YMC-Pack Polyamine II is based on ultrapure YMC silica as a support material. The functionality of the stationary phase is achieved by a covalently bonded polymer layer containing secondary (2°) and tertiary (3°) amino groups. The 2° and 3° amino groups of YMC-Pack Polyamine II are only weakly nucleophilic, exhibiting a significantly reduced reactivity towards carbonyl compounds. Therefore, unlike conventional amino phases with primary n-propylamino ligands, YMC-Pack Polyamine II does not form Schiff' bases or other stable condensation products. In addition, the 2° and 3° amino groups of the polymer layer are to a large extent resistant to oxidation and hydrolysis (Fig. 1).

Fig. 1: Life-time study of amino type packings [a] conventional amino phase [b] YMC-Pack Polyamine II

The low reactivity of the 2° and 3° amino groups preserves the long-term retention characteristics and selectivity of YMCPack Polyamine II. Compared to conventional amino phases, one of their most outstanding benefits is the significantly prolonged lifetime. As the silica matrix is completely polymer coated, even the short-term use of basic eluents up to pH 10.5 is possible. Reducing sugars are often adsorbed irreversibly to conventional amino phases. This causes problems in recovery and quantitation. With YMC-Pack Polyamine II columns however, the adsorption of reducing sugars plays only a minor role. As a result a high recovery of these compounds can be obtained which is beneficial for accurate and reliable quantitation.

Recommendations
The recommended pH range for YMCPack Polyamine II is 2-9. Remove acid and buffer salts before storage. Recondition and store the column in acetonitrile/ water = 75/25.
For maintenance, the following recommendations should be used: on loss of selectivity
due to contamination with polar compounds, flush the column thoroughly with water. After irreversible binding of anions, the column performance can be recovered by flushing with 50 mM borate buffer (50 mM boric acid, adjusted to pH 9.0 with NaOH). Remove undesired organic contaminants by flushing with acetonitrile or tetrahydrofuran (THF).
Clogged inlet frits can be cleaned by changing the flow direction. The column back pressure should be kept below 2900 psi (200 bar), and the temperature should not
exceed 50 °C.

Column Care
YMC-Pack Polyamine II is stable towards hydrolysis between pH 2.0-9.0. Remove acid and buffer salts before storage. For detailed information please refer to the “Column Care and Use Instructions” which are shipped with each analytical column.