Retention Characteristics of Four Different HILIC Stationary Phases in the Analysis of Meat Polar Compounds

Hydrophilic interaction chromatography has been used to investigate the retention characteristics of a group of polar compounds typically present in meat like carnosine (Car), anserine (Ans), creatine (Cr), creatinine (Cn), glutathione oxidised (GSSG), glutathione reduced (GSH) and nicotinamide adenine dinucleotide (NADH). These compounds were separated using four polar stationary phases composed by bare silica, amide and zwitterionic groups bound to porous silica and zwitterionic groups attached to a polymeric bead. Ammonium acetate salt used in the mobile phase was found to provide the best results in selectivity and reproducibility. The effect of salt concentration together with pH and acetonitrile (ACN) content of the eluent on the retention of the different polar stationary phases was also studied. A linear gradient of ACN from 80% to 30% with 10 mM ammonium acetate at neutral pH values (pH 6.0 and pH 7.8) offered retention factors k ≤ 10 while keeping a resolution higher than 1.5 for all the assayed compounds in bare silica and amide columns. The separation of NADH from GSSG was not possible under the studied conditions at any salt concentration using zwitterionic columns.