Direct determination of selenium in coconut water and coconut milk using graphite furnace atomic absorption spectrometry.

Selenium is both essential and toxic to man and animals, depending on the concentration and the ingested form. Most fruits and vegetables are poor sources of selenium, but coconut can be a good selenium source. Samples mere suspended (1 + 4 v/v) in a mixture of tertiary amines soluble in water (10% v/v CFA-C), This simple sample treatment avoided contamination and decreased the analysis time. The standard additions method was adopted for quantification, The action of the autosampler was improved by the presence of the amines mixture in the suspension. A Varian model AA-800 atomic absorption spectrometer equipped with a graphite furnace and a GTA 100 autosampler was used for selenium determination in coconut mater and coconut milk, Background correction was performed by means of the Zeeman effect. Pyrolytically coated graphite tubes mere employed. Using Pd as chemical modifier, the pyrolysis and the atomization temperatures mere set at 1400 and 2200 degrees C, respectively, For six samples, the selenium concentration in coconut mater varied from 6.5 to 21.0 mu g L-1 and in coconut milk from 24.2 to 25.1 mu g L-1. The accuracy of the proposed method was evaluated by an addition-recovery experiment and all recovered values are in the 99.5-102.3% range, The main advantage of the proposed method is that it can be directly applied without sample decomposition.