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Analytica Chimica Acta

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https://www.readbyqxmd.com/read/29655433/spectrophotometric-calibration-procedures-to-enable-calibration-free-measurements-of-seawater-calcium-carbonate-saturation-states
#1
Erin E Cuyler, Robert H Byrne
A simple protocol was developed to measure seawater calcium carbonate saturation states (Ωspec ) spectrophotometrically. Saturation states are typically derived from the separate measurement of two other carbon system parameters, with each requiring unique instrumentation and often complex measurement protocols. Using the new protocol, the only required equipment is a thermostatted laboratory spectrophotometer. For each seawater sample, spectrophotometric measurements of pH (visible absorbance) are made in paired optical cells, one with and one without added nitric acid...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655432/the-discrimination-threshold-a-selection-criterion-for-analytical-methods-based-on-measurement-uncertainty-application-to-animal-stress-studies
#2
Stephane Andanson, Isabelle Veissier, Max H Feinberg
Many biological studies seek to confirm the effect of a treatment on the levels of chemical markers in biological tissues. This requires choosing the analytical method best able to detect the difference between basal levels and those found after treatment. We propose a new approach to calculate a criterion we call the 'discrimination threshold' (DT), and we applied it to an analytical method that we developed to determine cortisol in cattle plasma to detect stress. DT is derived from the measurement uncertainty (MU), and combines the variabilities of both the analytical method and the marker...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655431/optical-trapping-raman-spectroscopy-ot-rs-with-embedded-microscopy-imaging-for-concurrent-characterization-and-monitoring-of-physical-and-chemical-properties-of-single-particles
#3
Zhiyong Gong, Yong-Le Pan, Gorden Videen, Chuji Wang
The study of physical and chemical properties of a microscopic object, such as a single particle, is made possible using optical trapping (OT) technology combined with other measuring techniques. Here we show a universal optical trap combined with Raman spectroscopy (RS) and microscopy imaging for single-particle studies. The universal optical trap is constructed using two counter-propagating hollow beams and is able to stably levitate single particles of a wide range of properties, such as transparent or absorbing materials, organic (polymers, bioaerosols, etc...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655430/use-of-dielectric-barrier-discharge-ionization-to-minimize-matrix-effects-and-expand-coverage-in-pesticide-residue-analysis-by-liquid-chromatography-mass-spectrometry
#4
Felipe J Lara-Ortega, José Robles-Molina, Sebastian Brandt, Alexander Schütz, Bienvenida Gilbert-López, Antonio Molina-Díaz, Juan F García-Reyes, Joachim Franzke
Although electrospray ionization (ESI) remains the gold standard ionization source for LC-MS, it exhibits two main limitations: the occurrence of matrix effects and the limited ionization coverage towards nonpolar compounds. Dielectric barrier discharge ionization (DBDI) has gained attraction in recent years as a versatile ionization method in different applications and formats. Here, we report a thorough evaluation of DBDI as ionization interface for LC-MS, which reveals attractive advantages over ESI and atmospheric pressure chemical ionization (APCI) provided its singular ionization mechanism versatility...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655429/mass-spectrometric-recommendations-for-quan-qual-analysis-using-liquid-chromatography-coupled-to-quadrupole-time-of-flight-mass-spectrometry
#5
Anne-Charlotte Dubbelman, Filip Cuyckens, Lieve Dillen, Gerhard Gross, Rob J Vreeken, Thomas Hankemeier
BACKGROUND: High-throughput simultaneous quantitative and qualitative (Quan/Qual) analysis is attractive to combine targeted with non-targeted analysis, e.g. in pharmacometabolomics and drug metabolism studies. This study aimed to investigate the possibilities and limitations of high-throughput Quan/Qual analysis by ultra-high performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS), to develop a widely applicable Quan/Qual UHPLC-HRMS method and to provide recommendations for Quan/Qual method development...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655428/simultaneous-determination-of-trace-levels-of-multiclass-fungicides-in-natural-waters-by-solid-phase-microextraction-gas-chromatography-tandem-mass-spectrometry
