Determination of efavirenz in diluted alkaline electrolyte by cathodic adsorptive stripping voltammetry at the mercury film electrode

A stripping method for the determination of the antiretroviral drug efavirenz at the submicromolar concentration levels in diluted alkaline electrolyte is described. Optimum experimental conditions were: 2.0 × 10-3 mol L-1 NaOH, accumulation potential of -0.10 V, pulse amplitude of 50 mV and scan rate of 50 mV s-1. The response is linear over the concentration range of 0.01-0.25 ppm. For an accumulation time of 10 min, the limit of detection was 1.0 ppb (3.0 × 10-9 mol L-1). The most convenient conditions to measure the efavirenz concentration in the presence of ATP, DNA, several metals, and other antiviral drugs was also investigated. The utility of the method is demonstrated by the determination of efavirenz in a synthetic mixture containing both lamivudine and zidovudine, which are frequently used in the clinic in association with efavirenz as part of highly active antiretroviral therapy (HAART).