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https://www.readbyqxmd.com/read/28738655/risk-of-false-decision-on-conformity-of-a-multicomponent-material-when-test-results-of-the-components-content-are-correlated
#1
Ilya Kuselman, Francesca R Pennecchi, Ricardo J N B da Silva, D Brynn Hibbert
The probability of a false decision on conformity of a multicomponent material due to measurement uncertainty is discussed when test results are correlated. Specification limits of the components' content of such a material generate a multivariate specification interval/domain. When true values of components' content and corresponding test results are modelled by multivariate distributions (e.g. by multivariate normal distributions), a total global risk of a false decision on the material conformity can be evaluated based on calculation of integrals of their joint probability density function...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738654/development-of-a-sensitive-and-quantitative-uhplc-ms-ms-method-to-study-the-whole-body-uptake-of-pharmaceuticals-in-zebrafish
#2
Stanislav Kislyuk, Jerome Kroonen, Erwin Adams, Patrick Augustijns, Peter de Witte, Deirdre Cabooter
An analytical procedure to measure the whole-body uptake of pharmaceuticals in zebrafish has been developed using state-of-the-art methodologies. A sample preparation procedure for 9 pharmaceuticals displaying a variety in physicochemical properties was developed using 10-day old zebrafish (TG898). For an efficient homogenization of the samples and subsequent recovery of the compounds of interest, different amounts of organic solvents in combination with acidic modifiers were added to zebrafish samples. Samples were subsequently processed using a powerful bath sonicator and centrifuged...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738648/matrix-interference-evaluation-employing-gc-and-lc-coupled-to-triple-quadrupole-tandem-mass-spectrometry
#3
S Uclés, A Lozano, A Sosa, P Parrilla Vázquez, A Valverde, A R Fernández-Alba
Gas and liquid chromatography coupled to triple quadrupole tandem mass spectrometry are currently the most powerful tools employed for the routine analysis of pesticide residues in food control laboratories. However, whatever the multiresidue extraction method, there will be a residual matrix effect making it difficult to identify/quantify some specific compounds in certain cases. Two main effects stand out: (i) co-elution with isobaric matrix interferents, which can be a major drawback for unequivocal identification, and therefore false negative detections, and (ii) signal suppression/enhancement, commonly called the "matrix effect", which may cause serious problems including inaccurate quantitation, low analyte detectability and increased method uncertainty...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738647/development-of-an-analytical-methodology-for-obtaining-quantitative-mass-concentrations-from-laap-tof-ms-measurements
#4
Rachel Gemayel, Brice Temime-Roussel, Nathalie Hayeck, Adrien Gandolfo, Stig Hellebust, Sasho Gligorovski, Henri Wortham
Laser ablation aerosol particle-time of flight mass spectrometer (LAAP-ToF-MS) measures the size number of particles, and chemical composition of individual particles in real-time. LAAP-ToF-MS measurements of chemical composition are difficult to quantify, mostly because the instrument sensitivities to various chemical species in the multicomponent atmospheric aerosol particles are unknown. In this study, we investigate a field-based approach for quantitative measurements of ammonium, nitrate, sulfate, OC, and EC, in size-segregated atmospheric aerosols, by LAAP-ToF-MS using concurrent measurements from high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), and multi-angle absorption photometer (MAAP)...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738626/elimination-of-interference-from-water-in-kbr-disk-ft-ir-spectra-of-solid-biomaterials-by-chemometrics-solved-with-kinetic-modeling
#5
Sherald H Gordon, Rogers E Harry-O'kuru, Abdellatif A Mohamed
Infrared analysis of proteins and polysaccharides by the well known KBr disk technique is notoriously frustrated and defeated by absorbed water interference in the important amide and hydroxyl regions of spectra. This interference has too often been overlooked or ignored even when the resulting distortion is critical or even fatal, as in quantitative analyses of protein secondary structure, because the water has been impossible to measure or eliminate. Therefore, a new chemometric method was devised that corrects spectra of materials in KBr disks by mathematically eliminating the water interference...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738624/multiplexed-analysis-combining-distinctly-sized-cdte-mpa-quantum-dots-and-chemometrics-for-multiple-mutually-interfering-analyte-determination
