Heparin colorimetric methods

Although widely used, colorimetric methods for determining total ur-onic acid and hexosamine are now regarded as providing, at best, only semi-quantitative estimates of heparin.42 Colorimetric reactions in a strong acid, such as the carbazole reaction for the uronic acids48 and the Morgan-Elson reaction for the hexosamines,49 are not specific for hepa-... 

For detailed description and discussion of methods of separation and characterization of GAG, the reader is referred to specific mono-graphs38-42-46-47 dealing with the advantages and drawbacks of different colorimetric, titrimetric, electrophoretic, chromatographic, spectroscopic, and enzymic methods for the qualitative and quantitative characterization of heparin and its most common contaminants. The present article is concerned only with analytical aspects of relevance to the structural characterization of heparin. 

More-specific methods are available for identifying and quantitating the typical, amino sugar component of heparin (and some heparan sulfate species), namely, 2-deoxy-2-sulfoamino-D-glucose. Most of these methods are based on conversion of these residues into 2,5-anhydro-D-mannose by deamination with nitrous acid (see Section VIII,2). The 2,5-anhydro-D-mannose residues may be determined either colorimetrically,52-54 or fluorimetrically.55... 

Fernandez and Kahn (F3) reported that the accuracy and precision of the Delves method are adequate for the determination of normal and excess lead levels in blood and that 30-50 samples could be analyzed in 1 hour. The correlation coefiicient between their results and those using a colorimetric dithizone procedure was 0.99. Heinemann (H4) was able to analyze a single heparinized blood sample in less than 5 minutes and 30-40 samples in 1 hour using the Delves procedure. He also analyzed untreated urine. Hicks et al. (H6) found a correlation coefficient of 0.96 between the Delves method and conventional macro atomic absorption measurements the coefficient of variation for the Delves method was 8% at 40 /tg of lead per 100 ml. In addition, the analysis of lead in capillary and intravenous blood samples correlated... 

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