Comparative Investigation of the Differences in Chemical Compounds between Raw and Processed Mume Fructus Using Plant Metabolomics Combined with Chemometrics Methods

Mume Fructus is a well-known herbal medicine and food with a long history of processing and application. Different processing methods impact the intrinsic quality of Mume Fructus. Thus, it is of great significance to investigate the changes in chemical components during processing (i.e., raw compared to the pulp and charcoal forms). In this study, plant metabolomics methods based on mass spectrometry detection were established to analyze the chemical ingredients of Mume Fructus comprehensively. Chemometric strategies were combined to analyze the profile differences of Mume Fructus after different processing methods. The established strategy identified 98 volatile and 89 non-volatile compounds of Mume Fructus by gas chromatography-mass spectrometry (GC-MS) and ultra-high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UHPLC-Q-TOF-MS/MS), respectively. Moreover, the orthogonal partial least squares discriminant analysis (OPLS-DA) indicated that raw Mume Fructus and the Mume Fructus pulp and charcoal were distributed in three regions. Subsequently, 19 volatile and 16 non-volatile components were selected as potential chemical component markers with variable importance in the projection using (VIP) >1 as the criterion, and the accuracy was verified by a Back Propagation Neural Network (BP-NN). To further understand the difference in the content of Mume Fructus before and after processing, 16 non-volatile chemical component markers were quantitatively determined by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS). The results revealed that, compared with raw Mume Fructus, the total content of 16 components in the pulp of Mume Fructus increased while it decreased in the charcoal. Therefore, this study used GC-MS, UHPLC-Q-TOF-MS/MS and UHPLC-MS/MS modern technology to analyze the differences in chemical components before and after the processing of Mume Fructus and provided a material basis for further research on the quality evaluation and efficacy of Mume Fructus.     

Preprocessing NIR Spectra for Aquaphotomics

Even though NIR spectroscopy is based on the Beer–Lambert law, which clearly relates the concentration of the absorbing elements with the absorbance, the measured spectra are subject to spurious signals, such as additive and multiplicative effects. The use of NIR spectra, therefore, requires a preprocessing step. This article reviews the main preprocessing methods in the light of aquaphotomics. Simple methods for visualizing the spectra are proposed in order to guide the user in the choice of the best preprocessing. The most common chemometrics preprocessing are presented and illustrated by three real datasets. Some preprocessing aims to produce a spectrum as close as possible to the absorbance that would have been measured under ideal conditions and is very useful for the establishment of an aquagram. Others, dedicated to the improvement of the resolution of the spectra, are very useful for the identification of the peaks. Finally, special attention is given to the problem of reducing multiplicative effects and to the potential pitfalls of some very popular methods in chemometrics. Alternatives proposed in recent papers are presented.     

Metabolite Fingerprinting Based on 1H-NMR Spectroscopy and Liquid Chromatography for the Authentication of Herbal Products

Herbal medicines (HMs) are regarded as one of the traditional medicines in health care to prevent and treat some diseases. Some herbal components such as turmeric and ginger are used as HMs, therefore the identification and confirmation of herbal use are very necessary. In addition, the adulteration practice, mainly motivated to gain economical profits, may occur by substituting the high price of HMs with lower-priced ones or by addition of certain chemical constituents known as Bahan Kimia Obat (chemical drug ingredients) in Indonesia. Some analytical methods based on spectroscopic and chromatographic methods are developed for the authenticity and confirmation of the HMs used. Some approaches are explored during HMs authentication including single-component analysis, fingerprinting profiles, and metabolomics studies. The absence of reference standards for certain chemical markers has led to exploring the fingerprinting approach as a tool for the authentication of HMs. During fingerprinting-based spectroscopic and chromatographic methods, the data obtained were big, therefore the use of chemometrics is a must. This review highlights the application of fingerprinting profiles using variables of spectral and chromatogram data for authentication in HMs. Indeed, some chemometrics techniques, mainly pattern recognition either unsupervised or supervised, were applied for this purpose.     

Prediction of beef color using time‐domain nuclear magnetic resonance (TD‐NMR) relaxometry data and multivariate analyses

Time‐domain nuclear magnetic resonance and chemometrics were used to predict color parameters, such as lightness (L*), redness (a*), and yellowness (b*) of beef (Longissimus dorsi muscle) samples. Analyzing the relaxation decays with multivariate models performed with partial least‐squares regression, color quality parameters were predicted. The partial least‐squares models showed low errors independent of the sample size, indicating the potentiality of the method. Minced procedure and weighing were not necessary to improve the predictive performance of the models. The reduction of transverse relaxation time (T₂) measured by Carr–Purcell–Meiboom–Gill pulse sequence in darker beef in comparison with lighter ones can be explained by the lower relaxivity Fe²⁺ present in deoxymyoglobin and oxymyoglobin (red beef) to the higher relaxivity of Fe³⁺ present in metmyoglobin (brown beef). These results point that time‐domain nuclear magnetic resonance spectroscopy can become a useful tool for quality assessment of beef cattle on bulk of the sample and through‐packages, because this technique is also widely applied to measure sensorial parameters, such as flavor, juiciness and tenderness, and physicochemical parameters, cooking loss, fat and moisture content, and instrumental tenderness using Warner Bratzler shear force. Copyright © 2016 John Wiley & Sons, Ltd.     

