Chapter Four · failure evidence
What Mass Spectrometry & Proteomics got wrong, from 38 dissertations
Mass spectrometry and proteomic methodologies frequently face obstacles stemming from sample preparation artifacts, sensitivity thresholds, and spectral interference. Downstream analytical challenges also arise from cross-instrument variation and algorithmic limitations during compound identification and classification. These records come from PhD theses at 11 institutions, 2021 to 2026. Each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Sample preparation procedures and matrix additives cause precipitation, contamination, and tissue damage
Chemical clean-up steps and bead handling frequently triggered protein precipitation, material loss during powder transfer, or bead aggregation that fouled columns. In addition, MALDI matrices and cryoprotectant additives caused chemical selectivity, abundant adduct formation, chromatographic broadening, and electrospray tissue ablation.
Tried and failed
magnetic bead-based sample preparation applied to mass spectrometry proteomics. Outcome: unstable. Reason: bead aggregation during detergent removal washes caused severe instrument and column contamination
Tried and failed
chemical carbamylation of intact proteins applied to intact proteins for mass spectrometry. Reason: protein precipitation and inefficient sample clean-up
Tried and failed
applying MALDI matrices for laser desorption mass spectrometry applied to ambient laser desorption mass spectrometry. Outcome: worse than baseline. Reason: caused severe chemical selectivity, abundant matrix adduct formation, and poor reproducibility
Towards single cell analysis using ambient mass spectrometry techniques · Imperial
Tried and failed
isotope dilution double spike mass spectrometry applied to detecting sample contamination in micro-drilled powders. Reason: mass loss during powder transfer and wet chemical processing made spike-to-sample ratios unreliable
Tried and failed
cryoprotectant additives in tissue embedding matrix applied to desorption electrospray ionization mass spectrometry. Outcome: worse than baseline. Reason: caused lower signal intensity, altered adduct profiles, and tissue ablation under electrospray
Tried and failed
on-bead chemical cleavage with mass-spec compatible surfactant applied to proteomic sample preparation for mass spectrometry. Reason: detergent and PEG contamination caused chromatographic peak broadening and excessive missed proteolytic cleavages
Novel chemical genetic tools for the proteomic profiling of S-acylation by ZDHHC enzymes · Imperial
Low target abundance, instrument sensitivity limits, and ion stability impede detection
Whole-cell shotgun and targeted assays often failed because low-abundance targets, photo-crosslinked adducts, or configured transition standards were undetectable. High-resolution mass spectrometry systems also exhibited higher quantification limits than triple quadrupoles, while low-charge precursor ions resisted fragmentation.
Tried and failed
mass spectrometry-based whole-cell shotgun proteomics applied to subcellular protein complex abundance and localization. Outcome: no signal. Reason: insufficient sensitivity for low-abundance proteins and subtle spatial or stoichiometric changes without sub-diffraction imaging
Systems Biology Approaches for Elucidating Early ALS Disease Processes · MIT
Lost to a baseline
High-resolution mass spectrometry (HRMS) systems like QTOF and Orbitrap exhibited inferior quantitative sensitivity and higher LOQs compared to triple quadrupole (QqQ) systems for routine multi-residue pesticide monitoring
Evaluación toxicológica de contaminantes químicos en piensos comerciales para perros y gatos · accedaCRIS
Tried and failed
MALDI mass spectrometry of photo-crosslinked adducts applied to membrane protein-lipid covalent complexes. Outcome: no signal. Reason: Adducts were undetectable in both intact protein and tryptic digest mass spectra
Probing the mechanism of the bacterial Lipid II flippase, MurJ · Harvard
Tried and failed
quantitative tandem mass spectrometry proteomics applied to low-abundance target protein depletion. Outcome: no signal. Reason: low baseline target protein expression prevented reliable detection of depletion in knockout mutants
CHARACTERIZING THE ROLES FOR HOST-DERIVED LIPIDS DURING MYCOBACTERIUM TUBERCULOSIS INFECTION · Cornell
Tried and failed
multiple reaction monitoring mass spectrometry applied to metabolite analytical standards quantification. Outcome: no signal. Reason: analytical standards failed detection using the configured MRM transition parameters
Metabolic investigation of dietary impact on colorectal cancer risk · Imperial
Tried and failed
multiplexed ion mobility spectrometry with tandem mass spectrometry applied to low-charge protein complex dissociation products. Outcome: no signal. Reason: low-charge precursor ions had high stability against fragmentation, yielding negligible product ion signal
Instrument tuning, quantitation normalization, and annotation flaws degrade profiling workflows
Extreme resolution settings and laser power fluctuations degraded relative isotope accuracy, signal repeatability, and enzymatic assay interpretation. Furthermore, single internal standards caused systematic recovery overestimation, while overlapping mass defect criteria and low annotation coverage hampered metabolite identification and pathway enrichment.
