Comparative Metabolite Fingerprinting of Four Different Cinnamon Species Analyzed via UPLC–MS and GC–MS and Chemometric Tools

The present study aimed to assess metabolites heterogeneity among four major Cinnamomum species, including true cinnamon (Cinnamomum verum) and less explored species (C. cassia, C. iners, and C. tamala). UPLC-MS led to the annotation of 74 secondary metabolites belonging to different classes, including phenolic acids, tannins, flavonoids, and lignans. A new proanthocyanidin was identified for the first time in C. tamala, along with several glycosylated flavonoid and dicarboxylic fatty acids reported for the first time in cinnamon. Multivariate data analyses revealed, for cinnamates, an abundance in C. verum versus procyandins, dihydro-coumaroylglycosides, and coumarin in C. cassia. A total of 51 primary metabolites were detected using GC-MS analysis encompassing different classes, viz. sugars, fatty acids, and sugar alcohols, with true cinnamon from Malaysia suggested as a good sugar source for diabetic patients. Glycerol in C. tamala, erythritol in C. iners, and glucose and fructose in C. verum from Malaysia were major metabolites contributing to the discrimination among species.     

Impact of Coffee Bean Roasting on the Content of Pyridines Determined by Analysis of Volatile Organic Compounds

The aim of the study was to analyze the process of roasting coffee beans in a convection–conduction roaster (CC) without a heat exchanger and a convection–conduction–radiation roaster (CCR) with a heat exchanger for determination of the aroma profile. The aroma profile was analyzed using the SPME/GC-MS technique, and an Agrinose electronic nose was used to determine the aroma profile intensity. Arabica coffee beans from five regions of the world, namely, Peru, Costa Rica, Ethiopia, Guatemala, and Brazil, were the research material. The chemometric analyses revealed the dominance of azines, alcohols, aldehydes, hydrazides, and acids in the coffee aroma profile. Their share distinguished the aroma profiles depending on the country of origin of the coffee beans. The high content of pyridine from the azine group was characteristic for the coffee roasting process in the convection–conduction roaster without a heat exchanger, which was shown by the PCA analysis. The increased content of pyridine resulted from the appearance of coal tar, especially in the CC roaster. Pyridine has an unpleasant and bitter plant-like odor, and its excess is detrimental to the human organism. The dominant and elevated content of pyridine is a defect of the coffee roasting process in the CC roaster compared to the process carried out in the CCR machine. The results obtained with the Agrinose showed that the CC roasting method had a significant effect on the sensor responses. The effect of coal tar on the coffee beans resulted in an undesirable aroma profile characterized by increased amounts of aromatic volatile compounds and higher responses of Agrinose sensors.     

化学计量学/信息学助推化学与分析测试科学研究范式转换

该文回顾了科学研究范式的形成并讨论了化学与分析测试科学的相关发展历程。实验科学向理论科学演进实际是现代科学的形成过程,对化学而言是一个困难的数学化进程,直到第三即计算科学范式形成,化学的现代科学地位才得以确定。分析化学或分析测试科学发展过程中遇到类似的问题,化学计量学/信息学在助推其完善分析化学“数学化”进程的同时,也能够挖掘更多有效信息。随着现代分析仪器的快速发展和数据海啸的到来,化学计量学/信息学作为成熟的化学学科分支和有力“武器”,正在协助并推动化学和分析测试科学步入第四即“数据密集型”的科学新范式。该文以作者实验室的研究工作为基础,论述了化学计量学/信息学助力推动化学与分析测试科学研究范式的转换过程中的相关进展,并对未来的研究动向进行了展望。     

遗传算法在分析化学中的应用

遗传算法是基于自然界生物进化基本法进而发展起来的一类新算法，在优化过程中，它无需体系的选验知识，能在许多局部较优中找到全局最优点，是一种全局最优化方法，能有效地处理复杂的非线性问题，有广阔的发展前景，目前在分析化学领域已经有多方面应用，本文简要地介绍遗传算法的原理及其在分析化学等方面的若干应用。     

