Sample Preparation Time Research Articles

Cryogenic Reliability Evaluation of Glass Fabric–Reinforced Composites Using Novel Slip-Prevention Method

Glass fabric-reinforced composites are the main insulating material components of the secondary barrier of cargo containment systems (CCSs), because they prevent liquefied natural gas (LNG) leakage during transport. Nevertheless, it is difficult to evaluate the material performance of glass fabric-reinforced composites at cryogenic temperatures (-163 °C) because it takes approximately 7 days to prepare the test specimens and because the slip-based test frequently fails. Although glass fabric-reinforced composites for the secondary barrier of LNG CCSs show various structural vulnerabilities, enhancing their material performance is significantly limited owing to the reasons mentioned above. This study evaluated the structural vulnerabilities and failure characteristics of glass fabric-reinforced composites by using the slip-prevention test method to determine the level difference and adhesive vacancies. The failure surface and the thermal expansion of the composites were also observed, to analyze their mechanical characteristics. By adopting our proposed test procedure, the failure rate of the experiment decreased by approximately 80%, and the sample preparation time for manufacturing was significantly shortened, to 1 day.

Rapid Analysis of α-Tocopherol and Its Oxidation Products Using Supercritical Carbon Dioxide and Proton Transfer Reaction Ionization Mass Spectrometry.

We have developed a rapid and sensitive analytical method for α-tocopherol and its oxidative products by combining online hyphenation of supercritical fluid extraction-supercritical fluid chromatography (SFC) with proton transfer reaction (PTR) ionization mass spectrometry (MS). α-Tocopherol is a well-known antioxidant that plays a vital role in the antioxidant defense system in plant cells. However, studies on the cellular mechanisms of α-tocopherol have been limited owing to the lack of a rapid analytical method, which limits the comparison of plant cells incubated in various conditions. Additionally, complex sample preparation and long chromatography separation times are required. Moreover, the majority of the involved molecules are a combination of isomers, which must be separated before applying tandem MS. α-Tocopherol produces the α-tocopheroxyl radical in the first step of its antioxidant function; another ion with the same mass may also be generated from the source. SFC separation effectively distinguished the observed ions from their oxidative products in the sample and those produced during the ionization reaction process. This method enabled the measurement of α-tocopherol and its oxidative products such as α-tocopheroxyl radical and α-tocopheryl quinone in approximately 3 min per sample, including the time required for sample preparation.

Development of a loop-mediated isothermal amplification assay for detection of Austropeplea tomentosa from environmental water samples

Lymnaeid snails are key intermediate hosts for the development and survival of Fasciola spp., the causative agent of Fascioliasis which are economically important parasites infecting humans and livestock globally. The current control method for treating Fascioliasis is heavily reliant on anthelmintic drugs, particularly Triclabendazole (TCBZ) which has resulted in drug-resistant parasites and poses significant risk as there are no long-term efficacious alternatives available. Sustainable control measures at the farm level could include both parasite and snail control will play an important role in Fasciola spp. control and reduce the reliance on anthelmintic drugs. Implementation of such sustainable control measures requires effective identification of snails on the property however Lymnaeid snails are small and difficult to physically locate. Snail identification using an environmental DNA approach is a recent approach in which physically locating snails are not required. Austropeplea tomentosa, is the primary intermediate snail host for F. hepatica transmission in South-East Australia and we present an in-field loop-mediated isothermal amplification and water filtering method for the detection of A. tomentosa eDNA from water samples to improve current surveillance methods. This methodology is highly sensitive with a detection limit of 5 × 10− 6 ng/μL, detected in < 20 minutes, with cumulative sample preparation and amplification time under 1 hour. This proposed workflow could assist in monitoring areas to determine the risk of Fascioliasis infection and implement strategies to manage snail populations to ultimately reduce the risk of infection for humans and livestock.

