Raman spectroscopy and microspectrophotometry of reactive dyes on cotton fibres: Analysis and detection limits

A collaborative study on Raman spectroscopy and microspectrophotometry (MSP) was carried out by members of the ENFSI (European Network of Forensic Science Institutes) European Fibres Group (EFG) on different dyed cotton fabrics. The detection limits of the two methods were tested on two cotton sets with a dye concentration ranging from 0.5 to 0.005% (w/w). This survey shows that it is possible to detect the presence of dye in fibres with concentrations below that detectable by the traditional methods of light microscopy and microspectrophotometry (MSP). The MSP detection limit for the dyes used in this study was found to be a concentration of 0.5% (w/w). At this concentration, the fibres appear colourless with light microscopy. Raman spectroscopy clearly shows a higher potential to detect concentrations of dyes as low as 0.05% for the yellow dye RY145 and 0.005% for the blue dye RB221. This detection limit was found to depend both on the chemical composition of the dye itself and on the analytical conditions, particularly the laser wavelength. Furthermore, analysis of binary mixtures of dyes showed that while the minor dye was detected at 1.5% (w/w) (30% of the total dye concentration) using microspectrophotometry, it was detected at a level as low as 0.05% (w/w) (10% of the total dye concentration) using Raman spectroscopy. This work also highlights the importance of a flexible Raman instrument equipped with several lasers at different wavelengths for the analysis of dyed fibres. The operator and the set up of the analytical conditions are also of prime importance in order to obtain high quality spectra. Changing the laser wavelength is important to detect different dyes in a mixture.     

Blocks of colour IV: the evidential value of blue and red cotton fibres.

Samples of blue and red cotton fibres were examined using light and fluorescence microscopy as well as UV/VIS microspectrophotometry and fluorescence microspectroscopy. The degree of fluorescence and spectral variation was recorded. Particular attention was paid to the recurrence of certain spectral patterns. The importance of spectral information in the UV range is emphasized again. Colour plays a critical role in the comparison of cotton fibres in forensic sciences. Normally, fibres producing spectral patterns that are frequently seen will tend to have a lower evidential value in criminal cases as the choice of putative sources is theoretically greater and vice versa. Besides black cotton, blue and red cotton fibres are very frequent in fibre casework. The very high discriminating power using a combination of light microscopy, fluorescence microscopy and UV/VIS microspectrophotometry shows that even blue and red cotton fibres can provide excellent evidence when involved in fibre transfer cases.     

快速溶剂萃取-气相色谱/质谱法分析血液中的4种滥用药物

目的 建立生物检材血液中滥用药物的快速溶剂萃取（ASE）方法.方法 通过优化快速溶剂萃取各参数,提取血液中的滥用药物进行GC/MS定性定量分析.结果 血液中美沙酮、可卡因、蒂巴因、海洛因4种滥用药物的平均回收率在87.8％～97.5％之间,滥用药物在0.4μg/mL～4.0μg/mL的浓度范围内线性良好.结论 该方法具有操作简便快捷,回收率高、重现性好等特点,可广泛应用于生物检材血液中滥用药物的检验鉴定.     

均匀设计法选择口红的最佳展开剂

目的用薄层色谱法鉴别口红，选择最佳展开剂，以达到理想的分离鉴别效果。方法利用数理统计中的均匀设计法和正交设计法安排实验，优选出薄层色谱法检验口红的最佳展开剂体系为二氧六环：正丁醇：水=12：5：0．5，并对49种口红样品进行了分析检验。结果该展开剂体系对口红的检验具有较好的分离效果。     

Solid phase micro extraction coupled with on-column GC/ECD for the post-blast analysis of organic explosives

Gas chromatographic analysis with electron capture detection is very sensitive to post-blast residues and useful for the determination of organic explosive molecules. But many compounds extracted from the matrices may interfere with the explosives. Using SPME, most interfering compounds are eliminated so the identification is easier. Another advantage of the technique is a low limit of detection. In this study, four different SPME fibers were tested to analyze the most common encountered organic explosives including nitro aromatics, nitramines and nitro-esters. Different parameters were tested (desorption time, agitation, ...) and a special device has been created to optimize the agitation. Direct desorption effect of the SPME fiber on the column compared to normal split-splitless injection is shown. In this way, the degradation of the most sensitive molecules is decreased. An application to a real case is also described in this paper.     

