Determination of Manganese in Cassava Leaves by Slurry Sampling Flame Atomic Absorption Spectrometry

Cassava, Manihot esculenta crantz, constitutes one of the main foods consumed by most of the population of developing countries, mainly in the population of low income. It is largely used for its low cost and the diversity of its root and leaves products. In this paper, a slurry sampling flame atomic absorption spectrometric method for the determination of manganese in cassava leaves is proposed. The slurry sampling was used in order to shorten the analysis time and to minimize the problems associated with solid sample treatment such as wet acid digestion, dry-ashing, sample contamination, and analyte loss. The samples of cassava leaves were washed with extran 10% (v/v), soon afterwards they were dried in an oven to 60 degrees C, triturated in a mill of spheres, and the obtained material was sifted in a mesh of 100 micrometers. Then 0.1 g of the sample was weighed in a balloons volumetric flask, the volume was completed with 25 mL of acid nitric 2,0 mol L-1, and followed by 20 minutes in an ultrasonic bath and subsequent reading in FAAS. The analyses of the certified reference material of spinach and apple leaves evidenced the accuracy of the method. The proposed method was applied for the determination of manganese in four samples of cassava leaves acquired in markets from Feira de Santana City, Brazil. The concentration of manganese found in cassava leaves varied from 202.7 to 181.3 mu g g(-1), with detection and quantification limits of 0.17 and 0.56 mu g g(-1), respectively. The precision expressed as relative standard deviation (RSD) was 1.7 and 3.2% (n = 10) for 100 and 12 mu g g(-1), respectively.