Effect of Supporting Electrolytes on Polarographic Anodic Waves of Paracetamol

Transcription

1 2014 3rd International Conference on Environment, Chemistry and Biology IPCBEE vol.78 (2014) (2014) IACSIT Press, Singapore DOI: /IPCBEE V Effect of Supporting Electrolytes on Polarographic Anodic Waves of Paracetamol Swaroopa Rani N. Gupta 1 1 Department of Chemistry, Brijlal Biyani Science College Amravati, Maharashtra, India Abstract. Paracetamol an analgesic and antipyretic drug determination in pharmaceuticals is important, since an overdose of paracetamol can cause toxic effects. The aim of present study is to study effect of supporting electrolytes on polarographic anodic waves of paracetamol so that these data can be utilized for development of procedures for their quantitative estimations and applications to various pharmaceutical preparations. Effect of suppporting electrolyte HCIO 4, CH 3 COOH, HCI, Borate buffer, H 2 SO 4 and NNO 3 on polarographic wave of paracetamol in presence of different maxima suppresors gelatin, fuchsin, methyl red, bromocresol green, cellosolve, salicylic acid, thymol blue, methyl thymol blue, bromophenol red were studied. Keywords: paracetamol, HCIO 4, CH 3 COOH, HCI, borate buffer, H 2 SO 4, HNO Introduction Bosch et al (2006) evaluated the utility of different techniques for quantification of paracetamol content in pharmaceutical formulations and biological samples [1]. Many methods for determination of paracetamol had been described in literature, including chromatography (RP - HPLC) [2], chemometric-assisted spectrophotometric [3], spectroscopy [4]-[6]. The review was described about some qantitative estimation of Paracetamol and Lornoxicam in bulk and tablet formulation. The quantitation was carried out by simultaneous equation method, absorption ratio method, stability indicating reversed phase high performance liquid chromatographic method, Reverse Phase High Performance Liquid Chromatographic method, and High Performance Thin Layer Chromatography method. All the methods were validated [7]. A simple, selective, accurate RP-HPLC method was developed and validated for the analysis of paracetamol, phenylephrine hydrochloride and loratadine in commercially available tablet formulations [8]. A simple, precise, and accurate reversed-phase liquid chromatographic method has been developed for the simultaneous determination of paracetamol (PCM), chlorzoxazone (CHZ), and nimesulide (NIM) in pharmaceutical dosage form [9]. Two simple, accurate and reproducible methods were developed and validated for the simultaneous determination of paracetamol (PARA) and pamabrom (PAMB) in pure form and in tablets. The first method was based on reserved-phase high-performance liquid chromatography, and the second method was based on thin-layer chromatography [10]. UV-Spectrophotometry and RP-HPLC methods were validated for the simultaneous analysis of acetaminophen in marketed tablets (Olufemi et al., 2013). Paracetamol is a common analgesic and antipyretic drug that is used for the relief of fever, headaches and other minor aches and pains. Their determination in pharmaceuticals is of paramount importance, since an overdose of paracetamol can cause toxic effects. The aim of the present study is to study effect of supporting electrolytes on polarographic anodic waves of paracetamol so that these data can be utilized for development of procedures for their quantitative estimations and applications to various pharmaceutical preparations. Corresponding author. Tel.: address: swargupta@yahoo.com. 61

2 Fig. 1: Effect of HClO 4 concentration on the anodic wave of 2.0 x 10-5 M Paracetamol in presence of % Gelatin Fig. 2: Effect of HClO 4 concentration on the anodic wave of 1.0 x 10-4 M Paracetamol in presence of 3.75 x 10-4 % Fuchsin 2. Methodology The effect of suppporting electrolyte HCIO 4, CH 3 COOH, HCI, Borate buffer, H 2 SO 4 and HNO 3 on polarographic wave of paracetamol in presence of different maxima suppresors gelatin, fuchsin, methyl red, romocresol green, cellosolve, salicylic acid, thymol blue, methyl thymol blue, bromophenol red were studied. Systems were prepared containing an aliquot of paracetamol solution, different amount of maxima 62

