表层微量油漆颜色的统计分析

本文介绍一种采集油漆的新方法,即多元统计取样法。采用显微分光光度计测量表层油漆的颜色,得出统计平均值后计算总色差,结果准确,不受油漆层数的影响,减小了受检样品量、人为或非人为因素的影响,提高了微量油漆颜色检测的准确度。     

用显微分光光度法鉴别圆珠笔油迹的研究

本文借助显微分光光度计系统对几种“色觉”相似的蓝色圆珠笔油墨进行了色度学分析。结果表明,显微分光光度法能有效地鉴别条件等色的圆珠笔油墨。该法准确、可靠,且不破坏检材,对实际检案有重要的意义。     

显微分光光度法区分油漆样品的研究

本文采用色度学和统计分析的方法,对用显微分光光度法区分油漆样品进行了研究。     

刑事技术专业

本室现有专业人员9名,其中高级职称5名、中级职称4名。拥有国内外较先进的专业仪器设备,如VSC文检仪、语图仪、录像检验设备、显微分光光度计、压痕仪、红外分光光度计及各种专业显微镜等。     

显微光谱成像技术在汽车油漆截面检验中的应用

目的对汽车多层油漆的横截面进行分层和比对研究。方法运用显微光谱成像技术对收集的12个省市623个汽车漆片样本进行分层,并对截面结构相同或相似的油漆样本进行了区分。结果 623个油漆样本均可以分层,分析出漆层为两层及以上的油漆样本数占总数的87.26%;截面结构相同或相似的油漆样本能够多层同时区分。结论该方法具有科学及实用价值,检验结果可靠,可见光谱成像技术完全可运用拓展到微量物证的检验中。     

大鼠死后肝细胞核DNA的组织化学定量研究

推断死亡时间是法医学尸体检验须解决的重要问题之一。本实验用显微分光光度计定量测定了不同环境温度下（１０℃、２０℃、３０℃）大鼠死后不同时间肝细胞核ＤＮＡ平均含量，发现１０℃、２０℃、３０℃下大鼠死后肝细胞核ＤＮＡ含量与死亡时间呈负线性相关，其相关系数分别为—０．９９０５、—０．９８６３、—０．９７０２，且随环境温度升高ＤＮＡ含量的下降速度明显加快。作者认为ＤＮＡ组织化学定量技术可望成为推断死亡时间的新方法。     

损伤皮肤中组胺荧光显微定位定量与损伤时间推断的实验研究

本文应用显微荧光分光光度计法研究大白鼠皮肤创缘组织中组胺的分布和含量,并用甲苯胺蓝法观察创缘肥大细胞形态和数量的变化。结果发现,创缘真皮乳头层出现扩散的细胞外黄色荧光和肥大细胞脱颗粒现象为生前伤的重要特点;组胺荧光分布范围及增多的程度与损伤时间密切相关。从而为损伤时间推断提供了一种新的方法。     

硫靛反应检验氟乙酰胺的方法改进

目的改进和完善硫靛反应检验氟乙酰胺的方法。方法用紫外可见分光光度计和气质联用仪检测硫靛反应产物。结果紫外可见分光光度计和气质联用仪检测硫靛反应产物特异性强、灵敏度高。结论该方法解决了硫靛法检验氟乙酰胺准确性不强的问题。     

分光光度法检验尿中某些有机磷农药降解物——硝基苯酚

运用医学生化检验技术,有机磷农药的定量测定法,利用医用分光光度计及一般生化仪器,对尿液进行检测,获得符合理论要求的结果.     

显微分光光度法检验蓝黑墨水字迹形成时间的适用性研究

本文利用显微分光光度法对八种不同品牌的蓝黑墨水字迹随时间变化的规律进行了研究,目的是考察该方法在鉴定蓝黑墨水字迹形成时间方面的适用性。实验分析了自然老化条件下的蓝黑墨水字迹在300~700nm波长范围内的反射光谱曲线,并计算墨迹与纸张的色差(△E),考查了△E与字迹形成时间的相关性,结果表明利用显微分光光度法测定蓝黑墨水字迹形成时间具有一定可行性。     

Color analysis of apparently achromatic automotive paints by visible microspectrophotometry

Chromatic secondary pigments are utilized in achromatic automotive paints to create unique paint systems. These pigments may not be observable in reflected light; however, utilizing visible microspectrophotometry (MSP) discriminating data may be gathered. This study analyzed 160 apparently achromatic automotive paints via this technique for spectral evidence of secondary pigmentation. These results were compared with visual observations made via polarizing light microscopy. Positive spectral results were attained in approximately 25% of the black and gray/silver topcoat sample sets, whereas the white topcoat and gray undercoat set yielded no probative spectral data. The black sample set did yield several samples that produced spectral evidence of pigmentation when no visual chromatic data was observed. The results of this study suggest that paint analysis schemes should incorporate visible MSP for apparently achromatic black and gray/silver paint samples.     

