title: A simple colorimetric method for estimation of tramadol hydrochloride in pure and tablet dosage forms.
abstract: OBJECTIVE
  The objective of this study was to develop and validate a simple method for estimation of tramadol hydrochloride (TH) in pure and pharmaceutical dosage forms using a colorimeter.
  
  
  METHODS
  TH on reaction with Eriochrome Black T in the presence of acetate buffer at pH 3.5 forms a colored complex. This complex was extracted with a fixed volume of chloroform. The optical density of this colored complex was measured against reagent blank using a colorimeter at 520 nm.
  
  
  RESULTS
  Beer's law was obeyed with a good correlation coefficient (0.999) in the concentration range of 2.5 μg/ml to 10 μg/ml. Drug content estimation and recovery studies carried out on commercial tablet dosage forms demonstrated the accuracy of the method and that excipients do not cause interference. Precision and robustness were measured and found to be acceptable (% relative standard deviation <2%).
  
  
  CONCLUSIONS
  The proposed method can be used for the rapid determination of TH content in tablets at a health-care provider level using already available staff and equipment.
authors.affiliation: Department of Pharmacology, Government Medical College, Thiruvananthapuram, Kerala, India.
authors.forename: Scaria P
authors.initials: SP
authors.lastname: Thomas
authors.affiliation: Department of Pharmacology, Government Medical College, Kottayam, Kerala, India.
authors.forename: Hari K N
authors.initials: HK
authors.lastname: Sankar
mesh_terms: D000085:Acetates / Q000737:chemistry; D000701:Analgesics, Opioid / Q000032:analysis / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry; D003124:Colorimetry; D004396:Coloring Agents / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015203:Reproducibility of Results; D013607:Tablets; D014147:Tramadol / Q000032:analysis* / Q000737:chemistry
chemical_list: D000085:Acetates; D000701:Analgesics, Opioid; D001391:Azo Compounds; D004396:Coloring Agents; D013607:Tablets; D014147:Tramadol; C014527:Eriochrome Black T
keywords: Colorimetry; Eriochrome Black T; tramadol