近红外光谱分析技术的最新进展与展望

在过去的几十年,近红外光谱是发展最为迅速的分析技术之一。振动光谱基础理论、光谱仪器硬件和化学计量学是现代近红外光谱分析技术的3大支柱,近些年,近红外光谱技术在这3个方面均取得了显著进展。该文结合上述3个方面的应用研究情况,对近红外光谱分析技术的最新进展进行了综述,并对未来发展趋势进行了展望。     

ASD系列光谱仪带您进入光谱分析时代

随着科学技术的日新月异,近红外光谱分析技术已经走向实质性应用阶段。包括中国在内的世界上越来越多的仪器制造厂商和用户将目光转向了近红外光谱仪器市场,由此带来该市场年增长率超过30％的繁荣景象。美国ASD公司生产的近红外系列光谱仪恰在此时进人中国,她的到来,无疑为中国的近红外光谱仪器市场增添了一道靓丽的色彩。     

手持式X-荧光光谱仪在云南边境口岸进口矿产品快速检测中的应用

为在云南边境口岸充分应用快速检测技术,利用手持式X-荧光光谱仪对标准样品及进口矿产品进行了定性、半定量分析,确定了矿产品中各种元素成分及其含量,与标准样品认证值以及实验室化学分析法测定结果相比较,分析了手持式X-荧光光谱仪对矿产品中元素分析的准确性。结果显示：手持式X-荧光光谱仪能够快速检测元素含量,初步识别、判断矿石品质,可有效提高工作效率,为口岸检测进口矿产品工作提供参考。     

关于召开“全国第一届近红外光谱学术会议”的征文通知

中国分析测试协会和中国石油学会石油炼制分会拟于2006年11月8~10日在北京举办全国第一届近红外光谱学术会议。届时邀请近红外光谱分析专家学者和仪器专家作专题报告,并进行近红外光谱分析技术交流。热忱欢迎光谱学界专家教授及广大从事分析测试技术工作的科技人员踊跃撰稿,会议将编辑论文集,并推荐优秀论文在《分析测试学报》及《现代科学仪器》等杂志上发表。会议热烈邀请国内外仪器厂商前来展出近红外光谱仪以及其它各种分析仪器。征文内容如下:(1)近红外光谱基础理论研究;(2)近红外光谱分析技术国内外发展综述;(3)近红外光谱仪器新设计…     

近红外光谱快检技术在口岸安全监管领域的应用展望

近红外快速检测技术在全球范围内作为一项新兴的快速检测手段,已在农业、食品、饮料、石油、材料、制药、医学、动植物检疫及其工业化过程等领域得到了广泛应用。该文结合近红外光谱快速检测原理及其应用现状,针对口岸安全监管中的商品智能归类、材料成分快速鉴定、动植物产品快速检疫鉴定、商品装卸载过程的在线监测等需求,提出引入近红外光谱检测技术应用于口岸安全监管领域的设想,力求为实现口岸贸易安全与贸易便利化双重目标奠定科技基础,并给出了近红外在口岸安全监管研究方面的应用展望。     

近红外光谱分析技术在快速分析上的应用

简要介绍了近红外光谱的原理、特点,综述了近红外光谱在农业、食品、制药、石油化工、高分子等领域快速分析上的研究及应用现状,并对近红外光谱的应用前景进行了展望．     

近红外光谱用于过氧化氢含量的定量分析研究

用长波近红外光谱仪（傅里叶变换,InGaAs检测器）和短波近红外光谱仪（光栅分光,CCD检测器）对比研究了25％～30％过氧化氢水溶液中过氧化氢含量的定量分析方法。结果表明,应用短波近红外光谱结合长光程样品池对25％-30％过氧化氢水溶液样品中过氧化氢含量进行定量分析,可以显著减少过氧化氢分解对定量分析的干扰,使定量分析的准确度和重复性显著提高。短波近红外光谱定量分析模型RMSECV和RMSEP分别为0．06和0．05;长波近红外光谱定量分析模型RMSECV和RMSEP分别为0．10和0．09。     

近红外光谱用于中药质控前景广阔

近年来，近红外光谱技术的应用研究已从农产品的实用技术扩展到许多领域，如石油化工、高分子化工和基本有机化工、食品工业、纺织工业和制药工业及临床医学等领域。在药物分析领域中，近红外光谱不仅适用于分析药物的多种不同状态，还可用于不同类型的药品，如蛋白质、中草药、抗生素等的分析。近红外光谱更适用于对原料药纯度、包装材料等的分析与检测，以及生产工艺的监控。     

