Rapid outdoor non‐destructive detection of organic minerals using a portable Raman spectrometer

Raman spectral signatures have been obtained for a series of organic minerals using a compact portable Raman instrument equipped with 785‐nm laser excitation. Well‐resolved Raman spectra of crystalline salts of carboxylic acids, whewellite and mellite, as well as of the aromatic mineral idrialite were recorded. For comparative purposes, an amorphous fossil resin, baltic amber, was also investigated. The results obtained confirm that portable Raman instruments can be considered as excellent tools for field geological applications, including the detection of organic minerals in the frame of outcrops of sedimentary rocks or coal beds. Organic minerals can be added to the list of established biomarkers, including porphyrins, hydrocarbons and organic acids, which are important for the study with regard to future exobiological missions such as the ESA ExoMars mission to detect the presence of extinct or extant life on Mars. Copyright © 2009 John Wiley & Sons, Ltd.     

Quantitative detection of adulterated olive oil by Raman spectroscopy and chemometrics

Commercially available extra virgin olive oils are often adulterated with some other cheaper edible oils with similar chemical compositions. A set of extra virgin olive oil samples adulterated with soybean oil, corn oil and sunflower seed oil were characterized by Raman spectra in the region 1000–1800 cm⁻¹. Based on the intensity of the Raman spectra with vibrational bands normalized by the band at 1441 cm⁻¹ (CH₂), external standard method (ESM) was employed for the quantitative analysis, which was compared with the results achieved by support vector machine (SVM) methods. By plotting the adulterant content of extra virgin olive oil versus its corresponding band intensity in the Raman spectrum at 1265 cm⁻¹, the calibration curve was obtained. Coefficient of determination (R²) of each curve was 0.9956, 0.9915 and 0.9905 for extra virgin olive oil samples adulterated with soybean oil, corn oil and sunflower seed oil, respectively. The mean absolute relative errors were calculated as 7.41, 7.78 and 9.45%, respectively, with ESM, while they were 5.10, 6.96 and 4.55, in the SVM model, respectively. The prediction accuracy shows that the ESM based on Raman spectroscopy is a promising technique for the authentication of extra virgin olive oil. The method also has the advantages of simplicity, time savings and non‐requirement of sample preprocessing; especially, a portable Raman system is suitable for on‐site testing and quality control in field applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Screening of textiles for contraband drugs using portable Raman spectroscopy and chemometrics

The impregnation of items of clothing with drugs of abuse that are then smuggled through airports and ports of entry is a growing problem for law enforcement. This work describes the application of portable Raman spectroscopic techniques for the analysis of a range of natural and artificial fibre items of clothing impregnated with drugs of abuse. Textile pieces were soaked with the solutions of the drugs then left overnight to dry prior to spectroscopic examination. The feasibility of detection of the characteristic Raman spectral bands in the presence of background matrix signals is demonstrated, even for dyed clothing. Definitive evidence for contamination of the items of clothing concerned can be acquired within 20–25 s, without any form of sample pre‐treatment or extraction being necessary. The feasibility of automatic spectral recognition of such illicit materials by Raman spectroscopy has been investigated by searching a database stored on the spectrometer computer and the use of principal component analysis. Copyright © 2014 John Wiley & Sons, Ltd.     

Fast detection of sulphate minerals (gypsum,anglesite, baryte) by a portable Raman spectrometer

Well‐resolved Raman spectra of gypsum, anglesite and baryte were detected using a portable Raman instrument (Ahura First Defender XL) in the laboratory and outdoor under atmospheric conditions. Spectra were obtained using a 785‐nm excitation. The portable spectrometers display generally lower spectral resolution compared with the laboratory confocal instrument but permit the fast, unambiguous detection of minerals under field conditions. Portable Raman instruments can be advocated as excellent tools for field geological, environmental as well as exobiological applications. A miniaturized Raman instrument will be included in the Pasteur analytical package of the ESA ExoMars mission and interesting research applications can now be proposed for in situ field planetary studies. Additionally, portable Raman instruments represent an ideal tool for demonstrating possible applications of Raman spectroscopic techniques outdoor. In geosciences this approach represents a new field which could completely change classical field work. Copyright © 2009 John Wiley & Sons, Ltd.     

Raman studies of Japanese art objects by a portable Raman spectrometer using liquid crystal tunable filters

Raman spectroscopic studies of a few Japanese art objects have been performed by using a portable Raman spectrometer constructed with liquid crystal tunable filters as dispersive elements. Interesting information has been obtained from the Raman spectra observed from ukiyo‐e's (Japanese woodblock prints) and their woodblocks. The performance data and the imaging capabilities of the constructed spectrometer are presented. Copyright © 2011 John Wiley & Sons, Ltd.     

