荧光光谱法鉴别棉纤维上的染料

棉纤维是法庭科学实验室中常见的微量物证之一。由于常用于棉纤维染色的染料种类较多,有直接染料、硫化染料、还原染料、冰染染料、活性染料等,所以在对棉纤维进行检验时,为了得到准确、可靠的结论,除应检验纤维的种类、形态外,还必须对棉纤维上的染料进行检验。曾有人用荧光光谱法对毛腈纤维上的染料和棉纤维上的还原染料进行了分析。本文采用荧光光谱法测定了红色、蓝色共30种棉纤维上的染料提取液,为纤维上染料的分析测定建立了一种灵敏度高,操作简便,快速的方法。     

碱催化裂解气相色谱法检测白色毛纤维的研究

本文利用气相色谱仪,配以CZ—100热丝裂解器和FID检测器,对25种白色毛纤维进行比对分析,系统考察了织物在使用过程中经过日晒、汗渍的侵蚀、皂洗的处理后,对碱催化裂解气相色谱法分析毛纤维的影响,达到鉴别不同厂家、产地以及不同生产工艺白色毛纤维的目的。此方法可靠、快速、有效、便于操作,为各类案件中同类白色毛纤维的鉴定提供了一种切实可行的方法。     

差示扫描量热法检验合成纤维

目的研究不同种类合成纤维以及不同厂家生产的同种类合成纤维的鉴别方法。方法应用功率补偿型差示扫描量热仪测定涤纶、腈纶、锦纶、丙纶、氨纶、氯纶等6种常见合成纤维和10个厂家生产的涤纶纤维的DSC曲线,并对热学参数进行计算和分析。结果涤纶、腈纶、锦纶、丙纶、氨纶、氯纶的DSC曲线明显不同,10个厂家生产的涤纶纤维的DSC曲线虽然非常相近,但对其熔融温度Tm、熔融峰顶温度Tmp、熔融焓变ΔHm、结晶温度Tc、结晶峰顶温度Tcp和结晶焓变ΔHc等热学参数的计算结果显示,10个涤纶纤维的参数并不完全相同。结论差示扫描量热法不但能对不同种类的合成纤维进行鉴别,也可区分不同厂家生产的同种类纤维,从而为案件侦破提供更为准确的方向、线索和证据。     

洁白不容玷污

洁白不容玷污驰原白色的呻吟人活世上，离不开“衣、食、住、行”，化学纤维发明之前，制衣的基本原料自然是棉花。时至今日，纯棉织品已呈卷土重来之势，即使化纤布料，混纺比例也越来越大。更何况医药用棉、材种用棉，尤其离不开纯而又纯的洁白棉花。棉花是神州大地的一...     

付立叶红外显微镜及其附件检验微量纤维

通过付立叶红外显微镜及其附件ATR、金刚石池对微量纤维进行检验,从而达到对微量或痕量纤维准确确定其种属和比对检验是否相同的目的,方法准确、快捷、可靠.     

显微激光拉曼光谱鉴别直接染料及其染色纤维

目的 研究显微激光拉曼光谱对直接染料及其染色纤维的鉴别.方法 使用显微激光拉曼光谱仪分别检验了9种直接蓝染料、6种直接黑染料和6种直接红染料及其染色的棉、苎麻和粘胶纤维.结果 当使用显微激光拉曼光谱仪检测直接染料时,514nm激光器的区分能力较强,且光谱基本不受荧光干扰;633nm和785nm激光器的区分能力相似,但较514nm激光器略弱,且光谱更易受到荧光干扰.当使用显微激光拉曼光谱仪检测染色纤维时,若染料本身拉曼光谱信号较强时,其染色纤维的拉曼光谱与染料基本一致;当染料本身拉曼光谱信号较弱且受荧光干扰时,其染色纤维的拉曼光谱受到更大荧光干扰;相同染料染色的不同纤维的拉曼光谱一致.结论 显微激光拉曼光谱是无损检验染料及其染色纤维的有效手段,染色纤维的拉曼光谱基本反映的是染料的拉曼信号.     

