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Sample preparation

Zhenqi Liu, Shunchen Qiu, Yiqun Gu, Meiying Ning
A specific and sensitive high performance liquid chromatography-tandem mass spectrometry method that could be used to determine the concentration of levonorgestrel (LNG) in Beagle dog plasma was developed. Specifically, terfenadine was used as the internal standard (IS). The separation was achieved on a Kinetex-C18 110A column (3 mm * 30 mm ID., 2.6 um, phenomenex) and a gradient mobile phase consists of methanol (0.1% formic acid) and water (0.1% formic acid) was used. The flow rate was 0.8 ml/min and the injection volume was 10 μl...
August 17, 2018: Biomedical Chromatography: BMC
Jingkun Li, Huijuan Li, Yanfang Zhao, Shanshan Wang, Xiangfeng Chen, Ru-Song Zhao
A solid-phase microextraction (SPME) fiber coated with a hollow microporous organic network (H-MON) was fabricated for the analysis of short-chain chlorinated paraffins (SCCPs). The sorbent was prepared by reacting tetra(4-ethynylphenyl)methane and 1,4-diiodobenzene using bis-(triphenylphosphine) palladium(II) as the catalyst in the presence of silica sphere templates, which then were removed by hydrofluoric acid. The SCCPs were quantified by GC-MS working in the negative chemical ionization mode. The H-MON has a high specific surface (701 m2 ·g-1 ) and microporosity (pore size <2 nm)...
August 17, 2018: Mikrochimica Acta
D Chekrygina, A Rothkirch, I Baev, F Kielgast, P Pandit, W Wurth, M Martins
Ultra-small clusters containing few atoms are of high interest in both fundamental research and applications due to their specific functional, magnetic or chemical properties which depend on size and composition. The experimental results of the morphology of the size-selected clusters, consisting of few atoms can be an ideal benchmark for sophisticated theoretical models. With this motivation we have investigated the geometrical structure of mass-selected Au9 clusters deposited on a silicon substrate prepared by soft-landing conditions...
August 17, 2018: Scientific Reports
Nadeem Muhammad, Abdul Rahman, Muhammad Adnan Younis, Qamar Subhani, Khurram Shehzad, Hairong Cui, Yan Zhu
Nowadays, there are rising concerns about the extensive use of the antibiotics such as chloramphenicol (CAP), has threatened the human life in the form of various vicious diseases. The limited selectivity and sensitivity of confirmatory techniques (UV and electrochemical) and non-fluorescence property of CAP make its determination a challenging task in the modern pharmaceutical analysis. In order to redeem the selective, sensitive and cost-effective fluorescence methodology, here by the dual role of synthesized porous SnO2 nanoparticles were exploited; (i) a porous sorbent in a µ-QuEChERS based sample preparation and as (ii) a stimulant for the transformation of non-fluorescent analytes namely CAP and p-nitrophenol (p-NP) into their respective fluorescent product...
August 17, 2018: Scientific Reports
Wilbur H Chen, Kathleen M Neuzil, C Rebecca Boyce, Marcela F Pasetti, Mardi K Reymann, Lionel Martellet, Nancy Hosken, F Marc LaForce, Rajeev M Dhere, Sambhaji S Pisal, Amol Chaudhari, Prasad S Kulkarni, Ray Borrow, Helen Findlow, Valerie Brown, Megan L McDonough, Len Dally, Mark R Alderson
BACKGROUND: Invasive meningococcal disease is an important public health problem, especially in sub-Saharan Africa. After introduction of MenAfriVac in 2010, Neisseria meningitidis serogroup A disease has been almost eliminated from the region. However, serogroups C, W, Y, and X continue to cause disease outbreaks. We assessed the NmCV-5 pentavalent meningococcal conjugate vaccine targeting A, C, Y, W, and X serogroups in a first-in-man, phase 1 study. METHODS: We did a single-centre, double-blind, randomised controlled trial at a research clinic in Baltimore (MD, USA)...
August 14, 2018: Lancet Infectious Diseases
Shu Wang, Yao Deng, Baomin Liu, Xiaolin Li, Xin Lin, Dongxing Yuan, Jian Ma
2-Aminoethylphosphonic acid (2-AEP) and 2-amino-3-phosphonopropionic acid (2-AP3) are two types of abundant and ubiquitous naturally occurring phosphonates used as sources of phosphorus by many prokaryotic lineages. The potential utilization mechanism of 2-AEP and 2-AP3 in eukaryotic phytoplankton is currently under investigation. However, the lack of suitable analytical methods in saline samples are the limitation of such researches. Herein, a high-performance liquid chromatography (HPLC) method for monitoring 2-AEP and 2-AP3 using precolumn fluorescence derivatization with o-phthalaldehyde-ethanethiol (OPA-ET) in seawater matrix was developed...
