How does MSI determine ink-over-seal sequencing?

By judging the spatial relationship of molecular signals at the crossing: the 'stamp first' group's marker pen shows signal break at the crossing, while the 'write first' group's seal signal is significantly lower, with clear features enabling unambiguous determination without destroying the evidence.

Besides seeing ridges, what else can fingerprint imaging obtain?

In DESI/PI mode it can simultaneously detect characteristic chemical components of the ridge region such as cholesterol and squalene, providing molecular evidence for tracing and individual identification.

Can forensic MSI alone serve as conviction evidence?

Usually it cannot stand alone. The molecular spatial map is one of the strong pieces of evidence, needing cross-validation with complementary methods such as microscopy and chromatography-mass spectrometry, and satisfying forensic procedural norms.

Why does forensic evidence imaging value non-damaging samples?

Forensics requires intact evidence, reproducible process and manageable chain-of-custody; DPI does not damage the sample at the front end and is detachable for cleaning, fitting this requirement.

Application · Mass Spectrometry Imaging

Forensic Evidence MSI: Letting the Molecules on Evidence 'Speak'

Forensic evidence is often a piece of handwriting, a fingerprint or a piece of tissue. Traditional microscopy or chemical methods struggle to present the molecular spatial distribution within them non-destructively. Forensic evidence MSI uses mass spectrometry imaging to acquire in-situ on the evidence, drawing ink, grease and characteristic metabolites into spatial maps, providing visualized and comparable scientific evidence for ink-over-seal sequencing, ink tracing and fingerprint identification.

Table of Contents
1. Entry Point of MSI in Forensics 2. Ink-Over-Seal Sequencing Determination 3. Ink Tracing and Fingerprint Imaging 4. Evidence Quality and Applicable Boundaries

Forensic Evidence MSI: Letting the Molecules on Evidence 'Speak' — schematic diagram

1. Entry Point of MSI in Forensics

The application notes of the Neo-Source MSI DPI list forensic science as a key area, covering forensic identification, fingerprint scanning, hair, abused substances and metabolites in tissue. Its matrix-free, low-ion-suppression design and ability to analyze complex samples directly allow evidence such as ink, fingerprints and tissue to be imaged with minimal destruction.

Engineered, DPI is compatible with mainstream mass spectrometers from Agilent, AB SCIEX and Thermo (including Thermo forensic-detection scenarios), and provides a self-developed titanium-alloy ion transfer tube that does not damage the sample at the front end and is detachable for cleaning, fitting the forensic requirement of 'intact evidence and reproducible process'.

2. Ink-Over-Seal Sequencing Determination

Ink-over-seal sequencing determination is a classic difficulty in document examination: distinguishing 'write first then stamp' from 'stamp first then write'. In the DPI case, the marker pen ink of the 'stamp first' group showed obvious signal break at the ink-seal crossing; the seal impression of the 'write first' group showed significantly lower signal at the crossing than the 'stamp first' group, with clear crossing-signal features enabling unambiguous determination.

The value of this method is 'seeing space without destruction': without scraping or chemical stripping, it can present the molecular signal relationship at the crossing at microscopic scale, preserving the original evidence for subsequent review.

3. Ink Tracing and Fingerprint Imaging

The DPI case shows successful distinction of neutral-pen inks of different brands and clear identification of fingerprint ridges, detecting characteristic components such as cholesterol (m/z 369) and squalene (411) in DESI/PI mode, fitting forensic-evidence detection scenarios. Fingerprint ridges are clearly visible while obtaining chemical information of the ridge region.

For abused substances and metabolites, MSI can present their spatial distribution in-situ in hair and tissue, providing molecular-level localization evidence for drug- and poison-related evidence, connecting with toxicological analysis and environmental chemistry.

4. Evidence Quality and Applicable Boundaries

Forensic applications have extremely high requirements for reproducibility, method validation and chain-of-custody. The molecular spatial map provided by MSI is one of the strong pieces of evidence, but conclusions usually need cross-validation with complementary methods such as microscopy and chromatography-mass spectrometry, and must satisfy forensic procedural norms.

From an industrial perspective, the engineering orientation of matrix-free preparation and ready-to-use is gradually pushing such high-threshold forensic analysis toward routine forensic laboratories; the two Neo-Source imaging sources are designed specifically in this direction.

Frequently Asked Questions (FAQ)

How does MSI determine ink-over-seal sequencing?: By judging the spatial relationship of molecular signals at the crossing: the 'stamp first' group's marker pen shows signal break at the crossing, while the 'write first' group's seal signal is significantly lower, with clear features enabling unambiguous determination without destroying the evidence.
Besides seeing ridges, what else can fingerprint imaging obtain?: In DESI/PI mode it can simultaneously detect characteristic chemical components of the ridge region such as cholesterol and squalene, providing molecular evidence for tracing and individual identification.
Can forensic MSI alone serve as conviction evidence?: Usually it cannot stand alone. The molecular spatial map is one of the strong pieces of evidence, needing cross-validation with complementary methods such as microscopy and chromatography-mass spectrometry, and satisfying forensic procedural norms.
Why does forensic evidence imaging value non-damaging samples?: Forensics requires intact evidence, reproducible process and manageable chain-of-custody; DPI does not damage the sample at the front end and is detachable for cleaning, fitting this requirement.

Get Specifications & Quotation

To obtain detailed specifications, compatible models, or a quotation for the MSI LDPI / DPI full series imaging ion sources, visit the Neo-Source official website, or contact the official team for compatibility advice tailored to your mass spectrometer (Agilent / SCIEX / Thermo and other mainstream MS).

DPI Dual-Photoionization Imaging Source Neo-Source MSI LDPI Laser Desorption Photoionization imaging ion source Forensic Field Applications: Letting the Molecules on Evidence 'Speak'Material Surface MSI: Drawing a Chemical Map on a Solid Surface In-situ Analysis (In-situ)

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