固相微萃取与气相色谱仪联用技术在火场助燃剂检验中的应用

目的建立检验纵火案件现场燃烧残留物中助燃剂的一种方法。方法利用固相微萃取器吸附浓缩燃烧残留物中的挥发性气体,使用气相色谱仪对挥发性气体进行定性分析。结果固相微萃取与气相色谱仪联用能较好地对火场不同介质燃烧残留物中汽油、煤油、柴油等助燃剂进行种类认定。结论该方法简便易行。     

应用SPME—GC／MS／PFPD技术测定烃类及硫化物标记物鉴别汽油、煤油、柴油燃烧残留物

目的利用汽油、煤油、柴油等助燃剂中特殊的硫化合物类标记物,建立一种新型的火场助燃剂残留物分析方法。方法应用固相微萃取气质联用一脉冲火焰光度检测器（SPMBGC／MS／PFPD）技术同步测定烃类、芳香烃类及硫化合物类。结果确定了13种特征硫化合物。质谱烃类数据和PFPD硫化合物数据稳定,RSD％值分别≤0．75和≤1．29。结论该方法能对各种纵火现场助燃剂微量燃烧残留物进行有效鉴别。     

ATD—GC—MS法测定火场样品中痕量汽油燃烧残留物

目的为火场样品中痕量汽油残留物的检测建立一种简便、高灵敏度的检验方法和可靠的检验结果评判方法。方法用TenaxTA吸附管吸附富集火场样品中的汽油成分,然后用ATD—GC—MS法自动解吸和检测。通过模拟燃烧实验,探讨了检验结果的评判方法：根据样品的m／z（57＋85）、m/z（91＋105＋119）、m／z（117＋131）和m/z（128＋142＋156）四个质量色谱图与已知汽油作比较来对检验结果作评判。结果6组模拟燃烧实验中凡有汽油作助燃剂的样品．均检出汽油残留物成分。结论所建立的方法具有操作简便,检测灵敏度高,杂质干扰少,定性结论准确可靠等特点。可用于实际火场样品中痕量汽油残留物的检测。     

建立火场样品中汽油残留物ATD-GC-MS检验结果的评价方法

目的建立火场中汽油燃烧残留物ATD-GC-MS检验结果评价方法。方法将模拟燃烧样品用ATD-GC-MS法检验,检验结果通过对芳烃、烷烃、茚满、和萘系列的4个特征离子色谱图与已知汽油作比较,并利用向量夹角法计算样品与汽油色谱指纹图的相似度来对检验结果作评价。结果有汽油作助燃剂的模拟燃烧样品与汽油色谱指纹图的相似度一般大于90%,无汽油作助燃剂的样品则在60%以下。结论利用样品的4个特征离子色谱图与已知汽油作比较,并结合样品与汽油色谱指纹图相似度的计算,能对检验结果作出客观、可靠和准确的评价。     

火场样品中汽油与稀释剂燃烧残留物的区分方法探讨

目的探讨火场样品中汽油与稀释剂燃烧残留物的区分方法。方法样品用ATD—GC—MS法检验,检验结果通过对芳烃、烷烃、茚满、和萘系列的4个特征离子色谱图与已知汽油和稀释剂作比较,并结合向量夹角法计算样品与汽油色谱指纹图的相似度来区分汽油与稀释剂残留物。结果个别品种的稀释剂燃烧残留物与汽油很相似,但彼此有某些差别。结论使用本方法,一般能将汽油与稀释剂燃烧残留物区分开。     

血中汽油成分的SPME-GC/MS/MS法分析

<正> 汽油的主要成分是低分子量高挥发性的低碳烃和甲苯、二甲苯等烷基苯,以及一些芳香族化合物。在以汽油为助燃剂的火灾现场,往往能从烧死尸体的血液中检测到汽油和其在燃烧分解过程中产生的碳氢化     

