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...     

Identification and structural characterization of the synthetic cannabinoid 3-(1-adamantoyl)-1-pentylindole as an additive in 'herbal incense'

Since the end of 2010, more than 20 synthetic cannabimimetics have been identified in 'Spice' products, demonstrating the enormous dynamic in this field. In an effort to cope with the problem, many countries have already undertaken legal measures by putting some of these compounds under control. Nevertheless, once a number of compounds were scheduled, they were soon replaced by other synthetic cannabinoids. In this article, we report the identification of a new--and due to its substitution pattern rather uncommon--cannabimimetic found in several 'herbal incense' products. The GC-EI mass spectrum first led to misidentification as the alpha-methyl-derivative of JWH-250. However, since both substances show different retention indices, thin-layer chromatography was used to isolate the unknown compound. After application of nuclear magnetic resonance spectroscopy, high-resolution MS and GC-MS/MS techniques, the compound was identified as 3-(1-adamantoyl)-1-pentylindole, a derivative of JWH-018 carrying an adamantoyl moiety instead of a naphthoyl group. This finding supports that the listing of synthetic cannabinoids as prohibited substances triggers the appearance of compounds with uncommon substituents. Moreover, it emphasizes the necessity of being aware of the risk of misidentification when using techniques sometimes providing only limited structural information like GC-MS.     

Raman spectroscopy and security applications: the detection of explosives and precursors on clothing

This study describes the application of confocal Raman microscopy to the detection and identification of explosives and their precursors in situ on undyed natural and synthetic fibres and coloured textile specimens. Raman spectra were obtained from explosives particles trapped between the fibres of the specimens. The explosives pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT), and ammonium nitrate as well as the explosives precursors hexamethylenetetraamine (HMTA) and pentaerythritol were used in this study. Raman spectra were collected from explosives particles with maximum dimensions in the range 5–10 µm. Despite the presence of spectral bands arising from the natural and synthetic polymers and dyed textiles, the explosive substances could be identified by their characteristic Raman bands. Furthermore, Raman spectra were obtained from explosives particles trapped between highly fluorescent clothing fibres. Raman spectra of the explosive and explosive precursor substances on dyed and undyed clothing substrates were readily obtained in situ within 90 s without sample preparation and with no alteration of the evidential material. Copyright © 2009 John Wiley & Sons, Ltd.     

Formation of oligomeric alkenylperoxides during the oxidation of unsaturated fatty acids: an electrospray ionization tandem mass spectrometry study

This study reports the identification of oligomeric alkenylperoxides by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS(2)), during the oxidation of oleic, linoleic and linolenic acids with Fenton's (Fe(2+)/H(2)O(2)) and Fe(2+)/O(2) systems. The reactions were followed by ferrous oxidation-xylenol orange method together with GC-MS and GC-FID, allowing to observe that both oxidation systems are different in terms of hydroperoxide evolution, probably due to the presence of different intermediate reactive species: perferryl ion and OH(·) radical responsible for the decomposition of lipid hydroperoxides and formation of new compounds. The analysis of ESI-MS in the negative mode, obtained after oxidation of each fatty acid, confirmed the presence of the monomeric oxidation products together with other compounds at high mass region above m/z 550. These new ions were attributed to oligomeric structures, identified by the fragmentation pathways observed in the tandem mass spectra.     

Reliable Comparison of Electron Ionization Mass Spectra Recorded Under Identical Experimental Conditions

For the most reliable identification by means of electron ionization mass spectrometry, the full mass spectra of unknown compound and possible candidate should be recorded under identical experimental conditions and compared. The main problem is how to compare full mass spectra, which may contain a lot of peaks. We have proposed a new approach (based on using principal component analysis) for the reliable comparison of electron ionization mass spectra recorded under identical experimental conditions. Applicability of the approach has been demonstrated on the example of xylenol isomers.     

