Extraction of marine organic matter on XAD-2: Effect of sample acidification and development of an in situ pre-acidification technique

Dissolved organic materials in seawater were extracted on XAD-2 from both acidified and non-acidified samples. Nearly three times as much material is extracted by acidification. The material extracted is chemically distinct from that extracted without acidification. Chelex-100 ion exchange resin was used as a solid phase pre-acidification device for organic matter extraction on XAD in situ. The compounds extracted on XAD using this means of pre-acidification are similar to those extracted using HCl as the pre-acidifier. The similar extraction efficiency and chemical nature of compounds separated using the traditional pre-acidification technique and the Chelex-100 system suggests that the cation exchange technique may be a promising means of in situ acidification of seawater with subsequent extraction of humic materials on XAD.