Spectral networking for dark matter annotation

Map structural relationships between named and unnamed features across your samples. Cosine similarity and neutral-loss propagation turn isolated annotations into a connected molecular map.

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Overview
Connect the dots in your data
A single identified compound rarely travels alone. Spectral networking links features that share structural motifs, adduct variants, or common fragmentation pathways — turning isolated annotations into a connected molecular map of your sample.
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Shared structure

Features linked by structural motifs, adduct variants, or common fragmentation pathways form a connected map, not isolated points.

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Inherited context

When one node earns an MSI Level 1a identification, its neighbours inherit structural context automatically.

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Named dark matter

Unknown features become "dark matter" with a family name, narrowing the search space for subsequent annotation.

How it works
From spectra to molecular families
Spectral networking builds connections that survive polarity, adduct form, and instrument variation — because they are grounded in physical measurement.
Method

Cosine Similarity

The MS² spectrum of each feature is compared pairwise across the dataset. A cosine score ≥ 0.85 between two spectra indicates they share a common substructure. VeroMass computes similarity in both ESI+ and ESI− independently, capturing complementary views of the same molecule.

Method

Molecular Families

Connected components in the similarity graph form molecular families: related glycosides, acylated derivatives, or oxidation products that differ by a known neutral loss. A single Level 1a assignment propagates structural knowledge to every member of the family.

Method

Neutral Loss Propagation

Network edges are annotated with the mass difference between connected nodes. Neutral losses of 162.053 Da (hexose), 146.058 Da (deoxyhexose), and 176.032 Da (glucuronide) are automatically flagged — turning a collision cell into a structural classifier.

Dark Matter
Annotating the unknown
Propagation rules
Confidence scoring

Propagation rules

Cosine ≥ 0.85 + consistent mass shift ≤ 5 ppm + RT correlation → structural family assignment. In any untargeted metabolomics experiment, the majority of detected features have no match in any reference library. When an unknown feature shares high cosine similarity with a Level 1a node and exhibits a consistent mass shift, it inherits the structural class of its neighbour — moving from "unknown" to "likely flavonol diglycoside" or "probable hydroxycinnamate ester," a hypothesis that can be tested. Each propagated annotation carries a confidence score derived from the distance to the anchor node and the number of independent edges supporting the connection.

Visualization
Interactive network graphs
The network is not a static diagram. Every node, edge, and annotation layer is inspectable, filterable, and connected to the underlying spectral evidence.
Interface

Force-Directed Layout

Nodes repel and edges attract — the graph automatically organises by structural similarity. Move, pin, and zoom any node. Layout parameters are adjustable for dense or sparse datasets.

Interface

Multi-Layer Views

Toggle between ESI+ and ESI− networks, overlay retention time gradients, colour by compound class, and filter by cosine threshold — all without regenerating the graph.

Interface

Selection to Evidence

Click any node to pull up its MS¹ and MS² spectra, retention time, adduct series, and gate status. Click an edge to see the cosine alignment between the two spectra side by side.

Integration
Works with your existing tools

The network graph, annotations, and edge tables are exportable in formats that feed directly into downstream analysis:

Turn unknowns into families
Bring your raw LC-MS/MS runs into VeroMass and see the network form around every confirmed identification. Anonymous nodes become structural neighbours, and the dark matter in your sample starts to take shape.