This paper presents the concentration of Cu, Zn, Fe, Pb and Cd in vegetables, soil and water samples. Samples were collected from Mayham (Adigrat, Tigray region). Total acid (7ml mixture of HNO3, H2SO4, HClO4) digestion method was employed and determination was made by flame atomic absorption spectroscopy. The percentage recoveries of the metals were in the range of 89% to 100% in vegetable, 84% to 100% in water and 82% to 103% in soil sample. The range of concentration(µg/g) of the metals on dry weight basis are: Cd 1.18-1.45 in vegetables, 1 in soil and 9 in water; Cu 9-18 in vegetables, 15-17 in soil and 4.3 in water; Pb 1.67-5.01 in vegetable, 3-5 in soil and 2.6 in water; Zn 40-398.5 in vegetable, 59-66.8 in soil and 9.2 in water; Fe 218.25-4987.5 in vegetables, 23705.75 – 29248.5 in soil and 177.5 in water sample. The result obtained imples that the plant is rich in iron, zinc and copper and has small concentration of non-essential trace elements like lead and cadmium.
This work uses a method that enhances the performance of glassy carbon electrode (GCE) for the determination of chloramphenicol (CAP). The electrochemical properties of chloramphenicol at electrochemically pretreated glassy carbon electrode were studied using cyclic voltammeter (CV). Electrochemical pretreatment of the electrode greatly enhanced the reduction peak current (Ip) of CAP. CAP shows an irreversible reduction peak at -0.674 V vs. Ag/AgCl at the GCE in 0.05 M acetate buffer of pH 5. Detailed experiments were carried out to establish the electrochemical property, the optimal buffer and its pH, electrode pretreatment potential, scan rate dependence study and effect of concentration. Following optimization pH of buffer solution, the peak current response for the reduction of CAP shows an enhanced response, 2.0 times greater than the bare GCE. A series of four CAP determination in 1.6 x 10-6 to 2 x 10-4 M concentration range show a linear calibration curve with r = 0.99997. At this range the limit of detection was LOD = 2.45 ?M with a standard deviation of SD = 0.03814. The method was successfully applied to three CAP containing pharmaceutical samples: CAP eye drop, CAP palmitat oral suspension and CAP as sodium succinate and the level of CAP in these samples was verified.