Traditionally, cesium (Cs) is challenging to measure with ICP-OES, mainly because its two most common wavelengths (455.531 nm and 459.320 nm) are less sensitive. However, the unique Avio® 220 Max hybrid simultaneous ICP-OES features an innovative optical system and detector, which provide both outstanding sensitivity and flexibility, along with the ability to use any wavelength up to 900 nm, allowing the use of the atomic Cs atom line at 894.347 nm, which has a much higher intensity than either the 455.531 or 459.320 nm lines. This allows for enhanced analyses and opens the potential for new analytical wavelengths, unlocking applications that are difficult to accomplish on other ICP-OES systems.