显微红外光谱仪与显微拉曼光谱仪对纺用无色单根纤维的检测

目的研究常见纺用单根无色纤维的有效鉴别方法。方法使用显微红外光谱仪、显微激光拉曼光谱仪研究7大类纺用单根无色纤维的分子光谱。结果显微红外光谱仪、显微激光拉曼光谱仪能有效区分包括棉、粘胶、羊毛、丝、聚酰胺、聚丙烯腈和聚酯在内的7种纤维,是检测单根纤维的有效手段。785nm激发光源是显微激光拉曼光谱仪研究这7类纤维的最佳波长。但由于纺用纤维生产过程的标准化,仅依据红外或者拉曼的峰位置区分同种类、不同产地纤维的效果一般。结论显微红外光谱仪、显微激光拉曼光谱仪是鉴别常见纺用单根无色纤维的有效方法。     

显微红外光谱仪与显微拉曼光谱仪对纺用无色单根纤维的检测

目的研究常见纺用单根无色纤维的有效鉴别方法。方法使用显微红外光谱仪、显微激光拉曼光谱仪研究7大类纺用单根无色纤维的分子光谱。结果显微红外光谱仪、显微激光拉曼光谱仪能有效区分包括棉、粘胶、羊毛、丝、聚酰胺、聚丙烯腈和聚酯在内的7种纤维,是检测单根纤维的有效手段。785nm激发光源是显微激光拉曼光谱仪研究这7类纤维的最佳波长。但由于纺用纤维生产过程的标准化,仅依据红外或者拉曼的峰位置区分同种类、不同产地纤维的效果一般。结论显微红外光谱仪、显微激光拉曼光谱仪是鉴别常见纺用单根无色纤维的有效方法。     

基于染色法两步检验近现代书刊纸纤维种类与制浆方法

目的 实现近现代书刊纸纤维使用种类以及制浆方法的准确识别。方法 通过两种染色剂对书刊纸纤维的染色观察结果进行两步检验分析，并对照原生纤维形态及特征细胞对各书刊纸所用纤维种类进行辨别，以得出各纸样中各类纤维原料组成及制浆方法。结果 相比于单一染色法检验，使用两种染色法两步检验得出的纤维种类及具体制浆方法结果更加全面具体，可以有效识别近现代书刊纸复杂样本。结论 此研究为书刊纸检验鉴定提供一种新的思路，为建立基于多特征融合的纸张鉴别分析方法奠定基础。     

纤维的红外光谱鉴别方法研究

对124例纤维样品进行红外光谱分析，研究了各种不同类型纤维的红外光谱特征峰。建立了常用纤维红外光谱图谱库。利用红外光谱对常用纤维进行光谱分析，是一种简便、快速、准确的鉴别方法。     

Single fiber analysis by internal reflection infrared microspectroscopy.

Attenuated total reflection (ATR) is a convenient mode for single fiber analysis by infrared microspectroscopy, particularly when transmission spectra are difficult to obtain or when surface preferenced sampling is desirable. Textile finishes such as spin finishes, anti-static finishes, and permanent press finishes are revealed by ATR techniques. Bicomponent fibers may be analyzed by a combination of ATR techniques, transmission techniques, and spectral subtraction.     

The Discrimination of Colored Acrylic,Cotton, and Wool Textile Fibers Using Micro‐Raman Spectroscopy. Part 1: In situ Detection and Characterization of Dyes

Raman spectroscopy has been applied to characterize fiber dyes and determine the discriminating ability of the method. Black, blue, and red acrylic, cotton, and wool samples were analyzed. Four excitation sources were used to obtain complementary responses in the case of fluorescent samples. Fibers that did not provide informative spectra using a given laser were usually detected using another wavelength. For any colored acrylic, the 633‐nm laser did not provide Raman information. The 514‐nm laser provided the highest discrimination for blue and black cotton, but half of the blue cottons produced noninformative spectra. The 830‐nm laser exhibited the highest discrimination for red cotton. Both visible lasers provided the highest discrimination for black and blue wool, and NIR lasers produced remarkable separation for red and black wool. This study shows that the discriminating ability of Raman spectroscopy depends on the fiber type, color, and the laser wavelength.     

