Analysis of oil-based ignitable liquid residues by GC–MS and DART–MS

IF 2.9 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry Pub Date : 2025-12-01 Epub Date: 2025-09-30 DOI:10.1016/j.forc.2025.100701

Wen Dong , Ngee Sing Chong , Qudus Ayodeji Thanni , Peter de Boves Harrington , Mengliang Zhang

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引用次数: 0

Abstract

Fatty acid-based ignitable liquids (ILs), such as biodiesels and bio-based lighter fluids, represent a growing class of accelerants with limited forensic characterization. In this study, we applied gas chromatography–mass spectrometry (GC–MS) and direct analysis in real time mass spectrometry (DART–MS) to analyze plant oil-derived IL residues on wood and fabric substrates. ILs were prepared from ten different plant oils, subjected to burning, and extracted from fire debris using the ASTM E1412 activated charcoal method. GC–MS analysis resolved characteristic fatty acid methyl esters (FAMEs) and identified diagnostic fragment ions (m/z 55, 67, 74, 79). The fragmentation patterns of unsaturated and saturated FAMEs were systematically examined and compared against experimental data and reference spectra from online databases, demonstrating strong agreement and validating the reliability of these ion ratios as qualitative indicators of FAME saturation. DART–MS enabled rapid confirmation of major unsaturated FAMEs through the detection of protonated molecular ions, offering complementary identification without chromatographic separation. Chemometric analysis using principal component analysis (PCA) and analysis of variance-PCA revealed that FAME profiles were strongly dependent on the IL sources and remained reliable across replicate preparations and synthesis conditions, while substrate and combustion effects were mitigated using targeted ion extraction. These findings demonstrate the practical casework relevance of combining GC–MS and DART–MS for the detection and classification of fatty acid–based ILs in fire debris, providing robust chemical evidence to support arson investigations and to guide the inclusion of these emerging accelerants in forensic ignitable-liquid classification schemes.

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油基可燃液体残留物的GC-MS和DART-MS分析

脂肪酸基可燃液体（ILs），如生物柴油和生物基打火机液体，代表了一类日益增长的促进剂，但法医鉴定有限。本研究采用气相色谱-质谱联用技术（GC-MS）和直接实时质谱联用技术（DART-MS）对木材和织物基质上的植物油源性IL残留进行了分析。从10种不同的植物油中制备il，经过燃烧，并使用ASTM E1412活性炭方法从火灾碎片中提取。GC-MS分析分离了特征脂肪酸甲酯（FAMEs），并鉴定了诊断片段离子（m/z 55、67、74、79）。系统地检查了不饱和和饱和FAMEs的碎片模式，并与在线数据库中的实验数据和参考光谱进行了比较，证明了这些离子比率作为FAME饱和度定性指标的一致性和可靠性。通过检测质子化分子离子，DART-MS能够快速确认主要不饱和fame，无需色谱分离即可进行互补鉴定。利用主成分分析（PCA）和方差分析（variance-PCA）进行的化学计量分析表明，FAME谱与IL源密切相关，并且在重复制备和合成条件下保持可靠，而底物和燃烧效应通过靶向离子提取得到缓解。这些发现证明了结合GC-MS和DART-MS对火灾残骸中脂肪酸基助燃剂的检测和分类的实际案例相关性，为支持纵火调查提供了强有力的化学证据，并指导将这些新兴助燃剂纳入法医可燃液体分类方案。

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来源期刊

Forensic Chemistry CHEMISTRY, ANALYTICAL-

CiteScore

5.70

自引率

14.80%

发文量

审稿时长

46 days

期刊介绍： Forensic Chemistry publishes high quality manuscripts focusing on the theory, research and application of any chemical science to forensic analysis. The scope of the journal includes fundamental advancements that result in a better understanding of the evidentiary significance derived from the physical and chemical analysis of materials. The scope of Forensic Chemistry will also include the application and or development of any molecular and atomic spectrochemical technique, electrochemical techniques, sensors, surface characterization techniques, mass spectrometry, nuclear magnetic resonance, chemometrics and statistics, and separation sciences (e.g. chromatography) that provide insight into the forensic analysis of materials. Evidential topics of interest to the journal include, but are not limited to, fingerprint analysis, drug analysis, ignitable liquid residue analysis, explosives detection and analysis, the characterization and comparison of trace evidence (glass, fibers, paints and polymers, tapes, soils and other materials), ink and paper analysis, gunshot residue analysis, synthetic pathways for drugs, toxicology and the analysis and chemistry associated with the components of fingermarks. The journal is particularly interested in receiving manuscripts that report advances in the forensic interpretation of chemical evidence. Technology Readiness Level: When submitting an article to Forensic Chemistry, all authors will be asked to self-assign a Technology Readiness Level (TRL) to their article. The purpose of the TRL system is to help readers understand the level of maturity of an idea or method, to help track the evolution of readiness of a given technique or method, and to help filter published articles by the expected ease of implementation in an operation setting within a crime lab.