Development and characterization of an inductively coupled plasma/electrospray ionization dual-source time-of-flight mass spectrometer

In recent years the importance of chemical speciation, i.e. the quantitative determination of an element amongst its various oxidation states and molecular or complex forms, has been recognized as more relevant than total elemental concentration. Although the total elemental concentration is often easier to evaluate, the bioavailability and toxicological information it yields is inherently limited. It has been demonstrated that identification based on chromatographic separation alone cannot provide sufficient qualitative information for native biological samples, due to the unknown nature of the sample. For this reason, researchers have begun employing two separate instruments to obtain the elemental and molecular information from such samples. However, employing separate instruments for the analysis of a given sample has several disadvantages. In the presented work, a single time-of-flight mass spectrometer (TOFMS) will be described that utilizes two ionization sources to obtain comprehensive atomic and molecular information simultaneously.;A dual-source TOFMS has been designed and constructed in our laboratory. The current arrangement for the instrument utilizes an inductively coupled plasma to obtain elemental, isotopic, and quantitative information. Meanwhile, an electrospray source is operated in parallel to provide molecular and structural information. Due to the wide mass range and high spectral-generation rate of TOFMS, ions from both sources can simultaneously be sampled by a single mass analyzer to provide excellent temporal resolution of transient signals, while simultaneously simplifying peak assignment from a chromatographic separation. Furthermore, since only a single chromatographic separation is necessary for the atomic and molecular channels, sample requirements, preparation time, and analysis time can be significantly reduced.