SciELO - Scientific Electronic Library Online

 
vol.39 número5A New Synthesized Schiff Base as Corrosion Inhibitor for Mild Steel in a HCl Medium: Experimental, Density Functional Theory and Molecular Dynamics Simulation Studies índice de autoresíndice de assuntosPesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Journal

Artigo

Indicadores

Links relacionados

  • Não possue artigos similaresSimilares em SciELO

Compartilhar


Portugaliae Electrochimica Acta

versão impressa ISSN 0872-1904

Port. Electrochim. Acta vol.39 no.5 Coimbra out. 2021  Epub 31-Out-2021

https://doi.org/10.4152/pea.2021390505 

Research Article

Potentiometric Determination of Oxymetazoline Hydrochloride Using Modified Carbon Paste Electrodes

Yousry M. Issa1 

Mohamed M. Khalil2 

Sayed I. M. Zayed3 

Naglaa Mustafa2 

1Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt

2Chemistry Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt

3Faculty of Technology and Education, Beni-Suef University, Beni-Suef, Egypt


Abstract

Two carbon paste electrodes for oxymetazoline hydrochloride were constructed based on ion pair complexes of this drug, with sodium tetraphenylborate (NaTPB) or ammonium reineckate, using dibutyl phthalate and dioctyl phthalate as solvent mediators, respectively. The developed electrodes displayed a fast, stable response over the concentration range from 3.98x10-5 to 1x10-2 M oxymetazoline hydrochloride, with a near-nernstian slope of 59.0, 58.2 mV of concentration decade-1 and a limit of detection (LOD) of 3.31x10-5 and 3.72x10-5 M, in the oxymetazoline-tetraphenylborate and oxymetazoline-reineckate cases, respectively. The developed electrodes have been successfully applied for oxymetazoline hydrochloride determination in the Afrin nasal drop pharmaceutical formulation.

Keywords: Oxymetazoline hydrochloride; modified carbon paste electrode; potentiometry; pharmaceutical formulation

Introduction

Oxymetazoline hydrochloride (OMCl), phenol, 3-[4,5-dihydro-1H-imidazol-2-yl)methyl]-6-(1,1-dimethylethyl)-2,4-dimethylmonohydrochloride [2315-02-8] (Scheme 1) is an adrenergic (nasal) drug [1].

Scheme 1 Structural formula of oxymetazoline hydrochloride. 

A review of the literature revealed that several methods have been used for oxymetaoline hydrochloride determination. These include high performance liquid chromatography (HPLC) [2-13], gas chromatography [14], a two phase titration method [15], flow injection chemiluminometry [16,17], spectrophotometry [18-33] and spectrofluorimetry [34]. A plastic PVC membrane ion selective electrode method, based on oxymetazoline-phosphotungstate, has been reported [35]. Carbon paste electrodes (CPEs) have attracted attention as ion selective electrodes, mainly due to their advantages over membrane electrodes, such as renewability, stable response, low ohmic resistance and no need of an internal solution [36]. The aim of this work is to describe the construction and performance characteristics of oxymetazoline modified carbon paste electrodes based on oxymetazoline-tetraphenylborate and oxymetazoline-reineckate as electroactive materials, using dibutyl phthalate and dioctyl phthalate as solvent mediators, respectively. The developed carbon paste selective electrodes were used for OMCl determination in Afrin nasal drops pharmaceutical preparation (0.05%).

Experimental

Reagents and materials

All chemicals were of analytical grade. Double distilled water was used throughout all experiments. Pure grade oxymetazoline hydrochloride and the Afrin nasal drops (0.05%) pharmaceutical preparation were provided by Medical Union Pharmaceuticals Co., Abou Sultan, Egypt. Sodium tetraphenylborate (NaTPB), ammonium reineckate, dioctyl sebacate (DOS) and tricresyl phosphate (TCP) were obtained from Fluka. Dibutyl phthalate (DBP) and dioctyl phthalate (DOP) were obtained from Merck. Graphite powder (1-2 micron) was obtained from Aldrich Co.

Apparatus

Potentiometric and pH measurements were carried out using a Seibold G-103 digital pH/mV meter (Vienna, Austria). A C-100 Techne circulator thermostat model was used to control the test solutions temperature. A saturated calomel electrode (SCE) was used as the reference electrode. The electrode electrochemical system may be represented as follows: OM-carbon paste electrode / test solution // KCl salt bridge // saturated calomel electrode.