#6
Dayana B Bittar, David S M Ribeiro, Ricardo N M J Páscoa, José X Soares, S Sofia M Rodrigues, Rafael C Castro, Leonardo Pezza, Helena R Pezza, João L M Santos
Semiconductor quantum dots (QDs) have demonstrated a great potential as fluorescent probes for heavy metals monitoring. However, their great reactivity, whose tunability could be difficult to attain, could impair selectivity yielding analytical results with poor accuracy. In this work, the combination in the same analysis of multiple QDs, each with a particular ability to interact with the analyte, assured a multi-point detection that was not only exploited for a more precise analyte discrimination but also for the simultaneous discrimination of multiple mutually interfering species, in the same sample...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738622/a-flow-based-procedure-exploiting-the-lab-in-syringe-approach-for-the-determination-of-ester-content-in-biodiesel-and-diesel-biodiesel-blends
#7
Samara Soares, Wanessa R Melchert, Fábio R P Rocha
The ester content is an important parameter to be monitored in biodiesel for evaluation of the transesterification reaction yield and for assessing the purity of the final product. This is also a relevant quality parameter in diesel/biodiesel blends to avoid frauds, because legislation establishes a minimum amount of biodiesel to be added to diesel. The official method EN14103 requires the addition of an alternative internal standard (methyl nonadecanoate) for analysis of biodiesel from bovine tallow because the methyl heptadecanoate is found in high amounts in this product...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738614/in-situ-synthesis-of-reduced-graphene-oxide-gold-nanoparticles-modified-electrode-for-speciation-analysis-of-copper-in-seawater
#8
Ming Liu, Dawei Pan, Wen Pan, Yun Zhu, Xueping Hu, Haitao Han, Chenchen Wang, Dazhong Shen
In this paper, reduced graphene oxide/gold nanoparticle/Nafion (rGO/AuNP/Nafion) modified electrode was fabricated through in-situ synthesis and used for determination of copper ions in strong salt electrolyte (0.5M NaCl) by differential pulse anodic stripping voltammetry (DPASV). This in-situ synthesis procedure was based on the ion-exchange and electrochemical reduction. The use of rGO provided a larger electrode surface and the presence of more active sites, while electron transfer was accelerated by incorporating AuNPs...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738612/sorption-luminescence-method-for-determination-of-terbium-using-transcarpathian-clinoptilolite
#9
V O Vasylechko, G V Gryshchouk, V P Zakordonskiy, L O Vasylechko, M Schmidt, I M Leshchack, Ya M Kalychak, S R Bagday
Sorption-luminescent method for terbium determination based on natural Transcarpathian clinoptilolite without using of complex synthetic organic compounds and toxic solvents was proposed. Optimal luminophore preparation conditions are sorption of Tb(III) on zeolite in the borate buffer solution with pH 8.25 and further calcination of clinoptilolite-Tb(III) samples at 500°C. For luminescence excitation the rays with wavelength of λ = 220nm of were used. Luminescence intensity at λ = 545nm was selected as analytical parameter for a quantitative terbium determination...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738608/a-fast-bioanalytical-method-based-on-microextraction-by-packed-sorbent-and-uplc-ms-ms-for-determining-new-psychoactive-substances-in-oral-fluid
#10
A M Ares, P Fernández, M Regenjo, A M Fernández, A M Carro, R A Lorenzo
The emergence in recent years of potentially dangerous new psychoactive substances (NPS) that are not under international control has led to the development of multi-analyte procedures for their unequivocal quantification. A fast ultra-performance liquid chromatography-tandem mass spectrometry method (UPLC-MS/MS), in combination with a sample pretreatment based on microextraction by packed sorbent (MEPS), was for the first time used in this work for the simultaneous determination of NPS in oral fluid. This matrix is an effective alternative to typical biological samples for drug control in substitution therapy programs, and also for the prevention and reduction of traffic accidents...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738604/electrochemical-investigation-and-determination-of-procaterol-hydrochloride-on-poly-glutamic-acid-carboxyl-functionalized-multiwalled-carbon-nanotubes-polyvinyl-alcohol-modified-glassy-carbon-electrode
