The molecular weight of Heparin, Fluorescein Conjugate (Cat. No. H7482) is ~18,000 and the information can be found on the Calcium Regulation—Section 17.2 page (see Data Table).
Heparin is quite soluble in water (10mg/ml) or aqueous buffer and you can prepare stock solutions of at least 1 mM using water as the solvent. Once dissolved, the stability of the nonsterile solution is very poor, so it should either be sterile filtered (0.2 µm) or an antibacterial (e.g., 0.06-1% benzyl alcohol) should be added. Heparin in solution should not be frozen, but is stable at 2-8 degrees C.
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