书刊征订

《现代近红外光谱分析技术》(第二版)新书出版近红外光谱是20世纪80年代中期才为人们所关注的一种新技术。该书系统地介绍了近红外光谱技术的概貌、近红外吸收光谱的基本原理、近红外光谱仪器、常用化学计量学方法及软件、定性与定量分析、在线过程分析技术,并重点介绍了该技术的最新进展和在石油化工领域的应用。该书可供从事分析化学、仪器分析、过程优化、化工和石油化工生产以及农业、食品、纺织、制药和环保等专业的广大科技工作者和大专院校有关师生阅读参考。《现代近红外光谱分析技术》由陆婉珍院士主编,中国石油化工出版社出版。欲…     

转动光谱学与微波光谱技术研究进展

转动光谱学是以量子力学为基础,研究分子、自由基,以及离子的转动光谱的基础科学,在天文观测以及大气成分监测等领域有着重要的应用。本文综述了转动光谱学的一些基本理论,两种傅里叶变换微波光谱仪的搭建原理,以及几种典型的微波光谱实例分析,并对微波光谱技术的未来发展做了展望。     

Complete quality analysis of commercial surface-active products by Fourier-transform near infrared spectroscopy

Using proper calibration data Fourier-transform near infrared spectroscopy is used for developing multivariate calibrations for different analytical determinations routinely used in the surfactants industry. Four products were studied: oleyl-cetyl alcohol polyethoxylated, cocamidopropyl betaine (CAPB), sodium lauryl sulfate (SLS) and nonylphenol polyethoxylated (NPEO). Calibrations for major as well as very low concentrated compounds were achieved and every model was validated through linearity, bias, accuracy and precision tests, showing good results and the viability of NIR spectroscopy as a full quality control method for this products. Duplicate and complete analysis on a single sample takes at most 3 min, requiring neither sample preparation nor the use of reagents. The analytical reference procedures involved in this work represent the typical ones used in the industry and the NIR method shows good results in the analysis of components with weight concentrations less than 1%.     

Construction of a Low Cost Photoacoustic Spectrometer for Characterization of Materials

During the past few years, another optical technique has been developed to study those materials, which cannot be studied, by the conventional transmission or reflection techniques. The present technique called Photoacoustic spectroscopy or PAS is different from the conventional techniques chiefly in that the interaction of the incident energy of the photons with the materials under investigation is studied not through subsequent detection and analysis of some of the photons, but rather through a direct measure of the energy absorbed by the material. The aim of this presentation is to highlight the construction of a simple Photoacoustic spectrometer which can easily be constructed even in high school and college laboratories with the available low cost but efficient components and use it for characterization of solid (opaque or transparent), liquid and gas samples under investigations. The essential parts of the photoacoustic spectrometer designed in the laboratory (MADURAI – PA SPECTROMETER), consists of three main components.The total cost comes around 900 Euros. It is an affordable cost for researchers working with paucity of funds and facilities and many constraints especially in the developing countries. In the next few years we aim to study material characterization using MADURAI –PA SPECTROMETER.     

Aromatic Fused [30] Heteroannulenes with NIR Absorption and NIR Emission: Synthesis,Characterization, and Excited‐State Dynamics

Two hitherto unknown planar aromatic [30] fused heterocyclic macrocycles (1.1.0.1.1.0), with NIR absorption in free‐base form and protonation‐induced enhanced NIR emission, have been synthesized from easy to make precursors. The induced correspondence of fusion on the macrocyclic structure, electronic absorption, and emission spectra have been highlighted.     

Near infra-red reflectance spectroscopic determination of metformin in tablets

A rapid and simple near infra red reflectance spectroscopic method was described for determination of anti-diabetic tablets. Partial least squares method was applied to the Savitsky-Golay smoothed first derivative spectral data revealed over wavelength range 1000-2500 nm from 11 different pulverized tablet batches in 2-mm quartz cell. The results were agreed well with those obtained by the official British Pharmacopoiea 1998 UV assay of metformin.     

Feasibility study for the use of near infrared spectroscopy in the qualitative and quantitative analysis of green tea, Camellia sinensis (L.)