Rapid determination, pollution characteristics and risk evaluations of antibiotics in drinking water sources of Hainan, China

A simple method using ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-MS/MS) was developed for simultaneous determination of 50 antibiotics in drinking water sources of Hainan Province, China. Antibiotics analyzed included 23 sulfonamides, 19 quinolones, 5 tetracyclines, and 3 chloramphenicols. This new method consisted of a simple water sample preparation procedure followed by direct injection into UPLC-MS/MS, rendering the method a time-saver which required much less sample preparation time and also smaller sample volumes than conventional techniques. The method detection limits (MDLs) were 0.8–12.0 ng/L. The average recoveries ranged from 74 to 118%, with a relative standard deviation of 0.21–11.3%. Six antibiotics, i.e., Oxytetracycline (OTC), sulfamonomethoxine (SMM), sulfamethoxazole (SMX), sulfachlorpyridazine (SCP), sulfadiazine (SD), and florfenicol (FF), were detected in drinking water sources of Hainan, with the highest concentrations being 9.5, 79.7, 42.5, 14.1, 41.5, and 62.3 ng/L, respectively. The median concentrations of antibiotics ranged from 5.7 to 20.8 ng/L with 3.3–30% detection frequencies. Based on ecological risk assessment, SMX posed a high risk to the pertinent sensitive aquatic organisms ( Synechococcus leopoliensis ) in two drinking water sources of Hainan. With regard to human health risk, the likelihood of posing a major risk to consumer health due to antibiotic exposure through drinking water intake was extremely low, as the risk quotients were all below 0.005. Nevertheless, the long-term ecological concerns and probable health risks of antibiotics in drinking water sources of Hainan need to be taken into consideration.

Efficient and sustainable microplastics analysis for environmental samples using flotation for sample pre-treatment

• Separation of microplastics from soil with water and air only • Robust, efficient and green sample preparation with a high separation quality • Investigations were performed by using TED-GC-MS and µRaman • Assessment of sample preparation approaches regarding green analytical chemistry Microplastics analysis in solid environmental samples like sediments and soils requires complex preparation steps to eliminate interfering matrix components. This is often combined with the use of highly concentrated, expensive, and environmentally harmful chemicals. These sample preparation methods can be very time-consuming. Hence, with regard to green analytical chemistry, reduction of emissions and hazards, these sample preparation methods should be modified or avoided, and more environmentally friendly methods should be developed. The characterization and evaluation of the optimized hydrophobicity-water/air-based enrichment cell for microplastics (µSEP) are presented in this study. The separation mechanism of µSEP is based on the hydrophobic adhesion of microplastic on finely dispersed upstreaming air bubbles, serving as a sustainable and practical microplastic sample preparation method. The separation mechanism requires only water and air to considerably reduce the matrix for microplastic analysis. Using soil samples as an example, the applicability of the µSEP sample preparation method for the analysis of microplastics by Raman microspectroscopy (µRaman) and thermal extraction-desorption gas chromatography-mass spectrometry (TED-GC-MS) is demonstrated. Within a sample preparation time of 60 minutes, for polyethylene terephthalate (PET), an average recovery of 77% ± 11%, for polystyrene (PS), 42% ± 11%, and for polypropylene (PP) 65% ± 12% was determined. Furthermore, this study evaluates µSEP and other sample preparation methods regarding their ecotoxicological impact based on the recently released software tool AGREEprep. This tool considers ten individual criteria to cover influencing factors of green analytical chemistry.

