Diffuse reflectance near-infrared spectroscopy as a nondestructive analytical technique for polymer implants

A near-infrared spectroscopic method to quantify drugs or excipients within polymeric matrixes is proposed. Cylindrical implants were fabricated by a melt-mold technique containing Various ratios of poly(epsilon-caprolactone) (PCL) and poly(ethylene glycol) (PEG) and Various loadings of lomefloxacin HCl with a constant ratio (70:30 w/w) of PCL/ PEG. Near-infrared (NIR) spe ctra were obtained on intact sections of larger implants using a Foss NIRSy stems Model 5000 monochrometer equipped with a Rapid Content Analyzer. Spec tral data were treated with second derivative transformation followed by li near regression and PLS to obtain correlation with lomefloxacin or PEG cont ent. Lomefloxacin content was separately determined procedure. The NIR meth od was tested by comparing predicted loadings of test implants with either theoretical Values based on weight (PEG) or with UV analysis results (lomef loxacin). Second derivative spectral values at particular wavelength ratios (PEG, 2064 nm/1698 nm; lomefloxacin, 2172 nm/2226 nm and 1824 nm/1862 nm) yielded linear results for PEG or lomefloxacin content. FEB content determi ned by NIR spectroscopy was in excellent agreement with theoretical content . Lomefloxacin content determined by NIR spectroscopy was also in excellent agreement with UV analysis. NIR analysis is interpreted through the use of corresponding mid-infrared spectral data.