分析化学计量学

本文是《分析试验室》第四篇“分析化学计量”专题定期评述文章，对我国分析化学计量学领域在１９９５年１月至１９９６年１２月间的研究工作进行了较为全面的概括和评述，内容涉及统计学与统计方法，试验设计与优化，多元校正，分析信号处理，化学模式识别，模拟与数据库及人工智能等方面，收入文献２４２篇。     

一种新型在线近红外光谱分析仪的研制

研制了一种新型的电荷耦合器件(CCD)在线近红外光谱分析仪，它由光谱仪系统、电源电路与控制系统、光纤及其附件与流通池系统、防爆系统、样品前处理系统、模型界外样品抓样系统、实时光谱测量和化学计量学软件等部分组成。在兰州炼油厂联合重整装置上连续5个月的工业实验表明，该仪表测定汽油辛烷值的准确性为0．3个辛烷值单位，重复性为0．2个辛烷值单位，具有准确性高、稳定性好、测量速度快、安全性强、自动化程度高和分析测试项目扩展性宽等特点。该仪表可与APC技术或其它自动化系统联用，对石化等大型生产装置的技术进步将产生积极的推动作用。     

一种测定中药复方制剂中活性成分的计算分析方法

提出了一种测定中药复方制剂中活性成分含量的计算分析新方法。该方法将主 成分分析和广义秩消因子分析集成用于处理HPLC／DAD数据，并改进了传统的IND因 子指示函数，适用于定量计算分析复杂混和物体系中的待测成分。将其用于测定复 方丹参制剂中三七皂苷R1的含量，计算分析结果表明，本方法明显优于广义秩消因 子法，同时证明IND函数的改进提高了计算分析准确度。     

分析化学中的非线性校准

对分析化学中的非线性校准作了系统的讨论，对近年来分析化学中非线性及有关问题的方法和研究进展作了较全面的评述，各种非线性校准方法可不同程度地成功地用于解决非线性问题，迄今为止，人工神经网络（ＡＮＮ）被认为是解决非线性校准问题的最优方法之一。     

An Experimental Design for Simultaneous Determination of Carbendazim and Fenamiphos by Electrochemical Method

This study is aimed to develop an electroanalytical methodology using a boron‐doped diamond electrode (BDD) associated with experimental design in order to determine simultaneously and selectively carbendazin (CBZ) and fenamiphos (FNP) pesticides. In previous studies oxidation peaks were observed at 1.10 V (CBZ) and 1.20 V (FNP), respectively, with characteristics of irreversible processes controlled by diffusion of species (in pH 2.0 (CBZ) and pH 3.5 (FNP)) using a BR buffer 0.1 mol L^?1 as support electrolyte. The differences between the potentials for both pesticides, (about 100 mV) indicate the possibility of selective determination of FNP and CBZ. However, employing an equimolar mixture of analytes, the peaks overlap to form a single oxidation peak. Thus, we used a 3⁴ full factorial design with four parameters to be analyzed in three levels, in order to obtain the optimized parameters for the separation of the peaks. The best separation conditions were pH 5.0, square wave frequency of 300 s^?1, pulse amplitude of 10 mV and scan increment of 2 mV. These parameters were used to obtain the calibration curves of CBZ and FNP. For CBZ the analytical curve was obtained in the concentration range of 4.95×10^?6 to 6.90×10^?5 mol L^?1 with good sensitivity and linearity (0.175 A/mol L^?1 and 0.999, respectively). The limits of detection (LOD) and quantification (LOQ) were 1.6×10^?6 mol L^?1 and 5.5×10^?6 mol L^?1, respectively. For FNP the linear concentration interval was 4.95×10^?6 to 3.67×10^?5 mol L^?1, with a sensitivity of 0,207 A/mol L^?1 and linearity of 0.996. The LOD and LOQ were 4.1×10^?6 mol L^?1 and 13.7×10^?6 mol L^?1, respectively. Using these experimental conditions it was possible to separate the oxidation peaks of CBZ (E_p=1.08 V) and FNP (E_p=1.23 V). The electroanlytical method was applied in lemon juice samples. The recovery values were 110.0 % and 92.5 % for CBZ and FNP, respectively. The results showed that the developed method is suitable for application in foodstuff samples.