Simultaneous determination of neutral sugars, alditols and anhydrosugars using anion-exchange chromatography with pulsed amperometric detection: Application for marine and atmospheric samples

Abstract

An improved high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) method is described for the simultaneous determination of neutral sugars (hexoses, pentoses and deoxysugars), alditols and anhydrosugars commonly found in atmospheric and marine samples. The method uses a CarboPac MA1 column, at a flow rate of 0.3 mL min−1, and a NaOH gradient (250–700 mM). The proposed method applies a temperature gradient (from 25 to 28 °C) to the column for the first 30 min of the analysis, followed by a constant temperature at 28 °C until the end of the analysis. These analytical conditions allowed the separation of 15 out of 17 carbohydrates in 75 min with resolution factors better than 0.5 for the critical pairs levoglucosan/arabitol, galactosan/arabinose, arabinose/mannose and glucose/xylose.The application of this method to field samples revealed that anhydrosugars represented 53% of total neutral carbohydrates (TCHO) in total suspended atmospheric particles (TSP), whereas they were detected for the first time in marine particulate organic matter (POM) and high-molecular-weight dissolved organic matter (HMWDOM) samples accounting 2% and 3% of TCHO, respectively. Levoglucosan and/or galactosan were the major anhydrosugars in all samples however, their concentrations are undoubtedly underestimated because hydrolysis was applied to the marine samples prior to the HPAEC-PAD analysis. Despite this underestimation, their presence in the marine samples clearly indicates possible terrestrial input most likely via atmospheric deposition as these compounds are considered terrestrial burring biomass tracers. Finally, deoxysugars were also detected for the first time in the TSP sample representing 1% of TCHO, while alditols accounted for 0.4% and 0.3% of TCHO in POM and HMWDOM, respectively.