title: Extractive spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations using bromocresol green, bromophenol blue, bromothymol blue and eriochrome black T.
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.
authors.affiliation: Department of Chemistry, Analytical Chemistry Division, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India. cht17nr@yahoo.co.in
authors.forename: Nafisur
authors.initials: N
authors.lastname: Rahman
authors.forename: Nadeem
authors.initials: N
authors.lastname: Ahmad Khan
authors.forename: Syed Najmul
authors.initials: SN
authors.lastname: Hejaz Azmi
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D001961:Bromcresol Green / Q000737:chemistry*; D001978:Bromphenol Blue / Q000737:chemistry*; D001979:Bromthymol Blue / Q000737:chemistry*; D005079:Excipients / Q000737:chemistry; D006851:Hydrochloric Acid / Q000737:chemistry; D009543:Nifedipine / Q000032:analysis* / Q000737:chemistry; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods
chemical_list: D001391:Azo Compounds; D005079:Excipients; D004364:Pharmaceutical Preparations; D012997:Solvents; D001978:Bromphenol Blue; D001961:Bromcresol Green; D009543:Nifedipine; C014527:Eriochrome Black T; D006851:Hydrochloric Acid; D001979:Bromthymol Blue