Ion pair preparation

The ion pairs, OM-TPB and OM-reineckate, were prepared by mixing a 100 mL of a 10-2 M OMCl solution with 100 mL of 10-2 M of sodium tetraphenyl borate or ammonium reineckate. The formed precipitates were filtered, washed thoroughly with bidistilled water and dried at room temperature. The composition of the ion pair was found to be 1:1, both for OM-TPB and OM-reineckate, as confirmed by elemental analysis data done at Microanalytical Center, Faculty of Science, Cairo University. The found percentage values were 82.54, 7.40 and 4.73, and the calculated values were 82.89, 7.65 and 4.83, for C, H and N, respectively, in the OM-TPB case, while in the OM-reineckate case, the found percentage values were 40.56, 4.93 and 18.62, and the calculated were 40.25, 5.40 and 18.77, for C, H and N, respectively.

Electrode assembly

Carbon paste was prepared by mixing the required amount of the ion pair with graphite powder (Aldrich, 1-2 micron) and dibutyl phthalate (DBP) or dioctyl phthalate (DOP) with a pasting liquid (the ratio of graphite powder to pasting liquid was 1:1) in a mortar, until it was uniformly wetted. The carbon paste electrode was prepared by successive packing of the carbon paste into the tip end of a home-made Teflon holder (2 mm), and electrical contact was achieved by a stainless steel rod (2 mm) connecting the paste to the mV meter.

Electrodes selectivity

The electrodes selectivity coefficients towards different Jz+ cationic species were determined by a separate solution method [37], in which the Nicolsky Eisenman equation was used:

where E1 and E2 are the electrode potentials in 1 x 10-3 mol L-1 OMCl and Jz+ interfering ions, respectively, and S is the slope in mV. In case of ions without charges, the selectivity coefficients were determined by the matched potential method (MPM) [38]. In this method, a known activity of the oxymetazoline ion solution was added into a reference solution containing a fixed activity of oxymetazoline ion, αOM (α'OM - αOM is the change in activity), and the corresponding potential change (ΔE) was recorded. Then, a solution of the interfering ion was added to the reference solution, until the same potential change (ΔE) was reached. The change in potential produced at the constant background of the primary ion must be the same in both cases:

where αj is the added interferent activity.

OMCl potentiometric determination

OMCl has been potentiometrically determined using the investigated electrodes by the standard addition method [39] and by potentiometric titration with a standard solution of NaTPB.

OMCl determination in Afrin nasal drops (0.05%)

The request amount of nasal drop solution (0.05%) was transferred to a separating funnel, 25 mL of a saturated solution of sodium borate were added and extracted with four 25 mL portions of chloroform, and then the extracts were combined in a second separating funnel. The combined chloroform extracts were extracted with two 20 mL portions of dilute hydrochloric acid (20 fold dilution), the acid extracts were combined in a 50 mL volumetric flask, and dilute hydrochloric acid was added to the mark and mixed. The contents of the measuring flask were transferred to a 100 mL beaker, and subjected to OMCl potentiometric determination, by using the standard addition method, as previously described in the pure drug solution case.

Results and discussion

Carbon paste electrodes composition

Four compositions containing the OM-TPB or OM- reineckate ion pairs, in the ratio of 5, 10, 12 and 15%, were prepared; the ratio of graphite to liquid mediators (DBP) was 1:1, after the electrodes soaking for 30 min in a 10-3 M OMCl solution (Table 1). Results indicated that the carbon paste electrode with an ion pair ratio of 10% exhibited the best performance characteristic, with slopes of 59.00 and 53.20 mV of concentration decade, at 25oC, for OM-TPB and OM-reineckate, respectively. The performance characteristics of the selective electrodes were primarily affected by the plasticizers, due to their effect on migration, ion pair formation and diffusion coefficient [40]. The plasticizers effect type on the OM electrodes performance characteristic was investigated by using four plasticizers with different polarities (DBP, DOP, DOS, and TCP), as shown in Table 2. The results indicate that DBP and DOP are the best solvent mediators for OM-TPB and OM-reineckate electrodes, respectively. Poor sensitivities for the electrodes using other plasticizers as liquid mediators are due to low distributions of the OM-TPB or OM- reineckate electroactive complexes in these solvents [41].

Table 1 Composition of oxymetazoline carbon paste electrodes and the slope of their calibration graphs, at 25 ± 1oC, and 30 min soaking in 1a 0-3 M OMCl solution. 

