A gravity‐independent single‐phase electrode reservoir for capillary electrophoresis applications

Abstract

Capillary electrophoresis (CE) holds great promise as an in situ analytical technique for a variety of applications. However, typical instrumentation operates with open reservoirs (e.g., vials) to accommodate reagents and samples, which is problematic for automated instruments designed for space or underwater applications that may be operated in various orientations. Microgravity conditions add an additional challenge due to the unpredictable position of the headspace (air layer above the liquid) in any two‐phase reservoir. One potential solution for these applications is to use a headspace‐free, flow‐through reservoir design that is sealed and connected to the necessary reagents and samples. Here, we demonstrate a flow‐through high‐voltage (HV) reservoir for CE that is compatible with automated in situ exploration needs, and which can be electrically isolated from its source fluidics (in order to prevent unwanted leakage current). We also demonstrate how the overall system can be rationally designed based on the operational parameters for CE to prevent electrolysis products generated at the electrode from entering the capillary and interfering with the CE separation. A reservoir was demonstrated with a 19 mm long, 1.8 mm inner diameter channel connecting the separation capillary and the HV electrode. Tests of these reservoirs integrated into a CE system show reproducible CE system operation with a variety of background electrolytes at voltages up to 25 kV. Rotation of the reservoirs, and the system, showed that their performance was independent of the direction of the gravity vector.

Submersible Capillary Electrophoresis Analyzer: A Proof-of-Concept Demonstration of an In Situ Instrument for Future Missions to Ocean Worlds

“…These include the reagent and waste unit, the fluidic selection and distribution unit, the CE unit, and the pneumatic unit. The CE unit utilizes components that have been previously reported, such as rotor-stator injection valves, a high voltage compatible flow sensor, two gravity-independent high-voltage reservoirs that can operate at any orientation, and six bubble traps.…”