Raman spectroscopic detection for liquid and solid targets using a spatial heterodyne spectrometer

Spatial heterodyne Raman spectroscopy (SHRS) is a new type of effective method for the analysis of structure and composition of liquid and solid targets with the characteristics of no moving parts, high spectral resolution, high optical throughput and large field of view. The technique is very suitable for detecting the targets from long distances or under the conditions with ambient light, which is essential for the exploration of planetary surface. In order to have a better understanding of the ability of SHRS for the detection of liquid and solid targets, a breadboard was designed, built and calibrated. Signal to noise was estimated at different integration time or laser power for carbon tetrachloride. Pure materials or materials contained in bottles were both tested. The mixture of organic liquids or inorganic solids were tested. In order to test the detection ability for natural targets, some composition‐unknown rocks and pebbles were tested. The results have shown that SHRS can meet the requirements for the detection of weak Raman signal scattered from artificial or natural targets. Standoff detection of sulfur from 5‐m or 10‐m distance without using any telescope or collimation optics was also tried to test the high optical throughput of SHRS. The potential feasibility of standoff detection has been proved. Copyright © 2015 John Wiley & Sons, Ltd.     

Application of portable Raman spectroscopy and benchtop spatially offset Raman spectroscopy to interrogate concealed biomaterials

In this paper, we demonstrate the ability of portable Raman spectroscopy and benchtop spatially offset Raman spectroscopy (SORS) techniques to rapidly identify real and fake ivory samples. Both techniques were able to identify exposed genuine from fake ivory samples. In contrast to conventional Raman spectroscopy, SORS was, in addition, able to identify ivory concealed by plastics, paints, varnishes and cloth. Application of the SORS technique allows the interrogation of biomaterial samples through materials in which conventional Raman spectroscopic instrumentation cannot penetrate. Copyright © 2009 John Wiley & Sons, Ltd.     

便携式拉曼光谱仪用于合成大麻素类物质快速定性分析探究

我国于2021年7月将合成大麻素类物质整类列入管制,在一线查缉现场对疑似合成大麻素样品进行快速定性分析是办案民警的迫切需求。研究系统考察了拉曼光谱对合成大麻素的整体区分能力,比较了四款手持式拉曼光谱仪分析实际缴获样品时的结果差异,探讨了制约拉曼光谱在一线查缉现场广泛应用的原因。ProTT-EZRaman-A7便携式拉曼光谱仪的整体性能介于台式拉曼和手持式拉曼之间,选用该仪器采集了90种合成大麻素对照品的拉曼光谱,并利用兼容性强的KnowItAll软件建立了90种合成大麻素通用拉曼光谱库。分析90种合成大麻素的拉曼光谱,结果表明,当不存在荧光干扰时,拉曼光谱可以区分所有合成大麻素物质,但对部分结构相差一个甲基、卤素原子等的结构类似物区分度欠佳。不同款拉曼光谱仪的性能差异大,为考察其原因,本研究选用了四款手持式拉曼光谱仪分别对120份实际缴获合成大麻素样品进行了测定,随后使用KnowItAll软件并选用包含90种合成大麻素的通用拉曼光谱库对每张光谱图进行谱库检索。四款手持式拉曼光谱仪的正确匹配率分别为71.7%, 68.3%, 46.7%和24.2%。抗荧光干扰能力和分辨率的不同是造成不同...     

基于拉曼特征峰的甲醇汽油甲醇含量测定

采用拉曼光谱分析技术定量分析甲醇汽油中的甲醇含量。首先,对采集到的原始拉曼光谱进行平滑除噪、荧光背景消除、标准归一化等预处理;其次,根据甲醇含量与拉曼光谱的相关性分析找出甲醇含量的特征点;最后,建立了基于拉曼特征峰的甲醇含量一元线性回归模型。针对实验室配制的19个甲醇汽油样本的实验结果表明,该方法准确、稳健、所需训练样本少,可以应用于甲醇汽油中甲醇含量的快速测定。     

In situ detection of cocaine hydrochloride in clothing impregnated with the drug using benchtop and portable Raman spectroscopy

This study describes the application of benchtop and portable Raman spectroscopy for the in situ detection of cocaine hydrochloride in clothing impregnated with the drug. Raman spectra were obtained from a set of undyed natural and synthetic fibres and dyed textiles impregnated with the drug. The spectra were collected using three Raman spectrometers: one benchtop dispersive spectrometer coupled to a fibre‐optic probe and two portable spectrometers. Despite the presence of some spectral bands arising from the natural and synthetic polymer and dyed textiles, the drug could be identified by its characteristic Raman bands. High‐quality spectra of the drug could be acquired in situ within seconds and without any sample preparation or alteration of the evidential material. A field‐portable Raman spectrometer is a reliable technique that can be used by emergency response teams to rapidly identify unknown samples. Copyright © 2009 John Wiley & Sons, Ltd.     