3 suppressors and supporting electrolyte. 50 ml total volume was maintained for each measurement. Polarogram of each system were recorded on D.C. Recording polarograph with OmniScribe recorder between 400 to 1400 mv using Rotating Platinum micro Electrode (RPE) as anode and Saturated Calomel Electrode (S.C.E.) as cathode. 3. Results and Discussion Effect of different supporting electrolyte i.e. HCIO 4, CH 3 COOH, HCI, Borate buffer, H 2 SO 4, and HNO 3 concentration on current voltage curve of paracetamol are shown in Fig. 1 to 14. Increasing concentrations of different supporting electrolytes are found to increase paracetamol wave height. Fig. 3: Effect of CH 3 COOH concentration on the anodic wave of 2.0 x 10-5 M Paracetamol in presence of % Gelatin Fig. 4: Effect of CH 3 COOH concentration on the anodic wave of 8.0 x 10-5 M Paracetamol in presence of 5 x 10-5 % 63

4 Fuchsin Fig. 5: Effect of CH 3 COOH concentration on the anodic wave of 1.0 x 10-3 M Paracetamol in presence of 1 x 10-3 % Methyl red Fig. 6: Effect of CH 3 COOH concentration on the anodic wave of 7.5 x 10-4 M Paracetamol in presence of 1.5 x 10-3 % Thymol blue 64

5 Fig. 7: Effect of CH 3 COOH concentration on the anodic wave of 6.0 x 10-4 M Paracetamol in presence of 2.5 x 10-2 % Bromocresol green Fig. 8: Effect of HCl concentration on the anodic wave of 1.5 x 10-4 M Paracetamol in presence of 1.5 x 10-3 % Fuchsin 65

6 Fig. 9: Effect of HCl concentration on the anodic wave of 1.0 x 10-4 M Paracetamol in presence of 2.5 x 10-4 % Methyl red Fig. 10: Effect of HCl concentration on the anodic wave of 1.0 x 10-4 M Paracetamol in presence of 1.25 x 10-3 % Thymol blue 66

7 Fig. 11: Effect of HCl concentration on the anodic wave of 1.0 x 10-4 M Paracetamol in presence of 3.78 x 10-3 % Bromocresol green Fig. 12: Effect of Borate buffer of different ph on the anodic wave of 3.0 x 10-4 M Paracetamol in presence of 2.5 x 10-5 % Fuchsin 67

8 Fig. 13: Effect of H 2 SO 4 concentration on the anodic wave of 3.0 x 10-5 M Paracetamol in presence of 1.25 x 10-2 % Fuchsin Fig. 14: Effect of HNO 3 concentration on the anodic wave of 6.0 x 10-5 M Paracetamol in presence of 1 x 10-3 % Fuchsin 3.1. Effect of perchloric acid on the anodic waves of paracetamol Effect of various concentrations of perchloric acid on the anodic waves of paracetamol in presence of % gelatin/3.75 x 10-4 % fuchsin as maxima suppressors is evident from Fig. 1 and 2. Good sigmoid C-V curves all starting at about mv are obtained. The apparent diffusion currents of very small concentration of oxidizable substance i.e. paracetamol increase markedly with increasing applied e.m.f., and when the proper correction is applied for the residual current the corrected diffusion current is found to be practically constant in case of gelatin as maxima suppressor. However in case of fuchsin this correction does not produce a constant limiting current, indicating that the limiting current is not entirely diffusion controlled. It is seen that the residual current increases markedly with increasing concentration of perchloric acid from 68

