Analytical methods for the determination of sugars in marine samples: A historical perspective and future directions
Limnol. Oceanogr. Methods 3:419-454 (2005) | DOI: 10.4319/lom.2005.3.419
ABSTRACT: Analytical techniques employed over the past three decades for sugar determination in marine samples are reviewed. This review first summarizes the different hydrolysis protocols used by marine biogeochemists to extract sugars from various marine matrices including sinking particulate organic matter (POM), dissolved organic matter (DOM), ultrafiltrated dissolved organic matter (UDOM), and sediments. The most commonly used methods for total sugar estimation are phenol sulfuric acid (PSA), 3-methyl-2-benzo thiazoline hydrazone hydrochloride (MBTH), and 2,4,6-tripyridyl-s-triazine (TPTZ). For individual sugars, gas chromatographyflame ionization detection (GC-FID), liquid chromatography-borate complexes (LC), high performance liquid chromatography-ethylenediamine derivatives (HPLC-EDA), high performance liquid chromatography-paminobenzoic acid derivatives (HPLC-p-AMBA), and high performance anion exchange chromatography-pulsed amperometric detection (HPAEC-PAD) have been employed, the last method being the most widely used. This study demonstrated that mild and strong hydrolysis give comparable results for open ocean samples, including POM, DOM, and UDOM (except for sediments) using chromatographic or colorimetric techniques. A survey of 130 sugar data sets revealed that more than half of the sugar-C escapes analysis using chromatographic or colorimetric techniques compared to 1H and 13C NMR techniques. The reconciliation of the NMR and colorimetric or chromatographic measurements is likely to be the key to the understanding of the composition of DOM. This study also demonstrated that most of the published sugar data obtained by chromatographic techniques are related to suspended or sinking POM and sediments, and that there is a need for data on sugar composition in DOM and UDOM, which involve further analytical difficulties for chromatographic analysis.