Dissolved carbohydrates in streamwater determined by HPLC and pulsed amperometric detection

Dissolved total saccharides (DTS) and dissolved free monosaccharides (DFMS) in streamwater were determined by high-performance liquid chromatography with pulsed amperometric detection (HPLC-PAD). HPLC identification was verified with gas chromatography/mass spectrometry measurements. The method for DTS was improved by using a column with an anion exchange capacity of 4,500 mu eq and a mobile phase of 350 mM NaOH. The detection limits for individual monosaccharides ranged from 2 to 14 nM. The average recovery for monosaccharide standards was 82% after hydrolysis, and 75% of the monosaccharides in streamwater hydrolysates were recovered following a desalting procedure. Hydrolysis of model substances showed recoveries of monosaccharides between 78 and 98%. The C.V. for a hydrolyzed stream sample was 15% for the DTS. Stream samples stored at room temperature after filtration and acidification to pH 1.1 were stable for at least 23 d. Concentrations of DTS in White Clay Creek, including sugar alcohols and amino sugars, ranged from 0.64 to 12.70 mu M and accounted for 2.9-12.1% of the dissolved organic carbon pool. Neutral sugars dominated the DTS pool, and glucose and galactose were the most abundant molecules. Concentrations of DFMS ranged from 0.05 to 0.38 CL hl and accounted for 0.06-0.33% of the dissolved organic carbon pool.