9 0.1 M to 3 M. The increase in residual current is attributed to the increase in the condenser current resulting from the charging of the double layer at the surface of R.P.E. With further increase in its concentration upto 7 M decrease in residual currents are observed where the capacity of the double layer changes markedly. In case of gelatin, at the former concentrations of perchloric acid, the waves has a flat slope and the diffusion current corrected for the residual current of the blank solution found to decrease slightly due to decrease in the apparent diffusion coefficient as perchloric acid concentration changes from 0.1 to 3 M. At higher concentration (> 3 M) of HCIO 4, the slope of waves becomes much flat which is indicative of irreversible reaction and wave height decreases considerably may be due to pronounced increasing character of viscosity. In case of fuchsin, in addition to increase in residual current due to rise in charging current with variation of HCIO 4 concentration from to 3 M they also increases wave height considerably. Increase of limiting current is caused by streaming of the solution which occurs over a wide potential range of the limiting current. Therefore the current rises above the diffusion controlled value over a wide range. Vigorous motion (streaming) of the solution is suppressed by gelatin and not by fuchsin hence in previous case an increase in wave height (due to streaming motion) with changing HCIO 4 concentration from 0.14 to 2.76 M is not observed Effect of acetic acid on the anodic waves of paracetamol Effect of various concentrations of acetic acid on the anodic wave of paracetamol in presence of % gelatin, 5 x 10-5 % fuchsin, 1 x 10-3 % methyl red, 1.5 x 10-3 % thymol blue and 2.5 x 10-2 % bromocresol green as maxima suppressors, shown in Fig. 3 to 7, are found to show no markable change in residual current. Decomposition oxidation potential is found to remain constant ( mv). In the dilute acetic acid medium the diffusion current appeared to be smaller than in concentrated acetic acid. This difference is due to the fact that the diffusion coefficient of paracetamol in dilute acetic acid is smaller than in concentrated acetic acid. In case of gelatin diffusion current as well as nature of C-V curve remains constant as acetic acid concentration changes from to 2.93 M. Current increases at fairly positive potentials, but no limiting current plateau is observed and the wave coincides with the curve of blank; indicating no restriction in the rate at which the participant (depolarizer) in the electrode process can be brought to the surface of the R.P.E. This is because supporting electrolyte i.e. acetic acid causes depolarization of the R.P.E. before the widest possible potential range of paracetamol reaches. In case of fuchsin, methyl red, thymol blue and bromocresol green as maxima suppressors markable rise in diffusion current values are noticed with increasing concentrations of acetic acid. Good sigmoid curves are obtained over a 4000 fold range acetic acid. For lower concentrations of acetic acid the waves have a flat slope and the diffusion current remained constant until the wave of supporting electrolyte appeared. But for higher concentrations of it waves became fairly steep making limiting current region indistinguishable Effect of hydrochloric acid on the anodic waves of paracetamol In hydrochloric acid solutions of paracetamol, catalytic waves are observed as may be seen in presence of 1.5 x 10-3 % fuchsin, 2.5 x 10-4 % methyl red and 1.25 x 10-3 % thymol blue (Fig. 8 to 10). Catalytic processes are manifested by a separate wave at potentials more positive than the wave for the oxidation of paracetamol as in case of 0.5 to 1.5 M HCI in presence of 1.5 x 10-3 % fuchsin. Only one wave appears at < 0.5 M HCI. At 0.5 M HCI a coalescence of two waves occurs, these waves separate at higher concentration values of HCI. Catalytic waves are characterized by a non-linear dependence on the paracetamol concentration and function of ph and increase with increasing HCI concentration. Thus in addition to oxidation processes polarographic curves also indicates catalytic processes. The apparent diffusion currents often increase markedly with increasing applied e.m.f. This is due to the increase of the residual current with increasing applied e.m.f. Further it is seen that the residual current increases with increasing HCI concentration from to 0.05 M HCI. The effect of HCI in presence of 3.78 x 10-3 % bromocresol green is particularly different. The height and shape of the wave depends on the concentration of the hydrochloric acid. The slope of the rising portion of the wave depends on the resistance of the solution. In very dilute solutions ( 0.01 M), which have a high resistance, the wave is flat and the current increases less steeply with increasing applied voltage. In more concentrated solutions the height of the wave decreases due to the reason that the diffusion coefficient of the paracetamol in concentrated HCI solution was smaller than that in 69

