A TOF MS is designed to separate ions that have identical kinetic energy but a different mass-to-charge ratio. In essence, it consists of a long tube, which connects the sample source to a detector, in which ions expelled from the source move toward the detector in order of increasing mass. When combined with an HPLC or other liquid separation technique, these instruments are ideal for analyzing large molecules or identifying compounds in complex matrices.

Following chromatographic separation, the LC-TOF MS instrument bombards the ions of the sample with electrons. This is often accomplished using electrospray ionization (ESI), although other techniques can be used as well. The positive ions are attracted to a negatively charged set of plates with a small gap between them. This accelerates the ions to the same kinetic energy and allows them to flow into a field-free drift region, also known as a flight tube, in which the lighter ions reach the detector first. In fact, the ions arrive at the detector in a sequential order of mass, making it theoretically possible to detect all the ions present in the source. The resulting spectra is used to perform identification and quantification of known and unknown analytes. In contrast to other MS techniques that only let through a narrow range of masses at each point in time, LC-TOF MS has very high sensitivity, speed and resolution but does not allow for structural analyses.

Popular modifications to the basic LC-TOF MS technique include Q-TOF MS instruments, which incorporate a quadrupole mass filter before ions reach the flight tube, and MALDI as an ionization method. Excluding Q-TOF and MALDI-TOF MS instruments, the total market for LC-TOF MS was almost $100 million in 2016. Even though LC-TOF MS lacks the capabilities of other enhanced MS techniques, it fills an important price-to-performance segment of the market and can be used in a wide range of applications.

The pharmaceutical industry accounts for the bulk of demand for LC-TOF MS instruments, for which the technique is considered cost effective for routine studies. Demand from environmental labs and the food industry is also substantial, as LC-TOF MS is a common technique for identifying contaminants in complex samples.

Waters is the leader in the LC-TOF MS market, as it has been for many years. Among its systems are the Xevo G2-XS TOF MS platform. Agilent Technologies and Bruker also maintain competitive market shares. Despite its sales growth being overshadowed by new Q-TOF MS products, the market for LC-TOF MS is expected to continue increasing in the low-to-mid single digits over the next few years, driven by replacement sales and growing demand in China.

Leading Suppliers:

• Waters
• Bruker
• Agilent Technologies

Largest Markets:

• Pharmaceuticals
• Environmental
• Foods

Instrument Cost:

• $150,000–$400,000