Sample Preparation Scheme Research Articles

A simultaneous dispersive liquid-liquid microextraction and GC-MS determination of PCBs and PAHs in nature waters

The subject of this study is polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) – super ecotoxicants and widely distributed organic pollutants in natural waters. Their danger lies in acute toxicity, cumulative action, and long-term effects on living organisms. The degree of water ecosystem pollution is assessed based on the levels of indicator compounds, with 16 PAHs and 7 PCBs. Assessing the levels of these super ecotoxicants when they are simultaneously present in natural waters is an urgent task of ecological monitoring in order to obtain reliable information about the pollution level of the water body. The aim of this study is to evaluate the possibility of dispersive liquid-liquid microextraction (DLLME) of PCBs and PAHs and GC-MS determination in natural waters in their simultaneous presence. To achieve the set goal, the peculiarities of simultaneous extraction and determination of PAHs and PCBs from natural waters were studied. The selected range of analyte concentrations was determined based on literature data on environmental monitoring and the maximum allowable concentrations (MAC) of the investigated components in natural waters. The similarity of the applied methods for extraction and detection of PAHs and PCBs allowed for the justification of the approach to selecting a universal sample preparation scheme for simultaneous extraction and GC-MS determination of both classes of analytes. The possibilities of modifications of DLLME extraction of PAHs and PCBs, differing in dispersion method and nature of the extractor, were studied in combination with chromatographic-mass spectrometric determination of the analytes. Simultaneous extraction of super-toxicants was achieved by applying DLLME with a binary dispersant – 500 μl acetone + 500 μl acetonitrile and 150 μl chloroform as the extractor. The chloroform extract after DLLME extraction of the analytes without re-dissolution was used for GC-MS determination of 16 PAHs and 7 PCBs on a specific 60 m long capillary column with a 5% polyarylene + 95% dimethylpolysiloxane stationary phase with gradual heating of the thermostat from 60 to 290°C. Using the selected ion monitoring (SIM) mode increased the reliability of component identification in matrices of natural waters. The possibility of mutual influence of ecotoxicants on their extraction in the presence of each other was studied. Dispersive liquid-liquid microextraction with a binary dispersant provided simultaneous extraction of analytes at a level of 80-97%. The proposed analysis scheme allowed for GC-MS determination of 16 PAHs and 7 PCBs in the presence of each other in natural waters over a wide range of concentrations (0.02-40 μg/L) with an accuracy of 7-18% (PAHs) and 11-18% (PCBs). The relative standard deviations of repeatability and reproducibility for PAHs were in the ranges of 3.1-6.5% and 4.3-7.7%, respectively, and for PCBs 2.8-5.3% and 3.4-6.0%.

A Highly Integrated Lab-on-a-CMOS Platform for Real-Time Monitoring of E. Coli Growth Kinetics.

Existing miniaturized and cost-effective solutions for bacterial growth monitoring usually require offline incubators with constant temperature to culture the bio-samples prior to measurement. Such a separated sample preparation and detection scheme requires extensive human intervention, risks contamination, and suffers from poor temporal resolution. To achieve integrated sample preparation and real-time bacterial growth monitoring, this article presents a lab-on-a-CMOS platform incorporates an optical sensor array, temperature sensor array, micro-heaters, and readout circuits. Escherichia coli's (E. coli) optimum growth temperature of 37 °C is achieved through a heat regulation system consisting of two micro-heaters and an on-chip temperature sensor array. A photodiode array with an in-pixel capacitive trans-impedance amplifier to reduce inter-pixel cross-coupling is designed to extract the optical information during bacterial growth. To balance the footprint, power consumption, and quantization speed, a 10 b column successive-approximation register (SAR)/single-slope (SS) dual-mode analog-to-digital converter (ADC) is designed to digitize the temperature and optical signals. Fabricated in a standard 0.18 um CMOS process, the proposed platform can regulate the sample temperature to 37 +/- 0.2/0.3 °C within 32 mins. Enabled by an on-chip heat regulation system and photodetectors, the prototype demonstrates a real-time monitoring of bacterial growth kinetics and antibiotic responses. Minute-level temporal resolution is achieved as this proposed platform is free of extensive and time-consuming human intervention. The proposed platform can be viably used in contamination sensitive applications such as antibiotic tests, stem cell cultures, and organ-on-chips.