10 dilute hydrochloric acid medium. The shift of the waves to more positive potentials with increasing concentration of hydrochloric acid is also noticed in Fig. 11 (E decom. = 600 mv at M HCI; E decom. = 725 mv at 3 M HCI). 1 M HCI containing 3.78 x 10-3% bromocresol green is found to be an optimum supporting electrolyte in which case the diffusion current as well as limiting current plateau is well developed before the wave of supporting electrolyte appeared Effect of borate buffer on the anodic waves of paracetamol Effect of borate buffer of different ph is shown in Fig. 12. At the former ph values two-step waves are found. The depolarization potential at the beginning of the first wave is found to shift 50 mv to more negative potentials with a unit increase in ph. E decom at ph 8, 9, 10 and 11 is found to be 300, 250, 200 and 200 mv respectively. At ph value of 11 only one wave is found. At a ph of 9 the first diffusion current is about equal to the total diffusion current found at lower ph values, the second wave comprising only a few percent of the total current. In a more alkaline medium the second wave increases. At a ph of 10 two waves of nearly equal height are found. In solutions containing free sodium hydroxide the diffusion current decreases with time since the red form of fuchsin is changed into the colourless carbional which probably has stronger adsorbability hence more it suppresses the wave. The polarographic method is found quite suitable for following the rate of colour fading of fuchsin in an alkaline medium. When the concentration of red form becomes so small that only one wave is obtained, all the colourless form now remains adsorbed. Basic Fuchsin Colourless Carbinol In buffered solutions of paracetamol, catalytic waves are observed. Catalytic processes are manifested by a separate wave at potentials more positive than the wave for the oxidation of paracetamol. Catalytic waves are characterized by a non-linear dependence on the paracetamol concentration. In buffered solutions, catalytic waves are found to increase with increasing buffer concentration Effect of Sulphuric acid on the Anodic Waves of Paracetamol In addition to increase in residual current, an increase in limiting current above the diffusion controlled value due to increase in the apparent diffusion coefficient is observed with increasing concentrations of sulphuric acid. The diffusion current remained constant until the wave of the supporting electrolyte appeared (Fig. 13) Effect of Nitric acid on the Anodic Waves of Paracetamol Similar results as described above are obtained with varying concentrations of HNO 3 in presence of 1 x 10-3 % fuchsin. The residual as well as diffusion current increases markedly as nitric acid concentration changes from 0.01 to 2 M (Fig. 14). At higher concentrations of it residual current of the supporting electrolyte alone predominates than that of diffusion current. 4. Conclusion The residual current increases markedly with increasing concentrations of perchloric aicd from 0.1 to 3 M (in presence of optimum concentration of gelatin / fuchsin). With further increase in its concentration upto 7 M decreases in residual currents are observed where the capacity of the double layer changes markedly. In case of gelatin at the former concentrations of perchloric acid the diffusion current decreases slightly due to decrease in the apparent diffusion coefficient. At higher concentration (> 3M) of HCIO 4, 70