Tried and failed
MALDI-TOF mass spectrometry enzymatic assay applied to detecting bacterial antibiotic degradation. Outcome: no signal. Reason: yielded highly inconsistent sensitivity and poor specificity across different hydrolysis and degradation peak interpretations
Tried and failed
MALDI-TOF mass spectrometry for quantitative purity analysis applied to defined synthetic polymer chain lengths. Reason: laser power-dependent signal intensities and poor repeatability prevented accurate quantitative measurement
Tried and failed
batch recovery correction with single internal standard applied to multi-analyte mass spectrometry quantification. Outcome: unstable. Reason: caused high intra-lab variability and systematic overestimation of recoveries in reference materials
PFAS: a new threat to human health Multi-analyte method development and background levels monitoring · IRIS - UNICAM - prod
Tried and failed
combining mass defect filtering with Kendrick mass applied to metabolite identification in mass spectrometry. Reason: Mass defect filtering overlapped with Kendrick mass defect without providing orthogonal identification confidence
Integrating Machine Learning Solutions into Untargeted Metabolomics and Xenobiotics Workflows · Georgia Tech
Tried and failed
metabolite pathway enrichment analysis applied to mass spectrometry imaging data. Outcome: no signal. Reason: low annotation coverage of small polar metabolites precluded statistical pathway significance
Machine Learning Enabled Stem Cell Lipidomics · Georgia Tech
Tried and failed
extreme resolution and high ion target settings applied to high-resolution mass spectrometry metabolomics. Outcome: worse than baseline. Reason: degraded relative isotope abundance accuracy and caused signal loss for low-abundance ions
Spectral interference and resolution constraints obscure isobaric and complex mixtures
Higher-order multiplexing, un-enriched phosphopeptide backgrounds, and co-eluting structural analogs produced severe spectral interference and fragmented cross-matches. Similarly, declining resolution at high molecular weights and unit-resolution limitations prevented clean separation of intact mixtures and trace analytes from isobaric matrix signals.
Tried and failed
higher-order isobaric multiplexing applied to mass spectrometry proteomics. Outcome: worse than baseline. Reason: increased sample complexity and spectral interference reduced peptide and protein identification rates
Tried and failed
top-down intact mass spectrometry proteomics applied to polyclonal antibody serum repertoires. Outcome: no signal. Reason: declining mass spec resolution at high molecular weights and poor chromatographic separation of intact mixtures
Polyreactivity, polarization and developability features of the vaccine elicited IgG serological repertoire · UT Austin
Tried and failed
data-dependent tandem mass spectrometry compound identification applied to structural congener mixtures in liquid chromatography. Reason: co-eluting structural analogs produced isobaric or fragmented cross-matches with low library match scores
Considered and rejected
Considered and rejected: Rejected label-free mass spectrometry of raw thiophosphate eluates without phosphopeptide enrichment in TMT-multiplexed tissue samples due to excessive non-phosphorylated peptide background obscuring phosphopeptide detection.
In vivo tissue-specific, multi-omics analysis of Egf-stimulated Egfr signaling · Harvard
Tried and failed
unit-resolution tandem mass spectrometry quantification applied to trace analytes in biological matrices. Reason: isobaric matrix interference with identical nominal mass caused severe target overestimation
Affinity purification and immunoprecipitation fail to recover transient or low-yield interactions
Chromatin and affinity pulldowns failed to capture transient substrate interactions, co-elute putative interactors, or recover sufficient unamplifiable protein yield. In other workflows, immunoprecipitation yielded predominantly keratin contaminants, or candidate degradation targets failed to replicate during orthogonal western blot validation.
