Infrared Microspectroscopy III A Capillary Cell for Liquids*†

Apparatus and methods are described for the determination of infrared spectral absorption of solutions containing about 1 gamma (10−6 g) of solute. The absorption cell used is a piece of capillary tubing made of silver chloride with a central hole about 0.075 mm in diameter. The cells have lengths of 1 to 1.5 mm and are filled by means of a micropipette. A magnified image of the cell is then projected on the entrance slit of a spectrometer, and the spectral data are recorded. Results with typical organic compounds indicate that satisfactory spectral resolution may be obtained with this capillary cell.