A new scheme of dispersive liquid-liquid microextraction of polychlorinated biphenyls having different degrees of chlorination from waters with subsequent identification by gas chromatography coupled with mass spectrometry

This study offers a theoretical rationale and experimental validation of extraction of 22 polychlorinated biphenyls (PCBs) having various degrees of chlorination (including five dioxin-like ones: PCB-105, PCB-118, PCB-156, PCB-157, and PCB-167) from waters of various salinity levels by dispersive liquid–liquid microextraction (DLLME) using various extractants and mixtures of aliphatic alcohols for additional dispersion, with subsequent identification by gas chromatography coupled with mass spectrometry. To optimize the conditions of DLLME and of concentrating PCBs of various degrees of chlorination, the experiment was planned via the three-factor Box–Behnken design (response surface methodology). Composition and ratios of components were found for the extractant mixture, and composition of the dispersive agent was optimized. Effective recovery of the 22 congeners from waters with salinity ranging between 1‰ and 22‰ was ensured by an extractant mixture consisting of chloroform, dichloromethane, and carbon tetrachloride and by a dispersive agent composed of acetone, ethyl acetate, ethyl alcohol, and isopropyl alcohol. The newly developed sample preparation scheme is compatible with gas chromatography coupled with mass spectrometry, and limits of detection and quantitation varied as follows: 0.0075–0.0150 and 0.025–0.050 µg/L, respectively. The newly developed assay allows to quantify the analytes at concentrations of 0.025–15 µg/L in waters, with recovery 90–105% and relative standard deviation 4–8%.

Simple, Fast and Convenient Magnetic Bead-Based Sample Preparation for Detecting Viruses via Raman-Spectroscopy.

We introduce a magnetic bead-based sample preparation scheme for enabling the Raman spectroscopic differentiation of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)-positive and -negative samples. The beads were functionalized with the angiotensin-converting enzyme 2 (ACE2) receptor protein, which is used as a recognition element to selectively enrich SARS-CoV-2 on the surface of the magnetic beads. The subsequent Raman measurements directly enable discriminating SARS-CoV-2-positive and -negative samples. The proposed approach is also applicable for other virus species when the specific recognition element is exchanged. A series of Raman spectra were measured on three types of samples, namely SARS-CoV-2, Influenza A H1N1 virus and a negative control. For each sample type, eight independent replicates were considered. All of the spectra are dominated by the magnetic bead substrate and no obvious differences between the sample types are apparent. In order to address the subtle differences in the spectra, we calculated different correlation coefficients, namely the Pearson coefficient and the Normalized cross correlation coefficient. By comparing the correlation with the negative control, differentiating between SARS-CoV-2 and Influenza A virus is possible. This study provides a first step towards the detection and potential classification of different viruses with the use of conventional Raman spectroscopy.

Accurate determination of four tetracycline residues in chicken meat by isotope dilution-liquid chromatography/tandem mass spectrometry

An analytical method based on isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC‒MS/MS) was developed to accurately determine four representative tetracyclines (tetracycline, chlortetracycline, doxycycline, and oxytetracycline) in chicken meat. Tetracyclines are known to have a great tendency for epimerization and keto-enol tautomerism, which often provoke major challenges in their determination. Since this isomerization was found to be unavoidable during the whole chain of the current analysis, the total content (µg kg‒1) of individual tetracycline was quantified as a sum of each parent compound and its respective isomeric forms. Using this approach in combination with IDMS analysis, more consistent, accurate, and reproducible measurement results for the four tetracyclines in chicken meat were acquired. LC-MS/MS conditions and sample preparation processes were comprehensively optimized to minimize the chelating effect of tetracyclines and possible co-extracted interferences. Details of the sample preparation scheme, LC‒MS/MS detection, calculation equation, and method validation are described in this article. The method provided very good accuracy (97.7–102.6%) for all analytes across the concentration range of 10–200 µg kg‒1, with relative standard deviations for intra-day and inter-day precision of less than 4%. The limits of quantification were below 0.2 µg kg‒1, demonstrating the high sensitivity of the method. Furthermore, the measurement uncertainty was generally below 5.5%. Hence, the established method exhibits high-order metrological quality with superior performance over various existing methodologies. Moreover, this method can provide references for general food testing laboratories close to and far below the established maximum residue limits (100 µg kg‒1) for animal muscle tissues.