Effect of pH

The effect of the solution pH on the electrode response was checked for two OMCl concentrations (1x10-4 and 1x10-3 M), by following the variation in potential with change in pH, by the addition of very small volumes of hydrochloric acid and sodium hydroxide (0.1-1.0 M). The results indicate that the investigated electrodes showed no pH response over the pH range from 2.0 to 9.4, for the two proposed electrodes. Fig. 1 represents potential versus pH profiles for OM-TPB electrode. The decrease in potential occurring at higher pH values is most probably attributed to the free oxymetazoline base formation in the solution, leading to a decrease in the oxymetazoline cation concentration (pKa = 10.6 [43]).

Table 2 Effect of solvent mediator on 10% OM-TPB and 10% OM-reineckate electrodes, and the slopes of their calibration graphs, at 25 ºC, and 30 min soaking in a 10-3 M OMCl solution. 

Figure 1 pH effect of the test solution on the OM-TPB electrode potential response: (a) 1 x 10-4 M and (b) 1 x 10-3 M OMCl solutions. 

Electrode life span

The life span of the proposed electrodes was investigated by periodically performing the calibration graphs, and calculating the response slope after the electrode was left in air without soaking in the drug; the electrode was preconditioned by soaking in 1x10-3 M OMCl, for 30 min, before use. The results indicate that, in the OM-TPB electrode case, the calibration graph slope remained constant, near 59.0 mV decade-1, for 1 day; then, it slightly decreased, reaching about 56.0, 55.0, 53.0, 52.0, 51.0 and 50.0 mV decade-1, after 8, 21, 30, 45, 60 and 90 days, respectively. In the OM-reineckate electrode case, the calibration graph slope remained constant near 58.0 mV decade-1, for 1 day; then, it slightly decreased, reaching about 52.0 and 50.0 mV decade-1, after 8 and 15 days, respectively. The response time of the proposed OM carbon paste electrodes was found to be < 10 seconds.

Effect of test solution temperature

To study the investigated electrodes thermal stability, calibration graphs were constructed at different test solution temperatures, and the isothermal coefficients (dE/dt) of these electrodes were calculated [44] to be 0.0010 and 0.0020 V/ ºC, for OM-TPB and OM-reineckate electrodes, respectively.

Selectivity

The influences of some inorganic cations, sugars, amino acids and vitamins, on the OM electrodes response, were investigated according to IUPAC recommendations, using the separate solution method (SSM) [37] or matched potential method [38]. The selectivity coefficients values, , presented in Table 3, indicate that the proposed carbon paste electrodes are highly selective towards the oxymetazoline cation. The inorganic cations do not interfere, because of the difference in their mobility and permeability, as compared to the oxymetazoline cation. In the sugars and amino acids case, the high selectivity is related to the difference in polarity and lipophilic nature of their molecules relative to the oxymetazoline cation.

Table 3 Selectivity coefficients,, for the OM electrodes. 

Analytical applications

The usefulness of the investigated electrodes was examined by using them for the OMCl potentiometric determination in pure solutions and in the Afrin nasal drops pharmaceutical preparation (0.05%). Standard addition and potentiometric titration methods were used in the pure solutions case. In the Afrin nasal drops pharmaceutical preparation case (0.05%), the standard addition method was used. The potentiometric titration method could not be used, because it had a lower OMCl concentration (0.5 mg / mL of the drops), and the potentiometric titration method needs a higher drug concentration. Fig. 2A and Fig. 2B represent the potentiometric titration methods using the OM-TPB electrode and OM-reineckate electrode, respectively.

Figure 2A Potentiometric titrations of (a) 10 and (b) 15 mL of the 10-2M OMCl drug in a 10-2 M NaTPB solution using OM-TPB electrode. 

Figure 2B Potentiometric titrations of (a) 10 and (b) 15 mL of the 10-2M OMCl drug in a 10-2 M NaTPB solution using an OM-reineckate electrode. 

The mean recovery and relative standard deviation values are briefed in Table 4.

The results were in good agreement with the label claims and with the values obtained using the official United States Pharmacopeia1 (Table 5). Statistical comparison of the accuracy and precision of the proposed methods with the official method was performed using Student's t- and F-ratio tests, at a 95% confidence level [45].

Table 4 OMCl determination by applying OM-TPB and OM-reineckate responsive electrodes. 

