How can mass spectrometry imaging be carried out on a limited budget? Retrofitting an imaging source to an existing mass spectrometer as an alternative to replacing the entire instrument

Mass spectrometry imaging capabilities are increasingly becoming an essential requirement in laboratories; however, purchasing a complete system often ties up a significant portion of the budget, making it impractical for teams with tight budgets or limited space. Retrofitting an imaging source onto an existing mass spectrometer is a viable alternative to purchasing a complete system. This article clearly explains the cost logic, applicability limits and implementation considerations of ‘retrofitting as an alternative to a complete system’, to help you make the right choice when working within a limited budget.

The hidden costs of a complete system extend beyond the purchase price

A complete system solution entails a brand-new mass spectrometry system, comprising a mass analyser, ion source, vacuum system, software and installation and commissioning. Even considering the equipment alone, the investment is far higher than that of a single imaging source module. Not to mention that once the complete system is in place, issues such as space, power supply and instrument time allocation must be addressed – for laboratories that already have a functioning main instrument, these costs are duplicated.

Retrofitting unlocks further value from your existing main unit

This retrofit approach involves purchasing only the imaging source (such as the MSI DPI or MSI LDPI) and connecting it to an existing Agilent, AB SCIEX or Thermo instrument. The mass analyser, vacuum system and software platform are all reused from the original equipment, thereby saving the cost of ‘purchasing a duplicate instrument’. Once installed, the main unit retains its standard mass spectrometry functionality whilst gaining imaging capabilities of 20–200 μm (DPI) or 2–3 μm (LDPI), effectively serving two purposes with a single instrument.

A cost comparison of the two approaches

The complete system solution is suitable for two scenarios: firstly, where the laboratory does not already have a usable mass spectrometer; and secondly, where the existing instrument is outdated or has an unstable vacuum system, making further investment unwise. The target audience for the retrofit solution is clear: instruments that are in good working order but lack imaging capability. In such scenarios, retrofitting typically significantly lowers the barrier to acquiring MSI capability, allowing funds to be spent on ‘additional functionality’ rather than ‘duplicate assets’.

It should be noted that the cost ratio between retrofitting and purchasing a complete system is influenced by the specific model, interface configuration and installation complexity; it cannot be summarised by a single fixed figure. Understanding it as a matter of ‘saving on the duplicate purchase of a main unit’ provides a more accurate basis for decision-making than applying a fixed percentage.

Hidden factors to confirm before retrofitting

When budgets are limited, it is all the more important to factor in hidden costs. Firstly, there is the cost of compatibility checks: verifying interfaces, vacuum systems and software protocols on a unit-by-unit basis—this step cannot be skipped. Secondly, there is installation and commissioning: whilst modifications to atmospheric pressure sources are typically minor, time must be set aside for engineering work if vacuum port modifications are required. Thirdly, there is staff training: imaging scan parameters differ from those of conventional mass spectrometry, so operators need to familiarise themselves with desorption/ionisation windows and calibration procedures.

Situations where retrofitting is not cost-effective

If the host instrument is nearing the end of its service life, or if the software protocols are completely closed and cannot be integrated with the scanning control system, forcing a retrofit will lead to a cycle of ‘repeated remedial work’, which may end up costing more than replacing the entire instrument. The criterion for judgement is: can the host instrument itself still reliably handle imaging tasks? If so, retrofitting is cost-effective; if not, it is more reliable to assess the cost of replacing the entire instrument.

Summary

When undertaking mass spectrometry imaging on a limited budget, retrofitting an imaging source is a practical alternative to replacing the entire instrument. Essentially, it involves ‘adding incremental functionality to a serviceable host instrument’, thereby avoiding the duplication of assets. This approach is contingent upon the host instrument being in good condition and compatibility having been thoroughly verified. Once these two points have been confirmed, limited funds can be spent where they are most needed.