What type of column is C18?

C18 columns are HPLC (high performance liquid chromatography) columns that use a C18 substance as the stationary phase. C18 HPLC columns are used in environmental sciences and chemical analysis, as well as industries such as pharmaceutical and environmental sciences, to analyze individual parts of chemical mixtures.

Why C18 column is used in HPLC?

C8 and C18 column in HPLC are two types of straight-chain alkyl groups used for the surface modification of silica in the reverse-phase chromatography of HPLC. Generally, silica is the most common type of stationary phase in the normal phase chromatography. However, it is a polar stationary phase.

Is C18 reverse phase?

A C18 column is an example of a “reverse phase” column. Reverse phase columns are often used with more polar solvents such as water, methanol or acetonitrile. The stationary phase is a nonpolar hydrocarbon, whereas the mobile phase is a polar liquid.

Is C18 column polar or nonpolar?

Why caffeine is used for HPLC calibration?

Caffeine is cheap, stable, safe and can be shipped without restrictions. It is not the best choice for wavelength calibration, but for injector precision and detector linearity it works well.

Is the stationary phase C18 polar or nonpolar?

nonpolar hydrocarbon
A C18 column is an example of a “reverse phase” column. Reverse phase columns are often used with more polar solvents such as water, methanol or acetonitrile. The stationary phase is a nonpolar hydrocarbon, whereas the mobile phase is a polar liquid.

Why pH is important in HPLC?

Since the retention of ionisable compounds are very sensitive to the mobile phase pH, it is necessary to control the pH of the mobile phase by the addition of a buffer. A buffer maintains the pH when a small amount of acid or base is added. Many different substances have been used for buffering in HPLC.