双波长薄层色谱扫描仪刑侦与司法鉴定应用介绍

 

双波长薄层色谱扫描仪刑侦与司法鉴定应用介绍

技术原理

核心功能与实战价值

1. 宽谱段高精度光学系统，适配文件检验微量检材检测需求

    

   仪器光谱范围覆盖 190nm 至 700nm 的紫外 - 可见光全区域，提供超过 80 个可选波长点，采用全息光栅单色器实现精准分光，波长准确度控制在 ±1nm 以内，确保扫描数据的精准性；基线噪声低至≤±0.02Abs，背景漂移≤±0.5Abs，具备极高的检测灵敏度，哪怕是从文件上提取的纳克级微量墨水、印油样品，也能获取清晰的特征色谱图谱，完美适配文件检验中检材微量、不可破坏性取样的核心司法需求，彻底解决了传统检验手段对微量有色成分无法精准定量的行业痛点。
    
2. 双波长扫描核心技术，精准消除背景干扰保障数据可靠性

    

   仪器独有的双波长扫描模式，可针对待测组分的光谱特征，同步设置检测波长与参比波长，通过算法精准扣除薄层板背景吸收、斑点扩散、基底不均匀带来的系统误差，大幅提升复杂基质中微量组分的检测准确性，有效避免假阳性、假阴性结果。同时支持反射法、透射法、荧光法三种测量模式，可根据墨水、油墨、印泥、染料、化学残留物等不同性质的待测物质，灵活选择最优检测模式，全面覆盖文件检验领域各类有色物质、荧光防伪材料的检测需求，无检材适配盲区。
    
3. 标准化合规设计，从根源保障检测数据的司法证据效力

    

   仪器设计、性能与检定严格遵循国家相关计量技术规范，具备权威计量认证资质，检测流程与数据输出完全符合司法鉴定实验室质量管理体系要求；内置符合《中国药典》等国家标准的分析方法库，支持外标法、内标法、归一化法等国际通用定量分析方法，为司法鉴定提供了标准化、可追溯、可复现的分析路径。所有检测流程、原始图谱、定量数据均可全程存储、追溯、打印归档，检测结果具备完整的司法证据效力，可直接作为刑事、民事案件法庭诉讼的合法证据使用。
    
4. 自动化智能分析系统，提升实验室批量案件检验效率

    

   仪器配套专业薄层色谱工作站，基于 Windows 操作系统开发，操作界面贴合司法鉴定工作流程，自动化程度高。可实现扫描过程全自动控制、色谱峰自动寻峰、智能积分、基线自动校正，自动计算峰面积、峰高、相对保留值，自动绘制标准工作曲线、生成回归方程与相关系数；检测重复性误差 RSD≤2.0%，具备批量样品连续分析能力，可大幅降低人工操作误差，提升文件检验实验室批量案件的检验效率与数据一致性，完美适配公安刑事技术部门、司法鉴定机构日常高频次案件检验需求。
    
5. 高稳定性系统架构，保障长期运行的可靠性与数据重现性

    

   仪器核心部件包括氘灯 - 钨灯组合光源、全息光栅单色器、高精度 X-Y 电动移动平台均采用精密工业级设计，建立在成熟的质量管理体系之上，运行稳定可靠，保障仪器在长期高频次使用中的检测数据重现性，确保不同时间、不同操作人员对同一样品的检测结果高度一致，完全符合司法鉴定对检测设备长期稳定性的严苛要求。
    

刑事侦查与司法鉴定实战应用

1. 书写与印刷墨水成分同源比对，锁定添改写变造事实

    

   是合同诈骗、票据诈骗、虚假诉讼、借条伪造等案件中，添改写笔迹鉴定的核心技术手段。不同厂家、不同型号、不同批次的书写墨水、印刷油墨，其染料、颜料、溶剂、助剂的成分组成与配比存在本质差异，通过薄层色谱分离与双波长扫描，可获取墨水 / 油墨的专属特征色谱图谱与组分相对含量。通过对文件可疑添改写部位与原文书写部位的墨水进行比对分析，可精准判断二者是否为同一种类、同一批次墨水，是否为同一支笔书写，为认定文件添改写、变造事实提供直接的化学成分证据，解决了传统光学检验手段无法区分外观颜色一致但成分不同墨水的核心难题。
    
2. 印章印泥印油成分鉴定，辅助伪造印章印文识别

    

