Simultaneous determination of acetaminophen and tramadol by second derivative spectrophotometry

• M. INÉS TORAL ^[1] ; JORGE RIVAS ^[1] ; MARTA SALDÍAS ^[1] ; CÉSAR SOTO ^[2] ; SANDRA ORELLANA ^[1]
  1. [1] Universidad de Chile

     Universidad de Chile

     Santiago, Chile

     
  2. [2] Universidad de Concepción

     Universidad de Concepción

     Comuna de Concepción, Chile

     
• Localización: Journal of the Chilean Chemical Society (Boletín de la Sociedad Chilena de Química), ISSN-e 0717-6309, ISSN 0366-1644, Vol. 53, Nº. 2, 2008, págs. 1543-1547
• Idioma: inglés
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• Resumen

  • A rapid method for the simultaneous determination of acetaminophen (A) and tramadol (T) by second derivative spectrophotometric has been developed. From a solvent effect studies and the spectral behaviours of A and T, ethanol was selected as solvent. For a Δλ value of 210 nm a smoothing factor of 8,000 and scale factor of 1,000,000 were selected, because in these conditions the signal/noise ratio was favoured in order to avoid error. In these conditions also it is possible the simultaneous determination of A/T in a molar relation of 17/1 contained in pharmaceutical formulations. At 285.7 nm the second derivative value is T concentration dependent, corresponding to zero-crossing point of A. On the other hand, T does not absorb between 296.0 to 400.0 nm, thus 308.0 nm was selected for A determination by graphic method. The determination ranges for A and T were 8.1x10-7 - 5 1x10-5 mol/L and 3.4 x10-7 - 5.0 x10-5 mol/L, respectively and can be determined with good precision and accuracy, without previous separation. A study of interferents, was carried out by using the excipients Zafin® tablet. The recoveries were 97.4 ± 2.0% and 100.6 ± 1.7% for A and T, respectively. This tablet containing both drugs was assayed using the methods developed, showing a good accuracy and precision.