Solo Mass Spectrometer versus Tandem Mass Spectrometry

As described previously, the use of MS as a TLC/HPTLC detector involves the detection and identification of the analyte in the presence of interfering compounds from the chromatographic process. At best, the mass spectra obtained from a single spot after planar separation will contain ions from the analyte and from these other compounds. When ionization is by FAB/LSIMS the situation may be exacerbated by the formation of matrix and salt ions (Figure 4). Although useful information can be obtained from TLC/HPTLC-MS

Figure 4 FAB-MS spectrum of paracetamol obtained from urine following ascending chromatography on diol bonded phase.

experiments, the information so obtained can be improved by using tandem mass spectrometric methods.

Tandem mass spectrometry is now a well-established analytical technique. Tandem mass spectro-metry offers advantages in three major areas: structure elucidation of organic and biological molecules; the identification of components in complex matrices with or without chromatographic separation; and in trace analysis.

Several types of instrument capable of performing MS-MS analyses are available, the two most common types being the triple-quadrupole and the sector/ quadrupole hybrid. In both types of instrument the ions selected in the first analyser are transmitted into the reaction region, normally a gas cell, where frag-

Figure 5 (A) FAB-MS-MS collision induced dissociation product ion spectrum of the (M # H) # ion from a standard sample of paracetamol following ascending chromatography on diol bonded phase. Collision energy, 60-40 eV; collision gas, argon at an indicated pressure of 3.0x10~6 mbar. (B) FAB-MS-MS collision induced dissociation spectrum of the (M#H)# ion from paracetamol extracted from urine and following ascending chromatog-raphy on diol bonded phase. Collision energy, 60-40 eV; collision gas, argon at an indicated pressure of 3.0 x 10~6 mbar.

mentation occurs by collisions with a target gas, to yield characteristic product ions to be analysed and detected by the second analyser (Figure 5).

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook

Post a comment