The Limit of Detection of a Reactant,in the Presence of Another,by Kinetic Analysis and Deviation-Pattern Recognition

Abstract

When a solution containing a single reactant is subjected to kinetic analysis with a reagent giving rise to a pseudo-first-order reaction, non-linear regression analysis of the concentrationtime data yields a random scatter of the residuals around the best fit to the pseudo-first-order equation. If the same equation is used when a second reactant is also present, systematic errors arise and yield a deviation plot having a characteristic shape. If the amplitude of that plot is substantially larger than the random error of measurement, the presence of the reactant can be detected, and its concentration can then be evaluated by non-linear regression onto the equation that takes its presence into account. The amplitude passes through a maximum as the relative concentration of the second reactant increases, or as the ratio of the rate constants increases. For any given ratio of concentrations, detection of the second reactant is impossible unless the ratio of the rate constants lies within a certain range, which will be governed by the data-acquisition schedule employed. For the particular schedule assumed here, examination of these dependences shows, for example, that it should be possible to detect the second reactant if its concentration is 2.5 per cent of that of the first reactant and if the ratio of the rate constants is between 7.1 and 21.7.     

i‐Chemometrics

When I was a young scientist, it was rare for me to read publications that were over 10 years old. How does one know what interesting information lies in publications older than oneself? A great deal of people investigate the roots of their family, likewise a scientist may also be interested in the roots of their science. This account attempts to achieve both: to provide some direction toward old and interesting literature and to share my passion of Chemometrics. Copyright © 2015 John Wiley & Sons, Ltd.     

Differential Sensing of MAP Kinases Using SOX‐Peptides

Five SOX peptides are used to classify the MAPK groups and isoforms thereof using chemometrics. The score plots show excellent classification and accuracy, while support vector machine analysis leads to the quantification of ERK and an ERK inhibitor concentration in kinase mixtures. Examination of the loading plots reveals cross‐reactivity among the peptides, and some unexpected surprises.     

An innovative impurity profiling of esmolol hydrochloride injection using UPLC-MS based multiple mass defect filter,chemometrics and in-silico toxicity prediction

Esmolol hydrochloride injection is indicated for the rapid control of ventricular rate in patients with atrial fibrillation or atrial flutter in perioperative, postoperative, or other emergent circumstances where short term control of ventricular rate with a short-acting agent is desirable. The potential toxic impurities in pharmaceuticals at micro levels or trace levels are of increasing concern to both pharmaceutical industries and regulatory agencies, due to their potential risk to human health. The impurity investigation of esmolol   remains incomplete. Thereby, efficient impurities monitoring and potential toxicity assessment should be emphasized to assure drug safety. Impurity profiling methods of esmolol were developed using ultraperformance liquid chromatography plus Q-Exactive Orbitrap tandem mass spectrometry (UPLC-QE-MS) based multiple mass defect filter and chemometrics. Impurities were characterized by both UPLC-QE-MS and reference substance comparison. The toxicities of esmolol impurities were predicted by employing quantitative structure–activity relationship. The results showed that a total of 20 impurities were detected and identified using the above integrated strategy, 14 impurities (EP2-3, EP5-6, EP8-9, EP12-13, EP15-20) have firstly found. EP20 was predicted as hepatotoxic and mutagenic using QSAR model, and its hepatotoxicity were verified in vivo. The EP1 contents showed maximum volatility in all batches, and varied by sample. EP1 and its accompanying product of methanol were measured. This UPLC-MS/MS based chemometrics strategy is useful for monitoring the manufacturing process and quality control of esmolol hydrochloride injection.     

快扫循环伏安曲线的单纯形优化-数值模拟拟合方法

采用Gl算法改进了快扫伏安曲线的数值模拟,提高了模拟计算的速度.使用单纯形优化-数值模拟方法,以电流、峰电位误差的加权值作为拟合参数的评价函数,对二茂铁在0,3mm直径铂盘电极上,不同扫速下的循环伏安图进行了拟合.在拟合过程中自动进行伏安图基线的校正,同时拟合出标准非均相速度常数k~0,未补偿溶液电阻R_u以及双电层电容C_(dl)等重要的参数值,所得k~0值与文献报道结果一致.     

定量构效关系在化学计量学发展中的作用

介绍定量构效关系及其常用研究方法.叙述了化学计量学在我国近年来的发展,以及定量构效关系作为一门新兴的研究手段对现代化学尤其是化学计量学的发展所起的推动作用.