Rapid and non-destructive differentiation of Shahtoosh from Pashmina/Cashmere wool using ATR FT-IR spectroscopy

Shahtoosh, the most expensive and sought-after wool in the illegal wildlife trade is obtained from the underfur of a critically endangered species-the Tibetan Antelope (Pantholops hodgsonii). It is often adulterated or mixed with the wool of Pashmina goat (Capra aegagrus hircus) for making shawls, scarves and other woolen articles to maximize the profit. The comparable fineness, color and texture, makes it a challenging task in wildlife forensics to differentiate them. In this study, an attempt has been made to differentiate 50 reference unprocessed underfur hairs from five individuals of each species using ATR FT-IR spectroscopy in combination with chemometric tools such as PCA, and PLS-DA. Results of PCA model demonstrated slight overlap and thus failed to distinguish hairs of these two species. Subsequently, PLS-DA model was employed, and also validation tests (external and blind testing) were carried out to ensure the predictive ability of the model, which resulted in 100% accuracy. The results of PLS-DA model exhibited complete differentiation between Shahtoosh, Pashmina and Angora (Oryctolagus cuniculus domesticus) wool used for external validation study with highly significant predictive ability (R-square value 0.99). This proof-of-concept study illustrates the potential of ATR FT-IR spectroscopy to complement current forensic microscopic and DNA based technique to analyze hair evidence in wildlife investigations owing to its rapid and non-destructive nature with high degree of confidence, and its ease-of-use with minimal to no sample preparation.     

Comparison of transmission and internal reflection infrared spectra of cocaine.

Comparing the infrared transmission spectrum of cocaine HCl to its attenuated total reflection (ATR) spectrum has raised questions about the use of ATR spectra for forensic drug analysis. Whenever infrared spectra are collected using different modes or sample preparation methods, small variations in peak intensity ratios or peak positions are possible. These variations in infrared spectra are small and do not interfere with qualitative analysis, but they can cause confusion when unrecognized as normal effects of the different spectroscopic techniques. Comparison of the absorption and ATR spectra of cocaine hydrochloride illustrates the type of differences that can be expected. These differences are explained by the fundamental differences in the collection techniques. For the best quantitative results, only spectra collected by the same technique should be compared.     

The analysis and comparison of blue wool fibre populations found at random on clothing.

Fifty-eight garments were taped and searched for mid to dark blue wool fibres. These were then removed from the tapings, mounted on slides and examined using a high-power microscope (400x). A total of 2,740 blue wool fibres were identified and visible range microspectrophotometry (MSP) was performed on them. Three hundred independent blue wool populations were identified on 56 of the 58 garments searched. The lack of control fibres meant the spectral range of each population was unknown. The number of populations may have been underestimated by grouping together the fibres that had broad single peaks and a lack of distinguishing features in the spectra. Although blue wool is considered to be a common fibre type, 300 unique spectral shapes were identified by the use of microspectrophotometry alone. This demonstrates that the dyes used in the dyeing of blue wool are variable. Showing that many different populations of blue wool occur on a range of garments should ensure that the forensic scientist does not underestimate or understate the strength of evidence in cases where blue wool is found. Hopefully this work will enlighten scientists and enable them to also assess the true value of their findings when other commonly occurring fibres are encountered.     