Accurate varietal classification and quantification of key quality compounds of grape extracts using the absorbance-transmittance fluorescence excitation emission matrix (A-TEEM) method and machine learning

Rapid and accurate quantification of grape berry phenolics, anthocyanins and tannins and identification of grape varieties are both important for effective quality control of harvesting and initial processing for winemaking. Current reference technologies, including High-Performance Liquid Chromatography (HPLC), can be rate-limiting and too complex and expensive for effective field operations. In this paper, we analyse robotically prepared grape extracts from several key varieties (n = Calibration/n = Prediction samples), including Cabernet-Sauvignon (64/10), Grenache (16/4), Malbec (14/4), Merlot (56/10), Petite Sirah (52/10), Pinot noir (54/8), Syrah (20/2), Teroldego (14/2) and Zinfandel (62/12). Key phenolic and anthocyanin parameters measured by HPLC included Catechin, Epicatechin, Quercetin Glycosides, Malvidin 3-glucoside, Total Anthocyanins and Polymeric Tannins. Split samples diluted 50-fold in 50 % EtOH pH 2 were analysed in parallel using the A-TEEM method following Multi-block Data Fusion of the absorbance and unfolded EEM data. A-TEEM chemical data were calibrated (n = 390) using Extreme Gradient Boosting (XGB) Regression and evaluated based on the Root Mean Square Error of the Prediction (RMSEP), the Relative Error of Prediction (REP) and Coefficient of Variation (R2P) of the Prediction data (n = 62). The regression results yielded an average Relative Error of Prediction (REP) of 5.89 ± 2.47 % and an R2P of 0.941 ± 0.025. While we consider the REP values to be in the acceptable range at significantly &lt; 10 %, we acknowledge that both the grape extraction method repeatability and HPLC reference method sample repeatability (5-8 % RSD) likely constituted the major sources of variation compared to the A-TEEM instrumental sample repeatability (&lt; 2 % RSD). The varietal classification was analysed using Agglomerative Hierarchical Cluster Analysis (HCA) and XGB discrimination analysis of the multi-block data. The classification results yielded 100 % True Positive and True Negative responses for the Calibration and Prediction Data for all tested varieties. We conclude that the A-TEEM method requires a minimum of sample preparation and rapid acquisition times (&lt; 1 min) and can serve as an accurate secondary method for both grape varietal identification and phenolic quantification. Importantly, the software application of the regression and classification models can be effectively automated for operators.

Determination of polyunsaturated and omega-3 fatty acids in vegetable oils and animal fats by the double-quantum filtered correlation spectroscopy (DQF-COSY)

Polyunsaturated fatty acids in vegetable oils and animal fats were one of the most important nutrient substances in the daily intake of humans and animals. These kinds of compounds were responsible for the source of energy, the structural unit of the cell membrane and important physical function. The conventional gas chromatography method inevitably used corrosive and carcinogenic chemicals, and spent long sample preparation time and detection time. To provide a determination method, the molar concentrations of omega-3 FAs and PUFAs in vegetable oils and animal fats were directly investigated with the DQF-COSY spectrum. The method was validated with trueness, selectivity, precision, limit of quantification, and linearity. The method could be used to quantify 14 kinds of vegetable oils, 5 kinds animal fats and 3 kinds of blend oils. The technique was found suitable for the quality control, the market supervision and the nutritional evaluation of FAs.

QuEChERS-based extraction and two-dimensional liquid chromatography-high resolution mass spectrometry for the determination of long chain chlorinated paraffins in sediments

In this study, a method was established for the analysis of long-chain chlorinated paraffins (LCCPs) in sediment based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and two-dimensional liquid chromatography-Orbitrap high resolution mass spectrometry (2DLCOrbitrap HRMS). Compared with other reported methods, this method greatly reduces sample preparation time (2 h) and solvent consumption. The QuEChERS extraction method presented satisfactory recoveries, 90.5–95.2, 84.7–86.6, and 81.4–83.4% of 5, 50, and 200 ng/g LCCPs with 49% Cl spiked into sediments. Meanwhile, no matrix effects were found in the LCCPs analysis after online purification by the 2DLC system. With the current commercial LCCP standards and a mixture of three chlorinated paraffins (CPs) industrial products, a suspect screening strategy was established and accurate identification of LCCPs (including vLCCPs, which carbon chain length greater than 20) under the plight that the reference standards for vLCCPs are currently unavailable. A total of 21 C18–20-LCCP and 22 vLCCP congeners were identified in sediment samples collected from Dongting Lake, China. The total concentrations of LCCPs in six sediment samples ranged from 1.69 to 18.0 ng/g (median 6.66 ng/g) and was dominated by C18 groups (mean, 28.8%), C19 groups (mean, 19.1%) and C21 groups (mean, 16.9%). Taken together, the successful application of this method to analyze sediment samples shows great potential for the analysis of LCCPs in environmental samples in future studies.