Photodegradation and laser desorption mass spectrometry for the characterization of dyes used in red pen inks

Photodegradation and laser desorption mass spectrometry (LDMS) is a powerful combination of methods capable of characterizing dyes found in pen inks. Rhodamine dyes in pens that contain red ink were analyzed directly from paper (no extraction step is necessary). Inks exposed to incandescent light form photodegradation products (compounds with lower molecular weights than that of the intact dye) and in some instances, photoproducts (compounds with higher molecular weights than that of the intact dye). The degradation products and photoproducts can be detected with LDMS, and the results can be used for dye identification. Advantages include: (1) the instrumental analysis takes less than a minute; (2) sample preparation is minimal; (3) LDMS is a minimally destructive technique; (4) incandescent light sources are inexpensive, safe to use, and readily available; and (5) isomeric dyes can be distinguished.     

New techniques for the identification of microscopic samples of textile fibres by infrared spectroscopy

Infrared spectroscopy has proved to be a very useful method for the routine identification of man-made textile fibres. This paper describes the way in which this technique can fit into casework procedure using two different preparative methods. Spectra can be recorded from samples of 3 μg down to less than 1 μg in weight.     

Identification of human hair stained with oxidation hair dyes by gas chromatographic-mass spectrometric analysis.

This paper describes the gas chromatographic-mass spectrometric (GCMS) analysis of oxidation hair dyes from human hair. Diamines from the dyes were directly extracted from the hair in basic solution and aminophenols were extracted after neutralization. Both extracts were derivatised with trifluoroacetic anhydride and analysed by GCMS. Five components of oxidation hair dyes namely, p-phenylenediamine, toluene-2,5-diamine, o-aminophenol, m-aminophenol and p-aminophenol were clearly identified, whilst no other compounds originating from the hair dyes were detected. The presence and relative amounts of these dye components from hair extracts may assist in the discrimination of human hair especially in cases involving forensic science.     

液相微萃取-气相色谱法检测尿液中三唑仑药物

目的建立液相微萃取与气相色谱联用技术快速分析尿液中三唑仑的方法。方法本方法考察了萃取溶剂、体积、萃取时间、萃取振荡速度等条件对液相微萃取的影响,优化的实验条件为:萃取溶剂为0.5ml三氯甲烷,萃取时间25min,振荡速度200r/min。结果采用本文所建立的方法,三唑仑回收率为88.0%~90.5%。结论实验结果表明该方法简便、快速、灵敏、消耗有机溶剂少,是尿液中三唑仑检测的一种有效方法。     

高效液相色谱法鉴别红色原子印油种类实验条件的选择

目的确定高效液相色谱法(HPLC)鉴别红色原子印油种类的实验条件。方法利用HPLC法对印油样品的提取剂、提取时间、纸张影响以及检测波长和流动相进行了测试。结果得到了样品的色谱图和定量分析数据。结论得到较佳实验条件。     

分子印迹固相萃取技术-液相色谱法测定鱼塘水中2甲4氯苯氧乙酸

目的建立分子印迹固相萃取技术对鱼塘水中2甲4氯苯氧乙酸进行提取和分析的方法。方法以2甲4氯分子印迹聚合物为固相萃取材料,对鱼塘水中2甲4氯进行分离提取,洗脱液直接进行液相色谱分析。结果鱼塘水中MCPA的提取率在80%以上,检出限0.040μg/mL,在0.2μg/mL～2.0μg/mL范围内线性关系良好。结论该方法的准确度和精密度较好,适合实际发生案件的检测分析。     

快速溶剂萃取-凝胶色谱净化-LC／MS／MS相结合测定血中的杀参毒素类农药

目的建立血中杀参毒素类农药残留的快速分析方法。方法取一定量的Al2O3放入萃取池中做吸附剂,通过快速溶剂萃取仪萃取血液中杀参毒素类农药,同时达到在线净化的效果,后运用凝胶色谱净化联用仪进一步净化浓缩到2ml,提取液经LC／MS／MS进行检验。结果杀虫双在1．2×10g／ml～1．2×10^-6g／ml范围内线性关系良好,检出限为0．04ppb,杀虫眯为1．2×10^-6g／ml～7．2×10g／ml,检出限为0．34ppm。2种杀参毒素农药的平均回收率为89％、90％,相对标准偏差为1．9％、3％。结论整个方法简便、快速、准确、重现性好、灵敏度高,杂质干扰少。     

Forensic discrimination of match heads by elemental analysis with inductively coupled plasma-atomic emission spectrometry

In arson and bombing cases, matches are often used as the ignition method. We have investigated the use of elemental analysis by inductively coupled plasma-atomic emission spectrometry to discriminate match heads used in arson cases. Six elements, magnesium, aluminum, calcium, iron, zinc, and barium, in match heads were detected after the match heads were dissolved in HNO3, and these elements were quantified in 8 wood stick matches and 5 paper stick matches by means of calibration curves prepared from standard sample solutions. Using this method, we were able to distinguish all the matches from one another both before and after combustion. The method has the potential to be very useful for resolving arson cases.     

