Multiplexed electrospray

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... 

Yang, L. et al. 2001. Evaluation of a four-channel multiplexed electrospray triple quadrupole mass spectrometer for the simultaneous validation of LC/MS/MS methods in four different preclinical matrixes. Anal. Chem. 73 1740. 

Morrison D., Davies, A.E., and Watt, A.P. 2002. An evaluation of a four-channel multiplexed electrospray tandem mass spectrometry for higher throughput quantitative analysis. Anal. Chem. 74 1896. 

Fang, L. et al. 2003. Parallel high-throughput accurate mass measurement using a nine-channel multiplexed electrospray liquid chromatography ultraviolet time-of-flight mass spectrometry system. Rapid Commun. Mass Spectrom. 17 1425. 

This assay can be a stand-alone approach, or can be coupled with different chromatographic or detection techniques such as column switching, parallel analytical columns, or multiplex electrospray sources. 

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). 

Bayliss M. Little D. Mallett D. Plumb R. Parallel ultra-high flow rate liquid chromatography with mass spectrometric detection using a multiplex electrospray source for direct, sensitive determination of pharmaceuticals in plasma at extremely high-throughput. Rapid Communications in Mass Spectrometry, 2000, 14, 2039-2045. 

Leclercq, L. Delatour, C. Hoes, 1. Brunelle, F. Labrique, X. et ah Use of a five-channel multiplexed electrospray quadrupole time-of-flight hybrid mass spectrometer for metabolite identification. Rapid Commun Mass Spectrom 2005, 19, 1611-1618. 

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.)...

Fig. 4. Schematic representation of a commercial parallel LC/MS system. Liquid flow is delivered to eight columns by a pump and a flowsplitter. Peaks are detected by a multichannel UV detector and a TOF mass spectrometer with a multiplexed electrospray source...

Fig. 5. Schematic diagram of an eight-channel multiplexed electrospray source. At the current representation, only spray 1 can pass through the sampling rotor to the mass analyzer, whereas sprays 2-8 are blocked. Reprinted with permission from Micromass, UK...

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. 

Figure 5.12 Four-channel multiplexed electrospray for four-channel parallel LC-MS, available from Waters. Reprinted with courtesy from Waters.

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, M.K. Little, D. Mallett, D.N. Plumb W.S. Parallel Ultra-high Plow Rate Liquid Chromatography with Mass Spectrometric Detection Using a Multiplex Electrospray Source for Direct, Sensitive Determination of Pharmaceuticals in Plasma at Extremely High Throughput, Rapid Commun. Mass Spectrom. 14, 2039-2045 (2000). 

Yang, L. Mann, T.D. Little, D. Wu, N. Clement, R.P. Rudewicz, P.J. Evaluation of a Four-Channel Multiplexed Electrospray Triple Quadrupole Mass Spectrometer for the Simultaneous Validation of LC/MS/MS Methods in Four Different Preclinical Matrixes, Anal. Chem. 73, 1740-1747 (2001). 

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