Abstract: | Three commercial heparins of different molecular weights and anticoagulant activities were dinitrophenylated (DNP) with 2,4-dinitrofluorobenzene under aqueous conditions. The absorption spectra observed for DNP heparins in a 1% NaHCO3 solution consisted of the two absorption spectra characteristic of DNP—amino (N—DNP) and DNP—hydroxyl (O—DNP) groups. The number of N—DNP, O—DNP, and (N + O)—DNP groups were determined as well as the number of N—DNP groups per heparin chain; different values (i.e., 0.16, 0.17, and 0.55) for the latter were obtained with the three heparins. Further calculations showed that two of the heparins had approximately two (N + O)—DNP groups per chain (i.e., 2.1 and 1.8) whilst the third sample, considered to be a “cruder” heparin, had a value of 1.4. |