Elemental analysis of soil samples for forensic purposes by inductively coupled plasma spectrometry--precision considerations

Major and trace elemental composition provides a powerful basis for forensic comparison of soils, sediments and rocks. However, it is important that the potential 'errors' associated with the procedures are fully understood and quantified, and that standard protocols are applied for sample preparation and analysis. This paper describes such a standard procedure and reports results both for instrumental measurement precision (repeatability) and overall 'method' precision (reproducibility). Results obtained both for certified reference materials and example soils show that the instrumental measurement precision (defined by the coefficient of variation, CV) for most elements is better than 2-3%. When different solutions were prepared from the same sample powder, and from different sub-sample powders prepared from the same parent sample, the CV increased to c. 5-6% for many elements. The largest variation was found in results for certified reference materials generated from 23 instrument runs over an 18 month period (mean CV=c. 11%). Some elements were more variable than others. W was found to be the most variable and the elements V, Cr, Co, Cu, Ni and Pb also showed higher than average variability. SiO2, CaO, Al2O3 and Fe2O3, Rb, Sr, La, Ce, Nd and Sm generally showed lower than average variability, and therefore provided the most reliable basis for inter-sample comparison. It is recommended that, whenever possible, samples relating to the same investigation should be analysed in the same sample run, or at least sequential runs.     

磁珠法自动化纯化现场检材DNA方法研究

目的利用TE-MAGS在TECAN工作站上结合磁珠试剂盒,建立自动化工作站批量纯化现场检材DNA的方法,并探讨其在法医物证检案中的应用。方法灵敏度测试:标准品使用0.1ng/μL 9947A,用200μL TES稀释制备DNA总量0.1ng~1ng共10种的标准样品,采用本文方法提取纯化,使用IdentifilerTM试剂盒扩增,用3130XL型测序仪检测,Gene Mapper ID-X分析,分析STR图谱质量;纯化能力测试:在1ng总量的标准样品中加入腐殖酸、血红素,采用本文方法提取纯化、扩增检测,分析STR图谱质量;实际案件应用对比:收集304份现场检材,分别采用本方法和硅珠法进行提取纯化,经扩增检测,统计对比两种提取纯化方法 STR分型成功率。结果灵敏度测试:0.1ng~0.2ng总量标准样品提取的DNA模板,扩增后可检测到部分基因座STR图谱,0.3ng~1ng总量标准样品提取的DNA模板,扩增后可以得到完整的STR图谱;纯化能力测试:对混合有一定浓度的腐殖酸、血红素的标准样品的提取产物检测图谱未见明显抑制;实际案件应用对比测试:304份现场检材工作站磁珠法检出成功率(50%)高于硅珠法(40.8%)。结论本文所建立的方法缓冲范围较大,回收率高,纯化能力强,提取产物STR分型成功率高,适合现场检材批量化DNA检验。     

固相萃取-气相色谱-质谱法检验人血浆中的右美托咪定

目的采用固相萃取结合气相色谱-质谱法(SPE-GC/MS)检验人血浆中盐酸右美托咪定。方法采用SPE提取血浆,用GC-MS/MS方法测定。结果盐酸右美托咪定在0.2μg/m L~5.0μg/m L范围内与峰面积呈现良好的线性关系(r2=0.999 1),检出限为20.0ng/m L,回收率为86.1%~91.5%,日内日间精密度均小于7.86%。结论本方法操作简单,结果准确,可以作为测定人血浆中右美托咪定的方法。     

DPX-GC/MS法分析尿液中新精神活性物质二苯基乙基哌啶

目的 建立一种枪头式分散固相微萃取-气相色谱质谱法,分析尿液中的二苯基乙基哌啶.方法 对影响萃取效果的吸附树脂种类、淋洗液种类、洗脱液种类和洗脱液用量进行优化考察.结果 在最佳实验条件下,尿液中二苯基乙基哌啶的线性范围为0.02～1.0 mg/L,相关系数r2>0.99,检出限为0.005mg/L,回收率在76.7％～...