Paint and tape: collection and storage of microtraces of paint in adhesive tape

The collection and preservation of microtrace evidence with the aid of an adhesive tape is a method of choice in forensic science. This technique is rapid and easy and allows the concentration of microtraces on a carrier, which facilitates further investigations in the laboratory. Adhesive tapes are currently used to secure microtraces of fibers and glass, but hardly for traces of automotive paint and other lacquers for fear of interference with the analysis of binders. A collection of automotive paint consisting of original and repair lacquers collected by tape has been evaluated. After various times of storage within the tape, these samples were compared with untreated references by microscope FT-IR and microspectrophotometry (MSP). Another set of paints was collected in 1984, stored within the tape until 1995, and examined the same way. About 170 layers of lacquer with various types of binder were examined. With the exception of one clear lacquer no difference between treated samples and references was detected. This small difference observed could be correlated to the exposure to xylene (extractant) and was not caused by the storage within the adhesive tape.     

An Examination of the Sequence of Intersecting Lines using Microspectrophotometry

The potential of microspectrophotometry as a technique to determine the sequence of intersecting lines was examined. The technique was used to determine the sequence of heterogeneous line intersections produced using inkpad, stamp‐pad ink and ballpoint pens, gel pens, fountain pens, laser and ink‐jet printers. The study was carried out with an assumption that the peak characteristics of spectra from the point of intersection should correspond to the peak characteristics of pure ink which was executed later. According to spectral reflectance curves, microspectrophotometry was possible to determine whether the ink was above or below the inkpad/stamp‐pad ink seals. In blind testing, microspectrophotometry technique results were directly compared to those obtained by five experienced forensic document examiners using optical microscopy regularly employed in casework. As the results obtained from the study were positive, microspectrophotometry technique was found to be very successful in determining the sequence of heterogeneous line intersections under some conditions.     

The discrimination of (non-denim) blue cotton

This study was conducted to determine the degree of discrimination obtained between non-denim blue cotton fibres using visible–UV range microspectrophotometry alone. To this end, samples of fibres were taken from 100, non-denim, blue cotton, outer garments, including t-shirts, trousers and jumpers and subjected to analysis by both visible and UV range microspectrophotometry. The results obtained from the samples of each garment were compared to determine if they ‘matched’ or not. From an initial visual comparison of the garments it was possible to subdivide the samples into two populations consisting of 73 ‘dark blue’ garments and 27 ‘mid-blue’ garments. It was found that of the 73 ‘dark blue’ garments, 22 distinct sub-populations could be distinguished using visible range MSP, this figure being increased to 43 when the analysis was extended into the UV range. In the case of the 27 ‘mid-blue’ garments, 9 distinct sub-populations were discriminated using visible range MSP, this figure being increased to 17 when the analysis was extended into the UV range. The discriminating power (i.e. the number of discriminated pairs divided by the number of possible pairs) of visible range microspectrophotometry was calculated as 0.89 for ‘mid-blue’ garments and 0.87 for ‘dark blue’ garments. Extending microspectrophotometry into the UV range increased discrimination by 7%, giving a discriminating power of 0.96 for both mid and dark blue cotton fibres which was similar to that reported by a previous study where this method was combined with light and fluorescence microscopy.Intra-garment variation was found to be negligible. The implications of this study for casework are discussed and a revised analytical pathway for the comparison of this fibre type/colour combination using microspectrophotometry as a primary screening tool, is proposed.     

