Determination of selenium in garlic by cathodic stripping voltammetry

The selenium content in a garlic sample was determined on hanging mercury d rop electrode (HMDE) using cathodic stripping voltammetry (CSV). In this me thod the dried garlic sample was digested in HNO3:HClO4 (I:I) by wet-digest ion procedure. The CSV voltammogram in 0.1 M HCl solution showed a peak for Se at -0.56 V. Effect of deposition potential, deposition time and sweep r ate on this peak were tried to determine the optimum experimental condition s. A deposition potential of -0.2 V was applied for 120 s while stirring th e solution by passing nitrogen and followed a potential scan of 50 mV/s in a negative direction. The standard addition method was used to determine se lenium in the sample. The linear domain range of Se (IV) was 2.0x10(-8)-6.0 x10(-7) M with a correlation coefficient of 0.9985. This method was used fo r the first time for the determination of selenium in garlic sample without any separation procedure and preconcentration techniques such as ion excha nge, solvent extraction or hydride generation. The amount of selenium deter mined in three different samples from three different regions were 370+/-26 (n = 5), 485 +/- 35 (n=4) and 365 +/- 46 (n=4) ng/g (dry-weight) with rela tive standard deviations of 7.0, 7.2 and 12.6%, respectively. (C) 1999 Else vier Science Ltd. All rights reserved.