Hasil untuk "Analytical chemistry"

Duxia Cao, Zhi-qiang Liu, P. Verwilst et al.

Coumarins are a very large family of compounds containing the unique 2H-chromen-2-one motif, as it is known according to IUPAC nomenclature. Coumarin derivatives are widely found in nature, especially in plants and are constituents of several essential oils. Up to now, thousands of coumarin derivatives have been isolated from nature or produced by chemists. More recently, the coumarin platform has been widely adopted in the design of small-molecule fluorescent chemosensors because of its excellent biocompatibility, strong and stable fluorescence emission, and good structural flexibility. This scaffold has found wide applications in the development of fluorescent chemosensors in the fields of molecular recognition, molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, as well as in the biology and medical science communities. This review focuses on the important progress of coumarin-based small-molecule fluorescent chemosensors during the period of 2012-2018. This comprehensive and critical review may facilitate the development of more powerful fluorescent chemosensors for broad and exciting applications in the future.

F. Aquilante, J. Autschbach, Rebecca K. Carlson et al.

Jian Shu, D. Tang

Photoelectrochemical sensing is an attractive tool for rapid and accurate monitor of chemical and biochemical mole-cules. Compared with conventional analysis techniques, photoelectrochemical sensing exhibits unique technique superiority and has become a hot topic in material chemis-try and analytical chemistry. This review provides an over-view of the important advances in the construction and application of photoelectrochemical sensing in recent year. In the first segment, we briefly introduce the general princi-ple and technical characteristic of photoelectrochemical sensing. In the subsequent sections, we primarily devote to elaborating the typical strategies of design and engineering photoactive materials for improve the light excitation as well as charge separation/transfer to modulate the perfor-mance of photoelectrochemical sensing system. Addition-ally, the current research status of photoelectrochemical sensing with a particular emphasis on the innovative sens-ing devices and detection modes for achieving specific sensing functions is describes in detail with the illustrative examples. Finally, the critical challenges on the journey to achieve real-life applications of photoelectrochemical sens-ing and the viable solutions for solving these problems as well as the future research perspectives are discussed.

D. Mecerreyes

S. Bankar, Mahesh Bule, R. Singhal et al.

Yan Ji, Xiaoliang Yang, Zhi Ji et al.

The infrared spectrum (IR) characteristic peaks of amide I, amide II, and amide III bands are marked as amide or peptide characteristic peaks. Through the nuclear magnetic resonance study, N-methylacetamide has been determined to have six fine components, which include protonation, hydration, and hydroxy structures. Then the independent IR spectrum of every component in N-methylacetamide is calculated by using the density functional theory quantum chemistry method, and the contribution of each component to amide I, II, and III bands is analyzed. The results of this research can help to explain the formation of the amide infrared spectrum, which has positive significance in organic chemistry, analytical chemistry, and chemical biology.

D. Broadhurst, R. Goodacre, S. Reinke et al.

BackgroundQuality assurance (QA) and quality control (QC) are two quality management processes that are integral to the success of metabolomics including their application for the acquisition of high quality data in any high-throughput analytical chemistry laboratory. QA defines all the planned and systematic activities implemented before samples are collected, to provide confidence that a subsequent analytical process will fulfil predetermined requirements for quality. QC can be defined as the operational techniques and activities used to measure and report these quality requirements after data acquisition.Aim of reviewThis tutorial review will guide the reader through the use of system suitability and QC samples, why these samples should be applied and how the quality of data can be reported.Key scientific concepts of reviewSystem suitability samples are applied to assess the operation and lack of contamination of the analytical platform prior to sample analysis. Isotopically-labelled internal standards are applied to assess system stability for each sample analysed. Pooled QC samples are applied to condition the analytical platform, perform intra-study reproducibility measurements (QC) and to correct mathematically for systematic errors. Standard reference materials and long-term reference QC samples are applied for inter-study and inter-laboratory assessment of data.

