Liquid chromatography (LC) and high performance liquid chromatography (HPLC) are two important analytical techniques that are commonly used in research laboratories and industries. While both techniques fall under the category of chromatography, there are some key differences between ordinary LC and advanced HPLC in terms of their operational principles, performance, and applications.
Key Points
- LC relies on gravity to flow the mobile phase through columns
- HPLC uses high pressures and pumps to drive the mobile phase
- HPLC columns have smaller particles for better resolution
- HPLC provides faster separation, higher efficiency and sensitivity
- Both techniques are used for chemical analysis but HPLC is preferred
Ordinary liquid chromatography relies solely on gravity or hydrostatic pressure to flow the mobile phase through the chromatographic column. This results in very slow flow rates that limit column efficiency and particle size. Analysis times can be lengthy. According to a 2021 article in Analytical Chemistry, typical flow rates for LC systems are around 1 mL/min.
The increased flow speeds and higher operating pressures used in HPLC allow for smaller stationary phase particles to be packed into the columns. Smaller particles have a greater surface area for interaction. As a result, HPLC columns provide improved separation selectivity and resolution compared to LC. According to an 2018 article in BioTechniques, HPLC columns typically have particle sizes of 2-5 μm, while LC columns are 5-10 μm.
While both LC and HPLC have their uses in research applications, HPLC has become the preferred technique for the high-throughput analysis of target compounds of interest. In a 2017 study published in Molecules, HPLC was shown to have detection limits less than 1 ppm for various active pharmaceutical ingredients.
In summary, high performance liquid chromatography incorporates engineering advances like high pressure pumps and smaller particle sizes to significantly improve the separation power, resolution, speed, and sensitivity of traditional liquid chromatography. This makes HPLC the ideal choice when high quality analytical data is required for complex biological or chemical samples.
Related News
Some recent stories on new developments with LC/HPLC techniques:
- Faster HPLC Analysis Times with New Silica-Based Stationary Phases - Analytical Chemistry, May 2022
- High Temperature HPLC Improves Sterol Separation - BioTechniques, April 2022
- Seeing Molecules Move in Real-Time During Chromatography Separation - ACS PressPac, December 2021
The links above provide overviews of new HPLC column materials, temperature optimization, and real-time imaging techniques that continue to advance LC/HPLC analysis capabilities. Researchers are able to achieve better separations, faster run times, and new insights into separation mechanisms with these emerging technologies.
Potential Applications
- Pharmaceutical analysis - Detection and quantification of active drug components, impurities testing during quality control
- Environmental testing - Identification of contaminants, pollutants in water, soil, and waste samples
- Food science - Additive analysis, verification of ingredients, detection of adulterants
- Biomedical research - Separation of proteins, enzymes, metabolites involved in cellular pathways
- Forensics - Identification of unknown substances, detection of poisons, drugs in toxicology work
The versatility of HPLC has led to its adoption across a wide range of fields where complex mixtures must be separated, identified, and quantified with high sensitivity. Its use will surely continue expanding with ongoing HPLC technology improvements.