Sample Standard addition method Potentiometric titration method
Taken (mg) Mean recovery (%) RSD (%) Taken (mg) Mean recovery (%) RSD (%)
OM-TPB
Pure solution 1.84 99.11 0.70 22.9 99.40 0.45
2.30 98.40 0.62 34.5 98.40 0.55
4.60 99.00 1.40
11.50 98.90 0.88
Afrin nasal drops (0.05%) 0.50 97.70 0.93
1.00 98.20 0.25
1.50 99.11 0.12
2.00 98.50 0.24
OM-reineckate
Pure solution 1.84 97.70 1.11 22.9 99.60 0.50
2.30 98.50 1.22 34.5 98.30 0.32
4.60 98.30 1.49
11.50 97.90 1.22
Afrin nasal drops (0.05%) 0.50 98.11 0.79
1.00 98.40 0.15
1.50 99.40 0.45
2.00 99.30 0.36

Relative standard deviation (four determinations).

Table 5 Statistical comparison between the results of the analysis of an Afrin nasal drop pharmaceutical preparation (0.05%), applying the proposed standard addition method and the official method, using carbon paste electrode. 

Parameter Standard addition method Official method [1]
OM-TPB electrode
Mean Recovery % 98.37 99.22
SD 0.378 0.598
RSD 0.385 0.603
F-ratio 2.45 (9.28)a
t-test 2.37 (2.447)b
OM-reineckate electrode
Mean Recovery % 98.80 99.43
SD 0.42 0.598
RSD 0.43 0.602
F-ratio 1.96 (9.28)a
t-test 1.70 (2.447)b

SD: Standard deviation; RSD: Relative standard deviation; a Tabulated F-ratio value at 95% confidence level; b Tabulated t-value at 95% confidence level and six degrees of freedom.

Conclusions

The proposed oxymetazoline modified carbon paste electrodes based on OM-TPB and OM-Rein ion pairs, as electroactive materials, are useful sensors for this drug determination in its pharmaceutical formulation, Afrin nasal drops (0.05%). These sensors have advantages of high selectivity, low cost and fast response and wide applicable range.

References

1. United States Pharmacopeia, XX National formulary XV, United States Pharmacopeial convention, Inc., 1980. [ Links ]

2. Kountourellis JE, Raptouli A. Simultaneous determination of 2-imidazolines and other pharmaceutical substances in commercial preparations by high performance liquid chromatography. Anal Lett. 1988;21(8):1361-1370. DOI: https://doi.org/10.1080/00032718808059869 [ Links ]

3. Hoffmann TJ, Thompson RD, Seifert JR. Determination of the nasal decongestant oxymetazoline hydrochloride in pharmaceutical formulations by HPLC. Drug Dev Ind Pharm. 1989;15(5):743-757. DOI: https://doi.org/10.3109/03639048909058529 [ Links ]

4. Li TP, Song YR. Determination of the stability of oxymetazoline hydrochloride in nasal drops by high performance liquid chromatography. Sepu.1994;12(4):304. [ Links ]

5. Hayes FJ, Baker TR, Dobson RLM, et al. Rapid liquid chromatographic-mass spectrometric assay for oxymetazoline in whole rat blood. J Chromatogr A. 1995;692(1-2):73-81. DOI: https://doi.org/10.1016/0021-9673(94)00630-R [ Links ]

6. De-Orsi D, Gagliardi L, Cavazzutti G, et al. Simultaneous determination of ephedrine and 2-imidazolines in pharmaceutical formulations by reversed phase HPLC. J Liq Chromatogr.1995;18(16):3233-3242. DOI: https://doi.org/10.1080/10826079508010447 [ Links ]

7. Li ZF, Huang JC. Qualitative evaluation of humoxal (nasal spray) by reversed phase high performance liquid chromatography. Yaowu-Fenxi-Zazhi. 1997;17(1):46-47. [ Links ]

8. Beata S, Wojciech N. Determination of oxymetazoline hydrochloride and decomposition products by high performance liquid chromatography. Acta Pol Pharm. 2000;57(6):399-401. [ Links ]

9. Sudsakorn S, Kaplan L, Williams DA. Simultaneous determination of triamcinolone acetonide and oxymetazoline hydrochloride in nasal spray formulations by HPLC. J Pharm Biomed Anal. 2006;40(5):1273-1280. DOI: https://doi.org/10.1016/j.jpba.2005.09.018 [ Links ]

10. Shaikh KA, Patil AT. Stability indicating HPLC method for the determination of mometasone furoate, oxymetazoline, phenyl ethanol and benzalkonium chloride in nasal spray solution. J Trace Anal Food and Drug. 2013:14-21. DOI: https://doi.org/10.7726/jtafd.2013.1002 [ Links ]

