7
High Sensitivity Separation of an Enolase Tryptic Digest
Figure 1: High sensitivity separation of an enolase tryptic digest as performed on a Waters nanoACQUITY UPLC System and a TRIZAIC nanoTile at 450 nl/min. flow rate.
generated by applying a voltage across this packed bed. An EK pump seemed perfect for a microfluidic system.
At the same time, we began looking at high pressure microfluidic platforms. Previously, microfluidics had been used for low pressure applications at pneumatic-type pressures (<1,000 psi) in silicon, glass, polymers, or other materials which are not appropriate for high-pressure LC/UPLC pressures up to 15,000 psi. These materials would burst at the hydraulic pressures that exist inside a typical LC channel. We didn’t want the materials of construction used in an LC microfluidic device to limit the pressure/performance envelope. Not coincidentally, it was about this same time we began working on UPLC, so 15,000 psi was
Replicate Injections of an
E.col Tryptic Digest with TRIZAIC UPLC
Figure 2: TRIZAIC UPLC nanoTile separations for triplicate injections of 700 ng of a tryptic digest of
E.coli. The separation conditions were three percent A to 40 percent A over 90 minutes at a flow rate of 450 nl/min.
the goal we set for a system operating pressure.
About 2004, we constructed microfluidic prototypes with multilayer ceramic platforms in LTCC and HTCC (low/high temperature co-fired ceramic). These ceramics have been used for years in the electronics industry to create rugged multilayer circuit boards. We learned that the internal channels on the ceramic devices could withstand extreme hydraulic pressures. And since the manufacturing process for these was quite straightforward, we decided to bring the manufacturing process in-house, and we refined the process to create microfluidic features and develop a ceramic that had the strength and inertness needed for many applications.
Which components within a ‘typical’ LC system stand to benefit most from integrating ‘chip technology’ into their design? Are there any other components which could benefit from utilising this technology but for one reason or another have not yet done so? How far away from seeing ‘full system benefits’ owing to this technology are we?
While we thought we could put an entire LC system on a microfluidic device by leveraging EK pumping technology, we quickly learned that this might be too big an initial step. Instead, replacing the consumable package that makes up a typical nanoLC system - the analytical and trap columns, and electrospray tips - and gaining
Figure 3: The TRIZAIC UPLC nanoTile incorporates traditional fittings, columns and electrospray emitters into a single device for performing nanoscale LC separations.
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