Color measurement of a solid active pharmaceutical ingredient as an aid to identifying key process parameters.

The color of a powdered active pharmaceutical ingredient (API) in an investigational drug was found to be the result of a number of process parameters. Color measurements of the solid material were derived from reflectance data obtained from a sphere spectrophotometer. These data provided a convenient and non-destructive way to track the effects of variations to the process parameters on the resulting material.

The formation of constants of mercury(II)--glutathione complexes.

The formation constants of the 1:1 and 1:2 complexes of Hg(II) with glutathione and their protonated species have been determined by using a competitive potentiometric titration with the competing ligand diethylenetriaminepentaacetic acid (DTPA). The formation constants of the 1:1 complex and its protonated species have not been reported previously. The formation constant of the 1:2 complex of Hg(II) and glutathione is substantially smaller than the accepted values that has been reported in the literature.

A new nonionic macrocyclic gadolinium(III) chelate as a potential magnetic-resonance-imaging contrast agent.

A new GdIII complex of a 17-membered macrocycle with three pendant carboxymethyl groups has been synthesized; the ligand has been obtained in a single step from diethylenetriaminepentaacetic dianhydride (pentetic dianhydride) and 1,4-butanediamine (putrescine). An X-ray crystal analysis has shown that the complex is a nonionic metal chelate with a coordinated water molecule. The near-zero electrical conductivity, 1 omega-1 cm2 mol-1, of a 1 mM solution indicated that the metal chelate is essentially undissociated.