E. Wagner, M. Plewa

B. Conway

K. Mittal, T. A. Roth

R. Perrone, N. Madias, A. Levey

P. Fox, T. Guinee, T. Cogan et al.

Qingqing Wang, Hui Wei, Zhiquan Zhang et al.

D. Birt, T. Boylston, S. Hendrich et al.

Xianlin Han

C G Fraser, E. K. Harris

J. W. Robinson, E. Frame, G. Frame

Concepts of Instrumental Analytical Chemistry Introduction to Spectroscopy Nuclear Magnetic Resonance Spectroscopy Infrared Spectroscopy Visible and Ultraviolet Molecular Spectroscopy Atomic Absorption Spectrometry Atomic Emission Spectroscopy X-Ray Spectroscopy Mass Spectrometry I: Principles and Instrumentation Mass Spectrometry II: Spectral Intrepretation Principles of Chromatography Gas Chromatography Chromatography with Liquid Mobile Phases Surface Analysis Electroanalytical Chemistry Thermal Analysis

Z. Takáts, J. Wiseman, R. Cooks

Shane McFarthing, Aidan Pellow-Jarman, Francesco Petruccione

Sample-based quantum diagonalization (SQD) offers a powerful route to accurate quantum chemistry on noisy intermediate-scale quantum (NISQ) devices by combining quantum sampling with classical diagonalization. Here we introduce HSQD, a novel half-qubit SQD approach that halves the qubit requirement for simulating a chemical system and drastically reduces overall circuit depth and gate counts, suppressing hardware noise. When modeling the dissociation of the nitrogen molecule with a (10e, 26o) active space, HSQD matches the accuracy of SQD on IBM quantum hardware using only half the number of qubits and 40% fewer measurements. We further enhance HSQD with a heat-bath configuration interaction (HCI) inspired selection of the samples, forming HCI-HSQD. This yields sub-millihartree accuracy across the N2 potential energy surface and produces subspaces up to 39% smaller than those from classical HCI, showing a significant improvement in the compactness of the ground-state representation. Finally, we demonstrate the scalability of HCI-HSQD using iron-sulfur clusters, reaching active spaces of up to (54e, 36o) while using only half as many qubits as the original SQD. For these systems, HCI-HSQD reduces SQD energy errors by up to 76% for [2Fe-2S] and 26% for [4Fe-4S], while also reducing subspace sizes, halving measurement requirements, and eliminating expensive post-processing. Together, these results establish half-qubit SQD as a noise-resilient and resource-efficient pathway toward practical quantum advantage in strongly correlated chemistry.

Ryushi Miyayama, Laura Kay Schaefer, Hiroshi Kobayashi et al.

Meteoroid entry into planetary atmospheres generates bow shocks, resulting in high-temperature gas conditions that drive chemical reactions. In this paper, we perform three-dimensional hydrodynamic simulations of meteoroid entry using the Athena++ code, coupled with chemistry calculations via Cantera to model the non-equilibrium chemistry triggered by atmospheric entry. Our aerodynamical simulations reveal the formation of complex shock structures, including secondary shock waves, which influence the thermodynamic evolution of the gas medium. By tracking thermodynamic parameters along streamlines, we analyze the effects of shock heating and subsequent expansion cooling on chemical reaction pathways. Our results demonstrate that chemical quenching occurs when the cooling timescale surpasses reaction rates, leading to the formation of distinct chemical products that deviate from equilibrium predictions. We show that the efficiency of molecular synthesis depends on the object\textquotesingle s size and velocity, influencing the composition of the post-entry gas mixture. Applying our model to Titan, we demonstrate that organic matter can be synthesized in the present environment of Titan. Also, we find that nitrogen, the dominant atmospheric component, remains stable, while water vapor is efficiently removed, a result inconsistent with equilibrium chemistry assumptions. Moreover, we compare our simulation results with laser experiments and find good agreement in chemical yields. Finally, we also evaluate the impact on Titan\textquotesingle s atmosphere as a whole, showing that meteoroid entry events could have played a significant role in supplying molecules such as HCN during early Titan\textquotesingle s history.