Ultrasound-assisted Soxhlet extraction: an expeditive approach for solid sample treatment. Application to the extraction of total fat from oleaginous seeds.

Conventional Soxhlet extraction assisted in the cartridge by ultrasound has been developed and used to extract the total fat content from oleaginous seeds such as sunflower, rape and soybean seeds. The application of ultrasound to the sample cartridge enormously decreases the number of Soxhlet extraction cycles needed for quantitative extraction of the fat, thus reducing the extraction time at least to half the time needed by the conventional procedures. The results agree well with those obtained by conventional Soxhlet extraction and the ISO reference method, both in terms of efficiency and precision. The repeatability of the proposed approach, expressed as relative standard deviation, was 0.9%; the within-laboratory reproducibility was 1.3%. Qualitative analysis of the extracted fat showed that the application of ultrasound does not change the composition of the oil.