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  • Extractive spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations using bromocresol green, bromophenol blue, bromothymol blue and eriochrome black T.

Extractive spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations using bromocresol green, bromophenol blue, bromothymol blue and eriochrome black T.

Farmaco (Societa chimica italiana : 1989) (2004-01-31)
Nafisur Rahman, Nadeem Ahmad Khan, Syed Najmul Hejaz Azmi
ABSTRACT

Four simple, sensitive and accurate spectrophotometric methods have been developed for the determination of nifedipine in pharmaceutical formulations. These methods are based on the formation of ion-pair complexes of amino derivative of the nifedipine with bromocresol green (BCG), bromophenol blue (BPB), bromothymol blue (BTB) and eriochrome black T (EBT) in acidic medium. The coloured products are extracted with chloroform and measured spectrophotometrically at 415 nm (BCG, BPB and BTB) and 520 nm (EBT). Beer's law was obeyed in the concentration range of 5.0-32.5, 4.0-37.5, 6.5-33.0 and 4.5-22.5 microg ml(-1) with molar absorptivity of 6.41 x 10(3), 4.85 x 10(3), 5.26 x 10(3) and 7.69 x 10(3) l mol(-1) cm(-1) and relative standard deviation of 0.82%, 0.72%, 0.66% and 0.68% for BCG, BPB, BTB and EBT methods, respectively. These methods have been successfully applied for the assay of drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Eriochrome® Black T, SAJ special grade
Sigma-Aldrich
Eriochrome® Black T, ACS reagent (indicator grade)
Supelco
Fructose, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Eriochrome® Black T solution
Supelco
Nifedipine, Pharmaceutical Secondary Standard; Certified Reference Material