Gradient elution method for successive separation of common cations and hydrophobic amines using suppressed ion chromatography

In mixed waste, the separation and sequential determination of alkali and alkaline earth metals mixed with hydrophobic amines represent a challenging analytical problem. The effect of a new mobile phase (amido-sulfonic acid, ASA) on the suppressed ion chromatographic separation of alkali and alkaline earth metals and hydrophobic amines on CS12A analytical column was investigated. The addition of surface modifier to the eluent appears to provide better interfacial compatibility between the mobile and stationary phase and facilitates the rapid equilibration of analytes. Incorporation of a very low concentration of the additive may also alter the stationary phase surface by creating a fine tuning and improves the partition characteristics of the analytes. A dramatic and sufficient elution capability of amido-sulfonic acid (ASA) for sequential separation of the analytes was reported and rational mechanisms for the separated analytes are proposed. ASA can act as an ion pairing agent resulting in the separation of a wide variety of amines. The new mobile phase ( ASA) is proven to have more successful separation over methansulfonic acid (MSA), even with eluent free solvent. The proposed method shows that a profound particular effect on the separation of aliphatic diamine ( Ethylenediamine) and organic amine (Cyclohexylamine) was achieved in addition to all common cations and amines using isocratic elution of 18 mM of ASA without organic eluent modifier.