Selenium determination in tissue samples of Nile tilapia using ultrasound-assisted extraction

This paper proposes a method to determine selenium in samples of fish muscle and liver tissue using ultrasound assisted extraction process, and analysed by graphite furnace atomic absorption spectrometry (GFAAS). The selenium content was extracted by 0.10 M HCl at the optimal extraction conditions which were established as follows: sample mass of 100 mg; granulometry of the sample < 60 A mu m; sonication time of five 40 s cycles; and sonication power of 136 W. The selenium determinations were performed by GFAAS, at a drying temperature of 120A degrees C/250A degrees C, pyrolysis temperature of 1300A degrees C, atomization temperature of 2300A degrees C, and cleaning temperature of 2800A degrees C. Palladium nitrate was used as a chemical modifier coinjected with the samples, and tungsten as a permanent modifier. The concentration of selenium determined in the pool of fish muscle and liver tissue were 280.4 +/- 4.2 e 592.3 +/- 6.7 mu g kg(-1), respectively. The accuracy and precision of the proposed extraction method were evaluated using certified standard Bovine Muscle - NIST 8414. The results obtained by the ultrasonic extraction method were equivalent to those obtained by the method of acid mineralization of samples in a microwave oven.