Determination of neutral sugars and hexosamines by high-performance liquid chromatography with pulsed amperometric detection

Abstract

Procedures are described using high-performance liquid chromatography with pulsed amperometric detection for the measurement of neutral sugars and amino sugars released upon acid hydrolysis of non-starch polysaccharides. One procedure measures the neutral sugars with near-baseline separation in a 36 min run. The second procedure measures amino sugars and all neutral sugars except rhamnose and arabinose, which co-elute under the conditions described, in a 40 min run. Neutral sugars released from non-starch polysaccharides are ionized at high pH and separated by anion-exchange chromatography using NaOH as the eluent. When hexosamines or N-acetylhexosamines are present, as in mycoprotein and mushrooms or in ileostomy effluent, separation is achieved isocratically using 0.1 mmol dm^–3 NaOH. The sulfate ions present in the hydrolysate are prevented from reaching the analytical column by a pre-column guard. Post-column addition of 300 mmol dm^–3 NaOH increases the analytical signal and minimizes baseline drift. When only neutral sugars are present in the hydrolysate a single dilution step is required before analysis. When neutral sugars and hexosamines are present, a simple two-step neutralization and dilution are performed before injection.