Tenax GR吸附解析技术在火场汽油残留物提取检验中的应用研究

目的针对火灾现场常规提取检验方法操作复杂、容易导致汽油残留物有效成分丢失等问题,研究建立采用Tenax GR吸附解析技术简便、高效提取检验汽油残留物的方法。方法将Tenax GR吸附管放入相关检材中,密封后在60℃烘箱中加热1h,经热脱附仪解析后使用气质联用仪分析。结果Tenax GR吸附解析技术可以检验汽油残留物中特征组分,主要包括甲苯、二甲基苯、三甲基苯、四甲基苯、萘、甲基萘及茚满类化合物。该技术的检测限为0.25pL/mL,同时放入6根吸附管做稳定性实验,其相对标准偏差(RSD)为2.43%。该技术进行7、15、30、60、90d等不同阶段的保存实验,其相对偏差分别为6.3%、14.4%、8.7%、18.3%、11.6%。结论该技术操作方便、灵敏度高、稳定性好,适用于火灾现场中汽油残留物的提取检验。     

聚乙烯塑料制品燃烧残留物对柴油分析鉴定的影响

本文以聚乙烯（PE）塑料制品——保鲜膜和聚乙烯原料为研究对象，探究二者对纵火现场助燃剂柴油分析鉴定的影响。利用固相微萃取–气相色谱–质谱法（SPME-GC-MS）对本体、未完全燃烧、完全燃烧至自燃熄灭三种不同燃烧状态下的样品与柴油的特征谱图进行对比分析。通过聚乙烯原料和PE保鲜膜本体进行对比分析发现，二者所含主要成分基本相同，PE保鲜膜中含有的个别组分在聚乙烯原料中并未检测到，主要是由于PE保鲜膜在生产过程中加入了一些添加剂所致。未完全燃烧保鲜膜对柴油分析影响最大，当m/z=85、178、192、183时，二者含有相同的成分且分布规律也基本相同，但当提取离子m/z=83时，未完全燃烧保鲜膜样品中不含有与柴油相同的环烷烃。应用SPME-GC-MS技术可以将未完全燃烧保鲜膜与柴油区分开，该方法灵敏度高，分析速度快，适用于火场中助燃剂的分析。     

纵火现场中汽油、煤油和柴油残留物的ATD／GC／MS法检测

目的为火场中汽油、煤油和柴油残留物的检测建立一种简便、高灵敏度的ATD／GC／MS检验方法。方法采用Tenax TA吸附管吸附富集检材中的汽油、煤油和柴油成分。然后用美国PE公司的ATD／GC／MS仪器进行全自动的解吸和分析检测。结果检材中汽油、煤油和柴油的检测极限分别达0．05、0.2、0．2pL／mL。结论该方法具解吸和分析检测过程自动化。操作简便快捷，检测灵敏度高。杂质干扰少等特点，可用于实际火场皆汽油、煤油和柴油残留物的检测。     

SPME—GC／MS／MS法分析血中助燃剂残留物

目的探讨检验血中助燃剂残留物的分析方法。方法运用SPME(固相微萃取)技术,利用100μmPDMS萃取纤维,于室温条件下以顶空方式直接从血中萃取、浓缩挥发性碳氢化合物,用GC/MS/MS检测分析助燃剂。结果从检验的实际案例显示,可从0.1ml血中检出痕量的助燃剂。结论该方法操作时间短,检材用量少,分析结果较理想。     

Using Alkylate Components for Classifying Gasoline in Fire Debris Samples

The characteristic that discriminates gasoline from other ignitable liquids is that it contains high‐octane blending components. This study elaborates on the idea that the presence of gasoline in fire debris samples should be based on the detection of known high‐octane blending components. The potential of the high‐octane blending component alkylate as a characteristic feature for gasoline detection and identification in fire debris samples is explored. We have devised characteristic features for the detection of alkylate and verified the presence of alkylate in a large collection of gasoline samples from petrol stations in the Netherlands. Alkylate was detected in the vast majority of the samples. It is demonstrated that alkylate can be detected in fire debris samples that contain traces of gasoline by means of routine GC‐MS methods. Detection of alkylate, alongside other gasoline blend components, results in a more solid foundation for gasoline detection and identification in fire debris samples.     

