[Turbidimetric determination of tenoxicam using molybdophosphoric acid]

A turbidimetric method was developed for tenoxicam quantification using the complexing reaction with molybdophosphoric acid in hydrochloric acid medium; the complex has a maximum of absorbance at 369 nm.

The practical working conditions were established. In the 2.5 division by 15.0 microg/mL concentration range of tenoxicam in 1N hydrochloric acid, were added 1 mL of 1% molybdophosphoric acid solution and 1 mL of 0.1% sodium lauryl sulphate. The stability of product was evaluated over 60 minutes. The developed method was validated.

The method showed a good linearity in the range of 2.5 division by 15.0 microg/mL (the correlation coefficient r = 0.9996). The detection limit (LD) was 0.44 microg/mL and the quantification limit (LQ) was 1.47 microg/mL. There were established the precision (RSD = 1.82%) and the accuracy (mean recovery is 100.79% in 97.55 division by BY 04.41% the range).

The experimental results demonstrated a good sensibility. The specific absorptivity for this method is A(1cm,369nm)(1%) higher than tenoxicam in hydrochloric acid medium A(1cm,354nm)(1%).