Time-of-flight mass spectrometry as a tool for speciation analysis

Time-of-flight mass spectrometry (TOFMS) has recently been introduced as an alternative to scanning-based mass analyzers for use in elemental analysis . Coupled with an inductively coupled plasma or alternative ion source, TOF MS can produce a complete atomic mass spectrum in less than 50 ys. Because of this high spectral-generation rate, even very brief transient signals ca n be recorded with high fidelity. Furthermore, each mass spectrum is derive d from the same sub-microsecond pulse of ions, so high precision can be ach ieved by using either isotope-ratioing or internal standardization techniqu es. All these features make TOFMS attractive for the measurement of transie nt signals, such as those commonly encountered in speciation analysis. In t his paper, the capabilities of TOFMS in speciation will be demonstrated thr ough the coupling of pas chromatography and capillary electrophoresis with an inductively coupled plasma-TOFMS. Additionally, the development of novel switched gas sampling glow discharge (GSGD) ionization sources will be des cribed and their role in chemical speciation will be evaluated. The switche d GSGD has the ability to collect both atomic and molecular mass spectra in rapid succession, to provide additional information about chemical species . The coupling of various sample introduction systems (flow-cell, exponenti al dilutor, capillary gas chromatography and electrothermal vaporization) t o the GSGD is outlined. (C) 2000 Elsevier Science B.V. All rights reserved.