基于太赫兹谱分析中药材鉴别

中草药分析与鉴定对中草药质量控制意义重大,以飞秒激光为基础的太赫兹时域光谱技术(THz-TDS)是一种新型相干远红外光谱测量技术。为了研究基于太赫兹谱的中药材鉴别可行性,应用THz-TDS研究了室温下黄芪、当归、杜仲及三种掺杂的黄芪在0.2~2.2 THz范围内的光学特性,得到了对应的时域谱、频域谱和吸收谱。结果表明在此波段三种中草药的时域谱、频域谱及吸收谱存在显著差异;三种掺杂黄芪的频域谱、吸收谱虽相似但也有明显不同。利用太赫兹时域光谱技术鉴别中药材是可行的,它可为中草药质量控制提供一种新的方法。     

Direct screening of herbal blends for new synthetic cannabinoids by MALDI-TOF MS

Since 2004, a number of herbal blends containing different synthetic compounds mimicking the pharmacological activity of cannabinoids and displaying a high toxicological potential have appeared in the market. Their availability is mainly based on the so-called "e-commerce", being sold as legal alternatives to cannabis and cannabis derivatives. Although highly selective, sensitive, accurate, and quantitative methods based on GC-MS and LC-MS are available, they lack simplicity, rapidity, versatility and throughput, which are required for product monitoring. In this context, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) offers a simple and rapid operation with high throughput. Thus, the aim of the present work was to develop a MALDI-TOF MS method for the rapid qualitative direct analysis of herbal blend preparations for synthetic cannabinoids to be used as front screening of confiscated clandestine preparations. The sample preparation was limited to herbal blend leaves finely grinding in a mortar and loading onto the MALDI plate followed by addition of 2 μl of the matrix/surfactant mixture [α-cyano-4-hydroxy-cinnamic acid/cetyltrimethylammonium bromide (CTAB)]. After drying, the sample plate was introduced into the ion source for analysis. MALDI-TOF conditions were as follows: mass spectra were analyzed in the range m/z 150-550 by averaging the data from 50 laser shots and using an accelerating voltage of 20?kV. The described method was successfully applied to the screening of 31 commercial herbal blends, previously analyzed by GC-MS. Among the samples analyzed, 21 contained synthetic cannabinoids (namely JWH-018, JWH-073, JWH-081, JWH-250, JWH-210, JWH-019, and AM-694). All the results were in agreement with GC-MS, which was used as the reference technique.     

Transient demonstration of exciton behaviours in solid state cathodoluminescence under different driving voltage

In the solid state cathodoluminescence (SSCL), organic materials were excited by hot electrons accelerated in silicon oxide (SiO₂) layer under alternating current (AC). In this paper exciton behaviours were analysed by using transient spectra under different driving voltages. The threshold voltages of SSCL and exciton ionization were obtained from the transient spectra. The recombination radiation occurred when the driving voltage went beyond the threshold voltage of exciton ionization. From the transient spectrum of two kinds of luminescence (exciton emission and recombination radiation), it was demonstrated that recombination radiation should benefit from the exciton ionization.     

Analysis of sonolytic degradation products of azo dye Orange G using liquid chromatography-diode array detection-mass spectrometry

In this paper, seven new sonolytic degradation products of Orange G were found and identified using powerful analytical techniques such as liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS), tandem mass spectrometry (MS/MS), and liquid chromatography with diode-array detection (LC-DAD). Each technique provided complementary information for the degradation products identification. In order to resolve the MS and MS/MS spectra obtained, the separation conditions were optimized. Among them, Orange G was unambiguously identified based on its abundant [M-H](-) ion, [M+H](+) ion, ultra-violet and visible spectra, retention time, and tandem mass spectrometric analysis compared with an authentic standard. The seven new degradation products were tentatively identified based on ultra-violet and visible spectra, [M-H](-) ions, and tandem mass spectrometry. The neutral losses of SO(2), SO(3), N(2) and H(2)O for MS/MS spectra which appear to be characteristic of the negative ion mode were observed. Based on this by-product identification, a possible multi-step degradation scheme is proposed. The analysis results of degradation products reveal that the degradation mechanism proceeds via reductive cleavage of the azo linkage, as well as intermolecular dehydration and desulfonation due to the powerful oxidizing hydroxyl radicals as well as hydrogen radical.     

