Comprehensive Guide to HPLC: Understanding Pumps

Introduction

Topic: Detailed overview of High-Performance Liquid Chromatography (HPLC) pumps.
The video aims to provide complete understanding of HPLC pumps, preparing viewers for more advanced topics in future series.

Purpose: Solvent delivery module that transports the mobile phase from solvent bottles to the column at a specified flow rate and composition.
Configuration: Modern pumps have at least one pair of reciprocating pistons and check valves to ensure one-way flow of the mobile phase.

Serial Pumps:
- Mechanism: The primary piston fills the pump head with mobile phase and pushes it into the system, partially filling the secondary pump.
- Operation: Secondary piston completes the delivery to the system.
- Challenges: Requires double operation cycles for primary piston, causing more wear on mechanical parts.
Parallel Pumps:
- Mechanism: Both pistons work independently, alternating to deliver the mobile phase.
- Benefits: Requires two pairs of check valves but ensures pulsation-free flow, reducing part wear.

Characteristics:
- No change in mobile phase mixing rate during analysis.
- Recommended for simple applications analyzing one or two analytes.
- Provides superior repeatability.
- Uses a single mobile phase line (isocratic pump).

Characteristics:
- Varies mobile phase mixing rate during analysis.
- Suitable for analyzing multiple analytes.
- Optimizes peak conditions, shortens analysis time, and sharpens peak shapes.
Subtypes:
- Low Pressure Gradient:
  - Uses gradient proportioning valve before pump head (quaternary pump).
  - Can mix up to four solvents.
- High Pressure Gradient:
  - Requires two pump heads, with a mixer following (binary pump).
  - Used for high productivity or resolution, can mix up to two solvents.

Stable Flow Rate: Should provide stable flow and pressure with pulse elimination.
Inert Flow Paths: Compatible with various solvents.
Durability: Parts should endure high-pressure conditions.
Operational Modes: Availability of both isocratic and gradient modes.

Degassing Solvents: Prevents flow fluctuation and poor repeatability by removing air bubbles.
Solvent Check: Ensure adequate solvent presence to avoid air introduction into the system.
System Rinsing: Necessary after using buffers to remove residual salts.
Solvent Miscibility: Ensure solvents are fully miscible for stable flow.
Pump Priming: Essential before use.
Pressure Monitoring: Keep track of pump pressure during analysis.

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