Development of a novel, label-free N-glycan method using charged aerosol detection

Monoclonal antibodies (mAbs) are complex glycoproteins that are developed for treatment of various therapeutic indications such as cancer and autoimmune diseases. MAbs are glycosylated at conserved asparagine residues (N-X-S/T) of the Fc region at amino acid position 297 of the heavy chain. Glycans are important in governing the functions of efficacy and serum half-life of protein therapeutics and are part of the critical quality attribute panel for release testing. Traditionally, N-linked glycans are released from glycoproteins after denaturation and enzymatic digestion with PNGase F, followed by fluorescent labeling of the liberated glycans. The labeled glycans are then separated using hydrophilic liquid chromatography (HILIC) with fluorescence detection to generate chromatographic profile. Despite decades of use, this strenuous process remains unchanged, utilizing toxic reagents and extended sample preparation time. As an intervention, this report showcases a novel, label-free approach to detect and quantify N-glycans without using fluorescent labeling. Separation of glycans using mixed-mode PGC column along with detection of non-derivatized glycans using charged aerosol detector, the overall turnaround time can be greatly reduced with significant cost savings. The label-free method provides similar quantitative results as the conventional fluorescent labeled method, confirming the validity of the method for product release.

Application of Headspace-SIFT-MS to Direct Analysis of Hazardous Volatiles in Drinking Water

Harmful volatile organic compounds (VOCs) are present in drinking water due to anthropogenic activities, such as oil refining (e.g., benzene) and disinfection (e.g., the so-called trihalomethanes, THMs). Gas chromatography (GC)-based techniques are widely applied for analysis of these compounds in the laboratory but have some throughput drawbacks due to sample preparation and the extended analysis time (due to chromatographic separation). Selected ion flow tube mass spectrometry (SIFT-MS) is a direct-injection mass spectrometry (DIMS) technique that has potential to reduce sample preparation and analysis times through direct analysis of aqueous headspace with no preconcentration, drying, or other water management. This study applies headspace-SIFT-MS to the analysis of benzene, related petroleum aromatics, and THMs to evaluate the potential for enhanced sample throughput for drinking water analysis (10 samples per hour). Headspace-SIFT-MS achieved a limit of quantitation (LOQ) of 0.1 to 0.2 μg L−1 for benzene, toluene, ethylbenzene and xylenes (BTEX), and 1 to 2 μg L−1 for the THMs. These LOQs achieve the current European Union and United States regulatory limits but are higher than modern GC methods. Therefore, the potential application of SIFT-MS is envisaged to lie in rapid screening in the laboratory, or field-based real-time monitoring.

Modification of the approach to the technology of preparation of samples of milk and dairy prod- ucts for the determination of the fatty acid profile using the gas chromatography method

The objects of the study are extractants and optimal extraction conditions that contribute to the full release of the substances being determined: the concentration and volume of the extractant, the extraction time and temperature regime. This work includes the technology of sample preparation for determining the fatty acid composition of milk with a fat mass fraction of more than 3 %, which is centrifuged for 10 minutes at 10000 rpm, 20 µl of oil is taken from the centrifuged laboratory sample into a test tube from the upper part, then dissolved in 2 cm3 of organic solvent (hexane), then mixed manually for 1-2 minutes, 100 ml of sodium methylate solution of 2 molar concentration is added to the resulting solution with a pipette and the tube is closed with a stopper, then intensively mixed manually for 2 minutes, insist for 5 minutesand filter through a paper filter the top layer containing methyl esters, the resulting solution will be ready for examination by gas chromatography. The proposed new approach to technology development reduces the sample preparation time (~19 min), reduces the amount of solvent consumed by more than 10 times, minimizes the number of actions when working with samples, and requires a minimum amount of equipment.

