• Home
  • Search Results
  • Design and performance evaluation of a microfluidic ion-suppression module for anion-exchange chromatography.

Design and performance evaluation of a microfluidic ion-suppression module for anion-exchange chromatography.

Journal of chromatography. A (2014-06-30)
Sam Wouters, Bert Wouters, Sander Jespers, Gert Desmet, Hamed Eghbali, Cees Bruggink, Sebastiaan Eeltink
ABSTRACT

A microfluidic membrane suppressor has been constructed to suppress ions of alkaline mobile-phases via an acid-base reaction across a sulfonated poly(tetrafluoroethylene)-based membrane and was evaluated for anion-exchange separations using conductivity detection. The membrane was clamped between two chip substrates, accommodating rectangular microchannels for the eluent and regenerant flow, respectively. Additionally, a clamp-on chip holder has been constructed which allows the alignment and stacking of different chip modules. The response and efficacy of the microfluidic chip suppressor was assessed for a wide range of eluent (KOH) concentrations, using 127 and 183μm thick membranes, while optimizing the flow rate and concentration of the regenerant solution (H2SO4). The optimal operating eluent flow rate was determined at 5μL/min, corresponding to the optimal van-Deemter flow velocity of commercially-available column technology, i.e. a 0.4mm i.d.×250mm long column packed with 7.5μm anion-exchange particles. When equilibrated at 10mM KOH, a 99% decrease in conductivity signal could be obtained within 5min when applying 10mM H2SO4 regenerant at 75μL/min. A background signal as low as 1.2μS/cm was obtained, which equals the performance of a commercially-available electrolytic hollow-fiber suppressor. When increasing the temperature of the membrane suppressor from 15 to 20°C, ion suppression was significantly improved allowing the application of 75mM KOH. The applicability of the chip suppressor has been demonstrated with an isocratic baseline separation of a mixture of seven inorganic ions, yielding plate numbers between 5300 and 10,600 and with a gradient separation of a complex ion mixture.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Sulfuric acid, ACS reagent, 95.0-98.0%
Sigma-Aldrich
Formic acid, reagent grade, ≥95%
Sigma-Aldrich
Sulfuric acid, 99.999%
Sigma-Aldrich
Formic acid, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥98%
Sigma-Aldrich
Formic acid, ACS reagent, ≥96%
Supelco
Sulfuric acid concentrate, 0.1 M H2SO4 in water (0.2N), eluent concentrate for IC
Sigma-Aldrich
Formic acid, puriss., meets analytical specifications of DAC, FCC, 98.0-100%
Sigma-Aldrich
Phenylacetic acid, 99%
Supelco
Sulfuric acid, for the determination of nitrogen, ≥97.0%
Sigma-Aldrich
Formic acid, ACS reagent, ≥88%
Sigma-Aldrich
Sulfuric acid, puriss. p.a., for determination of Hg, ACS reagent, reag. ISO, reag. Ph. Eur., 95.0-97.0%
Sigma-Aldrich
Formic acid, ≥95%, FCC, FG
Sigma-Aldrich
Sulfuric acid, puriss., meets analytical specification of Ph. Eur., BP, 95-97%
Sigma-Aldrich
Phenylacetic acid, ≥99%, FCC, FG
Sigma-Aldrich
Formic acid solution, BioUltra, 1.0 M in H2O
Sigma-Aldrich
Sulfuric acid solution, puriss. p.a., ≥25% (T)
Sigma-Aldrich
Phenylacetic acid, suitable for plant cell culture