Near-infrared spectroscopy is evaluated as an on-line technique for monitoring the homogeneity of a pharmaceutical blend during the blending process. Blends containing 10% sodium benzoate (model active), which provided an aromatic functionality typical of many pharmaceutical compounds, 39% microcrystalline cellulose (Avicel PH102), 50% lactose, and 1% magnesium stearate were developed to mimic the properties of an actual pharmaceutical blend. A twin-shell V-blender was modified to allow installation of a diffuse reflectance fiber-optic probe at the axis of rotation, and spectra were collected during three experiments using a commercially available near-infrared spectrophotometer. In each experiment, blender control and spectral data collection were controlled by a compilation of software packages. The experiments detected spectral changes which eventually converged to a point of constant variance. Further analysis of the spectral data showed the blend is homogeneous long before a typical blending period is complete. Near-infrared spectroscopy has proven to be a feasible and effective method for the "real time" noninvasive determination of homogeneity in a pharmaceutical blend.

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The synthesis of three chiral calixarene derivatives is described. One of these, an (S)-di-2-naphthylprolinol tetramer, is shown to exhibit significant ability to discriminate between enantiomers of 1-phenylethylamine (PEA) and norephedrine on the basis of the quenching of the (S)-di-2-naphthylprolinol fluorescence emission in chloroform. The chiral discrimination appears to arise from preorganization of the four (S)-di-2-naphthylprolinol substituents on the calixarene, which define a three-dimensional chiral space. The ability to measure the enantiomeric composition of PEA and norephedrine to within an error of 4.1% and 2.6%, respectively, on the basis of a single fluorescence measurement is demonstrated.