A simple, rapid, accurate, precise and sensitive spectrophotometric method for the determination
of amlodipine besylate (ADB) in bulk sample and in dosage forms is described. The
method is based on oxidation of the drug by potassium permanganate in acidic medium and determine
the unreacted oxidant by measuring the decrease in absorbance for five different dyes; methylene
blue (MB), acid blue 74 (AB), acid red 73 (AR), amaranth dye (AM) and acid orange 7 (AO)
at a suitable kmax 663, 609, 511, 520, and 484 nm, respectively. Regression analysis of Beer’s law
plots showed good correlation in the concentration ranges 1.0–24, 0.9–22, 1.2–26, 0.9–12.8 and
1.0–14 lg ml_1, respectively. The apparent molar absorptivity, Sandell sensitivity, detection and
quantitation limits were calculated. For more accurate results, Ringbom optimum concentration
ranges were 1.2–22.4, 1.1–20, 1.4–24.5, 1.0–12.3 and 1.3–13.2 lg ml_1, respectively. Statistical treatment
of the results reflects that the proposed procedures are precise, accurate and easily applicable
for the determination of amlodipine besylate in pure form and in pharmaceutical preparations.
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