Current World Environment

Introduction

Pralidoxime (2-[(hydroxyimino) methyl]-1-methylpyridin-1-ium) (PRL) and Obidoxime (1, 1'-[oxybis (methylene)]bis{4-[(E)- (hydroxyimino) methyl] pyridinium) (OBD) are used to combat poisioning by organophosphates. Azomethine group containing drugs have been in wide use because of their pharmacokinetic properties (1-3). Several researchers have reported the determination of azomethine group containing drugs. (4-10). Determination of PRL was carried out by HPLC (26). Spectrophotometric (29) and Potentiometric (30) methods.Determination of OBD was carried out by HPLC (32, 33) and Spectrophotometric (35) methods. In the present method, a simple, accurate and cheaper method has been described for the determination of PRL and OBD.

Experimental

Voltammograms were recorded with Metrohm 757 VA computrace (Herisau, Switzerland).Pralidoxime and obidoxime were purchased from Cipla labs India Ltd., (Mumbai). Standard stock solutions (1.0X10^-3 mol l ^-1) are prepared by dissolving an appropriate amount of electroactive species in deionised triple distilled water.
 

Table 1: Experimental data of PRL and OBD Click here to view table

Table 2: Determination of PRL and OBD in Pharmaceutical formulations Click here to view table

Table 3: Determination of PRL and OBD in human urine samples Click here to view table

Table 4: Determination of PRL and OBD in human serum samples Click here to view table

Recommended Analytical Procedure

Ten milli liters of BR buffer solution was deoxygenated in the cell with nitrogen gas. An aliquot of standard solution of the electroactive species was added to the buffer present in the cell. After recording the polarograms small increments (0.2 mL) of standard solution were added and polarograms were recorded after each addition under the same conditions.

Results and Discussion

Cyclic Voltammetry
 

Figure 1: Typical cyclic voltammogram of PRL Click here to view figure

Figure 2: Typical cyclic voltammogram of OBD Click here to view figure

Fig.1 and 2 Illustrate cyclic voltammograms (CV) of 1.6×10^-8 M pralidoxime and obidoxime in 0.04M BR buffer solution of p^H 2.0 at HMDE. On scanning from -0.4 to -1.4 v towards a negative potential two cathodic peaks are observed which are attributed to the reduction of azomethine group.

Differential Pulse Polarography
 

Figure 3: Typical DPP of PRL Click here to view figure

Figure 4: Typical DPP of OBD Click here to view figure

Fig. 3 and 4 explain the differential pulse polarogramms for 1.6×10^-8 M PRL and OBD in 0.04M BR buffer solution of p^H 2.0 at HMDE. While scanning towards cathodic direction two peaks were observed and no peak in anodic direction indicating the irreversible nature of reduction process. The peaks are attributed to the reduction of azomethine group.

Conclusion

From the experimental results obtained, PRL and OBD are found to give two well-defined peaks in the BR buffer solution of pH 2.0 which are attributed to the reduction of azomethine group.Standard addition method is employed for the estimation of these pharmacologically important drugs in their pharmaceutical formulations, serum samples and urine samples.

References