Cellulose in Foliage and Changes during Seasonal Leaf Development of Broadleaf and Conifer Species.

Stable isotope approaches are widely applied in plant science and many improvements made in the field focus on the analysis of specific components of plant tissues. Although technical developments have been very beneficial, sample collection and preparation are still very time and labor-consuming. The main objective of this study was to create a qualitative dataset of alpha-cellulose content of leaf tissues of arboreal species. We extracted alpha-cellulose from twelve species: Abies alba Mill., Acer pseudoplatanus L., Fagus sylvatica L., Larix decidua Mill., Picea abies (L.) Karst., Pinus sylvestris L., Quercus cerris L., Quercus petrea (Matt.) Liebl., Quercus pubescens Wild., Quercus robur L., Tilia platyphyllos Scop. and Ulmus glabra Huds. While these species show an increase in cellulose yield from bud break to full leaf development, the rates of increase in cellulose content and the duration of the juvenile phase vary greatly. Moreover, the veins display significantly higher alpha-cellulose content (4 to 11%) compared to blade tissues, which reflects their different structural and biochemical functions. A guide for the mass of sample material required to yield sufficient alpha-cellulose for a standard stable isotope analysis is presented. The additional benefits of the assessment of the mass of required sample material are reduced sample preparation time and its usefulness in preparing samples of limited availability (e.g., herbarium material, fossil samples).

Rapid Screening of Vaping Liquids by DART-MS.

E-cigarette, or vaping, product use-associated lung injury was reported in over 2800 cases from August 2019 to February 2020. Samples of vaping products were submitted for laboratory analysis in conjunction with investigation of the outbreak. A rapid screening method that was selective and sensitive for multiple analytes was required to aid in the investigation. To develop a multi-analyte method capable of screening vaping liquid samples that consumed small amounts of sample, required minimal sample preparation and analysis time, employed automated data processing, and provided the necessary sensitivity and selectivity. Vaping liquids were dissolved in acetonitrile and sampled with DIP-it® tips. The tips were analyzed by direct analysis in real-time mass spectrometry (DART-MS) and the resulting data processed with TraceFinder™ software. Laboratory-fortified samples consisting of various analytes and matrixes were evaluated prior to the analysis of submitted samples. The method was successful at detecting all target analytes in all matrixes evaluated, although the method detection limits varied by analyte/matrix combination: from 0.1% nicotine in poly(propylene glycol) average Mn 1000 (the lowest level evaluated) to 5.0% poly(ethylene glycol) average Mn 400 in cannabis concentrate. Results for the analysis of submitted samples by this method compared favorably to GC-MS and FTIR results. The DART-MS method met the objective of speed, sensitivity, and selectivity (although certain cannabinoid isomers could not be distinguished). The method may be easily adapted or expanded for additional analytes. This is a simple DART-MS method for screening vaping liquids for substances of concern in less than 2 min per sample.

Brownian Motion Influence on AFM Exosomes' Size Measurements.

