MS systems quantify and identify the chemical composition of a sample by generating its mass spectrum. A mass spectrum is a graph of the relative abundance of detected ions by mass within a sample. The process of generating mass spectra begins with the ionization of the sample, which can be achieved by a variety of methods.

One method is MALDI MS. MALDI MS instruments utilize pulsed lasers to partially vaporize a UV- or IR-absorbing matrix containing crystallized polymers of the sample. The resulting vapor contains ionized particles, which are injected into a mass analyzer.

In MALDI instruments, mass analyzers are typically TOF tubes. The time it takes for a vaporized ion to pass through a TOF analyzer is recorded and compared to known values to determine the composition of a sample.

Recently, MALDI-TOF MS systems have gained acceptance for clinical research. In 2013, the first MALDI-TOF instrument received FDA approval as a diagnostic tool in the US (see IBO 9/30/13). These instruments feature the ability to identify disease causing organisms, including bacteria and yeast, by comparing detected proteins in a sample against databases. Current instruments can identify up to 210 species or species groups, including 280 clinically relevant bacteria and yeast species.

Compared to the hours that it can take for conventional testing methods, MALDI-TOF instruments can provide diagnostic results in minutes. This speed does not come at the expense of accuracy, as the latest MALDI-TOF MS systems offer overall identification accuracy comparable to nucleic acid sequencing. Another advantage offered by MALDI-TOF mass spectrometers in the diagnostic field is their ability to process multiple samples at the same time. For example, bioMérieux’s VITEK MS is able to process up to 192 samples per run, and can be scaled down for smaller laboratories.

While a single instrument obtains readings from a small sample area, combined MALDI-TOF/TOF systems are able to obtain information from larger areas. Their expanded analysis range is essential to enabling MS imaging, which visualizes the spatial distribution of clinically relevant molecules such as biomarkers and proteins in tissues. The latest advancement in MALDI-TOF/TOF systems is an imaging technique that combines a rapidly pulsing laser with a continuously moving sample stage to obtain a truly square analysis area.

The market for MALDI-TOF clinical mass spectrometers is about $75 million. High growth is expected over the next five years as more funds are poured into clinical research and diagnostics. Leading vendors in the market are Bruker, Shimadzu and SCIEX. Other competitors include Agena Bioscience, bioMérieux and Waters. Instrument prices depend on the level of analysis required by the end-user, with high-end MALDI-TOF/TOF units costing in the low seven digits.

MALDI-TOF Clinical MS at a Glance:

Leading Suppliers

• Bruker

• Shimadzu

• SCIEX

Largest Markets

• Biotechnology

• Clinical

• Academia

Instrument Cost

• $80,000–$1.2 Million