结合异常样本检测的汽油族组成拉曼光谱分析

汽油族组成不仅决定了汽油品质,同时直接关系到燃烧尾气对环境的影响。文章成功地将拉曼光谱分析技术应用于汽油族组成的定量分析。通过对校正集进行异常样本检测,剔除个别异常样本,有效地提高了偏最小二乘的模型精度,得到了较好的预测效果。芳烃含量、烯烃含量和氧含量的标准预测误差分别达到了0.23,0.52和0.143,其预测复相关系数分别达到了0.987,0.927和0.971。实验结果表明：采用拉曼光谱分析技术可以有效的解决汽油族组成的定量分析问题,其分析精度显著高于近红外光谱法与多维气相色谱法;同时也适用于汽油生产过程中的在线分析。     

激光拉曼光谱技术对氯代有机混合物的快速检测研究

为实现对有机物混合物的快速、无损检测,提出一种基于激光拉曼光谱技术的二维分析方法。研究结果表明,采用532 nm波长激光作为激发光源,观测到236.2,348.9,449.4,513.6 cm-1四条振动拉曼谱线,且这些谱线的强度比为6.4∶1.7∶9.4∶1.0,可确定四氯乙烯的存在。观测到707.5,1 087.9,1 175.8, 3 078.6 cm-1四条振动拉曼谱线,其强度比为9.6∶6.4∶1.0∶3.9,可确定氯苯的存在。即通过综合分析特征谱线及若干特征谱线的强度比,可快速判断有机混合溶液中某种物质的存在。在定量分析方面,采用多光谱分析结合最小二乘法拟合提高了测量的可靠性,所测样品浓度的准确率为98.4%。本研究为有机物混合物成分识别和浓度探测提供了一套可行的光谱测量方法,有着十分重要的应用前景。     

近红外激发荧光光谱与拉曼光谱快速鉴别马铃薯品种

马铃薯是世界上最重要的食物之一,快速无损的进行马铃薯品种鉴别对其在应用中更好的发挥品种优势具有重要作用。研究了以近红外荧光光谱和近红外拉曼光谱的土豆品种鉴别,并对两者进行了比较。实验采用3个品种共98个土豆样本,随机将其分成校正集(74个)和预测集(24个)。首先使用785nm近红外激光激发,采集所有样本的荧光和拉曼混合光谱,然后从混合光谱中分别提取荧光光谱和拉曼光谱,最后对荧光光谱和拉曼光谱进行偏最小二乘判别分析(PLS-DA),PLS-DA模型采用留一法和全交互验证。结果显示,荧光光谱与拉曼光谱都能够对三个马铃薯品种进行鉴别,其中荧光光谱的PLS-DA模型预测Favorita品种效果较好(灵敏度为1,特异性0.86,准确性0.92),但Diamant品种(灵敏度为0.75,特异性0.75,准确性0.75)和Granola品种(灵敏度为0.16,特异性0.89,准确性0.71)预测的效果较差,而拉曼光谱图很好的解释了马铃薯中的主要营养成分,基于拉曼光谱的PLSDA模型的预测效果(三个品种预测灵敏度,特异性,准确性均为1)比荧光光谱判别效果显著提高。     

Optofluidic Raman sensor for simultaneous detection of the toxicity and quality of alcoholic beverages

We report a chemometric prediction of the toxicity and quality of liquor using an optofluidic sensor based upon Waveguide Confined Raman Spectroscopy (WCRS). The WCRS sensor was used to record the Raman spectra, each obtained from a 20 µl sample of a given alcoholic beverage with and acquisition time of 20 s. This was used to predict, simultaneously, both the methanol concentration (toxicity) and ethanol concentration (quality), with an accuracy of 0.1% and 0.7% by volume, respectively, using a Partial Least Squares‐based chemometric model. The model sensor is shown to be capable of identifying toxic liquors, based on the test performed on different types of liquor samples. Copyright © 2013 John Wiley & Sons, Ltd.     