激光剥蚀电感耦合等离子体质谱技术检测车辆油漆金属元素

目的建立车辆油漆的激光剥蚀电感耦合等离子体质谱（laser ablation inductively coupled plasma mass spectrometry,LA—ICP—MS）分析方法。方法对38种车辆油漆样品采用激光剥蚀,电感耦合等离子体质谱进行测定,通过各油漆样品本含有金属元素种类和金属元素响应相对比值的差异对油漆样品进行区分。结果38种样品中有30种可直接依据所含金属元素种类的差异进行对其进行区分,其余8种依据元素间响应值比值的差异进行区分,方法重现性良好,精密度（RSD）小于10％。结论所建立的LA—ICP—MS方法简便快速、精密度良好、对样品微损,适用于法庭科学对车辆油漆的检测。     

Direct identification of various copper phthalocyanine pigments in automotive paints and paint smears by laser desorption ionization mass spectrometry

Direct identification of copper phthalocyanine (CuPc) and chlorinated CuPcs in paints for discrimination between blue automobile paints by means of laser desorption mass spectrometry (LDMS) in the absence of a matrix is reported. The models consisted of eight commercially available CuPc pigments applied to a piece of plain white coating paper. The relationship between the peak intensity at m/z 575 of the CuPc, the number of pulsed laser shots, and laser power was compared to optimize laser abrasion. LDMS analysis of the model paints demonstrated that all characteristic components of the CuPc pigments in the paint films were in good agreement with those in the powder pigments. Further, the chlorinated CuPcs in the paint films could be distinguished. A quantity of 42 blue paint films, representing the paints used for painting Japanese domestic trucks, was examined by LDMS analysis. Results indicate that the paints can be classified into four categories based on the chlorinated CuPc components of the paints. Therefore, LDMS spectra of CuPc pigments would be useful for the identification of paints in forensic investigations. Herein, we report the successful identification of the CuPcs in a paint smear on the frame of a bicycle damaged in a hit-and-run accident, using the LDMS spectra.     

Experimental Research on Class Identification with a New Type of Erasable Gel Pens

A new type of erasable gel pen ink is becoming increasingly popular because of the modifiable characteristics for writing on documents. This study attempts to distinguish 12 types of blue and black erasable gel pens produced by mainstream stationery manufacturers using infrared (IR) visual analysis, Fourier transform infrared (FTIR) analysis, fluorescence analysis, and microspectrophotometry. The results demonstrate that IR visual, FTIR, and fluorescence analysis can be used to help distinguish each type of erasable gel ink. While microspectrophotometry can be used to effectively differentiate the blue gel inks in this study, there are limitations with respect to distinguishing black erasable gel pens. When these four optical analyses methods were used in combination, the gel inks could be accurately distinguished.     

The dye classification and discrimination of coloured polypropylene fibres

A sequential extraction and classification scheme for dyed polypropylene fibres is presented together with suitable thin-layer chromatography (TLC) systems for separating the extracted dyes.Pigment coloured polypropylene fibres are unaffected by solvents and are therefore characterised by microspectrophotometry.     

The use of indigo derivatives to dye denim material.

Recently, attention was again drawn to the use of microspectrophotometry to distinguish between fibres dyed with indigo and seven derivative dyes. Under normal circumstances, fibres dyed with indigo (Vat Blue 1 or CI Number 73000) are not included in fibre-transfer examinations as, being ubiquitous, they do not usually have any evidential value. Indigo substitutes are used for fashion dyeing. If their use is widespread, the assumption that all denim material is dyed with Vat Blue 1 may need revising. A positive finding might make it necessary to reconsider the use of certain denim fabrics as capable of providing target fibres. Fibres from 160 samples of denim articles in current use were examined by microspectrophotometry to determine whether either indigo derivative dyes, or other dyes, had been used instead of the traditional indigo.     

Stable isotope analysis of white paints and likelihood ratios

Architectural paints are commonly found as trace evidence at scenes of crime. Currently the most widely used technique for the analysis of architectural paints is Fourier Transformed Infra-Red Spectroscopy (FTIR). There are, however, limitations to the forensic analysis of white paints, and the ability to discriminate between samples.Isotope ratio mass spectrometry (IRMS) has been investigated as a potential tool for the analysis of architectural white paints, where no preparation of samples prior to analysis is required. When stable isotope profiles (SIPs) are compared, there appears to be no relationship between paints from the same manufacturer, or between paints of the same type. Unlike existing techniques, IRMS does not differentiate resin samples solely on the basis of modifier or oil-type, but exploits additional factors linked to samples such as geo-location where oils added to alkyd formulations were grown. In combination with the use of likelihood ratios, IRMS shows potential, with a false positive rate of 2.6% from a total of 1275 comparisons.