Vapour generation Fourier transform infrared spectrometry. A new analytical technique

A new technique has been developed for the direct introduction of samples in Fourier transform infrared (FT-IR) spectrometric analysis. The technique is based on the injection of discrete sample volumes into an electrically heated Pyrex glass reactor in which the compounds to be determined are volatilized. The vapour phases generated are transported by means a carrier gas inside an IR gas cell and the corresponding flow injection recording registered as a function of time. In the present study the effect of the main experimental variables on both the sensitivity and the precision of the analytical measurements have been evaluated, and the method has been applied to the determination of ethanol in chloroform. For this test system vapour generation FT-IR spectrometry provides a 3σ limit of detection of 0.02% (v/v) using peak height absorbance ratios between the bands of ethanol at 1066 cm−1 and chloroform at 931 cm−1 or alternatively between the first-order derivative values corresponding to these. Results obtained in the analysis of commercial samples of CHC13, stabilized with ethanol, were comparable with those found by a reference procedure based on flow injection-near infrared analysis.