Extracellular vesicles are evaluated by nanoparticle tracking analysis (NTA), providing information on their hydrodynamic diameters, and by atomic force microscopy (AFM) to calculate their geometric diameters. The aim of this study is to explore the influence of Brownian movements in a sample drop and preparation time on imaging-based measurements and to determine the relationship between the geometric and hydrodynamic sizes of the extracellular vesicles measured by the AFM and the NTA, respectively. Exosomes derived from the human prostate cancer cell line PC3 were evaluated by NTA and AFM, and those results were compared with Monte Carlo simulations. The mean size, evaluated by AFM shortly after application on the mica substrate, is less than its real value. It obtains the correct value faster for a thinner sample drop. Fitting the log-normal distribution to the geometric and hydrodynamic diameters leads to the conclusion that the latter could arise from the former by linear scaling by a factor that could be used to characterize the analyzed extracellular vesicles. The size of the vesicles attached to the mica substrate depends on time. The effect of Brownian motion and stretch of the lipid bilayer should be considered in the context of exosome AFM studies.

A rapid and sensitive ultra-performance liquid chromatography tandem mass spectrometry method for determination of anlotinib in plasma and dried blood spots: Method development, validation, and clinical application.

Anlotinib is a multi-target tyrosine kinase inhibitor, approved in China for treating several cancer types. Dose individualization based on therapeutic drug monitoring (TDM) is a useful tool to reduce toxicity. However, it is not convenient for patients to go to hospital for routine TDM via venous blood sampling at a certain time. An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for determination of anlotinib in human plasma and dried blood spot (DBS), characterized by simple sample preparation, high sensitivity, and short analysis time. The assay was validated in the concentration range of 0.2-200 ng/mL in plasma and 5-1000 ng/mL in DBS. This method was applied to monitor anlotinib exposure levels in patients with advanced biliary tract cancer (BTC) and non-small cell lung cancer (NSCLC). The trough plasma concentration (Ctrough ) of anlotinib was highly variable among BTC patients with coefficients of variation (CV) of 47.5%. DBS and venous blood samples were also collected from NSCLC patients to determine whether DBS sampling is a viable alternative sampling approach. Pearson correlation coefficient (R) between DBS and plasma concentration was 0.985. Bland-Altman plot demonstrated that the difference between estimated and measured plasma concentration was -2.9%. And 87% of sample pairs had a maximal deviation of ±20%. Anlotinib exhibits a high inter-individual variability in plasma exposure, and DBS sampling could be a promising tool for TDM of anlotinib.

ICP-MS Configuration and Optimization for Successful Routine Analysis of Undiluted Seawater

Inductively coupled plasma–mass spectrometry (ICP-MS) is a technique increasingly being used in commercial laboratories and industries that analyze samples with complex matrices, such as seawater, wastewater, saline groundwater, and other high salt samples. These laboratories often choose ICP-MS for its fast, multielement capability and high sample throughput, but time and cost pressures mean that laboratories have little time for sample preparation and method development. The time and cost pressures can lead to performance and operational issues because an ICP-MS instrument optimized for the highest sensitivity may not have the sufficient matrix tolerance to analyze high salt samples. In this article, we describe a method to optimize plasma robustness and interference control that enables a modern ICP-MS to perform simple, accurate, and routine analysis of critical trace elements in undiluted seawater.

Strategies to shorten turnaround time in outpatient laboratory.

BackgroundTurnaround time (TAT) is one of the most important indicators of laboratory quality. For the outpatient routine chemistry tests whose results are checked by clinicians on the same day, we set a quality goal that >90% of these samples should be reported within 60 min. As more than 20% of the samples failed to achieve this goal in 2020, we introduced an additional autoanalyzer and a real‐time monitoring system to improve this rate.MethodsAs the TAT of the pre‐analytical phase is the greatest contributor to TAT, we divided it into sampling, sample transport, and sample preparation times. An additional autoanalyzer was introduced, and its effect on TAT improvement was evaluated with the TAT data of June and July 2020. A real‐time monitoring system was introduced to sort delayed samples, and its effect was assessed with the TAT data of June and July 2021. TAT data from December 2019 to January 2020 were set as baseline controls.ResultsThe preparation time comprised the largest proportion of TAT. Although there was a slight decrease in overall TAT after the introduction of the above two strategies, the target TAT achievement rate increased significantly from 78.5% to 88.7% (p < 0.001).ConclusionsWe checked the cause of TAT prolongation and introduced new strategies to improve it. The addition of an autoanalyzer per se was not so effective but was better when combined with the real‐time monitoring system. Such strategies would increase the quality of the laboratory services.

