“LC-MS or MALDI?” is often an incomplete comparison. Liquid chromatography describes a separation, while MALDI describes an ionisation method. Chromatography can also feed a MALDI workflow. To make a useful choice, identify the whole route from sample separation to the particular peptide evidence you need.
Name the interfaces being compared
In a 2003 proteome-coverage study, researchers split the output of one nanoscale LC separation. One part went to online electrospray MS/MS; another was mixed with matrix and deposited for MALDI-MS/MS. Both branches therefore included chromatography.Complementary LC/MALDI/MS/MS and LC/ESI/MS/MS for proteome coverage (opens in a new tab)
That design separates the choice of ionisation route from the question of whether a separation was used at all. A direct MALDI analysis of an unfractionated mixture would be another workflow, with another set of comparisons.
| Feature | Record for each route |
|---|---|
| Before ionisation | Sample treatment and separation |
| At ionisation | ESI or MALDI and the tested configuration |
| After ionisation | Mass analyser, fragmentation and identification rules |
These details are particularly important when papers use different generations of instruments. A result from two complete platforms cannot always be assigned to their ion sources alone.
Complementarity means the detected sets differ
The split-flow study analysed a mammalian mitochondrial-ribosome digest. It found substantial overlap between the identified proteins, alongside peptides and proteins identified by only one of the two routes.Complementary LC/MALDI/MS/MS and LC/ESI/MS/MS for proteome coverage (opens in a new tab)
The useful conclusion is that the routes added different observations in that sample. It is not that each unique identification was impossible with every configuration of the other technique.
For a hypothetical example, one workflow detects 70 peptide identities and another detects 60, with 45 shared. Their combined set contains 85, not 130. Counting the overlap is essential when describing the information gained by combining methods.
A non-detection also has several possible explanations. It can reflect the sample, the signal obtained or whether that signal met the workflow’s identification criteria. It should not be translated directly into “the peptide was absent”.
Ask what changed besides ionisation
Yang and colleagues’ 2007 comparison examined LC-ESI-MS/MS and LC-MALDI-MS/MS with different mass analysers. After preliminary split-flow work, they used separately optimised LC configurations for the subsequent experiments.Yang and colleagues — Comparison of nLC-ESI and nLC-MALDI workflows (opens in a new tab)
Their E. coli analyses showed additional identifications when the methods were combined. The paper also cautions that repeating the ESI analysis could itself identify additional peptides.Yang and colleagues — Comparison of nLC-ESI and nLC-MALDI workflows (opens in a new tab)
That caveat changes the decision being made. If the question is whether a second method adds more than another run of the first, the relevant comparator is a repeated first method with a comparable analytical budget.
Choose around the evidence needed from the sample
For a defined research peptide, ask whether the intended parent and plausible related species are detected with adequate discrimination. For a complex digest, ask which sequence regions or identities are needed and what remains uncovered.
Keep identification and amount determination on separate lines. A larger list of detected peptides does not establish that their signal intensities provide unbiased relative concentrations.
The comparison becomes actionable when it names the missing information and the tested route that supplies it. That is more useful than selecting a technology by reputation or treating a single unsuccessful spectrum as a final identity decision.
Sources and further detail
- Complementary LC/MALDI/MS/MS and LC/ESI/MS/MS for proteome coverage (opens in a new tab)
Original 2003 abstract and split-flow/results passages read. Shared separation and complementary identifications retained without a universal instrument ranking.
- Yang and colleagues — Comparison of nLC-ESI and nLC-MALDI workflows (opens in a new tab)
Indexed original 2007 abstract, experimental comparison and coverage discussion read, including the caveat about additional identifications on repeated ESI analysis.
Sources checked 20 September 2026. Worked examples are illustrative unless a supplied report is explicitly identified. This article has not undergone independent scientific peer review.