11. Hegazy MA, El-Ghoashy MA, El Tanany BM, et al. Validated chromatographic methods for the simultaneous determination of sodium cromoglycate and oxymetazoline hydrochloride in a combined dosage form. J A C. 2015;11(8):2850-2859. DOI: https://doi.org/10.24297/jac.v11i8.2191 [ Links ]

12. Fathy ME, Aboel Abass Mohamed S, El-Mansi H, et al. Simultaneous determination of cromolyn sodium combined dosage forms using isocratic HPLC method. J Chromatogr Sci. 2017;55(1):14-22. DOI: https://doi.org/10.1093/chromsci/bmw142 [ Links ]

13. Sreelakshmi M, Sasidhar RLC, Raviteja B. Reverse phase HPLC method for simultaneous estimation of tetracaine and oxymetazoline in bulk samples. J Pharm Sci Res. 2017;9(9):1589-1594. [ Links ]

14. Massaccesi M. Gas chromatographic determination of some imidazolines in pharmaceutical preparations by using FFAP as stationary phase. Pharm Acta Helv. 1987;62(10-11):302-305. [ Links ]

15. Massaccesi M. Two-phase titration of some imidazole derivatives in pharmaceutical preparations. Analyst. 1986;111:987-9. DOI: https://doi.org/10.1039/an9861100987 [ Links ]

16. Garcia-Campana AM, Bosque-Sendra JM, Bueno-Vargas MP, et al. Flow injection analysis of oxymetazoline hydrochloride with inhibited chemiluminescent detection. Anal Chim Acta. 2004;516(1):245-249. DOI: https://doi.org/10.1016/j.aca.2004.03.067 [ Links ]

17. Bueno-Vargas MP, Garcia-Campana AM, Bosque-Sendra JM, et al. Determination of oxymetazoline hydrochloride by flow injection analysis with inhibited chemiluminescent detection. Luminescence. 2002;17(4):204-205. [ Links ]

18. Shingbal DM, Sawant KV. Colorimetric determination of oxymetazoline hydrochloride. Indian Drugs. 1982;20(3):106-107. [ Links ]

19. Kamalapurkar OS, Priolkar SRS. Estimation of oxymetazoline hydrochloride and terbutaline sulphate using Folin-Ciocalteu reagent. Indian Drugs. 1983;20(4):164-166. [ Links ]

20. Sane RT, Nayak VG, Joshi SK, et al. Spectrophotometric methods for determination of six drugs using Folin-Ciocalteu phenol reagent. Indian Drugs. 1983;20(8):329-330. [ Links ]

21. Shingbal DM, Naik SD. Spectrophotometric determination of oxymetazoline hydrochloride. East Pharm. 1983;26(308):201-202. [ Links ]

22. Sane RT, Shinde BR, Parikh AK, et al. Application of cobalt thiocyanate in the photometric determination of nine drugs from pharmaceutical preparations. Indian Drugs. 1984;21(6):257-260. [ Links ]

23. Dixit RK, Misra SK, Awasthi BB. Sensitive colorimetric estimation of oxymetazoline hydrochloride. Indian Drugs. 1984;22(1):31-33. [ Links ]

24. Anjaneyulu Y, Chandra-Sekhar K, Anjaneyulu V, et al. Extractive spectrophotometric determination of some imidazoline drugs as ion pair with rose Bengal. Indian Drugs. 1985;22(12):655-657. [ Links ]

25. Sankar DG, Sastry CSP, Reddy MN, et al. Spectrophotometric determination of some adrenergic drugs using 2,6-dichloroquinone chlorimide. Indian J Pharm Sci. 1987;49(2):69-71. [ Links ]

26. Sankar DG, Sastry CSP, Reddy MN, et al. Spectrophotometric determination of some adrenergic agents using iron (III) and 2,4,6-tri-2-pyridyl-1,3,5-triazine. Indian J Pharm Sci. 1988;50(3):178-180. [ Links ]

27. Sankar DG, Sastry CSP, Reddy MN, et al. Extraction spectrophotometric determination of some adrenergic drugs using fast green FCF or orange II. Indian Drugs. 1989;26(7):348-351. [ Links ]

28. Zakaria SA. Spectrophotometric determination of oxymetazoline hydrochloride via coupling reaction with 4-aminoantipyrine in the presence of potassium periodate. Raf J Sci. 2011;22(4):97-108. [ Links ]

