title: Copper complexing properties of melanoidins and marine humic material.
abstract: Melanoidins, condensation products of sugars and amino acids, represent a key link in the transformation of polysaccharides to humic material in the marine environment. We investigated the complexing capacity of melanoidins that were prepared in deionized water and seawater and separated into different molecular mass fractions. The copper complexing properties of humic material isolated from marine lagoon sediments were determined for comparison. Melanoidins prepared using condensation times longer than two days exibit complexation properties towards copper ions that appear to depend on the basicity of the amino acid precursor and the molecular mass of the product. Pseudomelanoidins, prepared from glucose only, do not complex copper ions at all, regardless of the molecular mass. The highest copper complexing capacity value among melanoidins was measured for a glucose-lysine melanoidin with molecular mass fraction >10 kD (L(T)=2.1x10(-7) molCu(2+)/L). Melanoidin prepared from glucose and glutamic acid >10 kD was similar in complexing capacity to fulvic acid (1-20 kD molecular mass) isolated from lagoon sediments. The presence of calcium and magnesium ions and other macro and microconstituents in the seawater used to prepare melanoidins influences its complexing properties towards metal ions.
authors.affiliation: Ruder Bosković Institute, Center for Marine and Environmental Research, POBox 180, HR-10002 Zagreb, Croatia. plavsic@rudjer.irb.hr
authors.forename: Marta
authors.initials: M
authors.lastname: Plavsić
authors.forename: Bozena
authors.initials: B
authors.lastname: Cosović
authors.forename: Cindy
authors.initials: C
authors.lastname: Lee
mesh_terms: D000596:Amino Acids / Q000032:analysis / Q000737:chemistry; D001578:Benzopyrans / Q000032:analysis / Q000737:chemistry; D002118:Calcium / Q000737:chemistry; D002241:Carbohydrates / Q000032:analysis / Q000737:chemistry; D003300:Copper / Q000032:analysis / Q000737:chemistry*; D004563:Electrochemistry; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry; D008970:Molecular Weight; D011108:Polymers / Q000032:analysis / Q000737:chemistry*; D012623:Seawater / Q000032:analysis / Q000737:chemistry*; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D000596:Amino Acids; D001578:Benzopyrans; D002241:Carbohydrates; D006812:Humic Substances; D011108:Polymers; D014874:Water Pollutants, Chemical; C011908:melanoidin polymers; D003300:Copper; D008274:Magnesium; D002118:Calcium; C005023:fulvic acid