A Sensitive and Selective Optical Sensor for Determination of Benzaldehyde in Injection Pharmaceuticals Based on Utilization of 2, 4-Dinitrophenylhydrazine

In this research a novel and economic optical sensor for determination of benzaldehyde (BA), which is a dangerous oxidation product of benzyl alchol in injection pharmaceuticals, is introduced. The optode is based on immobilization of 2, 4- dinitrophenylhydrazine in a PVC membrane. The response of the proposed optode was based on the nucleophilic addition of 2, 4- dinitrophenylhydrazine to BA that cause an increase in absorbance at 366 nm. Different variables affect the optical signal such as pH of solution, compositions of the membrane components and type of plasticizer were optimized. A universal buffer solution with pH 2 and dibutylphthalate were used as optimum measurement media and plasticizer, respectively. Under the optimum conditions, the optode has a response time of 6 min, linear concentration range of 4.0 − 100.0 ppm of BA with a detection limit of 0.6 ppm. The influence of interfering compounds possibly found in injection formulations on the BA determination was studied. The results showed that the prepared optical sensor has good selectivity to BA. The proposed optode has a reversible response and good repeatability. This optode was successfully applied to assay benzaldehyde in sodium diclofenac and piroxicam ampoules.