Mass Spectrometry: The Only Method with Many Ionization Techniques
This chapter addresses some elementary aspects of the mass spectrum, discusses tools used by experienced practitioners, and provides some glimpses into current advances in the science and art of deriving unambiguous answers from unknown spectra. Two techniques improve the signal-to-noise ratio of a mass spectrum: (1) filtering ions via quadrupole, double quadrupole, and triple quadrupole tandem mass spectrometry (MS) and (2) use of accurate isotopic masses. The quantitative variable is the intensity of the peaks, which is proportional to the concentration of the analyte in the sample. The qualitative variable is the ratio between the two most intense peaks. MS presents high sensitivity: 0.04 for small molecules and two atomic units of mass for large proteins. It shows extremely low limits of detection and quantification, which can be used in concentrations of traces and ultra-traces. Modern techniques and 48scientific rigor are applied to research. Tu and co-workers determined the proteins bonded to artemisinin via MS. Thanks to the technique, it was determined and analyzed artemisinin proteins and created the effective medicine versus malaria.