   针对伪造国家机关印章、公司企业印章、伪造票据等案件，可对可疑印文的印泥、印油进行微量提取与薄层色谱扫描分析，获取其特征成分图谱，与真实备案印章的印泥印油样本、不同厂家生产的印泥印油标准品进行比对，精准鉴别印泥印油的种类一致性，为识别伪造印章、虚假印文提供成分学支撑，同时可通过印泥印油的成分特征，锁定涉案印泥的生产厂家、批次，为案件侦查提供关键方向。
    
3. 变造文件与污损文件检验，揭露变造手法与化学残留

    

   针对经过化学消褪、刮擦、涂抹、掩盖处理的变造文件，可通过仪器对可疑处理区域进行微量提取与分析，检测残留的原始墨迹成分、消褪剂化学残留物，精准识别文件变造手法，哪怕是肉眼完全无法识别的微量消褪剂残留，也能实现精准定性；同时可对污损、浸泡、烧毁的文件残留墨迹进行成分分析，还原文件原始内容，为案件定性提供关键科学依据。
    
4. 防伪证件与有价证券真伪鉴别，打击制假售假犯罪

    

   针对伪造居民身份证、护照、银行票据、有价证券、人民币等案件，可通过仪器对证件、票据上的防伪油墨、特种荧光染料、安全印刷油墨进行成分分析，比对真品的防伪材料特征图谱，精准鉴别证件票据的真伪，为打击伪造变造居民身份证、伪造货币、伪造金融票证等犯罪提供技术支撑，同时可用于重大活动安保场景的证件防伪快速核验。
    
5. 微量物证成分分析，实现案件关联与物证溯源

    

   针对案发现场提取的文件、衣物上附着的微量有色颗粒、纤维染料、油漆碎片、农药 / 毒物残留物等微量物证，可通过薄层色谱分离与双波长扫描实现精准定性分析，获取其成分特征图谱，实现微量物证的种类认定与同源性比对，将涉案文件、嫌疑人、作案工具、案发现场进行精准关联，为刑事案件侦查提供关键线索，完善案件全链条证据体系。
    
6. 投毒、中毒案件毒物快速筛查，辅助案件定性

    

   针对投毒、不明原因中毒等案件，可对案发现场提取的剩余食物、呕吐物、容器残留物、生物检材中的常见毒物、农药、鼠药进行薄层色谱分离与扫描分析，实现毒物的快速定性筛查与半定量分析，为案件性质判定、侦查方向锁定、受害人救治提供快速、精准的技术支撑。
    

核心技术参数

实战应用案例

1. 某特大跨省虚假诉讼案中，原告提交了标称签署时间为 3 年前的借条作为核心证据，被告主张借条中借款金额、还款期限条款为原告事后添改写，双方对借条真实性产生重大争议。传统光学检验、文检仪检验仅发现可疑笔划的墨迹颜色存在肉眼难以分辨的细微差异，无法得出明确鉴定结论。司法鉴定人员使用本仪器，对借条可疑添改写部位与原文部位的墨迹进行微量提取，通过薄层色谱分离与双波长扫描分析，发现二者的染料组成、色谱峰相对保留值存在显著差异，明确二者并非同一种墨水书写，最终出具了借条存在添改写变造的司法鉴定意见。该意见被法庭全部采信，成功驳回原告诉讼请求，同时为公安机关追究其虚假诉讼刑事责任提供了核心科学证据。
2. 某系列伪造银行承兑汇票诈骗案中，犯罪团伙伪造了数十张巨额银行承兑汇票，票据的印刷、防伪特征仿真度极高，常规肉眼检验、光学检验难以精准识别真伪。司法鉴定人员通过本仪器，对涉案票据上的防伪油墨、印刷油墨进行成分分析，与真实银行承兑汇票的油墨特征图谱进行比对，发现涉案票据的防伪油墨成分、染料配比与真品存在本质差异，同时锁定了票据印刷油墨的种类与来源，为案件定性提供了关键依据。公安机关根据该线索顺线追查，成功打掉了这个跨省伪造金融票证、实施诈骗的犯罪团伙，涉案金额超 5 亿元。

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Application Introduction of the Dual-Wavelength Thin Layer Chromatography Scanner in Criminal Investigation and Forensic Identification

Technical Principle

Core Functions and Practical Value

1. Wide-Spectrum High-Precision Optical System, Adapting to the Detection Demand of Trace Specimens in Questioned Document Examination

    

   The spectral range of the instrument covers the full ultraviolet-visible region from 190nm to 700nm, providing more than 80 optional wavelength points. It adopts holographic grating monochromator to realize accurate light splitting, and the wavelength accuracy is controlled within ±1nm to ensure the accuracy of scanning data. The baseline noise is as low as ≤±0.02Abs, and the background drift is ≤±0.5Abs, with extremely high detection sensitivity. Even for nanogram-level trace ink and stamp pad ink samples extracted from documents, clear characteristic chromatographic maps can be obtained, which perfectly adapts to the core judicial demand of micro and non-destructive sampling of specimens in questioned document examination, and completely solves the industry pain point that traditional inspection methods cannot accurately quantify trace colored components.
    
