Massselective

Massselective, often written mass-selective, is an adjective used in analytical chemistry and spectroscopy to describe approaches, detectors, or analyses that discriminate or isolate signals by mass-to-charge ratio (m/z). In mass spectrometry, mass-selective detection means that the instrument responds primarily to ions within a defined m/z window, enabling selective monitoring of target species.

In practice this is achieved by mass analyzers such as quadrupole, triple quadrupole, time-of-flight, Orbitrap, and ion trap instruments, which separate ions by m/z and allow selective detection. Common mass-selective modes include selected ion monitoring (SIM) and tandem MS modes such as selected reaction monitoring (SRM) or multiple reaction monitoring (MRM), often used in scheduled formats to quantify specific compounds with high sensitivity and specificity.

Applications of massselective techniques span trace analysis of pollutants, pesticides, and drugs; proteomics and metabolomics; forensic toxicology; and pharmaceutical and environmental monitoring. In gas chromatography–mass spectrometry (GC-MS) or liquid chromatography–mass spectrometry (LC-MS), mass-selective detection improves analytical performance by focusing on characteristic ions, reducing matrix interferences and enhancing signal-to-noise ratios.

Limitations and considerations include the need for sufficient mass resolution to distinguish closely spaced ions and potential isobaric interferences in complex matrices. Accurate mass measurements, isotopic pattern analysis, and proper calibration help confirm identifications. Instrument tuning and routine maintenance are essential to maintain mass-selective performance and reliable quantification.

Terminology notes: massselective detection is sometimes described more broadly as mass-selective detection or, in practice, through SIM or MR/MRM workflows in tandem mass spectrometry. The term emphasizes discrimination based on mass-to-charge ratio rather than general, non-selective detection.