A Portable Liquid Chromatograph with a Battery-operated Compact Electroosmotic Pump and a Microfluidic Chip Device with a Reversed Phase Packed Column

Abstract

Although the dimensions (410 mm × 250 mm × 230 mm; w × l × h) were similar to those of the above system, the weight was reduced to approximately 10 kg. Boring et al. also presented a portable ion chromatograph that fits in a standard briefcase (280 × 430 × 150 mm) with a weight of 10 kg. A compact and lightweight liquid chromatography system is presented with overall dimensions of 26 cm width × 18 cm length × 21 cm height and weight of 2 kg. This system comprises a battery-operated compact electroosmotic pump, a manual injector, a microfluidic chip device containing a packed column and an electrochemical detector, and a USB buspowered potentiostat. The pumping system was designed for microfluidic-based reversed-phase liquid chromatography in which an electroosmotically generated water stream pushes the mobile phase via a diaphragm for the output. The flow rate ranged from 0 to 10 μL/min and had a high degree of precision. The pumping system operated continuously for over 24 h with dry batteries. The column formed in the microfluidic device was packed with 3-μm ODS particles with a length of 30 mm and a diameter of 0.8 mm.The results presented herein demonstrate the performance of the pumping system and the column using alkylphenols, catecholamine, catechin, and amino acids.

A Concentric Ring Electrode for a Wall‐jet Cell in a Microfluidic Device

“…Figure S7 displays the fluid velocity profile in this flow cell as determined by numerical simulation, which demonstrates that radial flow forms in this flow cell. The dead volume in the flow cell was 0.7 pL, while the channel flow cell that we previously reported had a dead volume of ∼20 nL . The use of a Ag/AgCl reference electrode shortened the time for the baseline to stabilize to 2 min, which is to be compared with the PDMS‐flow cell with a pseudo gold reference electrode that required over 1 h for the baseline to stabilize.…”

“…The optimized DEC2 ring array electrode was evaluated using the flow cell with the PEEK channel described above, with catechol (10 μmol/L) as the model target compound. Current was measured at a flow rate of 10 μL/min, which is a typical flow rate for chip‐based liquid chromatography . Figures a and b reveal that the current and the current density at DEC2 were 1.9‐ and 1.8‐times higher than those at the DISC electrode, respectively.…”

“…The PS substrate was used as received from the supplier without further cleaning following removal of the surface‐protection film. The electrodes (working, counter, and reference) were fabricated by directly depositing gold film on PS substrates without any adhesion layer (e. g., Cr and Ti) with an EBX‐8C vacuum coating system (ULVAC, Japan) . Electrodes were then patterned on the Au‐coated substrates using a standard photolithography and chemical‐etching process.…”

“…A microchannel (channel height: 15 μm) was fabricated in PDMS by soft lithography . The SU‐8 master was fabricated on a Pyrex 7740 glass plate.…”

Zero electrical power pump for portable high-performance liquid chromatography

“…Ishida et al presented a compact electroosmotic pumping system used in conjunction with a microfluidic chip based column and electrochemical detector. 4 The system was not able to achieve high pressure and fell short of LC pressures (0.75 MPa) restricting the choice of chromatographic columns and resulting in long analysis times, even for exemplar separations. Importantly it was the first demonstration of a completely integrated system incorporating a microfluidic chip being lightweight with an overall weight of 2 kg, not including the requisite computer system.…”