Recent developments in electrospray mass spectrometry including implementation on an ion trap.

Mass spectrometry (MS) may be the ultimate detection technique when combined with modern condensed phase separation sciences. The technique combines sensitivity with excellent specificity, so the pharmaceutical analyst can obtain definitive information regarding components separated in a mixture. Thus, mass spectrometric detection not only provides evidence of a chromatographic peak, but it also provides important information including molecular weight and structural information enabling identification of the components. The coupling of an atmospheric pressure ionization (API) mass spectrometer to most of the separation science techniques offers a simpler alternative from earlier non-routine, less sensitive systems where the vacuum systems struggled to handle the liquid effluent from these systems. Contemporary sensitive and analytically rugged API systems can be operated unattended for extended periods of time thus reducing the cost per sample to a reasonable value especially given the wealth of information provided. Although the mass spectrometer is more complicated than conventional spectroscopic detectors, present day API systems effectively decouple the liquid-phase separation inlet from the high-vacuum system where mass analysis occurs. The ability to form gas-phase ions at atmospheric pressure and sample primarily the analyte ions into the mass spectrometer promises a bright future for combining on-line condensed phase separation science techniques with mass spectrometry. The increasing ease of performing these experiments offers new analytical opportunities for pharmaceutical laboratories.