Helium for HPLC solvent degassing
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HPLC is commonly used in pharmaceutical research and development applications such as drug discovery. Clinical laboratories also rely on HPLC for blood and urine sample analysis.
HPLC is used to separate chemicals in a liquid sample to allow qualitative and quantitative analysis in the detector which follows the chromatography column. Mass spectrometer (LC-MS), photodiode array (PDA) and UV/visible light spectroscopy detectors are the most common ones to use in combination with HPLC, although fluorescence, FID and other detectors may also be used. The technique finds common application in many branches of organic chemistry, such as pharmaceutical production quality control, drug discovery R&D and forensic testing, and clinical diagnosis.
In the LC-MS system, at the point where the liquid mobile phases leave the HPLC column, the liquid sample is sprayed, or nebulised, to produce micro-droplets. These rapidly evaporate to release ionised analyte molecules, which are then separated and detected by the mass spectrometer. High-flow sprays require a high flow of nitrogen to assist with nebulization of the sample. Coregas Nitrogen 5.0 is recommended as a LG-MS nebuliser gas.
HPLC has many similarities to gas chromatography. Both use a column packed with an adsorbent material to separate the components of the sample, which is passed through the column in the mobile phase. The main difference is that HPLC operates in the liquid phase and the carrier is a liquid solvent (typically water mixed with methanol or acetonitrile), whereas the carrier for the mobile phase in gas chromatography will be a gas, such as helium. Helium is also used in HPLC for degassing the mobile phase solvents.