A Comparison of High Performance Liquid Chromatography and Ultra Performance Liquid Chromatography

Those who have experience with experiments know that High-Performance Liquid Chromatography (HPLC) and Ultra Performance Liquid Chromatography (UPLC) are commonly used component separation techniques in the laboratory. Given their common functions, many may find it difficult to distinguish between the two. In the following paragraphs, the writer will provide a brief explanation of the dissimilarities between HPLC and UPLC to aid readers in comprehending these two methods.

Definition of High-Performance Liquid Chromatography
High-Performance Liquid Chromatography (HPLC), also known as “High-Pressure Liquid Chromatography,” “High-Speed Liquid Chromatography,” “High Separation Efficiency Liquid Chromatography,” and “Modern Column Chromatography,” is an important branch of chromatography. It uses liquid as the mobile phase and a high-pressure delivery system to pump a single solvent with different polarities or a mixture of solvents and buffers with different ratios as the mobile phase into a chromatographic column packed with a stationary phase. After each component is separated within the column, it enters the detector for analysis, thereby achieving sample analysis.
Definition of Ultra Performance Liquid Chromatography
Ultra Performance Liquid Chromatography (UPLC) utilizes the theories and principles of High-Performance Liquid Chromatography (HPLC) and includes new technologies such as small particle packing, very low system volumes, and rapid detection methods. These new technologies increase the analysis throughput, sensitivity, and peak capacity of chromatography.
The principles of ultra-performance liquid chromatography (UPLC) and high-performance liquid chromatography (HPLC) are essentially the same, with the following few differences:

1. The emergence of small particle, high-performance stationary phases. The particle size of the chromatography column used in HPLC, such as the commonly used C18-bonded silica gel column, is 5μm or 3μm, while the chromatography column used in UPLC can reach 1.8μm or even 1.7μm. Such a particle size is more conducive to substance separation.
2. The use of ultra-high-pressure pumps.
   Due to the smaller particle size of the chromatographic column used in UPLC, the pressure generated during use naturally increases by several times. Therefore, the liquid delivery pump of the chromatography system is also changed to an ultra-high-pressure pump.
3. The use of low-diffusion, low-cross-contamination automatic injectors. Equipped with a needle-injection probe and pressure-assisted injection technology.
4. High-speed and sensitive detectors for fast sampling.
5. Optimized design of the entire system. The chromatography workstation is equipped with various software platforms, allowing for automatic switching between UPLC and HPLC analysis methods.

Compared with traditional HPLC, UPLC has 9 times faster speed, 3 times higher sensitivity, and 1.7 times better separation performance. It reduces analysis time, and solvent usage, and lowers costs.

However, due to the high pressure generated inside the instrument during the experiment, corresponding problems may arise. For example, the pump’s service life may decrease, the aging speed of the instrument’s connection parts may accelerate, and components such as one-way valves are prone to failure.

Application

Due to its higher sensitivity, UPLC can be used for more complex samples, where the amounts of various components may be smaller. Some examples include dietary supplements and biological samples. On the other hand, high-performance liquid chromatography is used for relatively simpler applications, such as water purification and the detection of impurities in drugs.