ATR-FTIR spectroscopic imaging with expanded field of view to study formulations and dissolution

Abstract

Fourier transformed infrared (FTIR) spectroscopic imaging in combination with a novel attenuated total reflection (ATR) accessory with an expanded field of view has been applied to simultaneously obtain infrared spectra of more than 150 miniature samples, and to study the dissolution process of several different formulations in separate mini-channels simultaneously. This is the first time FTIR spectroscopic imaging using such an ATR accessory with an expanded field of view has been reported. The resultant imaging area with this approach was found to be ca. 15.4 x 21.4 mm(2) (6 x expansion). The potential of this approach includes imaging up to 440 samples simultaneously. The same accessory was used to prepare mini-channels (4 mm wide, 15 mm long and 0.5 mm deep) which were made of a PDMS grid that was self-adhered to the surface of the ATR crystal. Different molecular weights of poly(ethylene glycol) (PEG), with or without the addition of ibuprofen, have been used as model pharmaceutical formulations and chemical imaging of the simultaneous dissolution of five different formulations of PEG/ibuprofen has been demonstrated. Direct comparison between these different formulations under identical conditions was possible due to this imaging approach.