HPLC system care and troubleshooting is an important activity in any analytical chemistry lab. Liquid chromatography systems have become real workhorses for laboratory chemical analysis, but scientists have developed a love-hate relationship with these systems. The wide range of applications delights users, while varied complexity, robustness, and performance frustrate them. Unlike other laboratory tools, these systems are not a “plug and play” solution. There are several brands and models, but the basic operation is similar across the board. Lab technicians need some training and experience to get LC systems to perform well. This article will cover the basics of maintaining and troubleshooting your HPLC system.
All liquid chromatography systems have the same four basic components – Injectors, Pumps, Columns, and Detectors. There can be other components added before, after, or inline with these items. For example:
Autosampler (before) – automatically feed multiple samples unattended
Fraction Collector (after) – collect portions of the eluent as it comes off of the column
Additional Detector (inline) – analyze the sample with different technologies
Sample Preparation Automation (before) – perform complex sample prep assays prior to HPLC separation
Mass Spectrometer (after) – essentially another detector, but there’s enough here to cover in a separate article.
Most pump-related issues are due to a failure to prime the system properly. Upon startup, users should always prime the pump and verify that the flow is constant on all channels. Pump-priming issues can be detrimental to chromatography results in several ways, including no flow, erratic flow, mixing problems, incorrect gradients, bubble formation, and more.
Isocratic Pump – This is the simplest pump type. It uses a single pump to deliver a single solvent for the mobile phase.
Binary Pump – This pump uses two pumps and can mix up to two different solvents in varying proportions over the course of a run for gradient mobile phases.
Quaternary Pump – This pump uses a single pump, but has a special proportioning valve to mix up to four different solvents for complex mobile phase gradients.
Typical Binary Pump (Agilent 1200 Series)
Typical Quaternary Pump (Agilent 1100 Series)
what out for the concluding part!
Posted by Opeyemi Akinbuli
[email protected], www.aasnig.com