title: Effect of Ca2+ on the 1H NMR chemical shift of the methyl signal of oversulphated chondroitin sulphate, a contaminant in heparin.
abstract: The chemical shift of the methyl signal of oversulphated chondroitin sulphate (OSCS) is dependent on the type and concentration of the counterion. When OSCS is present as a contaminant in heparin sodium, the reported methyl 1H chemical shift is 2.15 +/- 0.02 ppm. In this report, a value of 2.18 +/- 0.01 ppm is reported for the OSCS in the presence of Ca2+. The chemical shift of the methyl signal of pure OSCS varies linearly from 2.13 ppm to 2.18 ppm with increasing amounts of Ca2+, until reaching the saturation point of four Ca2+ ions per OSCS disaccharide unit, which contains four sulphate groups (a 1:1 ratio between sulphate groups and Ca2+). This Ca2+ effect can be used for OSCS identification as well as to facilitate quantification.
authors.affiliation: Medical Products Agency, Box 26, SE-75103 Uppsala, Sweden. ian.mcewen@mpa.se
authors.forename: Ian
authors.initials: I
authors.lastname: McEwen
authors.forename: Torgny
authors.initials: T
authors.lastname: Rundlöf
authors.forename: Marianne
authors.initials: M
authors.lastname: Ek
authors.forename: Birgit
authors.initials: B
authors.lastname: Hakkarainen
authors.forename: Gunnar
authors.initials: G
authors.lastname: Carlin
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Arvidsson
mesh_terms: D000925:Anticoagulants / Q000032:analysis*; D002118:Calcium / Q000737:chemistry*; D002240:Carbohydrate Sequence; D002809:Chondroitin Sulfates / Q000032:analysis*; D004340:Drug Contamination; D006493:Heparin / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D008969:Molecular Sequence Data; D017762:Nadroparin / Q000032:analysis; D013431:Sulfates / Q000737:chemistry
chemical_list: D000925:Anticoagulants; D017762:Nadroparin; D013431:Sulfates; C006871:calcium heparin; D006493:Heparin; D002809:Chondroitin Sulfates; D002118:Calcium