Analysis of 30 synthetic cannabinoids in serum by liquid chromatography-electrospray ionization tandem mass spectrometry after liquid-liquid extraction

The analysis of synthetic cannabinoids in human matrices is of particular importance in the fields of forensic and clinical toxicology since cannabis users partly shift to the consumption of 'herbal mixtures' as a legal alternative to cannabis products in order to circumvent drug testing. However, comprehensive methods covering the majority of synthetic cannabinoids already identified on the drug market are still lacking. In this article, we present a fully validated method for the analysis of 30 synthetic cannabinoids in human serum utilizing liquid-liquid extraction and liquid chromatography-electrospray ionization tandem mass spectrometry. The method proved to be suitable for the quantification of 27 substances. The limits of detection ranged from 0.01 to 2.0 ng/mL, whereas the lower limits of quantification were in the range from 0.1 to 2.0 ng/mL. The presented method was successfully applied to 833 authentic serum samples during routine analysis between August 2011 and January 2012. A total of 227 (27%) samples was tested positive for at least one of the following synthetic cannabinoids: JWH-018, JWH-019, JWH-073, JWH-081, JWH-122, JWH-200, JWH-203, JWH-210, JWH-307, AM-2201 and RCS-4. The most prevalent compounds in positive samples were JWH-210 (80%), JWH-122 (63%) as well as AM-2201 (29%). Median serum concentrations were all below 1.0 ng/mL. These findings demonstrate a significant shift of the market of synthetic cannabinoids towards substances featuring a higher CB(1) binding affinity and clearly emphasize that the analysis of synthetic cannabinoids in serum or blood samples requires highly sensitive analytical methods covering a wide spectrum of substances.     

N-邻羟基萘甲酰胺基-N′-苯基硫脲的合成及其对阴离子的识别

设计合成了3种N-邻羟基萘甲酰胺基-N′-苯基硫脲类化合物,通过核磁共振谱和质谱表征了其结构。应用吸收光谱和荧光光谱考察了在乙腈中其与F-、CH3CO2-、H2PO4-、HSO4-、Cl-和Br-等阴离子的相互作用。结果表明,该类主体分子与阴离子形成结合比为1∶1氢键配合物,通过改变萘环上酰基和羟基的相邻位置可调控识别作用的选择性,它们与阴离子作用分别在355、367nm和372nm出现最大吸收峰,荧光光谱显示它们对F-有突出的响应灵敏度,可选择性识别F-。     

甲烷电离特性的等离子体发射光谱法研究

应用等离子体发射光谱法,用CCD(charge coupled device)光栅光谱仪记录并标识了脉冲电晕甲烷等离子体370～1 100 nm的发射光谱,确定了常温常压下高纯甲烷(99.99%)经100 kV, 100 Hz脉冲高压电离后的产物为H,C+,CH,C,C₂,C₃, C₄,C₅和烃等。通过分析实验检测到的甲烷等离子体发射光谱,给出了甲烷经脉冲高压电离形成电晕等离子体的机理和自由基CH_n(n=3,2,1)、碳、烃等产物的电离途径。结果显示甲烷分子经高能电子非弹性碰撞后脱氢程度很高,大量氢原子及其离子和甲烷自由基在进一步被高能电子作用下合成了烯烃、炔烃、烷烃和高聚碳化物。实验所获得的脉冲甲烷等离子体发射光谱及其机理分析可为甲烷及其转化研究提供相关依据。     