August 8, 2018: Journal of Chromatography. A
Ali Mohebbi, Saeid Yaripour, Mir Ali Farajzadeh, Mohammad Reza Afshar Mogaddam
A dispersive solid phase extraction coupled with deep eutectic solvent-based air-assisted liquid-liquid microextraction has been developed and applied to the extraction and preconcentration of some tricyclic antidepressant drugs in the human urine and plasma samples prior to their determination by gas chromatography-mass spectrometry. In this method, a sorbent (C18 ) is first added into an alkaline aqueous sample and dispersed by vortexing. By this action, the analytes are adsorbed onto the sorbent. Then, the sorbent particles are isolated from the aqueous solution by centrifugation...
August 10, 2018: Journal of Chromatography. A
Jean de Dieu Habimana, Jian Ji, Fuwei Pi, Eric Karangwa, Jiadi Sun, Wei Guo, Fangchao Cui, Jingdong Shao, Claudine Ntakirutimana, Xiulan Sun
Herein, a novel class-specific artificial receptor-based on molecularly imprinted polymer (MIP)-coated quantum dots (QDs@MIP) was synthesized, characterized, and used for the detection and quantification of the bacterial quorum signaling molecules N-acyl-homoserine lactones (AHLs), a class of autoinducers from Gram-negative bacteria. The QDs@MIP was prepared by surface imprinting technique under controlled conditions using CdSe/ZnS QDs as the signal transducing material. The synthesis of the QDs@MIP was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, and fluorescence spectroscopy...
November 15, 2018: Analytica Chimica Acta
Avinash A Patil, Cheng-Kang Chiang, Chen-Hao Wen, Wen-Ping Peng
A forced dried droplet method (FDD) is developed to overcome the drawbacks of the conventional dried-droplet (DD) method for matrix assisted laser desorption/ionization (MALDI) sample preparation. The crystals produced by the DD method are heterogeneous and irregularly distributed, and thus many methods have tried to solve the problems. However, most of them spend more time or need additional instruments to generate homogeneous microcrystals. The FDD sample preparation method can produce uniform microcrystals with homogeneous size distribution in few minutes without additional instruments...
November 15, 2018: Analytica Chimica Acta
Hongyue Ma, Jing Zhou, Hongbo Guo, Erxin Shang, Zhenhua Zhu, Uros Kuzmanov, Xiang Lv, Liuqing Di, Boyang Yu, Qinan Wu, Jinao Duan
Natural medicinal substances (NMS) have great inconsistency due to chemical variability, seriously limiting their development as therapeutics. Here, we chose toad venom with anti-tumor activities as a model and developed a pipeline of metabolomics-based screening and quality consistency control (MSQCC) as one potential solution to this long-standing problem. Our study firstly exemplified the power of the co-correlation screen of metabolomic and biological profiles of 180 fractions prepared from natural heterogeneous venom samples, to identify a series of bufadinolides as quality control markers for cancer cell inhibition...
November 15, 2018: Analytica Chimica Acta
Renmeng Liu, Ning Pan, Yanlin Zhu, Zhibo Yang
The exploration of single cells reveals cell heterogeneity and biological principle of cellular metabolism. Although a number of mass spectrometry (MS) based single cell MS (SCMS) techniques have been dedicatedly developed with high efficiency and sen-sitivity, limitations still exist. In this work, we introduced a microscale multifunctional device, the T-probe, which integrates cellu-lar contents extraction and immediate ionization, to implement online in situ SCMS analysis at ambient conditions with minimal sample preparation...
August 17, 2018: Analytical Chemistry
Xin Zheng, Weicong Wang, Yanbao Zhang, Yuxiang Ma, Hongyun Zhao, Pei Hu, Ji Jiang
Osimertinib (AZD9291) is a highly selective irreversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) designed to treat non-small cell lung cancer (NSCLC) patients with EGFR active and T790M resistant mutations. A rapid and sensitive method for quantitative analysis by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) of osimertinib and its metabolite AZ5104 in human plasma was developed and validated. The samples were prepared by protein precipitation (PP) and separated on a BEH C18 column (2...
August 17, 2018: Biomedical Chromatography: BMC
Faizan Ahmad, Ra J Prabhu, Jun Liao, Shwe Soe, Michael D Jones, Jonathan Miller, Parker Berthelson, Daniel Enge, Katherine M Copeland, Samar Shaabeth, Richard Johnston, Ian Maconochie, Peter S Theobald
Neonatal heart disorders represent a major clinical challenge, with congenital heart disease alone affecting 36,000 new-borns annually within the European Union. Surgical intervention to restore normal function includes the implantation of synthetic and biological materials; however, a lack of experimental data describing the mechanical behaviour of neonatal cardiac tissue is likely to contribute to the relatively poor short- and long-term outcome of these implants. This study focused on characterising the mechanical behaviour of neonatal cardiac tissue using a porcine model, to enhance the understanding of how this differs to the equivalent mature tissue...