Tried and failed
mass spectrometry screening followed by western blot validation applied to identifying viral-host protein degradation targets. Outcome: no signal. Reason: candidate targets identified by proteomics failed to show differential expression on orthogonal validation
ZER1 CONTRIBUTES TO THE GROWTH OF HPV-POSITIVE CANCERS · Penn
Tried and failed
chromatin immunoprecipitation combined with mass spectrometry applied to chromatin-bound protein complexes. Outcome: data insufficient. Reason: insufficient protein yield harvested without the ability to amplify unamplifiable protein targets
PROTEIN-PROTEIN INTERACTION NETWORK PERTURBATIONS CAUSED BY ONCOGENIC FUSION EVENTS · Cornell
Tried and failed
affinity purification mass spectrometry with protease cleavage applied to enzyme substrate identification. Outcome: no signal. Reason: pulldowns failed to capture and definitively identify transient substrate interactions
Tried and failed
immunoprecipitation-mass spectrometry and multimer structure prediction applied to detecting plant protein-protein interactions. Outcome: no signal. Reason: IP-MS yielded only keratin contaminants and structure prediction crashed on full-length protein complexes
The role of h3k27me3 reprogramming in arabidopsis development · Imperial
Tried and failed
affinity purification mass spectrometry with protease elution applied to detecting protein-protein hetero-oligomers. Outcome: no signal. Reason: the putative interactor did not co-elute with any tested target protein construct
Inter-instrument spectral differences and sampling shifts degrade classification models
Supervised learning models trained on mass spectrometry features failed cross-instrument validation or cross-modality testing due to spectral variance and distribution shifts. Restricting feature sets solely to variables shared across platforms worsened performance by discarding predictive information.
Tried and failed
mass spectrometry feature classification for sensory prediction applied to meat quality and palatability classification. Outcome: did not generalise. Reason: models failed cross-instrument validation on an off-site mass spectrometer due to inter-instrument spectral variance
Tried and failed
restricting feature selection to shared platform variables applied to mass spectrometry tissue classification models. Outcome: worse than baseline. Reason: filtering for features present across both instruments discarded predictive information, lowering classification accuracy
Tried and failed
cross-modality supervised learning without domain adaptation applied to mass spectrometry tissue classification. Outcome: did not generalise. Reason: distribution shift and spectral feature differences between differing sampling and ionization techniques
Advanced development of mass spectrometry technologies for intraoperative molecular diagnostics · UT Austin
Left open by the authors
Problems the authors named and did not get to.
Left open
Validate sialylation changes and elevated mannosylation levels as clinical biomarkers for endometriosis using mass spectrometry of patient samples. Blocker: Requires clinical patient biospecimens and wet-lab mass spectrometry facilities to validate biomarkers
Mass spectrometric investigation into glycomes implicated in human reproductive biology · Imperial
Left open
Perform biological validation and literature analysis of discordant reaction essentiality predictions using CRISPR datasets (Achilles, Sanger) and mass spectrometry. Blocker: Mass spectrometry experiments require wet-lab facilities and physical apparatus.
Identifying therapeutic weak spots in cancer using network analysis · Imperial
Left open
Validate mouse lipidomic and metabolomic alterations in human patient cohorts using mass spectrometry and classification models. Blocker: Requires human clinical serum samples, wet lab mass spectrometry apparatus, and clinical cohorts
Metabolomics and Machine Learning for Early-Stage Cancer Diagnosis · Georgia Tech
Left open
Validate identified biomarkers and metabolic hypotheses on larger clinical patient cohorts. Blocker: Requires access to new clinical patient tissue cohorts, wet lab preparation, and mass spectrometry imaging equipment
Mass spectral imaging of clinical samples using deep learning · Imperial
Left open
Refine mass spectrometry quantification methods and evaluate lectin microarrays for high-throughput glycome profiling. Blocker: Requires mass spectrometry instruments, wet-lab facilities, and clinical samples
Mass spectrometric investigation into glycomes implicated in human reproductive biology · Imperial
Left open
Develop and validate a mass spectrometry acquisition workflow combining SureQuant trigger peptides with isobaric multiplex labeling for sample multiplexing. Blocker: Requires wet lab sample preparation, isobaric mass tags (TMTpro), and a high-resolution mass spectrometer (Orbitrap Exploris 480).
Left open
Compare the quantification of monoclonal proteins using the Hevylite immunoassay against liquid chromatography-tandem mass spectrometry (LC-MS/MS). Blocker: Requires patient serum samples and wet lab LC-MS/MS equipment.
Left open
Validate DESI-MSI lipid findings using positive ionisation mode UPLC-MS on cellular extracts. Blocker: Requires wet lab facilities, tissue samples/cellular extracts, and mass spectrometry instruments
A next-generation -omics analysis of the radiotherapy response in rectal cancer · Imperial
Left open
Evaluate whether antibody enrichment, IMAC-only, or no enrichment is required for SureQuant-based mass spectrometry of low-abundance pTyr targets. Blocker: Requires wet-lab sample preparation, enrichment reagents, and an Orbitrap mass spectrometer
Left open
Validate mass spectrometry protein overexpression results using immunofluorescence techniques in a mouse neuroma model. Blocker: Requires wet lab facilities, tissue samples, and immunofluorescence reagents/equipment
Approaches to improve the diagnosis and treatment of traumatic neuropathic pain · Harvard
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