#6
Maria Celeiro, Rocio Facorro, Thierry Dagnac, Maria Llompart
A solvent-free method based on solid-phase microextraction (SPME) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for the simultaneous determination of eleven fungicides at trace levels in different types of waters. Several experimental SPME parameters such as temperature, fibre coating, and SPME mode, were optimized in order to obtain the highest extraction efficiency. Under the optimal conditions, 100 °C, polyacrilate fibre (PA) and direct-immersion mode, the method was validated showing good linearity, repeatability and reproducibility...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655427/enhanced-cleanup-efficiency-hydroxy-functionalized-magnetic-graphene-oxide-and-its-comparison-with-magnetic-carboxyl-graphene-for-prime-pass-through-cleanup-of-strychnine-and-brucine-in-human-plasma-samples
#7
Jian-Bo Ma, Hai-Wen Qiu, Qiu-Hong Rui, Yu-Feng Liao, Yan-Min Chen, Jin Xu, Yun Zhang, Yan Zhu, Yong-Gang Zhao
An enhanced cleanup efficiency hydroxy functionalized-magnetic graphene oxide (EH-Mag-GO) fully covered porous nano-titania as coating has been designed and synthesized. It has been evaluated in PRiME (process, robustness, improvements, matrix effects, ease of use) pass-through cleanup procedure for human plasma prior to analysis of strychnine and brucine by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). Comparing with the magnetic carboxyl-graphene (Mag-CG), EH-Mag-GO is much more effective for the removal of matrix effect resulted from blood phospholipids...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655426/highly-efficient-dna-extraction-and-purification-from-olive-oil-on-a-washable-and-reusable-miniaturized-device
#8
Joana Carvalho, Gema Puertas, João Gaspar, Sarah Azinheiro, Lorena Diéguez, Alejandro Garrido-Maestu, Manuel Vázquez, Jorge Barros-Velázquez, Susana Cardoso, Marta Prado
Sample preparation from complex matrixes with minute DNA content could highly benefit from the miniaturization of solid phase extraction (SPE) based devices due to an increased surface area-to-volume ratio. However, the adaptation of "bench-top" based protocols for DNA purification to miniaturized devices is not as straightforward as it might seem, and several issues need to be considered. A careful evaluation of DNA extraction and purification protocols needs to be performed, taking into account the complexity of such samples, and in order to facilitate the integration with the subsequent step, normally DNA amplification...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655425/estimating-the-number-of-components-and-detecting-outliers-using-angle-distribution-of-loading-subspaces-adls-in-pca-analysis
#9
Y J Liu, T Tran, G Postma, L M C Buydens, J Jansen
Principal Component Analysis (PCA) is widely used in analytical chemistry, to reduce the dimensionality of a multivariate data set in a few Principal Components (PCs) that summarize the predominant patterns in the data. An accurate estimate of the number of PCs is indispensable to provide meaningful interpretations and extract useful information. We show how existing estimates for the number of PCs may fall short for datasets with considerable coherence, noise or outlier presence. We present here how Angle Distribution of the Loading Subspaces (ADLS) can be used to estimate the number of PCs based on the variability of loading subspace across bootstrap resamples...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655424/simultaneous-elastase-hyaluronidase-and-collagenase-capillary-electrophoresis-based-assay-application-to-evaluate-the-bioactivity-of-the-red-alga-jania-rubens
#10
Syntia Fayad, Mona Tannoury, Philippe Morin, Reine Nehmé