“Omic” Approaches to Bacteria and Antibiotic Resistance Identification

The quick and accurate identification of microorganisms and the study of resistance to antibiotics is crucial in the economic and industrial fields along with medicine. One of the fastest-growing identification methods is the spectrometric approach consisting in the matrix-assisted laser ionization/desorption using a time-of-flight analyzer (MALDI-TOF MS), which has many advantages over conventional methods for the determination of microorganisms presented. Thanks to the use of a multiomic approach in the MALDI-TOF MS analysis, it is possible to obtain a broad spectrum of data allowing the identification of microorganisms, understanding their interactions and the analysis of antibiotic resistance mechanisms. In addition, the literature data indicate the possibility of a significant reduction in the time of the sample preparation and analysis time, which will enable a faster initiation of the treatment of patients. However, it is still necessary to improve the process of identifying and supplementing the existing databases along with creating new ones. This review summarizes the use of “-omics” approaches in the MALDI TOF MS analysis, including in bacterial identification and antibiotic resistance mechanisms analysis.

Structural characterization of mushroom polysaccharides by cyclic ion mobility-mass spectrometry

Polysaccharides are biopolymers known to possess various bioactivities. Because of their molecular complexity, the structural characterization of polysaccharides remains challenging, and difficult to be completed with a single analytical method. In this study, a novel approach for the characterization of linkages and anomeric configuration of polysaccharides was proposed. Based on ion mobility-mass spectrometry (IM-MS), a database containing 5 glucotriose standards was set up. Information about the arrival time distribution and fragmentation patterns of these standards were included. The method was validated by three commercially available purified polysaccharides, namely laminarin, dextrin, and dextran, each having distinct connectivity and configuration of the glycosidic bonds. Lastly, the method was successfully applied to analyze polysaccharides prepared from three medicinal mushrooms, namely Xylaria nigripes, Grifola frondosa, and Laetiporus sulphureus. The results showed that water-soluble non-digestible polysaccharides of X. nigripes and G. frondosa were mainly composed of (1→3)-β-glucan, while that of L.sulphureus was composed of (1→3)-ɑ-glucan. The present method has the advantages of being simple in sample preparation and short analysis time.

Determination of trace metals by ICP-OES in petroleum cokes using a novel microwave assisted digestion method

Trace metals must be strictly controlled in petroleum coke when it is used as anode, as the function of electrodes depends on their concentration, being detrimental in process operations affecting the purity of the final product.In this research, the determination of Si, Fe, V, Ni, Ca, Na, P, Al, Ti, Mg, K, Zn, Mo, Ba, and Co at trace level in green and calcined petroleum cokes using a new digestion method was performed. The method involved microwave-assisted digestion of the sample using a single-reaction chamber (SRC) followed by ICP-OES measurement. This method aimed for a low sample preparation time and a quantitative extraction of the analytes.After optimization of the digestion process it was found that the best condition to digest green and calcined cokes was mixing 9 g HNO3 and 3 g HCl, heating at a temperature of 260 °C for 55 min, and taking 0.5 g of sample, leading to a recovery higher than 98% for all the elements analyzed. In addition, the developed method allowed the determination of the elements in 1.5 h versus the standard method, which takes about 8 h. The validation of the developed methodology was carried out analyzing certified reference materials and using independent methods, such as, wavelength dispersive X-ray fluorescence spectrometry (WD-XRF).The developed methodology is faster, more accurate and more environmentally friendly than other available methodologies as it does not require the decomposition process involving high temperatures and waste generation is minimized. In addition, low limits of quantification and low uncertainties have been reached enabling this method to be used as a control method.