July 29, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Amanda L Adrian, Jeffrey L Thomas, Amy B Adler
OBJECTIVE: The present study investigated the association between previous deployment experience and somatic symptoms, mental health, unit climate perceptions, anger, and risk taking among junior-enlisted soldiers who were preparing to deploy or who were in garrison, or home duty station. The study also investigated potential differences in these variables based on unit leader deployment history. METHOD: Soldiers in a combat unit were surveyed either in a predeployment (n = 1,554; one week before deployment) or garrison setting (n = 1,326)...
August 17, 2018: Psychiatry
Emmanuelle Casanova, Timothy David James Knowles, Christopher Williams, Matthew P Crump, Richard Peter Evershed
Preparative capillary gas chromatography (pcGC) is widely used for the isolation of single compounds for radiocarbon determinations. While being effective at isolating compounds, there are still genuine concerns relating to contamination associated with the isolation procedure, such as incomplete removal of solvent used to recover isolated samples from the traps and cross-contamination, which can lead to erroneous 14C determinations. Herein we describe new approaches to identifying and removing these two sources of contamination...
August 17, 2018: Analytical Chemistry
Yiran Liang, Ying Zhu, Maowei Dou, Kerui Xu, Rosalie K Chu, William B Chrisler, Rui Zhao, Kimberly K Hixson, Ryan T Kelly
Due to sensitivity limitations, global proteome measurements generally require large amounts of biological starting material, which masks heterogeneity within the samples and differential protein expression among constituent cell types. Methods for spatially resolved proteomics are being developed to resolve protein expression for distinct cell types among highly heterogeneous tissues, but have primarily been applied to mammalian systems. Here we evaluate the performance of cell-type-specific proteome analysis of tomato fruit pericarp tissues by a platform integrating laser capture microdissection (LCM) and a recently developed automated sample preparation system (nanoPOTS, Nanodroplet Processing in One pot for Trace Samples)...
August 17, 2018: Analytical Chemistry
Wangwei Ao, Yuan Li, Yinsheng Zhang
To more accurately and rapidly achieve quantitative detection of clinical crizotinib samples, stable isotope labeled crizotinib was required as an internal standard. We have developed a method to prepare racemic [D9 ] crizotinib using a base-catalyzed H/D exchange of both nitro compound 2 and the acetophenone compound 6 with D2 O and NaBD4 reduction of 7 as the key steps to introduce the nine deuterium atoms. Starting with 4-hydroxypiperidine, 14 step-synthesis furnished the desired racemic [D9 ] crizotinib 18...
August 17, 2018: Journal of Labelled Compounds & Radiopharmaceuticals
David Schneider, Manuel Sancho-Puchades, Goran I Benic, Christoph Hf Hämmerle, Ronald E Jung
The objectives of this study were to compare conventional and computer-assisted implant planning and placement (CAIPP) protocols regarding surgical planning predictability, intraoperative complications, and patient-centered outcomes. Partially edentulous patients (N = 73) were randomly allocated to one of three treatment groups: control (C, n = 26), with preoperative planning based on conventional radiography and freehand implant placement; and test 1 (T1, n = 24) and test 2 (T2, n = 23), with two different CAIPP protocols...
2018: International Journal of Periodontics & Restorative Dentistry
Robin S S Kramer, Mila Mileva, Kay L Ritchie
Researchers have long been interested in how social evaluations are made based upon first impressions of faces. It is also important to consider the level of agreement we see in such evaluations across raters and what this may tell us. Typically, high levels of inter-rater agreement for facial judgements are reported, but the measures used may be misleading. At present, studies commonly report Cronbach's α as a way to quantify agreement, although problematically, there are various issues with the use of this measure...
2018: PloS One
Summer L Martins, Susan M Mason, Wendy L Hellerstedt, Sonya S Brady
CONTEXT: International travel is common and may influence women's sexual and reproductive health through myriad pathways. Existing studies focus on travelers' risk of acquiring STDs, but not their pregnancy prevention behaviors. Further, it is unclear whether sexual and reproductive health outcomes observed for female travelers are associated with travel itself, because few studies compare travelers with nontravelers. METHODS: An online survey was conducted in 2016-2017 among females attending a U...
August 17, 2018: Perspectives on Sexual and Reproductive Health
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