2. Dual-Wavelength Scanning Core Technology, Accurately Eliminating Background Interference and Ensuring Data Reliability

    

   The unique dual-wavelength scanning mode of the instrument can set the detection wavelength and reference wavelength synchronously according to the spectral characteristics of the component to be measured, and accurately deduct the system error caused by background absorption of the thin layer plate, spot diffusion and uneven substrate through the algorithm, which greatly improves the detection accuracy of trace components in complex matrix, and effectively avoids false positive and false negative results. At the same time, it supports three measurement modes: reflection method, transmission method and fluorescence method. According to the different properties of the substances to be measured such as ink, printing ink, stamp pad ink, dye and chemical residues, the optimal detection mode can be flexibly selected, which fully covers the detection needs of various colored substances and fluorescent anti-counterfeiting materials in the field of questioned document examination, with no specimen adaptation blind area.
    
3. Standardized Compliance Design, Ensuring the Judicial Evidence Validity of Test Data from the Source

    

   The design, performance and verification of the instrument strictly comply with the relevant national metrological technical specifications, and have authoritative metrological certification qualifications. The detection process and data output fully meet the requirements of the quality management system of forensic identification laboratories. It has a built-in analysis method library that complies with national standards such as the Pharmacopoeia of the People's Republic of China, and supports international general quantitative analysis methods such as external standard method, internal standard method and normalization method, providing a standardized, traceable and reproducible analysis path for forensic identification. All detection processes, original maps and quantitative data can be stored, traced, printed and archived throughout the process. The test results have complete judicial evidence validity and can be directly used as legal evidence for court litigation in criminal and civil cases.
    
4. Automatic Intelligent Analysis System, Improving the Inspection Efficiency of Batch Cases in the Laboratory

    

   The instrument is equipped with a professional thin layer chromatography workstation, developed based on the Windows operating system, and the operation interface fits the work flow of forensic identification with a high degree of automation. It can realize full automatic control of the scanning process, automatic peak finding of chromatographic peaks, intelligent integration, and automatic baseline correction, and automatically calculate the peak area, peak height, relative retention value, automatically draw the standard working curve, and generate the regression equation and correlation coefficient. The detection repeatability error RSD is ≤2.0%, and it has the continuous analysis capacity of batch samples, which can greatly reduce the manual operation error, improve the inspection efficiency and data consistency of batch cases in the questioned document examination laboratory, and perfectly adapt to the daily high-frequency case inspection needs of public security criminal technology departments and forensic institutions.
    
5. High-Stability System Architecture, Ensuring the Reliability of Long-Term Operation and Data Reproducibility

    

   The core components of the instrument, including the deuterium lamp-tungsten lamp combined light source, holographic grating monochromator, and high-precision X-Y electric moving platform, adopt precision industrial grade design, built on a mature quality management system, with stable and reliable operation, ensuring the reproducibility of detection data of the instrument in long-term high-frequency use, and ensuring that the test results of the same sample by different operators at different times are highly consistent, which fully meets the strict requirements of forensic identification for the long-term stability of testing equipment.
    

Practical Application in Criminal Investigation and Forensic Identification

1. Homology Comparison of Writing and Printing Ink Components, Locking the Fact of Added and Altered Writing

    

   It is the core technical means for the identification of added and altered handwriting in cases such as contract fraud, bill fraud, false litigation, and IOU forgery. Writing inks and printing inks of different manufacturers, different models and different batches have essential differences in the composition and ratio of dyes, pigments, solvents and additives. Through thin layer chromatography separation and dual-wavelength scanning, the exclusive characteristic chromatographic map and relative component content of the ink/printing ink can be obtained. By comparing and analyzing the ink of the suspicious added and altered parts of the document with the ink of the original writing part, it can accurately judge whether the two are the same type and the same batch of ink, and whether they are written by the same pen, providing direct chemical composition evidence for determining the fact of document addition, alteration and tampering, and solving the core problem that traditional optical inspection methods cannot distinguish inks with the same appearance color but different components.
    
