USE OF PRINCIPAL COMPONENT AND CLUSTER-ANALYSIS FOR THE COMPARISON OFREVERSED-PHASE HPLC COLUMNS

The retention of ethoxylated nonylhylphenyl surfactants was determined in reversed-phase high-performance liquid chromatography (RP-HPLC) us ing various supports (C1, C2, C6, C8, C18, polyethylene-coated silica, and polyethylene-coated alumina). The retention data matrix was evalu ated both by principal component analysis and cluster analysis. The re tention characteristics of both polyethylene-coated supports were simi lar to that of C1, the retention capacity of RP columns for surfactant s increased with the increasing length of the covalently bonded hydroc arbon chain. The retention of ethoxylated surfactants depended nonline arly on the length of ehtyleneoxide chain suggesting that the polar et hyleneoxide chains are in folded state under the chromatographic separ ation.