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In-syringe electrokinetic ampholytes focusing coupled with electrospray ionization mass spectrometry
journal contribution
posted on 2019-07-01, 00:00 authored by I E Mikhail, M Tehranirokh, A A Gooley, Rosanne GuijtRosanne Guijt, M C BreadmoreA 25 μL analytical glass syringe has been used for isoelectric focusing (IEF) utilizing the stainless-steel needle and plunger as electrodes. The generation of protons and hydroxyl ions at the electrodes facilitated a neutralization reaction boundary (NRB) mechanism to focus different amphoteric compounds, such as hemoglobin, bovine serum albumin, R-phycoerythrin, and histidine, within minutes. After optimization of different experimental parameters affecting the IEF process and the coupling of the IEF syringe with electrospray ionization mass spectrometry (ESI-MS), a BGE composed of NH4Ac, 1.0 mM, pH 4.0, in 70.0% (v/v) acetonitrile was used for the IEF of histidine. A voltage of -200 V was applied for 5.0 min to accomplish the IEF and increased to -400 V during the infusion to ESI-MS at a flow rate of 4.0 μL/min. The coaxial sheath liquid consisting of 0.2% (v/v) formic acid was added at 4.0 μL/min. The detection limit was found to be 2.2 μg/mL and a nonlinear quadratic fit calibration curve was constructed for histidine over the range of 4.0-64.0 μg/mL with a correlation coefficient (r) = 0.9998. The determination of histidine in spiked urine samples as relevant for the diagnosis of histidinemia was demonstrated by the IEF syringe-ESI-MS system with accuracy from 88.25% to 102.16% and a relative standard deviation less than 11%.
History
Journal
Analytical chemistryVolume
91Issue
13Pagination
8259 - 8266Publisher
American Chemical SocietyLocation
Washington, D.C.Publisher DOI
ISSN
0003-2700eISSN
1520-6882Language
engPublication classification
C Journal article; C1 Refereed article in a scholarly journalUsage metrics
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