NH2 HPLC Columns
NH2 (Amino) HPLC columns are a type of high-performance liquid chromatography (HPLC) column that contains a stationary phase with amino functional groups (-NH2) attached to the surface. These columns are commonly used for the analysis of polar and moderately polar compounds. The amino groups on the stationary phase can interact with analytes through hydrogen bonding, polar interactions, and other mechanisms, making NH2 columns particularly useful for compounds that have polar functional groups or are capable of forming hydrogen bonds.
NH2 HPLC columns can be used in the positive phase or in the negative phase, but it should be noted that the positive phase solvent and the negative phase solvent are usually not mutually soluble. New NH2 HPLC columns are preserved in the positive phase environment under normal circumstances.
Key features of NH2 HPLC columns
- Polar selectivity: NH2 columns are well-suited for the separation of polar compounds such as amino acids, peptides, saccharides, and other small polar molecules. They can provide different selectivity compared to traditional reversed-phase columns.
- Hydrogen bonding: The amino groups on the column surface can form hydrogen bonds with analytes, leading to unique retention and separation characteristics.
- Normal-phase mode: NH2 columns are typically used in the normal-phase mode, which means the stationary phase is more polar than the mobile phase. This is in contrast to the reversed-phase mode where the stationary phase is nonpolar and the mobile phase is polar.
- Applications: NH2 columns are commonly used in the pharmaceutical, biotechnology, food and beverage, and environmental industries for a wide range of applications including the analysis of polar metabolites, small organic molecules, and other compounds that may not be easily separated using traditional reversed-phase columns.
Preservation of NH2 HPLC column
For the reversed phase, it can be preserved with 95% methanol or acetonitrile for short-term storage. Methanol should be replaced successively with isopropanol and chloroform, and finally preserved with n-ethane for long-term storage.
Usage of the NH2 HPLC column
1. For positive phase usage
It is not suitable to analyze the compounds containing aldehyde compounds, carbonyl compounds, and reducing sugar. The mobile phase shall be completely degassed and shall not contain carbonyl compounds or peroxides. When replacing the mobile phase of NH2 HPLC columns, ensure that the new mobile phase is mutually soluble with the original column storage solution.
2. For reversed phase usage
The ideal PH range is 3.0-7.0. The lower the PH the more risk of hydrolysis. If there is buffer salt in the mobile phase, use the same proportion mobile phase without buffer salt to avoid the precipitation of buffer salt.
It’s important to note that the choice of an HPLC column, including NH2 columns, depends on the specific analytes you’re working with, the desired separation, and the mobile phase conditions. Column selection should be based on the chemical characteristics of the compounds you’re analyzing, as well as the goals of your analysis.
When working with NH2 columns, be sure to follow the manufacturer’s guidelines for column care, conditioning, and usage to maintain the column’s performance and lifespan.