the method was used to obtain age constraints for an ice core from the cold, high Alpine firn saddle Colle Gnifetti (Switzerland). Analysis of the bottom ice core sections revealed a basal age of 4171–3923 cal yr BP but also a so far enigmatic discontinuity in the age-depth relationship.

Evaluation of the use of a reflux system for sample preparation of processed fruit juices and subsequent determination of Cr, Cu, K, Mg, Na, Pb and Zn by atomic spectrometry techniques

The acid decomposition method was applied for the sample preparation of processed fruit juice. The decomposition of 15mL of juice sample using HNO3 and H2O2 was performed in a digester block with reflux system and heated at 200°C for 150min. The limits of detection were 0.03; 0.24; 0.8; 0.008; 0.026 and 0.056mgL−1 for Cr, Cu, K, Mg, Na and Zn, respectively and for Pb was 0.99μgL−1. The accuracy was evaluated by spiked experiments (80 to 119%). Four processed fruit juice samples commercialized in Brazil (strawberry, mango, peach, and orange) were analyzed and indicated the absence of Cr, Zn and Cu in the samples, except for Cu in strawberry juice. Pb was found in the mango juice sample (17.8±0.9μgL−1) and the concentration is below the maximum values recommended by Brazilian legislation for juices of citric fruits (0.3mgkg−1).

Tubular metal membranes for cleaning the primary-circuit coolant of a pressurized water reactor (WWER)

The fabrication of tubular microfiltration membranes from PKh18N15 corrosion-resistant steel by the method of radial isostatic pressing and magnetron plasma ion deposition of the surface layer is described. Scanning electron microscopy has been used to study the structure of the substrate and surface layers of the membrane. The flux values of tubular membranes have been found to be 1.39 × 10−8, 1.88 × 10−8, and 5.53 × 10−8 m3/(m2 Pa s) for the membranes with pore sizes of 1, 5, and 20 μm, respectively. The possibility of regenerating tubular membranes and restoring their productivity by backwashing has been shown. The service life of the membranes with different pore sizes has been determined during the treatment of make-up water for the sample preparation system of the primary circuit coolant of a pressurized water reactor (WWER).