Closed Single-Phase Electrode Reservoir with High Voltage Decoupling for Capillary Electrophoresis

Capillary electrophoresis is an analytical technique demonstrated in various setups for multiple analytical tasks, including the analysis of (bio)substances. Classical and modern capillary electrophoresis instrumentation operates with open reservoirs (e.g., vials) to accommodate reagents and samples. However, this approach is inappropriate for space applications, especially in microgravity conditions, due to the presence and unpredictable position of the headspace (air layer above the liquid). A potential solution for microgravity is to use a headspace-free flow-through mechanism to deliver liquid reagents and samples. However, fluidic paths connected to high-voltage (HV) reservoirs, if not properly electrically isolated, introduce the risk of damage to connected instrumentation due to electric current leakage. This paper aims to take the first step toward space-appropriate design, namely, to demonstrate a flow-through HV reservoir for capillary electrophoresis. The reservoir has an easily serviceable HV electrode housing and an HV decoupling mechanism to protect HV-sensitive components. The length of the background electrolyte-filled channel that connects the separation capillary with the HV electrode is 19 mm; its inner diameter is 1.8 mm. Current stability and electrophoretic separation tests indicate that the device performs well up to 25 kV of separation voltage with low- and high-conductivity acidic and alkaline background electrolytes.