便携式拉曼光谱仪快速检测唾液中盐酸吡格列酮的含量

人体唾液与血液中的相应成分有着密切关系。利用唾液代替血液进行检测,可极大地缩短分析时间、减少检测限制、降低安全隐患等,因此在临床医学、毒品管控等方面均有重要意义。发展了便携式拉曼光谱仪利用表面增强拉曼光谱技术快速定量检测唾液中盐酸吡格列酮(口服降血糖药物)含量的方法。借助纳米金溶胶的表面增强拉曼散射效应,在激发光源波长为785 nm时,可以得到低浓度盐酸吡格列酮的高质量拉曼光谱图。同时,不同浓度盐酸吡格列酮表面增强拉曼光谱分析结果表明,该方法还可直接用于唾液中盐酸吡格列酮的定量检测。盐酸吡格列酮含量与其特征峰强度线性相关,相关系数为0.992 3,且最低检测浓度达10 μg·L-1。     

Quantitative analysis of essential oils from rosemary in virgin olive oil using Raman spectroscopy and chemometrics

In this work, virgin olive oil mixed with essential oils from rosemary has been analyzed by means of Raman spectroscopy. First of all, experimental design has been employed in order to define the Raman spectroscopy's parameters, final measuring conditions were: acquisition time of 30 s, five accumulations, and the intensity of the laser power at 75 mW. The Raman spectra were initially measured at full range (150–3000 cm⁻¹), but a narrower window assured faster accumulations and more accurate predictions. The calibration solutions of eucalyptol and camphor in olive oil were prepared following a central composite design and different spectra pre‐processing algorithms were evaluated. To conclude, essential oils obtained by means of Supercritical Fluid Extraction, Ultrasounds, and hydrodistillation were mixed with virgin olive oil and quantified with Raman spectroscopy. Predicted concentrations of the olive oil mixtures were compared with concentrations obtained for the same samples by a Comprehensive Two‐Dimensional Gas Chromatographic (GC × GC) method. Copyright © 2011 John Wiley & Sons, Ltd.     

傅里叶变换红外光谱和近红外傅里叶变换拉曼光谱法无损鉴定中国字画

利用傅里叶变换红外(FTIR)和近红外傅里叶变换拉曼(NIR FT-Raman)光谱法鉴定了中国字画,结果表明：与荧光光谱法相比,根据谱峰的强度和位置可更容易地将真伪字画区别开来。拉曼光谱和红外光谱相互印证,互相补充,在鉴定中具有快速、准确、操作简单、重复性好、不需对样品进行预处理的优点,适于珍贵字画的无损鉴定。     

基于等离激元增强拉曼光谱的便携式快速检测仪设计与实现

用于食品安全、环境污染、毒品、化学战剂检测等的现场快速检测要求检测设备便携、快速和准确。目前的常规实验室检测方法虽然能够实现准确检测,但是其实时性较差,无法满足现场快速检测的要求。因此,设计开发了基于等离激元增强拉曼光谱的便携式快速检测仪,能够实现对滥用添加剂、违禁食品添加剂、农药残余、毒品、化学战剂和环境水污染等大量有害物质的现场快速定性检测。该检测仪基于ARM嵌入式系统开发,编写了其操作交互界面和底层驱动程序,实现了拉曼光谱数据自动标定和特征谱图快速识别等算法。在仪器中搭建了检测物质拉曼光谱的标谱数据库,数据库根据检测科目进行分类,每种科目包含该类别的多种物质,每种物质均包含其高中低多种浓度的标准品和样本谱图。设计实现了大类科目的辨识比对算法和GPU硬件加速算法,实现了对某一类科目的所有物质的快速比对,与传统的纯CPU算法实现相比较,在辨识速度上提高了20倍以上。通过市场购买的功能饮料、违规葡萄酒与果汁等实际样品对所制备的样机仪器进行测试,测试结果符合预期,具有良好的灵敏度与重现性,满足了现场快速检测的要求。     

激光拉曼光谱对苯的低浓度探测研究

激光拉曼光谱技术是基于拉曼散射理论的检测技术,具有快速、无损、样品无需预处理等优点。运用激光拉曼光谱技术对苯的25种不同浓度的样品进行了研究,结果表明,在184.8g/L~0.264g/L浓度范围内,苯的振动拉曼光谱强度与其浓度呈线性关系,利用最小二乘法拟合得到线性相关系数R=0.99626,检出限为0.223g/L。     

Nasopharyngeal carcinoma detection by tissue smears using surface-enhanced Raman spectroscopy

Nasopharyngeal carcinoma is one of the most common malignant neoplasms in head and neck. In this work, surface-enhanced Raman spectroscopy technique was used to study the molecular differences between cancerous and noncancerous smear samples which were obtained after clinical biopsy by smearing the tissue on the slides. Principal component analysis combined with linear discriminant analysis provided a sensitivity of 79.4% and a specificity of 81.8% for differentiation between cancerous and noncancerous nasopharyngeal tissue smears. This work provides a good basis for the methodology of nasopharyngeal tissue smear based on surface-enhanced Raman spectroscopy technique and is worth further studying.