Intact quantitative bioanalytical method development and fit-for-purpose validation of a monoclonal antibody and its related fab fragment in human vitreous and aqueous humor using LC-HRMS.

Ranibizumab is an FDA-approved drug used to treat wet age-related macular degeneration (AMD), diabetic retinopathy, macular edema, and myopic choroidal neovascularization. Bevacizumab is another drug often used off-label to treat wet AMD. In order to reduce unwanted angiogenesis, ranibizumab and bevacizumab target circulating VEGF-A in the eye. Concentration levels in human vitreous and aqueous humor can be used to provide valuable efficacy information. However, vitreous and aqueous humor's aqueous environment, and vitreous humor's viscosity, as well as the stickiness of the analytes can provide bioanalytical challenges. In this manuscript, we describe the development, optimization, and fit-for-purpose validation of an LC-HRMS method designed for intact quantitative bioanalysis of ranibizumab and bevacizumab in human vitreous and aqueous humor following intravitreal administration. In order to fully develop this method, evaluations were conducted to optimize the conditions, including the data processing model (extracted ion chromatograms (XICs) vs deconvolution), carryover mitigation, sample preparation scheme optimization for surrogate and primary matrices, use of internal standard/immunocapture/deglycosylation, and optimization of the extraction and dilution procedure, as well as optimization of the liquid chromatography and mass spectrometry conditions. Once the method was fully optimized, a fit-for-purpose validation was conducted, including matrix parallelism, with a linear calibration range of 10 to 200µg/mL. The development of this intact quantitative method using LC-HRMS provides a proof-of-concept template for challenging, but valuable new and exciting bioanalytical techniques.

Fast Identification of Soybean Seed Varieties Using Laser-Induced Breakdown Spectroscopy Combined With Convolutional Neural Network.

Soybean seed purity is a critical factor in agricultural products, standardization of seed quality, and food processing. In this study, laser-induced breakdown spectroscopy (LIBS) as an effective technology was successfully used to identify ten varieties of soybean seeds. We improved the traditional sample preparation scheme for LIBS. Instead of grinding and squashing, we propose a time-efficient method by pressing soybean seeds into rubber sand filled with culture plates through a ruler to ensure a relatively uniform surface height. In our experimental scheme, three LIBS spectra were finally collected for each soybean seed. A majority vote based on three spectra was applied as the final decision judging the attribution of a single soybean seed. The results showed that the support vector machine (SVM) obtained the optimal identification accuracy of 90% in the prediction set. In addition, PCA-ResNet (propagation coefficient adaptive ResNet) and PCSA-ResNet (propagation coefficient synchronous adaptive ResNet) were designed based on typical ResNet structure by changing the way of self-adaption of propagation coefficients. Combined with a new form of input data called spectral matrix, PCSA-ResNet obtained the optimal performance with the discriminate accuracy of 91.75% in the prediction set. T-distributed stochastic neighbor embedding (t-SNE) was used to visualize the clustering process of the extracted features by PCSA-ResNet. For the interpretation of the good performance of PCSA-ResNet coupled with the spectral matrix, saliency maps were further applied to visually show the pixel positions of the spectral matrix that had a significant influence on the discrimination results, indicating that the content and proportion of elements in soybean seeds could reflect the variety differences.

Laser-Induced Breakdown Spectroscopy-Based Coal-Rock Recognition: An in Situ Sampling and Recognition Method

Coal and rock recognition (CRR) has important theoretical and practical significance in unmanned coal mining. Laser-induced breakdown spectroscopy (LIBS) is considered a cutting-edge technology in the field of material analysis due to its real-time analysis capability, minimal to no sample preparation scheme, high sensitivity to low atomic weight elements, and ability to perform nearby and distant detection. In this research, a new fast and accurate coal-rock recognition method for unmanned coal mining based on LIBS is presented. The LIBS in situ sampling method of the coal mining face and the LIBS-based CRR method are discussed. Partial least squares discriminant analysis (PLS-DA) is used to analyze the LIBS spectrum and to construct a simplified spectral model (SSM). Finally, SSM and neural network classifiers are used to recognize coal and rock, and the results are presented and discussed. These results show that the CRR method proposed in this research has a high recognition accuracy rate.