#11
Dexian Kong, Lili Jiang, Yijun Liu, Zeming Wang, Libin Han, Rixin Lv, Jiandi Lin, Chun-Hua Lu, Yuwu Chi, Guonan Chen
Poly(glutamic acid) (P-GLU)/carboxyl functionalized multiwalled carbon nanotubes (MWCNTs-COOH)/polyvinyl alcohol (PVA) modified glassy carbon electrode (GCE) has been successfully prepared and the electrochemical behavior of procaterol hydrochloride (ProH) was studied. The results show that the as-prepared modified electrode exhibits a good electrocatalytic property towards the oxidation of ProH in 0.2M phosphate buffer solution (PBS) (pH 6.0) due to the enhanced oxidation peak current at ~+0.59V. Under optimal reaction conditions, the oxidation peak current of ProH is proportional to its concentration in the linear dynamic ranges of 0...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738601/biosensor-assisted-selection-of-optimal-parameters-for-designing-molecularly-imprinted-polymers-selective-to-phosmet-insecticide
#12
Nadin Aftim, Georges Istamboulié, Elena Piletska, Sergey Piletsky, Carole Calas-Blanchard, Thierry Noguer
Molecularly imprinted polymers (MIPs) for phosmet insecticide were synthesized by batch polymerization. The affinity of functional monomers to phosmet was tested using an original method involving an electrochemical biosensor based on acetylcholinesterase inhibition. It was demonstrated that association of phosmet with appropriate functional monomers resulted in a decrease of enzyme inhibition. Using this method, it was shown that N,N-methylenebis(acrylamide) displayed the highest interactions with phosmet using DMSO as solvent...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738596/chromatographic-separation-of-racemic-praziquantel-and-its-residual-determination-in-perch-by-lc-ms-ms
#13
Limin He, Fuming Gao, Erfen Li, Jauh Tzuoh Lee, Liangqiao Bian, Daniel W Armstrong
An enantioselective depletion study of praziquantel (PZQ) in perch muscle was done using a simple, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Two cyclic polypeptides and two cyclic saccharide chromatographic columns were evaluated. The new hydroxypropyl β-cyclodextrin (HP-RSP) superficially porous particle (SPP) column produced the optimum separation and was selected for the study. Deuterium labeled PZQ-d11 was used as the internal standard. The method was linear over concentration ranges of 5...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738586/development-of-a-solid-phase-extraction-method-with-simple-mekc-uv-analysis-for-simultaneous-detection-of-indole-metabolites-in-human-urine-after-administration-of-indole-dietary-supplement
#14
Apichai Phonchai, Prapin Wilairat, Rattikan Chantiwas
This work presents the development of a solid phase extraction method with simple MEKC-UV analysis for the simultaneous determination of indole-3-carbinol (I3C) and its metabolites (3, 3'-diindolylmethane (DIM), indole-3-carboxaldehyde (I3CAL), indole-3-acetonitrile (I3A)) in human urine after oral administration of an indole dietary supplement. Solid phase extraction (SPE) method was applied for the first time for simultaneous analysis of these indole metabolites. The MEKC separation method was developed in a previous work...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738582/metaboqc-a-tool-for-correcting-untargeted-metabolomics-data-with-mass-spectrometry-detection-using-quality-controls
#15
Mónica Calderón-Santiago, María A López-Bascón, Ángela Peralbo-Molina, Feliciano Priego-Capote
Nowadays most metabolomic studies involve the analysis of large sets of samples to find a representative metabolite pattern associated to the factor under study. During a sequence of analyses the instrument signals can be subjected to the influence of experimental variability sources. Implementation of quality control (QC) samples to check the contribution of experimental variability is the most common approach in metabolomics. This practice is based on the filtration of molecular entities experiencing a variation coefficient higher than that measured in the QC data set...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738580/true-lab-in-a-syringe-technology-for-bioassays
#16
Lenka Hárendarčíková, Daniel Baron, Andrea Šebestová, Jan Rozsypal, Jan Petr
