Determination of Nifedipine in Pharmaceutical forms using Selective Flow-Injection Spectrophotometric Technique combined with Immobilized Manganese dioxide as a Solid Phase Reactor

A sensitive new economic method was presented to determine nifedipine (NIF) in pharmaceutical forms using oxidative coupling reaction between reduced NIF and pyrocatechol oxidized by MnO₂ packed in solid phase reactor fastened in reversed flow injection manifold with one channel solution stream. The optimization conditions for solid phase reactor, flow injection system and pyrocatechol concentration were studied and established. The results revealed that the range (5–160)μg.mL⁻¹obey beer's low with high sensitivity and good linearity (r =0.9990) and the limit of detection and quantitation 2.243μg.mL⁻¹ and 7.478μg.mL⁻¹ respectively. The method offered good accuracy and precision; moreover the sample frequency was 45 injections per hour and found that the solid phase reactor lifetime 40 replicated injection with RSD%=2.93 as acceptable value. Application carried out by the use of NIF tablets in different concentrations, high recovery and repeatability was recorded. The proposed method was compared with standard method by calculated student-t and F-test which confirmed that no significant differences between the two methods, so it could be used in routine pharmaceutical analysis.