Sensitive detection of oversulfated chondroitin sulfate in heparin sodium or crude heparin with a colorimetric microplate based assay
Research article published in Analytical chemistry (2011)
Abstract
In this work we describe a 96-well microplate assay for oversulfated chondroitin sulfate A (OSCS) in heparin, based on a water-soluble cationic polythiophene polymer (3-(2-(N-(N'-methylimidazole))ethoxy)-4-methylthiophene (LPTP)) and heparinase digestion of heparin. The assay takes advantage of several unique properties of heparin, OSCS, and LPTP, including OSCS inhibition of heparinase I and II activity, the molecular weight dependence of heparin-LPTP spectral shifts, and the distinct association of heparin fragments and OSCS to LPTP. These factors combine to enable detection of the presence of 0.003% w/w spiked OSCS in 10 μg of heparin sodium active pharmaceutical ingredient (API) using a plate reader and with visual detection to 0.1% levels. The same detection limit for OSCS was observed in the presence of 10% levels of dermatan sulfate (DS) or chondroitin sulfate A (CSA) impurities. In addition, we surveyed a selection of crude heparin samples received by the agency in 2008 and 2009 to determine average and extreme DS, CSA, and galactosamine weight percent levels. In the presence of these impurities and the variable heparin content in the crude heparin samples, spiked OSCS was reliably detected to the 0.1% w/w level using a plate reader. Finally, authentically OSCS contaminated heparin sodium API and crude samples were distinguished visually by color from control samples using the LPTP/heparinase test.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
In this work we describe a 96-well microplate assay for oversulfated chondroitin sulfate A (OSCS) in heparin, based on a water-soluble cationic polythiophene polymer (3-(2-(N-(N'-methylimidazole))ethoxy)-4-methylthiophene (LPTP)) and heparinase digestion of heparin.
Why This Matters for Hirudotherapy
This study describes a sensitive 96-well microplate colorimetric assay for detecting oversulfated chondroitin sulfate (OSCS) contamination in heparin sodium active pharmaceutical ingredient and crude heparin, using a cationic polythiophene polymer and heparinase digestion. The assay detected OSCS at 0.003% w/w by plate reader and 0.1% visually, even in the presence of dermatan sulfate or chondroitin sulfate A impurities, and distinguished authentically contaminated samples from controls. There is no connection to hirudotherapy, leeches, or the leech secretome in this study. The work is entirely focused on heparin quality control and analytical methodology.
Citation
Sensitive detection of oversulfated chondroitin sulfate in heparin sodium or crude heparin with a colorimetric microplate based assay
Sommers CD et al. · Analytical chemistry, 2011
Added to ASH library: May 27, 2026 · Site last updated: June 18, 2026