Development of a Method for the Extraction of the Total Proteome of Bacillus anthracis Spores

We have developed a method for obtaining the total proteome of <i>Bacillus anthracis</i> spores, which combines efficient protein extraction with reliable disinfection of samples. We used 7 strains of <i>B. anthracis</i>: 4 plasmid-free, 3 diplasmid, one of which with an atypical type of capsule formation in air. The schemes for isolating the total spore proteome were tested using various lysis solutions in the presence of bacterial protease inhibitors, with the inclusion of the stages of treatment of spores with trichloroacetic acid and mechanical disintegration and with their exclusion. The quality and completeness of the extraction of the total proteome of the spores of the samples was assessed in one-dimensional (1D) and twodimensional (2D) electrophoresis. Treatment of spores with trichloroacetic acid increased the reliability of material disinfection and reduces the loss of the final product. Mechanical disintegration after treatment of spores with lysing solutions increases the completeness of extraction of spore proteins in a wide range of molecular weights and facilitated the process of sterilizing filtration. Final filtration of the lysate through a PVDF filter with a pore size of 0.22 μm provided additional decontamination of samples without reducing their quality. Thus, the use of the proposed sample preparation scheme makes it possible to obtain complete protein extracts of spores of <i>B. anthracis</i> strains, suitable for comparative analysis of the proteome and search for a possible correlation with the features phenotypic properties and mechanisms that ensure the preservation of the pathogen anthrax in environmental objects, including soil

Simultaneous determination of alachlor and its metabolites in beef muscle, liver, milk, and egg by liquid chromatography–tandem mass spectrometry

AbstractAlachlor is a chloroacetanilide herbicide used to control annual grasses in grazing system and has been observed along with its metabolites in animal foodstuffs. Its residue violations in animal foodstuffs are increasing significantly and therefore, useful and efficient assay is required. In this study, a rapid, useful, routine, and sensitive liquid chromatography with tandem mass spectrometry for simultaneously determining and confirming alachlor and its metabolites (2‐chloro‐N‐(2,6‐diethylphenyl) acetamide, 2,6‐diethylaniline, and 2‐ethyl‐6‐(1‐hydroxyethyl) aniline) in beef muscle, liver, milk, and egg samples was examined. The proposed method uses a simple extraction with methanol followed by dispersive and solid‐phase extraction cleanup. Observably, absolute calibration curves were linear from the limit of quantification to 100 ng/mL (r2 > 0.999). The recovery values fortified at 0.02 and 0.2 μg/g ranged from 70.4 to 107.6% with a relative standard deviation ≤ 7.1%. Alachlor and its metabolites in applied samples from Japanese markets were undetected using developed method. We examined the useful and efficient method and sample preparation scheme for actual and rational process of alachlor's residue.

Analysis of crude mineral sample preparation schemes

Introduction. Sample preparation schemes are multi-stage. Sample reduction in the process of preparation introduces extra inaccuracy in the result of sampling, consequently, sample preparation schemes inaccuracy should be calculated with further selection of its rational parameters. Research methodology is based on calculation by the formula of sample reduction random inaccuracy. Inaccuracy calculation of a sample preparation scheme. Calculation has been carries out of the scheme recommended by GOST 14180-80. Paradoxical growth of inaccuracy of sample preparation has been shown with ore homogeneity growth. Determination of sample mass by the stages of preparation. Standards and techniques of ore and nonferrous metals concentrates sampling for the creation of sample preparation schemes recommend finding the coefficient in minimum mass formula depending on the mass fraction variation coefficient in the sampled product. Sample preparation is carried out in laboratory conditions, and sample mass cannot depend on this coefficient of variation. Sample inhomogeneity in the laboratory depends only on the inhomogeneity of separate lumps of a sample. Sample inhomogeneity in the preparation laboratory is defined by lump dispersion, and the coefficient is the function of this dispersion, admissible inaccuracy of sample reduction and the dimensions of grain impregnations of the mineral which contains the analyte. 78 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 1. 2020 ISSN 0536-1028 For each factory, individual coefficient can be found, and sample masses can be calculated by the stages of preparation. Analysis of sample preparation schemes. Sample preparation scheme inaccuracy formula is given. Calculation and analysis of the model scheme of sample preparation according to GOST 14180-80 have shown that at the third crushing stage the sample is advisable to be crushed not up to 3, but up to 2 mm, and the recommended sample size at the final stage 8.08 hardly improves the result of preparation, that is why the previous recommendation of 0.1 mm can be used.

