Electrospray ionization interface to high pressure mass spectrometry and related methods
摘要
說(shuō)明書
Microchip ESI devices were fabricated from B-270 (Telic Corp., Valencia, Calif.) glass using photolithography and wet etching techniques described in detail previously. See, J. S. Mellors, V. Gorbounov, R. S. Ramsey, and J. M. Ramsey, Anal. Chem., 2008, 80, 6881-6887; and N. G. Batz, J. S. Mellors, J. P. Alarie, and J. M. Ramsey, Anal. Chem., 2014, 86, 3493-3500. Devices were coated with APDIPES via chemical vapor deposition (CVD) using a LabKote CVD system (Yield Engineering Systems, Livermore, Calif.). Id. The pumping channels were then functionalized with a 20 kDa polyethylene glycol (PEG) reagent (NanoCS, Boston, Mass.). The PEG reagent terminates with an N-hydroxysuccinimide ester that reacts with the primary amine of the APDIPES surface, forming a covalent bond between the PEG chain and the surface coating.
Both CE-ESI and infusion designs were operated by application of voltages to the reservoirs via platinum wire electrodes. Applied voltages were controlled by a custom HV power supply consisting of five independent voltage modules. Three modules had a maximum output of ?25 kV, and the other two had a maximum output of +10 kV (UltraVolt Inc., Ronkonkoma, N.Y.). The power supply was connected to a computer via a SCB-68 breakout box and a PCI-6713, 8-channel analog card (National Instruments, Austin, Tex.). A custom LabVIEW program was used to operate the power supply. For CE-ESI, the voltages applied to the S, B, SW, and EO reservoirs were ?14, ?14, ?12, and +6 kV, respectively. To perform a gated injection, voltages were switched to ?14, ?13, ?13, and +6 kV for 0.5 seconds. This produced an electric field strength of 400 V/cm with an approximate flow rate of 165 nL/min For infusion-ESI, typical voltages were +5 kV at the S reservoir and +0.5 kV for the EO reservoir.