A solid-phase microextraction method for the detection of ignitable liquids in fire debris

A solid-phase microextraction (SPME) procedure involving direct contact between the SPME fibers and the solid matrix and subsequent gas chromatography/mass spectrometric analysis for the detection of accelerants in fire debris is described. The extraction performances of six fibers (100 mum polydimethylsiloxane, 65 mum polydimethylsiloxane-divinylbenzene, 85 mum polyacrylate, 85 mum carboxen-polydimethylsiloxane, 70 mum Carbowax-divinylbenzene, and 50/30 mum divinylbenzene-Carboxen-polydimethylsiloxane) were investigated by directly immersing the fibers into gasoline, kerosene, and diesel fuel. For simulated fire debris, in the direct contact extraction method, the SPME fiber was kept in contact with the fire debris matrix during extraction by penetrating plastic bags wrapping the sample. This method gave comparable results to the headspace SPME method in the extraction of gasoline and kerosene, and gave an improved recovery of low-volatile components in the extraction of diesel fuel from fire debris. The results demonstrate that this procedure is suitable as a simple and rapid screening method for detecting ignitable liquids in fire debris packed in plastic bags.     

A method for forensic gasoline comparison in fire debris samples: A numerical likelihood ratio system

In many arson cases gasoline is used as a means to start the fire. In this paper results are presented for a likelihood-ratio (LR) system aimed at comparing gasoline traces from fire debris to a reference gasoline. The LR-system is able to deal with disturbing effects caused by burning and exposure to surroundings: pyrolysis products, preferential adsorption and evaporation. This paper focusses on the criminalistic and statistical aspects of the design of the LR-system, and presents results on performance of the LR-system. The details of trace gasoline recovery from fire debris will be presented in an accompanying paper.Validation and performance measures show that this system gives well-calibrated LRs for comparisons involving trace samples with a spread in quantity of gasoline, evaporation levels, and matrices that are typically encountered in casework. Rates of misleading evidence are less than 3.5%.We conclude that, despite limitations in experimental design, this LR-system can be useful to the comparison of gasoline profiles in casework practice.     

Comparison of gasolines using gas chromatography-mass spectrometry and target ion response

Gas chromatography-mass spectrometry was used to compare gasoline samples obtained from different sources based on the difference in amounts of certain components found in the headspace of gasoline using target response data. Many suspected arson cases involve comparing an ignitable liquid extracted from fire debris to a liquid found in a suspect's possession to determine if they could have had a common source. Various component ratios are proposed for determining if an unevaporated gasoline sample could have originated from the same source as an evaporated gasoline extracted from fire debris. Fifty and 75% evaporated gasoline samples were both found to contain similar ratios of certain components when compared with its unevaporated source gasoline. The results of the comparisons in this study demonstrate that for cases involving gasoline that has been evaporated up to 50% and extracted from pine, it is possible to eliminate comparison samples as originating from the same source. The results of the 75% comparisons suggest it may be possible to apply the same type of comparison to cases involving 75% evaporated gasoline.     

Progress Toward the Determination of Correct Classification Rates in Fire Debris Analysis II: Utilizing Soft Independent Modeling of Class Analogy (SIMCA)

A multistep classification scheme was used to detect and classify ignitable liquid residues in fire debris into the classes defined by the ASTM E1618‐10 standard method. The total ion spectra (TIS) of the samples were classified by soft independent modeling of class analogy (SIMCA) with cross‐validation and tested on fire debris. For detection of ignitable liquid residue, the true‐positive rate was 94.2% for cross‐validation and 79.1% for fire debris, with false‐positive rates of 5.1% and 8.9%, respectively. Evaluation of SIMCA classifications for fire debris relative to a reviewer's examination led to an increase in the true‐positive rate to 95.1%; however, the false‐positive rate also increased to 15.0%. The correct classification rates for assigning ignitable liquid residues into ASTM E1618‐10 classes were generally in the range of 80–90%, with the exception of gasoline samples, which were incorrectly classified as aromatic solvents following evaporative weathering in fire debris.     

GC/MS/MS时间编程在火灾现场助燃剂检测中的应用

运用Varian SATURN2000气质联用仪通过GC/MS、GC/MS/MS、时间编程 GC/MS/MS对汽油样品进行分析比对,发现利用时间编程GC/MS/MS,对检测火灾现场残留汽油效果很好,可彻底排除样品中基体的背景干扰,大大提高检测灵敏度;同时对混合助燃剂（汽油+煤油、汽油+柴油）进行了实验探索。