Assessment of strategies for the formation of stable suspensions of titanium dioxide nanoparticles in aqueous media suitable for the analysis of biological fluids.

Due to their omnipresence in consumer products, there is a growing concern about the potential effects of nanoparticles on human health. Toxicological assessment and NP end-product studies require proper quantification of these materials in biological fluids. However, their quantifications in these media require stable predispersed NP solutions in aqueous media to enable the fortification in the matrices of interest or the preparation of calibration standards. In this study, a sample preparation scheme was developed by studying various dispersion media (polyvinylpyrrolidone and polyethylene glycol) and sonication strategies (bath and ultrasonic probe) to ensure homogeneous dispersion of titanium dioxide nanoparticles. Optimization of the various parameters was performed using SRM NIST 1898 NP reference material, composed of rutile and anatase phases. Number-based size distribution for titanium dioxide NPs was determined by dynamic light scattering and single-particle inductively coupled plasma mass spectrometry to evaluate the procedure efficiency. Changes in mean size and most frequent size distribution were also studied to determine if the agglomeration of nanoparticles occurs at the various dispersion conditions tested. Among the different dispersion parameters tested herein, the use of polyvinylpyrrolidone combined with a sonication process generated by a probe leads to a significant improvement in terms of suspension efficiency and stability over 72h. The dispersion efficiency of the proposed methodology was assessed by single-particle inductively coupled plasma mass spectrometry with spiked biological fluids such as urine and blood. Graphical abstract.

Measurements of mass-dependent Te isotopic variation by hydride generation MC-ICP-MS

A new method for precise measurements of tellurium stable isotope variations by hydride generation MC-ICP-MS is presented, including a revised sample preparation scheme.

FEATURES OF THE ELEMENTAL COMPOSITION OF WHOLE BLOOD IN CHILDREN’S POPULATION OF THE WESTERN URAL

Introduction. The element composition of blood is the most relevant index in biomonitoring studies to assess public health risks. The authors determined the elemental composition of the whole blood in 100 the unexposed children residing in the West Ural region using the ICP-MS method and standard biomonitoring methodology of the World Health Organization (WHO). This study allows for improving the comparability and reliability of the analysis results, as well as to supplement information on human biomonitoring for various territories of the Russian Federation. A comparative assessment of the contents of vanadium, chromium, manganese, nickel, copper, zinc, arsenic, selenium, strontium, cadmium, thallium and lead with reference concentrations used in national programs for human biomonitoring (BMC) of European countries and the United States was made. Material and methods. The authors determined mass concentrations of V, Cr, Mn, Ni, Cu, Zn, As, Se, Sr, Cd, Tl, and Pb by ICP-MS in conformity with Methodical Guidelines 4.1. 3230-14 (FR.1.31.2014.17064) developed by the authors. The article contains setting parameters for quadrupole mass spectrometer with inductively coupled plasma (Agilent 7500cx), the optimal sample preparation scheme for eliminating the “matrix” effect. The operating mode of the mass spectrometer with a response/collision cell to mitigate interferences and the choice of internal standards is justified. The sample preparation of whole blood was made by acid dissolution followed by centrifugation. The detection limits (LOD) for each element are calculated. Results. The results are presented in the form of basic statistics: minimum and maximum values, arithmetic mean (AM), geometric mean (GM), 5, 50, 95 percentiles and interpreted in accordance with modern international requirements. The geometric mean (GM) of element content in blood amounted to 0.11 µg/l (V); 5.34 µg/l (Cr); 13.1 µg/l (Mn); 3.15 µg/l (Ni); 854.7 µg/l (Сu); 4655.0 µg/l (Zn); 0.13 µg/l (As); 84.97 µg/l (Se); 28.0 µg/l (Sr); 0.28 µg/l (Сd); 0.05 µg/l (Tl); 18.63 µg/l (Pb). The validity of the results was confirmed by means of SERONORM TM Whole Blood L2 standard samples (Norway). The results of the study relied upon the 95 percentile (P95) can be used as approximate reference data as a basis for assessing the risk associated with exposure to metals. Conclusion. Regional differences from levels found in other Europe countries (Italy, Norway) and the USA included higher concentrations of Mn, Cr and Ni and lower levels of Cu, Zn and Se in blood of children in the rural areas of the West Ural region. The optimal method for determining the content of essential and toxic elements in blood by mass spectrometry with inductively coupled plasma has been substantiated and recommended for practical use (MG 4.1. 3230-14, FR.1.31.2014.17064).

