The assaying and stability testing in pharmaceutical analysis occupies an important role to meet the requirement of statutory certification of drugs and their formulations by the industry. The analysis of pure drug substances and their pharmaceutical dosage forms occupies a pivotal role in assessing the suitability to use in patients. Most widely used methods are based on HPLC/ UPLC, GC. Capillary electrophoresis and super critical fluid chromatography are slowly gaining ground in recent years. The selectivity and sensitivity of the visible spectrophotometric method depends only on the nature of chemical reactions involved in color development and not on the sophistication of the equipment. The colorimetric procedure must give reproducible results under specific experimental conditions. HPLC method validation studies include system suitability, linearity, precision, accuracy, specificity, ruggedness, robustness, limit of detection, limit of quantification, stability of samples. The variable method parameters adapted to carryout robustness in HPLC technique may involves the studies on the flow rate, column temperature, sample temperature, pH and mobile phase composition.