两种常用合成抗氧化剂的拉曼光谱研究

随着社会的不断进步,食品工业得到快速发展,随之食品安全问题也层出不穷。由于合成抗氧化剂价格较低且对食品有较好的防腐保鲜作用,常被一些食品生产商过量添加在食品中,严重危及人们身心健康。因而,对于食品中合成抗氧化剂的检测研究是十分必要的。丁基羟基茴香醚(BHA)和叔丁基对苯二酚(TBHQ)是两种常见的合成抗氧化剂。实验上, 利用共聚焦显微拉曼光谱仪分别对BHA和TBHQ进行拉曼光谱检测,获得样品的拉曼散射谱。理论上,应用密度泛函理论DFT(B3LYP)的三参数混合方法及6-31G(d, p)基组对其进行空间结构优化并计算其拉曼光谱,给出了光谱强度图。将理论结果与实验结果进行对比发现,在50～4 000 cm-1范围内BHA及TBHQ分子拉曼特征明显且拉曼活性较强,其振动频率在实验上和理论上显示出较好的一致性。另外,给出了BHA和TBHQ分子的红外活性、拉曼活性以及各频率谱线对应的振动模式归属。结果表明,BHA和TBHQ分子的拉曼频移表征物质的特征结构,可以作为鉴定和识别的检测依据。该研究报道了抗氧化剂BHA和TBHQ的拉曼光谱,并对其理论机制进行分析,为拉曼光谱技术应用于食品添加剂研究领域提供了理论和实验依据。     

基于二维相关光谱分析的纯棉与丝光棉制品鉴别分析

纯棉与丝光棉制品是日常生活中常用的两种纤维制品,但是由于二者在物理结构和化学结构上非常相似,以至于使用一些简单的方法难以准确识别一部分纯棉与丝光棉制品。提出一种使用水含量作为扰动的二维相关光谱结合机器学习方法来对二者进行鉴别的新方法。共使用从专业机构获得的200个标准样本来设计实验对新方法进行验证,其中包括100个纯棉样本与100个丝光棉样本。对每一个样本,使用水含量作为扰动,分4次改变样本水含量并采集该水含量下样本的一维光谱,其中4次的水含量分别为20.20%,14.52%,7.77%与0%。根据四条不同的一维构造每一个样本的动态光谱,再通过二维相关算法来计算其同步二维相关光谱,从该同步二维相关光谱中使用移动窗口技术提取三组不同的分类特征,每组特征分别对应一个设计好的支持向量机(SVM)分类器。之后本文提出一种基于信息熵的多分类器融合方法,根据权值不同,将三个分类器融合为一个具有更优效果的强分类器。为了验证方法的准确性与有效性,设计了严谨的实验对方法进行验证。实验首先按照传统的从一维光谱中提取特征的方法对纯棉与丝光棉样本进行鉴别,使用两种样本各50个来进行分类模型建立,剩余的进行模型验证,分类效果最高只有76%。但是基于从二维相关光谱中提取的三组特征设计的三个支持向量机(SVM)分类器的准确率分别可以达到88%,90%,88%,最后根据提出的基于信息熵的多分类器信息融合方法将三个分类器进行融合同一可以得到92%的分类准确率,比三个基础分类器准确率都有提升。与从一维光谱中提取特征并设计分类器进行分别鉴别相比,从二维相关光谱中提取特征设计多个分类器并使用基于信息熵的多分类器信息融合方法进行分类鉴别具有更高的分类准确率。二维相关光谱将光谱信息扩展到更高的维度,将一维光谱中隐藏的折叠峰进行展开,因此具有更高的分类准确率。提出的方法是一种快速准确鉴别纯棉与丝光棉制品的新方法。     

Analysis of seized drugs using portable Raman spectroscopy in an airport environment—a proof of principle study

The rapid identification for drugs‐of‐abuse in airports is of critical importance. In this study we demonstrate the viability of Raman spectroscopy for the rapid identification of illicit substances in their containers in an airport environment. Raman spectra of drugs‐of‐abuse in situ were collected using portable Raman spectrometers; this technique offers distinct advantages to government agencies, first responders and forensic scientists working in the security field. We have demonstrated that the spectrometers are able to collect the spectra of suspect powders, including cocaine HCl and d‐amphetamine sulphate with unknown constituents rapidly and with a high degree of discrimination. Copyright © 2008 John Wiley & Sons, Ltd.     

香荆芥酚的荧光光谱和吸收光谱研究

研究了中药活性成分香荆芥酚(Carvacrol)的荧光光谱和吸收光谱,依据光谱数据测量了香荆芥酚的电离常数和荧光量子产率.在pH＜2.0时,香荆芥酚的荧光随溶液pH增大而增强;在pH2.0～8.0范围内,香荆芥酚有稳定的强荧光,最大激发波长为278 nm,最大发射波长为306 nm; pH＞8.0时荧光强度随pH的增大...     