29. Al-Sabha TN, Rasheed BA. Spectrophotometric determination of oxymetazoline hydrochloride based on the oxidation reactions. Jordan J Chem. 2011;6(4):403-411. [ Links ]

30. Othman NS, Fathe SA. Indirect spectrophotometric determination of oxymetazoline hydrochloride. Raf J Sci. 2013;24(1):84-95. DOI: https://doi.org/10.33899/rjs.2011.6805 [ Links ]

31. Abbdel-Aziz O, El Kosasy AM, Magdy N, et al. Novel spectroscopic methods for determination of cromolyn sodium and oxymetazoline hydrochloride in binary mixture. Spectr Chim Acta. 2014;131:59-66. DOI: https://doi.org/10.1016/j.saa.2014.04.047 [ Links ]

32. Hegazy MA, Al-Ghobashy MA, El-Tanany BM, et al. Spectral resolution and simultaneous determination of oxymetazoline hydrochloride and sodium cromoglycate by derivative and ratio based spectrophotometric methods. Eur J Chem. 2015;6(3):319-324. DOI: https://doi.org/10.5155/eurjchem.6.3.319-324.1278 [ Links ]

33. Al Sabha TN, Mohammed NMS, Abdul-Jabar PA. Spetrophotometric determination of oxymetazoline hydrochloride via charge transfer reaction using 2,3-benzoquinone reagent. Eur Chem Bull. 2015;4(8):372-377. [ Links ]

34. Salama F, Abdel-Salam K, Abdel-Halim A, et al. Validated spectrofluorimetric method for the determination of oxymetazoline hydrochloride via derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3- diazole. Eurasian J Anal Chem. 2018;13(4), DOI: https://doi.org/10.29333/ejac/87092. [ Links ]

35. Issa YM, Zayed SIM. Construction and analytical applications of plastic membrane electrode for oxymetazoline hydrochloride. Anal Sci. 2004;20(2):297-300. [ Links ]

36. Ganjali MR, Khoshsafar H, Shirzadmehr A, et al. Improvement of carbon paste ion selective electrode response by using room temperature ionic liquids and multiwalled carbon nanotubes. Int J Electrochem Sci. 2009;4(3):435-443. [ Links ]

37. Guibault GG, Durst RA, Frant MS, et al. Recommendations for nomenclature of ion selective electrodes. Pure App Chem. 1976;48:127-132. [ Links ]

38. Umezawa Y, Buhlmann P, Umezawa K, et al. Potentiometric selectivity coefficients of ion selective electrodes. Pure Appl Chem. 2000;72:1851-2082. [ Links ]

39. Baumann EW. Trace fluoride determination with specific ion electrode. Anal Chim Acta. 1968;42:127-132. DOI: https://doi.org/10.1016/S0003-2670(01)80277-4 [ Links ]

40. Zook JM, Langmaier J, Lindner E. Current polarized ion selective membranes: The influence of plasticizer and lipophilic background electrolyte on concentration profiles, resistance, and voltage transients. Sens Actuators B. 2009;136(2):410-418. DOI: https://doi.org/10.1016/j.snb.2008.12.047 [ Links ]

41. Armstrong RD, Horvai G. Properties of PVC based membranes used in ion selective electrodes. Electrochem Acta. 1990;35(1):1-7. DOI: https://doi.org/10.1016/0013-4686(90)85028-L [ Links ]

42. Buck RP, Lindner E. Recommendations for nomenclature of ion selective electrodes. Pure Appl Chem. 1994;66:2527-2536. [ Links ]

43. Meloun M, Syrovy T, Vrana A. The thermodynamic dissociation constants of ambroxol, antazoline, naphazoline, oxymetazoline and ranitidine by the regression analysis of spectrophotometric data. Talanta. 2004;62(3):511-522. DOI: https://doi.org/10.1016/j.talanta.2003.08.027 [ Links ]

44. Oesch U, Ammann D, Simon W. Ion selective membrane electrodes for clinical use. Clin Chem. 1986;32(8):1448-1459. DOI: https://doi.org/10.1093/clinchem/32.8.1448 [ Links ]

45. Miller J.C, Miller JN. Statistics for Analytical Chemistry. 3rd edition. Chichester: Ellis Horwood; 1993. [ Links ]

Received: December 20, 2018; Accepted: March 02, 2021

Corresponding author: simzayed2011@hotmail.com

Creative Commons License This is an open-access article distributed under the terms of the Creative Commons Attribution License