Investigation of the quantitative capabilities of an electrospray ionization ion trap/linear time-of-flight mass spectrometer

Abstract

The quantitative analysis of pharmaceutical or environmental compounds represents an important application area of electrospray ionization (ESI) mass spectrometry (MS). Typically, these analyses are carried out using quadrupole mass analyzers. Recently, several other mass spectrometric configurations have been developed for ESI, including time-of-flight (TOF), which offers high sensitivity and fast data acquisition capabilities. This work investigates the capabilities and limitations of using ESI ion trap/TOFMS for quantitation. The analysis of sulfonamides, an important class of compounds used in the food industry, was selected for this study. It is demonstrated that a calibration curve exhibits a linear response for almost 3 orders of magnitude. The lower limit of the linear range is restricted by the chemical background noise while the upper limit is governed by the ESI source. The short term and long term reproducibility of the instrument are both demonstrated to be better than 8% relative standard deviation. The detection limits and linear dynamic range of this instrument are comparable with those obtained using a single quadrupole mass spectrometer for a single compound and superior for multicomponent analyses. For the analysis of five components, the detection limits using ESI ion trap/TOFMS are about three times lower. It is argued that improving the detection limits, through the use of tandem mass spectrometry, should further extend the linear dynamic range of the instrument for quantitation. © 1998 John Wiley & Sons, Ltd.