使用质谱学识别物质的专家算法:在使用二进制分类模型的不同仪器上对可卡因的识别的应用
Samantha A Mehnert1,2, J Tyler Davidson1, Alexandra Adeoye1
1Department of Forensic and Investigative Science, West Virginia University, Morgantown, West Virginia 26506, United States.
概括
质谱的一般线性建模 (GLM) 能够在实验室中准确识别可卡因. 这种方法,EASI,比传统方法提供了更高的性能,在法医分析中实现了高的真阳性率和低的假阳性率.
科学领域:
- 法医化学 法医化学
- 分析化学 分析化学
- 频谱学是一种光谱学.
背景情况:
- 质谱分析对于法医科学中识别物质至关重要.
- 传统的光谱识别方法在准确性和错误报告方面可能受到限制.
- 一般线性建模 (GLM) 为光谱数据分析提供了潜在的进步.
研究的目的:
- 评估GLM在从质谱数据中识别可卡因的有效性.
- 将基于GLM的识别与传统方法的性能进行比较.
- 建立可靠的可卡因鉴定方法,在不同实验室中具有可报告的错误率.
主要方法:
- 使用了一套128个可卡因重复质谱的训练集,用于GLM建模.
- 将GLM模型应用于来自多个实验室的175个测试可卡因光谱和716个负光谱.
- 使用诸如平均绝对残余和NIST光谱相似度等指标评估光谱相似性.
- 将GLM预测与传统的示例/共识频谱方法进行比较.
主要成果:
- 使用GLM的EASI (基于实证的光谱信息分析) 在无监督模型中实现了>95%的真正阳性率和0%的假阳性率.
- 使用EASI预测的四个关键片段的丰度 (m/z 152, 198, 272, 303) 的监督二进制后勤回归模型获得了100%的准确性.
- 与传统的示例方法相比,基于GLM的EASI显示出更高的性能和更低的错误率.
- 作为一个监督的二进制分类器,EASI被证明比Mahalanobis距离更可靠.
结论:
- 质谱数据的GLM为法医环境中可卡因识别提供了强大而准确的方法.
- 该EASI方法显著改进了传统的光谱识别技术.
- 这种方法使得可报告错误率的特定和选择性识别成为可能,提高了法医可靠性.
相关概念视频
Mass Spectrometry: Complex Analysis
832
Mass spectrometry is an important technique for the identification of pure compounds. However, it has some limitations for the analysis of complex mixtures, often due to excessive fragmentation making the spectrum too complicated to decipher. Mass spectrometry can be combined with suitable separation methods in sequence, forming hyphenated methods, which are useful in the analysis of complex mixtures.
GC–MS is a powerful hyphenated method commonly used in forensics and environmental...
GC–MS is a powerful hyphenated method commonly used in forensics and environmental...
832
Mass Spectrum: Interpretation
1.3K
An unknown compound can be established by identifying the molecular ion peak in the mass spectrum. The molecular ion peak is often weak or absent due to the predominance of fragmentation in high-energy electron beams. In such cases, a low-energy electron beam can be used to scan the spectrum to enhance the intensity of the molecular ion peak. Additionally, chemical ionization, field ionization, and desorption ionization spectra are used to obtain a relatively intense molecular ion peak.
To...
To...
1.3K
Peptide Identification Using Tandem Mass Spectrometry
6.6K
Tandem mass spectrometry, also known as MS/MS or MS2, is an analytical technique that employs two mass analyzers. Essentially it is a series of mass spectrometers that helps isolate a particular biomolecule and then helps study its chemical properties.
This technique helps gather information regarding the protein from which the peptide was obtained and to study the peptides’ amino acid sequence. Identifying peptides from a complex mixture is an important component of the growing field of...
This technique helps gather information regarding the protein from which the peptide was obtained and to study the peptides’ amino acid sequence. Identifying peptides from a complex mixture is an important component of the growing field of...
6.6K
High-Resolution Mass Spectrometry (HRMS)
1.5K
The resolution of a mass spectrometer depends on the efficiency of separating ions with different ion masses. The mass of an atom is approximated to the sum of the masses of protons and neutrons inside, considering the masses of protons and neutrons as equal. However, the masses of the proton (1.6726 × 10−24 g) and neutron (1.6749 × 10−24 g) are not truly equal. There is a minor error in the expression of atomic masses relative to the simplest atom of hydrogen. For...
1.5K
NMR Spectroscopy and Mass Spectrometry of Aldehydes and Ketones
4.2K
In aldehydes, the hydrogen atom connected to the carbonyl carbon helps distinguish aldehydes from other carbonyl compounds using ¹H NMR spectroscopy. The closeness of aldehydic hydrogen to the electrophilic carbonyl carbon highly deshields the hydrogen atom causing its signal to appear around 10 ppm in the ¹H NMR spectra. α hydrogens split the aldehydic proton signal, which helps identify the number of α hydrogens in the molecule. For instance, one α hydrogen creates a...
4.2K
High-Performance Liquid Chromatography: Types of Detectors
631
The role of the detectors in High-Performance Liquid Chromatography (HPLC) is to analyze the solutes as they exit from the chromatographic column. The detector recognizes the solute's property and generates corresponding electrical signals, which are converted into a readable graph of the detector's response versus elution time called a chromatogram at the computer. There are several types of HPLC detectors, each with its own advantages and limitations, depending on the analyte...
631


