HPLC, or high-performance liquid chromatography, is an analytical technique performed in many laboratories in the separation of chemical compounds in a mixture. A sample is injected and carried into the system through a series of liquid pumps. The sample becomes separated through the HPLC column and enters a detector which analyses each chemical component. However, some analytical samples are not optimal for HPLC analysis. Understanding the strengths and weaknesses of an HPLC will help scientists determine when it is suitable to use this type of instrumentation.
Advantages: Short Analysis Time
HPLC requires the use of high-pressure pumps to push the liquid sample through a narrow bore column packed with silica beads. These pumps operate at pressures ranging from 100 to 400 pressure bars, depending on the solvent and size of column used. After the sample is separated through the column, a subsequent sample can be injected after a short period of time. This allows for a high throughput of sample analysis, which takes minutes per sample as opposed to hours with traditional chromatography.
A wide variety of organic compounds can be analysed using HPLC. Unlike gas chromatography, HPLC samples do not require volatility and do not need to be suspended in an organic solvent such as hexane or methanol. This allows for a wider range of possible analytical compounds.
Operating an HPLC system requires using many consumables, such as solvent, filters and plastic tubing. Pump seals and rotors must also be replaced on a routine basis for optimal operation. Lastly, HPLC columns have a limited lifespan (about 500 to 2000 injections) and must be replaced for proper chromatography. Columns are the most expensive item in an HPLC system, and depending on the composition of the packing material, they can range from £195 to £585.
Disadvantages: High Maintenance
HPLC systems are complex pieces of machinery with many moving parts. Software errors and leaks may occur at any time, so knowing the symptoms of the system is key in fixing any problem. Proper preventive maintenance procedures must be performed by a trained technician to prevent major malfunctions in the system. Replacing various pump seals, rotors and columns are just a few of the tasks that need to be performed on a routine basis.