Multiplexed electrospray interface

The first reported case of timesharing for a mass spectrometer9 involved the design of an Ionspray interface with multiple sprayers to support the analysis of effluents from multiple columns. This approach led to the development of a multiplexed electrospray interface (MUX)10 using an LC/MS interface and multiple (identical) sprayers linked to a HPLC system and a spinning screen to allow the output of only a single sprayer to enter the MS (Figure 4.5). The injections of the HPLC systems... 

V. D. Di Biasi, N. Haskins, A. Organ, R. Bateman, K. Giles, and S. Jarvis, High throughput liquid chromatography/mass spectrometric analyses using a novel multiplexed electrospray interface. Rapid Commun. Mass Spectrom. 13 (1999), 1165-1168. 

De Biasi, V. Haskins, N. Organ, A. Bateman, R. Giles, K. Jarvis, S. High Throughput Liquid Chromatography/Mass Spectrometric Analyses Using a Novel Multiplexed Electrospray Interface, Rapid Commun. Mass Spectrom. 13, 1165-1168 (1999). 

Bayliss and co-workers [10] combined ultra-high flow rates, parallel LC columns, a multiplex electrospray source, and mass spectrometric detection for the rapid determination of pharmaceuticals in plasma using four narrow bore (50 mm x 1 mm, 30 pm Oasis HLB) or capillary (50 mm x 0.18 mm, 25 pm Oasis HLB) HPLC columns with large particle sizes (to avoid high system back-pressure) in parallel with a multiple probe injector and a MUX MS interface. Small sample aliquots were injected directly into the system without sample pre-treatment procedure, obtaining very low limits of quantification (from 1 to 5 ng/mL). 

Figure 6.15 The schematic of the four-way multiplexed electrospray LC/MS interface in combination with a TOF-MS. (Reprinted with permission from de Biasi et al., 1999. Copyright 1999 John Wiley Sons.)...

From an analytical standpoint, we would ideally prefer to maintain discrete solvent lines even upon introduction into the mass spectrometer. This would ensure that continued data integrity throughout the analytical process could be maintained and no there would be constraints on sample adjacencies. We embarked on a technical collaboration with Micromass (UK) to develop and construct an interface into a mass spectrometer that would achieve our goal. The result of this collaboration is the construction of a novel four-channel multiplex electrospray liquid chromatography interface that has been used to analyze single components and quaternary mixtures by LC-MS as well as synthetic samples prepared by automated procedures. 

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