There have been many efforts to search for affordable and efficient cosmetic ingredients from natural sources and to evaluate their bioactivities using eco-responsible tools. Hyaluronidase, elastase and collagenase are responsible for the degradation of the main components of the extracellular matrix, namely the hyaluronic acid, elastin and collagen, respectively. The aim of this work was to develop a single capillary electrophoresis method to monitor simultaneously the activities of these three enzymes, without reactant immobilization or radioactivity use...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655423/aerosol-sampler-for-analysis-of-fine-and-ultrafine-aerosols
#11
Pavel Mikuška, Lukáš Čapka, Zbyněk Večeřa
A new aerosol sampler based on the original version of Aerosol Counterflow Two-Jets Unit (ACTJU) is described. The ACTJU collector, connected with a water-based Condensation Growth Unit (CGU) placed upstream of the ACTJU, accomplished the quantitative collection of fine and ultrafine aerosol particles down to a few nanometers in diameter. Condensation of water vapor in the CGU enlarges nanometer sized particles to larger sizes in the supermicrometer range and the formed droplets are then collected into water in the ACTJU collector...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655422/aptamer-based-microcantilever-array-biosensor-for-profenofos-detection
#12
Chao Li, Guangping Zhang, Shangquan Wu, Qingchuan Zhang
Profenofos, a highly poisonous organophosphorus pesticide, has been widely used in agricultural production. These pesticide residues have seriously influenced food security and threatened human health, and new methods with high sensitivity are greatly needed to detect profenofos. Here, we developed an aptamer-based microcantilever-array sensor operated in stress mode to detect profenofos, with advantages of being a label-free, highly sensitive, one-step immobilization method capable of quantitative and real-time detection...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655421/a-novel-colorimetric-aptasensor-for-ultrasensitive-detection-of-cocaine-based-on-the-formation-of-three-way-junction-pockets-on-the-surfaces-of-gold-nanoparticles
#13
Khalil Abnous, Noor Mohammad Danesh, Mohammad Ramezani, Seyed Mohammad Taghdisi, Ahmad Sarreshtehdar Emrani
Herein, a novel colorimetric aptasensor was introduced for detection of cocaine based on the formation of three-way junction pockets on the surfaces of gold nanoparticles (AuNPs) and the catalytic activity of the surfaces of AuNPs. Simplicity and detection of cocaine in a short time (only 35 min) are some of the unique features of the proposed sensing strategy. In the presence of cocaine, triple-fragment aptamer (TFA) forms on the surfaces of AuNPs, leading to a significant decrease of the catalytic activity of AuNPs and the color of samples remains yellow...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655420/dual-enzyme-free-amplification-strategy-for-ultra-sensitive-fluorescent-detection-of-bisphenol-a-in-water
#14
Wen Yun, Hong Wu, Lin Chen, Lizhu Yang
An ultra-sensitive strategy for bisphenol A (BPA) detection based on dual enzyme-free strategies: hybridization chain reaction (HCR) and enzyme-strand recycling reaction has been developed. The BPA aptamer can form hairpins structure by the partly self-complementary sequence. In the presence of BPA, the released BPA aptamer sequence can trigger the HCR between two hairpins to from a long nicked double-helix DNA. The tails of hairpins on the duplex DNA were closely enough to hybridize with molecular beacon (MB) on the gold nanoparticles (AuNPs) to circularly cleave the loop of MB, leading to a "turn-on" fluorescent signal...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29655419/a-two-dimensional-metal-organic-framework-nanosheets-based-fluorescence-resonance-energy-transfer-aptasensor-with-circular-strand-replacement-dna-polymerization-target-triggered-amplification-strategy-for-homogenous-detection-of-antibiotics
#15
Qian Yang, Lingying Zhou, Yong-Xiang Wu, Kai Zhang, Yuting Cao, You Zhou, Dazhen Wu, Futao Hu, Ning Gan
In the study, a novel two dimensional metal-organic framework (Cu-TCPP nanosheets) based fluorescence resonance energy transfer (FRET) aptasensing platform was developed for detecting antibiotics. Cu-TCPP nanosheets were employed for quenching the background fluorescence and circular strand-replacement DNA polymerization (CSRP) for signal amplification. To fulfill the purpose, we designed an aptamer hairpin probe (HP) whose stem can be opened while specifically binding to target. Then the opened HP would bind with the primer...