Quantitative analysis of PET microplastics in environmental model samples using quantitative 1H-NMR spectroscopy: validation of an optimized and consistent sample clean-up method.

Identification and quantification of microplastics (MP) in environmental samples is crucial for understanding the risk and distribution of MP in the environment. Currently, quantification of MP particles in environmental samples and the comparability of different matrices is a major research topic. Research also focusses on sample preparation, since environmental samples must be free of inorganic and organic matrix components for the MP analysis. Therefore, we would like to propose a new method that allows the comparison of the results of MP analysis from different environmental matrices and gives a MP concentration in mass of MP particles per gram of environmental sample. This is possible by developing and validating an optimized and consistent sample preparation scheme for quantitative analysis of MP particles in environmental model samples in conjunction with quantitative 1H-NMR spectroscopy (qNMR). We evaluated for the first time the effects of different environmental matrices on identification and quantification of polyethylene terephthalate (PET) fibers using the qNMR method. Furthermore, high recovery rates were obtained from spiked environmental model samples (without matrix ~ 90%, sediment ~ 97%, freshwater ~ 94%, aquatic biofilm ~ 95%, and invertebrate matrix ~ 72%), demonstrating the high analytical potential of the method. Graphical abstract.

Important factors to consider for acrylamide mitigation in potato crisps using pulsed electric fields

Abstract This preliminary study aimed to compare the application of pulsed electric field (PEF) with a traditional blanching as pre-treatments before frying for the mitigation of acrylamide content in potato crisps. Measuring the degree of cell disintegration index (po) and the changes in water electrical conductivity during washing of potato slices, PEF protocol and sample preparation scheme were optimized. Peeled potato slices (thickness 1.5 ± 0.2 mm) were subjected to PEF (1.5 kV/cm, pulse duration 10 μs, total treatment time 10 ms, pulse frequency 100 Hz) and to blanching (85 °C for 3.5 min) pre-treatments and then to washing in water, evaluating the reduction of acrylamide precursors (reducing sugars and free asparagine). After frying (175 °C, 3 min), product quality, in terms of colour, texture and acrylamide content were evaluated. Results showed that PEF promoted acrylamide precursors leaching followed by a reduction of the final acrylamide content of around 30%, significantly higher if compared to the reduction obtained with blanching, with only slight modifications of the final quality of the product, in terms of colour and texture. Industrial relevance The Commission Regulation (EU) 2017/2158 of 20 November 2017 has introduced new benchmark levels and mitigation strategies for the reduction of the presence of acrylamide in foods, directing food businesses to the research of measures to lower the acrylamide formation in foods. The actual industrial production process of fried potato crisps involves the use of many mitigation strategies, such as a blanching of raw potatoes. However, the traditional blanching treatment presents several practical drawbacks and leads to undesirable changes of the product quality. The application of PEF as a pre-treatment could reduce the acrylamide content in deep-fat fried potato crisps. This preliminary study gives important indications regarding the possibility of combining a PEF pre-treatment on raw potato slices with subsequent industrial processing steps for the production of potato crisps with low acrylamide concentration.

Investigation of organic additives in Italian Renaissance devotion stucco reliefs from French collections

Abstract A series of Italian Renaissance stucco artworks from Museum of Fine Arts of Strasbourg and Louvre Museum in Paris were investigated with the aim of revealing and characterizing possible organic additives. As the stucco and its additives are little known but, according to the literature, could be complex and contain many different matters, the methodology was first tuned on the laboratory models prepared with gypsum or gypsum/lime plaster with various quantities of organic matter: animal glue or gum Arabic. The methodology consisted of observation of the surfaces of sampled fragments by optical and electronic microscopy, preliminary investigation of the presence of organic compounds by infrared spectroscopy, then extraction of the organic matters from the samples, preparation, and analysis by gas chromatography. The adopted sample preparation scheme allows screening the substances from various classes of organic products from one sample. The optimized analytical approach was applied to the samples from historical objects, showing the presence of proteins, oils, wax and sugars in reliefs. The interpretation of obtained results is not straightforward because of the low response of these substances in the samples, their possible mixture, or unknown origin. In some cases, the protein matter response varies with the deepness of sampling in the matter of stucco, which could be connected with its layered structure or particular surface treatment.