紫外导数光谱法与吸收光谱法的比较

作者通过导数光谱法与吸收光谱法的对比实验,归纳出导数光谱法不但具有吸收光谱法的一般优点,还具有以下特点;(1)高分辨率和灵敏度;(2)定性准确;(3)能精确测定λmax和“肩”峰的波长;(4)能消除背景干扰;(5)能分析混和样品。     

Advanced statistical analysis of Raman spectroscopic data for the identification of body fluid traces: Semen and blood mixtures

Conventional confirmatory biochemical tests used in the forensic analysis of body fluid traces found at a crime scene are destructive and not universal. Recently, we reported on the application of near-infrared (NIR) Raman microspectroscopy for non-destructive confirmatory identification of pure blood, saliva, semen, vaginal fluid and sweat. Here we expand the method to include dry mixtures of semen and blood. A classification algorithm was developed for differentiating pure body fluids and their mixtures. The classification methodology is based on an effective combination of Support Vector Machine (SVM) regression (data selection) and SVM Discriminant Analysis of preprocessed experimental Raman spectra collected using an automatic mapping of the sample. This extensive cross-validation of the obtained results demonstrated that the detection limit of the minor contributor is as low as a few percent. The developed methodology can be further expanded to any binary mixture of complex solutions, including but not limited to mixtures of other body fluids.     

红外光谱微量水平衰减全反射技术检验常见胶水的应用研究

目的建立无损快速检验胶水红外光谱法。方法利用红外光谱衰减全反射技术（ATR）对8种常见胶水样品进行光谱分析,根据出峰位置差异,对8种胶水样品进行鉴别,并建立相应的红外光谱数据库。结果不同类型的胶水其红外图谱有明显差异,而同一类胶水在某些波数区间也存在着一定的差异。结论利用红外光谱衰减全反射技术可以快速、准确、无损的检验鉴别胶水样品。     

Evaluation of Raman spectroscopy for the analysis of colored fibers: a collaborative study

A collaborative study on Raman spectroscopy was carried out by members of the ENFSI (European Network of Forensic Science Institutes) European Fibres Group (EFG) on three dyed fibers: two red acrylics and one red wool. Raman instruments from six different manufacturers were tested as well as nine different laser wavelengths ranging from blue (lambda = 458 nm) to near infrared-NIR (lambda = 1064 nm). This represents the largest comparison study of Raman analytical parameters carried out on identical fiber samples. For the chosen fiber and dye samples, red lasers (lambda = 633 and 685 nm) gave the poorest spectral quality whereas blue (458 nm), green (514 nm) and near infrared lasers (785, 830 and 1064 nm) provided average results. Blue (488 nm) and green lasers (532 nm) globally gave the best quality spectra. Fluorescence problems were often encountered with some of the excitation wavelengths and therefore a flexible Raman instrument equipped with different lasers can be recommended to measure forensic fiber samples. The instrument should also be equipped with a Raman microscope in order to be able to focus on a single fiber. This study shows that Raman spectroscopy usually enables the identification of the main dye present in a colored fiber; however, minor dye components are much more difficult to detect. SERRS (Surface Enhanced Resonance Raman Scattering) techniques give an improvement of the dye's spectral intensity but no spectral improvement was observed for the two red acrylic and red wool fibers tested.     

Identification of Different Forms of Cocaine and Substances Used in Adulteration Using Near‐infrared Raman Spectroscopy and Infrared Absorption Spectroscopy

Identification of cocaine and subsequent quantification immediately after seizure are problems for the police in developing countries such as Brazil. This work proposes a comparison between the Raman and FT‐IR techniques as methods to identify cocaine, the adulterants used to increase volume, and possible degradation products in samples seized by the police. Near‐infrared Raman spectra (785 nm excitation, 10 sec exposure time) and FT‐IR‐ATR spectra were obtained from different samples of street cocaine and some substances commonly used as adulterants. Freebase powder, hydrochloride powder, and crack rock can be distinguished by both Raman and FT‐IR spectroscopies, revealing differences in their chemical structure. Most of the samples showed characteristic peaks of degradation products such as benzoylecgonine and benzoic acid, and some presented evidence of adulteration with aluminum sulfate and sodium carbonate. Raman spectroscopy is better than FT‐IR for identifying benzoic acid and inorganic adulterants in cocaine.