11 wave height decreases considerably may be due to pronounced increasing character of viscosity. While in case of fuchsin, variation of perchloric acid concentration from to 3 M increases wave height considerably. Effect of various concentrations of acetic acid on the anodic wave of paracetamol in presence of optimum concentration of gelatin, fuchsin, methyl red, thymol blue and bromocresol green as maxima suppressors is found to show no markable change is residual current. Decomposition oxidation potential is found to remain constant. ( mv). In the dilute acetic acid medium the diffusion current appeared to be smaller than in concentrated acetic acid. This difference is due to the fact that the diffusion coefficient of paracetamol in dilute acetic acid is smaller than in concentrated acetic acid. In hydrochloric acid solutions of paracetamol in addition to oxidation processes polarographic curves also indicate catalytic processes. The shift of the waves to more positive potentials with increasing concentration of hydrochloric acid is also noticed. The depolarization potential is found to shift, 50 mv to more negative potentials with a unit increase in ph. In solutions containing free sodium hydroxide the diffusion current decreases with time since the red form of fuchsin is changed into the colourless carbinol form which probably has stronger adsorbability hence more it suppresses the wave. In addition to increase in residual current, an increase in limiting current above the diffusion controlled value due to increase in the apparent diffusion coefficient is observed with increasing concentrations of sulphuric acid. Similar results are obtained with varying concentrations of nitric acid. Maxima suppressor-supporting electrolyte combinations as shown in Table 1 were found to give good results and were used for further determination of paracetamol. Table 1: Optimum concentration of Maxima Suppressor-Supporting Electrolyte for Paracetamol determination. Supporting Supporting Maxima Suppressor Maxima Suppressor electrolyte electrolyte 8 x 10-3 % Gelatin 0.14 M HCIO x 10-3 % Fuchsin 0.1 M HCI 3.75 x 10-4 % Fuchsin 0.1 M HCIO x 10-4 % Methyl red 0.01 M HCI 1 x 10-6 % Gelatin 0.1 M CH 3 COOH 1.25 x 10-3 % Thymol blue 1.0 M HCl 5 x 10-5 % Fuchsin 0.1 M CH 3 COOH 3.78 x 10-3 % Bromocresol green 1.0 M HCl 1 x 10-3 % Methyl red 0.1 M CH 3 COOH 2.5 x 10-5 % Fuchsin 1.5 x 10-2 % Thymol blue 2.5 x 10-2 % Bromocresol green Borate Buffer of ph M CH 3 COOH 1.25 x 10-2 % Fuchsin 0.99 M H 2 SO M CH 3 COOH 1 x 10-3 % Fuchsin 0.1 M HNO 3 5. References [1] M. E. Bosch, A. J. R Sánchez, F. S. Rojas, C. B. Ojeda. Determination of paracetamol: Historical evolution. Journal of Pharmaceutical and Biomedical Analysis 26 September 2006; Volume 42, Issue 3, pp [2] R. Joshi, R. Sharma. Anal. Lett. 2008; 41(18), [3] S. Wafaa. Am. J. Applied Sci. 2008; 5(8) [4] G. Garg, S. Saraf, S. Saraf. Indian J. Pharm. Sci. 2007; 69(5), [5] K. Karla, S. Naik, G. Jurmal, N. Mishra. Asian J. Research Chem. 2009; 2(2), [6] S. Narayan, P. Kumar, R. Sindhu, A. Tiwari, M. Ghosh. Der Pharma Chemica. 2009; 1(2), [7] T. Banerjee, B. Banerjee & A. Banerjee. A Review On Paracetamol & Lornoxicam. Asian Journal of Biochemical and Pharmaceutical Research 2011; Issue 4,Vol

12 [8] N. Dubey, R. Siddiqui, D. Jain. Simultaneous Determination of Paracetamol, Phenylephrine Hydrochloride and Loratadine. Asian Journal of Chemistry 2012; Vol. 24 Issue 11, p5409. [9] S J More, S S Tandulwadkar, A R Nikam, A S Rathore, L Sathiyanarayanan, K R Mahadik. Application of HPLC for the Simultaneous Determination of Paracetamol, Chlorzoxazone, and Nimesulide in Pharmaceutical Dosage Form. ISRN Chromatography 2012; Volume 2012, Article ID , 8 pages. [10] O M El-Houssini. RP-LC and TLC Densitometric Determination of Paracetamol and Pamabrom in Presence of Hazardous Impurity of Paracetamol and Application to Pharmaceuticals. Analytical Chemistry Insights 2013; [11] A G Olufemi and O A Lawrence. UV-Spectrophotometry and RP-HPLC methods for the simultaneous estimation of acetaminophen: Validation, comparison and application for marketed tablet analysis in South West, Nigeria. Journal of Chemical and Pharmaceutical Research 2013; 5(5):