气相色谱-质谱联用(GC-MS)在纵火案件现场残留物分析中如何鉴别是否使用了汽油类加速剂?
How does gas chromatography–mass spectrometry (GC-MS) identify gasoline-type accelerants in debris samples from an arson scene?
火灾残渣通常先用顶空吸附或溶剂萃取富集挥发性组分,再经 GC 分离、MS 检测。汽油的鉴定不依赖单一化合物,而是识别其特征谱图模式:烷烃、环烷烃、芳烃(甲苯、二甲苯异构体、1,2,4-三甲苯等)及茚满系列的相对丰度分布构成指纹。将未知谱图与 ASTM E1618 标准分类和标准油样库比对,可给出类别级鉴定结论(如判定为汽油类);由于不同品牌油品配方相近且风化会改变组成,通常不作品牌级的同一认定。
Fire debris is typically enriched by headspace adsorption or solvent extraction, then separated by GC and detected by MS. Identification does not rest on a single compound but on characteristic pattern recognition: the relative abundances of alkanes, cycloalkanes, aromatics (toluene, xylene isomers, 1,2,4-trimethylbenzene) and the indane series form a fingerprint. Comparing unknown chromatograms against ASTM E1618 classifications and reference ignitable-liquid libraries supports class-level identification (e.g., gasoline); because commercial formulations are similar and weathering alters composition, brand-level attribution is generally not made.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
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ASTM E1618-19 Standard Test Method for Ignitable Liquid Residues by GC-MS
ASTM E1618-19, Standard Test Method for Ignitable Liquid Residues in Extracts of Fire Debris Samples by GC-MS
#法庭化学 #痕量加速剂检测
一氧化碳为什么无色无味却很致命？
Why is carbon monoxide colorless, odorless yet deadly?
CO与血红蛋白的结合力比氧强约200倍，抢占位置让血液运不了氧，人在不知不觉中缺氧昏迷。
CO binds hemoglobin about 200 times tighter than oxygen, so blood can't carry O2, causing silent hypoxia and coma.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
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武汉大学 主编,《分析化学》第6版,高等教育出版社
Wuhan University eds., Analytical Chemistry, 6th ed., Higher Education Press
#一氧化碳 #血红蛋白 #中毒
鲁米诺(luminol)检测血迹时,铁血红素中的什么成分催化其化学发光?该检测是否会被常见干扰物误导?
In luminol testing for bloodstains, which component of heme catalyzes the chemiluminescence, and can common substances interfere with the result?
血红素基团中的Fe^2+/Fe^3+铁离子在过氧化氢存在下催化鲁米诺氧化,产生激发态3-氨基邻苯二甲酸二价阴离子,退激时发射蓝紫色光。该方法灵敏度极高但并非血迹特异,漂白剂中的次氯酸盐以及铜、铁等某些金属离子也能触发类似发光。因此现场阳性结果只能作为筛查线索,仍需后续免疫层析或DNA确证。
The iron center of the heme group cycles between Fe2+ and Fe3+ and catalyzes oxidation of luminol by hydrogen peroxide, generating excited-state 3-aminophthalate dianion that emits blue-violet light on relaxation. Although extremely sensitive, the test is not specific for blood: hypochlorite from household bleach and certain metal ions such as copper can trigger similar glow. A positive scene test is therefore only presumptive and must be confirmed by immunoassay or DNA analysis.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
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Creamer等2003年发表于Luminescence的对鲁米诺血迹检测工业、生活与环境常见干扰物的系统实验研究(DOI: 10.1002/bio.723)
J. I. Creamer et al., A comprehensive experimental study of industrial, domestic and environmental interferences with the forensic luminol test for blood, Luminescence, 2003, 18 (DOI: 10.1002/bio.723)
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1002/bio.723：A comprehensive experimental
#化学发光 #推定试验