Multiplexed capillary columns

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 5 Schematic of a complete multiplexed and integrated instrumental design with eight capillaries. Stars at I, U1, and U2 represent the multiplexed freeze/ thaw valves. The T-assembly is made up of eight pieces of commercial junctions stacked together. These connect to the manifold M1, the SEC (size-exclusion chromatography) purification columns, and the reaction loops. The cross-assembly is made of eight pieces of standard crosses packed together with built-in heaters. V8 is an eight-position motorized titanium valve with a center port. S1 is a two-position motorized PEEK valve. V6 is a six-position motorized PEEK valve. (Reprinted from Ref. 33 with permission.)...

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