WHAT IT IS
Pumps in ion chromatography (IC) deliver the eluent through the system at controlled flow rates and pressures. They play a central role in maintaining reproducible separations and enabling precise timing for suppression and detection. Most IC systems use dual-piston pumps arranged in series to reduce pulsation and ensure smooth flow. The specific pump type determines whether the system supports isocratic or gradient operation, the number of eluents that can be mixed, and compatibility with microbore or high-pressure workflows.
TYPES OF PUMPS IN IC
Dual-Piston Pumps – The most common pump type in IC, featuring two pistons working in alternating cycles to provide a nearly continuous, low-pulse flow. These pumps are often microprocessor-controlled and used in both isocratic and gradient systems. Suitable for routine analysis, they balance robustness with precision.
Gradient-Capable Pumps – Designed for binary to quaternary gradient formation, these pumps support the mixing of multiple eluents. They allow dynamic changes in eluent composition, improving resolution and peak shape for complex separations. Often found in advanced or upgradeable systems.
Isocratic Pumps – Deliver a constant eluent composition and are typically used in simpler, cost-effective systems. While limited in method flexibility, they are reliable for routine applications with stable separation conditions.
Microbore-Compatible Pumps – Engineered to operate at lower flow rates with minimal pulsation, these pumps are used with narrow-bore columns and capillary IC formats. They enable sensitive analysis with smaller sample and eluent volumes.
Digitally Controlled or “Smart” Pumps – Feature integrated diagnostics, flow correction algorithms, and adaptive control for viscosity or wear. These pumps improve long-term stability and reduce maintenance requirements, especially in multi-solvent environments.
IMPACT ON PERFORMANCE
Flow Stability: Dual-piston designs ensure continuous, low-pulsation flow, improving retention time precision and detector response.
Method Flexibility: Gradient-capable pumps expand separation options, supporting complex or multi-analyte methods.
Pressure Range: High-pressure pumps enable the use of long or small-particle columns for better resolution.
Application Fit: Isocratic pumps suit high-throughput or single-method labs, while microbore and smart pumps address sensitivity or automation needs.
Service and Reliability: Pump type affects maintenance frequency, solvent compatibility, and long-term performance under demanding conditions.