August 22, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29625688/development-of-a-general-method-for-quantifying-igg-based-therapeutic-monoclonal-antibodies-in-human-plasma-using-protein-g-purification-coupled-with-a-two-internal-standard-calibration-strategy-using-lc-ms-ms
#16
Huai-Hsuan Chiu, Hsiao-Wei Liao, Yu-Yun Shao, Yen-Shen Lu, Ching-Hung Lin, I-Lin Tsai, Ching-Hua Kuo
Monoclonal antibody (mAb) drugs have generated much interest in recent years for treating various diseases. Immunoglobulin G (IgG) represents a high percentage of mAb drugs that have been approved by the Food and Drug Administration (FDA). To facilitate therapeutic drug monitoring and pharmacokinetic/pharmacodynamic studies, we developed a general liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify the concentration of IgG-based mAbs in human plasma. Three IgG-based drugs (bevacizumab, nivolumab and pembrolizumab) were selected to demonstrate our method...
August 17, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29625687/ultra-sensitive-stable-isotope-assisted-quantification-of-multiple-urinary-mycotoxin-exposure-biomarkers
#17
Bojan Šarkanj, Chibundu N Ezekiel, Paul C Turner, Wilfred A Abia, Michael Rychlik, Rudolf Krska, Michael Sulyok, Benedikt Warth
There is a critical need to better understand the patterns, levels and combinatory effects of exposures we are facing through our diet and environment. Mycotoxin mixtures are of particular concern due to chronic low dose exposures caused by naturally contaminated food. To facilitate new insights into their role in chronic disease, mycotoxins and their metabolites are quantified in bio-fluids as biomarkers of exposure. Here, we describe a highly sensitive urinary assay based on ultra-high performance liquid chromatography - tandem mass spectrometer (UHPLC-MS/MS) and13 C-labelled or deuterated internal standards covering the most relevant regulated and emerging mycotoxins...
August 17, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29625686/automated-bundled-hollow-fiber-array-liquid-phase-microextraction-with-liquid-chromatography-tandem-mass-spectrometric-analysis-of-perfluorinated-compounds-in-aqueous-media
#18
Shalene Xue Lin Goh, Hian Kee Lee
An automated bundled hollow fiber array (BHF)-liquid-phase microextraction (LPME) methodology in combination with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed for the determination of perfluorinated compounds (PFCs) in environmental aqueous matrices. Eight PFCs were considered, including perfluoroheptanoic acid, perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorotetradecanoic acid...
August 17, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29625685/molecularly-imprinted-mesoporous-silica-nanoparticles-for-specific-extraction-and-efficient-identification-of-amadori-compounds
#19
Xianghua Pan, Xinpei He, Zhen Liu
Amadori compounds are an important family of chemical species with high values in the quality control and research of food and tobacco products as well as disease diagnosis. Since they are present in a large population with close structure and nature, recognition of specific Amadori compounds from complex sample matrices presents a challenging task. Particularly, few reagents or materials that can recognize specific Amadori compounds have been reported. In this study, we synthesized molecularly imprinted mesoporous silica nanoparticles (MIMSNs) that can highly specifically recognize and efficiently extract an Amadori compound of interest from complex samples...
August 17, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29625684/multivariate-estimation-of-the-limit-of-detection-by-orthogonal-partial-least-squares-in-temperature-modulated-mox-sensors
#20
Javier Burgués, Santiago Marco
Metal oxide semiconductor (MOX) sensors are usually temperature-modulated and calibrated with multivariate models such as partial least squares (PLS) to increase the inherent low selectivity of this technology. The multivariate sensor response patterns exhibit heteroscedastic and correlated noise, which suggests that maximum likelihood methods should outperform PLS. One contribution of this paper is the comparison between PLS and maximum likelihood principal components regression (MLPCR) in MOX sensors. PLS is often criticized by the lack of interpretability when the model complexity increases beyond the chemical rank of the problem...
August 17, 2018: Analytica Chimica Acta
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