Identifying Per- and Polyfluorinated Chemical Species with a Combined Targeted and Non-Targeted-Screening High-Resolution Mass Spectrometry Workflow.

Historical and emerging per- and polyfluoroalkyl substances (PFASs) have garnered significant interest from the public and government agencies from the local to federal levels. The continuing evolution of PFAS chemistries presents a challenge to the environmental monitoring, where ongoing development of targeted methods necessarily lags the discovery of new chemical compounds. There is a need, therefore, to have forward-looking methodologies that can detect emerging and unexpected compounds, monitor these species over time, and resolve details of their chemical structure to enable future work in human health. To this end, non-targeted analysis by high-resolution mass spectrometry offers a broad base detection approach that can be combined with almost any sample preparation scheme and provides significant capabilities for compound identification after detection. Herein, we describe a solid-phase extraction (SPE) based sample concentration method tuned for shorter chain and more hydrophilic PFAS chemistries, such as per fluorinated ether acids and sulfonates, and describe analysis of samples prepared in this fashion in both targeted and non-targeted modes. Targeted methods provide superior quantification when reference standards are available but are intrinsically limited to expected compounds when performing analysis. In contrast, a non-targeted approach can identify the presence of unexpected compounds and provide some information about their chemical structure. Information about chemical features can be used to correlate compounds across sample locations and track abundance and occurrence over time.

Determination of methyl isopropyl hydantoin from rat erythrocytes by gas-chromatography mass-spectrometry to determine methyl isocyanate dose following inhalation exposure

Methyl isocyanate (MIC) is an important precursor for industrial synthesis, but it is highly toxic. MIC causes irritation and damage to the eyes, respiratory tract, and skin. While current treatment is limited to supportive care and counteracting symptoms, promising countermeasures are being evaluated. Our work focuses on understanding the inhalation toxicity of MIC to develop effective therapeutic interventions. However, in-vivo inhalation exposure studies are limited by challenges in estimating the actual respiratory dose, due to animal-to-animal variability in breathing rate, depth, etc. Therefore, a method was developed to estimate the inhaled MIC dose based on analysis of an N-terminal valine hemoglobin adduct. The method features a simple sample preparation scheme, including rapid isolation of hemoglobin, hydrolysis of the hemoglobin adduct with immediate conversion to methyl isopropyl hydantoin (MIH), rapid liquid-liquid extraction, and gas-chromatography mass-spectrometry analysis. The method produced a limit of detection of 0.05 mg MIH/kg RBC precipitate with a dynamic range from 0.05–25 mg MIH/kg. The precision, as measured by percent relative standard deviation, was <8.5%, and the accuracy was within 8% of the nominal concentration. The method was used to evaluate a potential correlation between MIH and MIC internal dose and proved promising. If successful, this method may be used to quantify the true internal dose of MIC from inhalation studies to help determine the effectiveness of MIC therapeutics.

Adhesion energy of as-grown graphene on copper foil with a blister test

Interfacial adhesion energy between as-grown graphene and its growth substrate reveals the nature of bonding, as well as provides insights for large-scale roll-to roll graphene transfer. In this study, a novel sample preparation scheme was developed and a unique quasi-static blister test was performed to measure the adhesion energy between as-grown graphene and its copper foil substrate. The copper foil was treated with acetic acid for 4 h, 24 h and 48 h prior to graphene growth. The corresponding adhesion energy was determined to be 0.74 ± 0.13 J/m2, 1.10 ± 0.16 J/m2, and 1.53 ± 0.11 J/m2, respectively. Longer exposures to acetic acid led to rougher copper foil surfaces, and thus higher adhesion energy. This trend is in contrast to that for transferred graphene, which has been found to have weaker adhesion to rougher substrates. The experimental results from this study suggest that the interaction between as-grown graphene and its seed layer was mainly due to van der Waals, instead of covalent or ionic bonds and that surface roughness of the growth substrate could be a significant factor in determining the as-grown graphene adhesion energy.