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In-syringe electrokinetic ampholytes focusing coupled with electrospray ionization mass spectrometry

Mikhail, IE ORCID: 0000-0001-5414-7401, Tehranirokh, M, Gooley, AA, Guijt, RM ORCID: 0000-0003-0011-5708 and Breadmore, MC ORCID: 0000-0001-5591-4326 2019 , 'In-syringe electrokinetic ampholytes focusing coupled with electrospray ionization mass spectrometry' , Analytical Chemistry, vol. 91, no. 13 , pp. 8259-8266 , doi: 10.1021/acs.analchem.9b00942.

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A 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%.

Item Type: Article
Authors/Creators:Mikhail, IE and Tehranirokh, M and Gooley, AA and Guijt, RM and Breadmore, MC
Keywords: analytical chemistry
Journal or Publication Title: Analytical Chemistry
Publisher: Amer Chemical Soc
ISSN: 0003-2700
DOI / ID Number: 10.1021/acs.analchem.9b00942
Copyright Information:

Copyright 2019 American Chemical Society

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