José Paulo Santos
Professor Catedrático do Departamento de Física da FCT/UNL
DF - FCT NOVA, Quinta da Torre, 2829 -516 MONTE DA CAPARICA , PORTUGAL (email)
DF - FCT NOVA, Quinta da Torre, 2829 -516 MONTE DA CAPARICA , PORTUGAL (email)
An ultrasonic assisted solid‚Äìliquid extraction method was developed to determine the level of lead in the brain and urine of rats. Lead was determined by electrothermal atomic absorption spectrometry with longitudinal-Zeeman background correction. Several analytical drawbacks were addressed and overcome, namely small brain sample mass and the formation of precipitate in the urine samples. Utrasonication provided by an ultrasonic probe succeeded in extracting lead from brain samples. Furthermore, it was demonstrated that the formation of a precipitate lowered the lead content in the liquid phase of the urine. Lead was back extracted from the precipitate to the liquid phase with the aid of ultrasonic energy and acidifying the urine with 10% v/v nitric acid. A microwave-assisted acid digestion protocol was used to check the completeness of the lead extraction. The within bath and between bath precision was 5% (n = 9) and 7% (n = 3) respectively. The limit of quantification was 1.05 Œºg g‚àí1 for brain samples and 2.1 Œºg L‚àí1 for urine samples. A total of 6 samples of urine and 12 samples of brain from control rats and another 6 samples of urine and 12 samples of brain from rats fed with tap water rich in lead acetate were used in this research. Lead levels in brain and urine from exposed rats ranged from1.9 ¬± 0.2 Œºg g‚àí1 to 3.5 ¬± 0.2 Œºg g‚àí1 and from 752 ¬± 56 Œºg L‚àí1 to 60.9 ¬± 1.2 mg L‚àí1 respectively. Statistically significant differences of levels of lead in brain and urine were found between exposed and non exposed rats.
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