Electrochemical evaluation of a boron-doped diamond electrode for simultaneous determination of an antihypertensive ternary mixture of amlodipine, hydrochlorothiazide and valsartan in pharmaceuticals

The simultaneous voltammetric determination of a ternary mixture containing antihypertensive drugs amlodipine (AML), hydrochlorothiazide (HCTZ) and valsartan (VAL) by square-wave voltammetry using a cathodically pretreated boron-doped diamond electrode is reported for the first time. Three very well-resolved and reproducible oxidative processes of AML, HCTZ and VAL were found at 0.781 V, 1.14 V and 1.41 V, respectively, in Britton-Robinson buffer solution (pH 5.0). The linearity ranges were 4.9 × 10 −7 -7.2 × 10 −6 mol L −1 , 2.9 × 10 −6 -4.5 × 10 −5 mol L −1 , and 9.7 × 10 −6 -1.3 × 10 −4 mol L −1 for AML, HCTZ and VAL, with detection limits of 2.3 × 10 −7 mol L −1 , 7.5 × 10 −7 mol L −1 , and 6.2 × 10 −6 mol L −1 , respectively. The proposed method was successfully applied to the simultaneous analysis of these antihypertensive drugs in their combined pharmaceutical tablets available in the market. The simultaneous voltammetric determination of amlodipine, hydrochlorothiazide and valsartan using a boron-doped diamond electrode is reported for the first time.