The luminescence characteristics of six osmium carbonyl complexes with phenanthroline (phen) or bipyridine (bpy) and pyridine (py), 4-phenylpyridine (4-phpy), or triphenylphosphine (PPh3) complexes in the presence of polyanion heparin were studied in both ethanol and aqueous solutions. The influence of heparin on the luminescence of the complexes is heavily dependent on the type of ligands in the complexes and the solvent used. In the ethanol solutions, the heparin solution enhanced the luminescence of the five osmium complexes, with the strongest enhancement to the 4-phenylpyridine complexes; linear curves were obtained in the luminescence enhancement ratio ( ) versus the heparin concentration range of 1–40？μg/mL. In aqueous solutions, heparin quenching of the complexes was more significant; a linear quenching curve was obtained with [Os(phen)2CO(PPh3)](PF6)2 in the lower concentration range of 1–12？μg/mL. The interaction of these complexes with heparin in the solutions is discussed. The complexes are shown to be successful in the fast and sensitive detection of heparin in commercial injectable samples. 1. Introduction Heparina, a highly sulfated glycosaminoglycan, has the highest negative charge density of any known natural biological molecule [1]. Heparin has been extensively used as an injectable anticoagulant in many clinical procedures for the prevention of blood clotting, especially during open heart surgery [2, 3]. Pharmaceutical-grade heparin is derived from mucosal tissues of slaughtered meat animals such as porcine intestine and bovine lung [4]. Native heparin is a polymer with a molecular weight ranging from 3,000 to 50,000, and the average molecular weight of most commercially prepared heparin is in the range of 12,000 to 15,000. Under physiological conditions, the sulfate groups are deprotonated and attract positively charged counterions (usually sodium) to form a heparin salt. It is in this form that heparin is usually administered as an anticoagulant [5, 6]. At the end of the medical procedure, the heparin has to be rendered inactive to prevent possible bleeding problems. Therefore, clinicians need to know the exact concentration of heparin remaining when they attempt to neutralize the anticoagulant activity of heparin via precise doses of protamine. The current heparin detection method used in hospital is based on the blood clotting time [7, 8] and varies widely due to variation in the blood content of the different individuals. Thus, the discovery of accurate, rapid, reliable safe, and low-cost methods of heparin detection remains an
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