This paper indicates the possibility to use near infrared spectroscopy (NIR) combined with PLS as a rapid method to estimate the quality of green tea. NIR is used to build calibration models to predict the content of caffeine, epigallocatechin gallate (EGCG) and epicatechin (EC) and for the prediction of the total antioxidant capacity of green tea. For the determination of the total antioxidant capacity, the trolox equivalent antioxidant capacity (TEAC) method is used. Until now, the prediction of the antioxidant capacity as such by use of NIR has not been reported. For caffeine and TEAC, models are build for the whole green tea leaves and also for the ground leaves. For the polyphenols (EGCG and EC), only models for the whole leaves are investigated. A partial least squares (PLS) algorithm is used to perform the calibration. To decide upon the number of PLS factors included in the PLS model, the model with the lowest root mean square error of cross-validation (RMSECV) for the training set is chosen. The correlation coefficient (r) between the predicted and the reference results for the test set is used as an evaluation parameter for the models: for the TEAC results r=0.90 for the model with the whole leaves, r=0.86 for the model with the powdered leaves are obtained. The caffeine prediction model has a correlation coefficient r=0.96 for the whole leaves and r=0.93 for the ground leaves. The correlation coefficient for the EGCG and the EC content models are, respectively 0.83 and 0.44.     

Preliminary evaluation of laser induced breakdown spectroscopy for slurry samples

Laser-induced breakdown spectroscopy (LIBS) was applied to the analysis of simulant slurry samples used in the vitrification process of liquid radioactive wastes. A spectroscopic analysis was performed by two different detection systems: Czerny-Turner spectrometer coupled with intensified diode array detector (IDAD) and an Echelle spectrometer with intensified charge coupled device (ICCD). For the Czerny-Turner detection system, the normalized intensity method, which is the normalization of the atomic emission intensity by the released whole plasma emission area intensity, was employed to improve the reproducibility of LIBS signals. The Echelle detection system showed a high efficiency in simultaneous multi-element detection and determination of the physical quantities of the simulant.     

Free-radical polymerization upon near-infrared light irradiation,merging photochemical and photothermal initiating methods

Polymerization of (meth)acrylate resins upon near-infrared (NIR) light remains a huge challenge. In this study, a new photoinduced method of polymerization of methacrylic monomers is presented, originally merging a photochemical and a photothermal pathway. A four-component system is proposed comprising an NIR dye combined with an iodonium salt, a phosphine, and a thermal initiator. A selection of dyes is suggested regarding electron transfer properties and/or light-to-heat conversion abilities. Several thermal initiators are studied: an alkoxyamine (BlocBuilder MA), an azo derivative, and a peroxide. For the first time, an NIR absorbing dye is used in photopolymerization using both its capacities of light-to-heat conversion and its ability to initiate an electron transfer reaction. Three wavelengths of irradiation will be presented here: 785, 940, and 1064 nm. These long wavelengths are challenging because the energy of photons is extremely low but these wavelengths offer significant advantages in term of light penetration (e.g., for the access to composites through photopolymerization processes). The different systems presented here exhibit high and rapid conversions of methacrylate functions. The underlying chemical mechanism will be fully depicted by real-time Fourier transform infrared spectroscopy and thermal imaging measurements. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 300–308     

Classification of biodiesel using NIR spectrometry and multivariate techniques

This article describes the classification of biodiesel samples using NIR spectroscopy and chemometric techniques. A total of 108 spectra of biodiesel samples were taken (being three samples each of four types of oil, cottonseed, sunflower, soybean and canola), from nine manufacturers. The measurements for each of the three samples were in the spectral region between 12,500 and 4000 cm⁻¹. The data were preprocessed by selecting a spectral range of 5000-4500 cm⁻¹, and then a Savitzky-Golay second-order polynomial was used with 21 data points to obtain second derivative spectra. Characterization of the biodiesel was done using chemometric models based on hierarchical cluster analysis (HCA), principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA) elaborated for each group of biodiesel samples (cotton, sunflower, soybean and canola). For the HCA and PCA, the formation of clusters for each group of biodiesel was observed, and SIMCA models were built using 18 spectral measurements for each type of biodiesel (training set), and nine spectral measurements to construct a classification set (except for the canola oil which used eight spectra). The SIMCA classifications obtained 100% accurate identifications. Using this strategy, it was feasible to classify biodiesel quickly and nondestructively without the need for various analytical determinations.     

Rapid Determination of Methyl Chloride in Ambient Air Samples by GC-MS

Abstract

The methyl chloride concentration distribution in the atmosphere is of importance to the discussion of potential ozone destruction by chlorine-catalyzed reactions in the stratosphere. A gas chromatographic-mass spectrometric technique for rapid measurement of methyl chloride in air samples is described. The procedure provides both better sensitivity and better precision than previously reported determinations of methyl chloride in air. Some representative data are presented to illustrate the use of the method.