Amino stationary phases are incredibly versatile, finding applications in reverse phase, normal phase, and even HILIC (hydrophilic interaction liquid chromatography) separations.
Amino columns are built upon a silica-based amino propyl-bonded sorbent. This bonded stationary phase is what gives amino columns their versatility. The aminopropyl ligand is covalently connected to the silica base. In USP classification, amino stationary phases are often labeled as L8.
One of the standout features of amino columns is their high polarity, attributed to the primary amine moiety (NH2). Nitrogen (N) in NH2 is highly electronegative, leading to permanent polarization of the stationary phase. This feature is especially useful when you need to retain polar compounds in reverse phase mode. The retention time on an amino column is directly influenced by the analyte's polarity.
Amino columns exhibit a weak anion exchange phenomenon, making them ideal for retaining anions and organic acids. This feature is particularly valuable when working with acidic compounds.
The amino group (NH2) also plays a crucial role in hydrogen bonding. The analyte can retain for a longer time with Hydrogen bonding interaction.
Amino columns are a versatile and powerful tool in chromatography. Their ability to retain polar compounds, respond to pH changes, and engage in hydrogen bonding make them indispensable in various chromatographic applications. Whether you're working with polar analytes, acidic compounds, or carbohydrates, amino columns are your go-to stationary phase for consistent and reliable results in liquid chromatography.