Evaluation of extraction alternatives for Fourier transform infrared spectrometric determination of oil and greases in water

Liquid-liquid extraction (LLE), solid phase extraction (SPE) and microwave-assisted extraction are evaluated for Fourier transform infrared (FTIR) spectrometric determination of oil and grease in polluted waters. A fast microwave-assisted quantitative procedure is proposed for the total extraction of oil and grease into CCl4 from water samples, with an irradiation time of 1 min at an exit power of 520 W using closed PTFE vessels. The FTIR quantification of oil and grease is carried out by the measurement of the area under the absorbance spectra in the range between 3058 and 2780 cm−1, with a baseline established between 3200 and 2700 cm−1. The analytical features of the proposed method and those of LLE-FTIR spectrometry are evaluated and samples spiked with different types of oils examined. Additionally a SPE-FTIR procedure has been evaluated and results obtained compared with those found by SPE-gravimetric analysis for a series of synthetic and real samples.