2. Component Identification of Stamp Pad Ink, Assisting in the Identification of Forged Seal Impressions

    

   For cases involving forgery of state organ seals, company and enterprise seals, and forged bills, trace extraction and thin layer chromatography scanning analysis can be carried out on the stamp pad ink of suspicious seal impressions, to obtain its characteristic component map, and compare it with the stamp pad ink samples of real registered seals and the standard products of stamp pad inks produced by different manufacturers, to accurately identify the consistency of the type of stamp pad ink, provide component support for identifying forged seals and false seal impressions, and at the same time, lock the manufacturer and batch of the involved stamp pad ink through the component characteristics of the stamp pad ink, providing a key direction for case investigation.
    
3. Inspection of Altered and Defaced Documents, Exposing Alteration Methods and Chemical Residues

    

   For altered documents processed by chemical erasure, scraping, smearing and covering, the instrument can be used for trace extraction and analysis of the suspicious processing area, to detect the residual original ink components and erasing agent chemical residues, and accurately identify the document alteration method. Even the trace erasing agent residues that are completely unrecognizable by the naked eye can be accurately qualitatively identified. At the same time, it can analyze the composition of residual ink of defaced, soaked and burned documents, restore the original content of the document, and provide key scientific basis for case characterization.
    
4. Authenticity Identification of Anti-Counterfeiting Certificates and Securities, Combating Counterfeiting and Selling Fake Crimes

    

   For cases of forging resident identity cards, passports, bank bills, securities, RMB, etc., the instrument can be used to analyze the composition of anti-counterfeiting inks and special fluorescent dyes on certificates and bills, compare the characteristic maps of anti-counterfeiting materials of genuine products, accurately identify the authenticity of certificates and bills, provide technical support for combating crimes such as forgery and alteration of resident identity cards, counterfeiting of currency, and forgery of financial bills, and can also be used for rapid anti-counterfeiting verification of certificates in major event security scenarios.
    
5. Component Analysis of Trace Evidence, Realizing Case Correlation and Physical Evidence Traceability

    

   For trace physical evidence such as trace colored particles, fiber dyes, paint fragments, pesticide/poison residues attached to documents and clothes extracted from the crime scene, thin layer chromatography separation and dual-wavelength scanning can be used to achieve accurate qualitative analysis, obtain its component characteristic map, realize the type identification and homology comparison of trace physical evidence, accurately correlate the involved documents, suspects, murder weapons and crime scene, provide key clues for criminal case investigation, and improve the whole chain evidence system of the case.
    
6. Rapid Screening of Poisons in Poisoning Cases, Assisting in Case Characterization

    

   For cases of poisoning and unexplained poisoning, thin layer chromatography separation and scanning analysis can be carried out on common poisons, pesticides and rodenticides in the remaining food, vomit, container residues and biological specimens extracted from the crime scene, to realize rapid qualitative screening and semi-quantitative analysis of poisons, providing rapid and accurate technical support for the determination of case nature, locking of investigation direction and treatment of victims.
    

Core Technical Parameters

Practical Forensic Application Cases

1. In an extra-large cross-provincial false litigation case, the plaintiff submitted an IOU with a nominal signing time 3 years ago as the core evidence. The defendant claimed that the loan amount and repayment term clauses in the IOU were added and altered by the plaintiff afterwards, and the two parties had a major dispute over the authenticity of the IOU. Traditional optical inspection and document examination instrument inspection only found subtle differences in the ink color of the suspicious strokes that were difficult to distinguish by the naked eye, and could not draw a clear identification conclusion. Using this instrument, forensic examiners carried out trace extraction of the ink from the suspicious added and altered parts and the original text parts of the IOU. Through thin layer chromatography separation and dual-wavelength scanning analysis, they found that there were significant differences in the dye composition and relative retention value of chromatographic peaks between the two, and clearly confirmed that the two were not written with the same ink. Finally, a forensic expert opinion that the IOU had added and altered alterations was issued. This opinion was fully accepted by the court, successfully dismissed the plaintiff's claim, and provided core scientific evidence for the public security organ to pursue his criminal responsibility for false litigation.
2. In a series of forged bank acceptance bill fraud cases, the criminal gang forged dozens of huge bank acceptance bills. The printing and anti-counterfeiting features of the bills were highly simulated, and it was difficult to accurately identify the authenticity by conventional naked eye inspection and optical inspection. Through this instrument, forensic examiners analyzed the composition of the anti-counterfeiting ink and printing ink on the involved bills, compared with the ink characteristic map of the real bank acceptance bill, and found that the anti-counterfeiting ink composition and dye ratio of the involved bills were essentially different from the genuine ones. At the same time, they locked the type and source of the printing ink of the bills, providing a key basis for the case characterization. According to this clue, the public security followed the line and successfully eliminated the cross-provincial criminal gang that forged financial bills and committed fraud, with the involved amount exceeding 500 million yuan.