Determination of chloramphenicol by differential pulse voltammetry at carbon paste electrodes the use of sodium sulphite for removal of oxygen from electrode surface
Abstrakt
The possibility of determination of chloramphenicol by differential pulse voltammetry at four different carbon paste electrodes, in the full pH range of Britton-Robinson buffer (2 - 12) was investigated. Electrodes were prepared by mixing spectroscopic graphite powder or glassy carbon microbeads with mineral oil (Nujol) or tricresyl phosphate.
Under optimal conditions (Britton-Robinson buffer pH 12, the electrode prepared from glassy carbon microbeads and tricresyl phosphate), linear calibration graph was obtained only in 10(-5) M chloramphenicol concentration range. Determination of lower concentrations of chloramphenicol was complicated by irreproducible peak of oxygen from the carbon paste, which overlapped with peak of chloramphenicol.
Addition of sodium sulphite removed the oxygen peak without influence on the peak of chloramphenicol. Under optimal conditions (electrode paste made from glassy carbon microbeads, Britton-Robinson buffer pH 10 and 0.5 M sodium sulphite), straight calibration line was obtained in the 10(-6) and 10(-5) M chloramphenicol concentration range.
Limit of determination was 5 x 10(-7) M.