In our work, we introduced a novel concept of the lab-in-a-syringe tests. We solved the problem of detection in already published LIS tests by putting all the reaction and detection pads directly into the syringe barrel. We also used more layers to make the results visible for users. Two detection layouts: (i) with using rounded pads-based detection, and (ii) with using rectangular detection pads, were studied. As the proof of concept, we studied the determination of Ni(II) using dimethylglyoxime as the reagent and blocking of the interference of Fe(II)...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738579/compositional-engineering-of-vopcpho-tio2-nano-composite-to-reduce-the-absolute-threshold-value-of-humidity-sensors
#17
Mohamad Izzat Azmer, Fakhra Aziz, Zubair Ahmad, Ehsan Raza, Mansoor Ani Najeeb, Noshin Fatima, Tahani M Bawazeer, Mohammad S Alsoufi, R A Shakoor, Khaulah Sulaiman
This research work demonstrates compositional engineering of an organic-inorganic hybrid nano-composites for modifying absolute threshold of humidity sensors. Vanadyl-2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine (VOPcPhO), an organic semiconductor, doped with Titanium-dioxide nanoparticles (TiO2 NPs) has been employed to fabricate humidity sensors. The morphology of the VOPcPhO:TiO2 nano-composite films has been analyzed by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM)...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738557/multielemental-analysis-of-18-essential-and-toxic-elements-in-amniotic-fluid-samples-by-icp-ms-full-procedure-validation-and-estimation-of-measurement-uncertainty
#18
B Markiewicz, A Sajnóg, W Lorenc, A Hanć, I Komorowicz, J Suliburska, R Kocyłowski, D Barałkiewicz
Amniotic fluid is the substantial factor in the development of an embryo and fetus due to the fact that water and solutes contained in it penetrate the fetal membranes in an hydrostatic and osmotic way as well as being swallowed by the fetus. Elemental composition of amniotic fluid influences the growth and health of the fetus, therefore, an analysis of amniotic fluid is important because the results would indicate abnormal levels of minerals or toxic elements. Inductively coupled plasma mass spectroscopy (ICP-MS) is often used for determination of trace and ultra-trace level elements in a wide range of matrices including biological samples because of its unique analytical capabilities...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738549/chemical-and-structural-characterization-of-char-development-during-lignocellulosic-biomass-pyrolysis
#19
Lihle D Mafu, Hein W J P Neomagus, Raymond C Everson, Christien A Strydom, Marion Carrier, Gregory N Okolo, John R Bunt
The chemical and structural changes of three lignocellulosic biomass samples during pyrolysis were investigated using both conventional and advanced characterization techniques. The use of ATR-FTIR as a characterization tool is extended by the proposal of a method to determine aromaticity, the calculation of both CH2/CH3 ratio and the degree of aromatic ring condensation ((R/C)u). With increasing temperature, the H/C and O/C ratios, XA and CH2/CH3 ratio decreased, while (R/C)u and aromaticity increased. The micropore network developed with increasing temperature, until the coalescence of pores at 1100°C, which can be linked to increasing carbon densification, extent of aromatization and/or graphitization of the biomass chars...
July 6, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28738543/phenolic-compounds-of-triplaris-gardneriana-can-protect-cells-against-oxidative-stress-and-restore-oxidative-balance
#20
Thiago Silva de Almeida, José Joaquim Lopes Neto, Nathanna Mateus de Sousa, Igor Parra Pessoa, Leonardo Rogério Vieira, Jackeline Lima de Medeiros, Aline Augusti Boligon, Astrid R M Hamers, Davi Felipe Farias, Ad Peijnenburg, Ana Fontenele Urano Carvalho
This work aimed to add value to an underexploited plant species from Brazil, Triplaris gardneriana. To that, the phenolic compounds profile of its seed ethanolic extract and fractions was examined by HPLC and the antioxidant capacity assessed using chemical assays as well as in vitro cell imaging. Twelve compounds were quantified and classified as either phenolic acids or flavonoids. The fractionation process did not generate fractions with different compositions except for chloroformic fraction, which showed only 6 out of 12 standard compounds used...
July 20, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
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