Composition and Purity of Combinatorial Aryl Ether Collections Analyzed by Electrospray Mass Spectrometry

Electrospray mass spectrometry (ESI-MS), tandem massspectrometry and on-line RP-HPLC-ESI-MS were used toevaluate the composition and purity of three differentaryl ether mixtures consisting of 10 and 45 arylethers synthesized on solid support by Williamsonetherification. The libraries feature two potentialpharmacophores connected with three different spacersand serve as models for a detailed component analysis.Individual members of the library and by-products wereidentified rapidly and conveniently by product ionscans. Compound collections obtained by two differentsynthetic methods, the split/combine approach and thepremix method, showed different mass distributions inthe ESI-MS spectra. Some components were not detectedin direct ESI-MS measurements, but were found by MS/MSexperiments. Precursor ion and constant neutral lossscans allowed the identification of components withcommon structural features.     

中草药植物白光漫反射光谱研究

测定了 5 7种中草药植物的药用部分的白光漫反射光谱 ,与传统的紫外分光光度法及红外分光光度法相比 ,这种测定方法不用截取样品 ,可作无损检测 ,且测定过程简便。从测定结果发现 ,这些白光漫反射光谱都具有可作识别的特征峰 ,显然中草药的白光漫反射光谱可作为中草药鉴别的一种辅助方法。从测定的白光漫反射光谱中 ,还发现药用部分为地上部分的 (阳光下生长的 )在 6 5 0～ 6 90nm区间具有明显的大吸收峰 ,而药用部分为地下部分的或植物体内的 (不在阳光下生长的 ,如种子 )则没有 ,因此可利用某些中草药植物在 6 5 0～ 6 90nm区间的吸收特性用光控方法调控中草药的栽培生产 ,提高中草药的质量与产量。     

基于显微聚焦拉曼光谱技术的丹参产地鉴别研究

产地是影响中药材质量的重要因素,产地差异导致中药材质量参差不齐,为维护市场秩序,有必要建立中药材产地鉴别方法,以便更加精准地判别和分析中药材品质。以多产地临床大宗药材丹参为研究对象,收集不同产地丹参样品150份,采用显微聚焦拉曼光谱技术在无损条件下对每份丹参样品的每根药材表面随机扫描1～n次,求每份样品扫描1～n次的平均光谱。分析原始光谱数据发现丹参表面光谱信号同时包含了丹参酮类成分的拉曼光谱和杂质的荧光光谱,主要表现在特定波长范围内不同产地丹参存在各自的聚集区和丹参表面光谱信号强度明显弱于或强于丹参酮类对照品的拉曼光谱信号强度。对扫描1～n次的平均光谱数据进行预处理后运用偏最小二乘判别分析（PLS-DA）和随机森林分类算法[不筛选（RF）或筛选重要变量（RF-VS）]建立扫描1～n次的丹参产地分类模型。结果随机扫描1次所得最优模型训练集和测试集预测准确率分别为88%和87%,且对质量差和质量优的丹参样品区分准确率高达97%;随机扫描2次和3次所得最优模型训练集和测试集预测准确率均分别为89%和87%,结合模型运行效率和成本,选择随机扫描1次所得光谱,经一阶导数（1ST-D）预处理和RF-VS计算所得模型为丹参最终产地鉴别模型。综上,在无损伤条件下显微聚焦拉曼光谱技术能建立快速、准确的丹参产地鉴别预测模型,为该技术进一步用于贵细中药材的产地和真伪鉴别提供参考。     

一种皮革产品的红外无损检验

基于红外光谱法可以对不同形态物质进行结构分析,可对皮革产品进行定性分析。依据红外光谱谱带的数目、位置、形状和强度都随化合物不同而各不相同的特点,将牛皮革、羊皮革和聚氯乙烯（PVC）革的红外谱图进行比对和剖析,并用于皮革产品的检验。通过实验得出,利用红外方法可以快速对皮革产品进行红外无损检验。