Indirect spectrophotometric determination of folic acid based on the oxidation reaction and studying some of the thermodynamic parameters


N. S. Othman1, Sh. H. Hasan2 & K. M. Surchi3

1 College of Science, University of Mosul, 2 College of Agriculture, University of Salahaddin, 3 College of Science, University of Salahaddin


Abstract
A simple and sensitive indirect spectrophotometric method was developed for the determination of folic acid in pure form and in its pharmaceutical formulations. The method was based on the oxidation of folic acid by iron (III) in acidic medium, then reaction of liberated iron (II) with 2, 2'-bipyridyl to produce a red complex which is water-soluble, stable, and has a maximum absorption at 520 nm against the reagent blank with a molar absorptivity of 2.8338 x 105 L .mol-1.cm-1. Beer’s law is valid over the concentration range of 0.5-18.0 µg/ml folic acid. The values of some thermodynamic parameters [free energy change (∆G), enthalpy change (∆H), and entropy change (∆S)] were estimated from the values of stability constants (K) at different temperatures .It was found  that  colored product formation was spontaneous, exothermic and accompanied by an increase of random. The proposed method has been applied successfully to determine folic acid in different pharmaceutical preparations. 

Keywords: Spectrophotometry, Folic acid, 2,2'-Bipyridyl/FeCl3 Thermodynamic, Parameters

References

[1]      A.A. Al-Warthan, “Flow injection chemiluminometric determination of folic acid in pharmaceutical formulations.”, Anal. Sci., 10, pp. 919–922, (1994).

[2]      B. Klejdus, J. Petrlova, D. Potesil, V. Adam, R. Mikelova, J. Vacek, R. Kizek, and V. Kuban,“Simultaneous determination of water-and fat soluble vitamins in pharmaceutical preparations by high-performance liquid chromatography coupled with diode array detection”, Anal. Chim. Acta, 520, pp.57-67, (2004).

[3]      D. Fruhauf  and M. Juza, “ Development, optimization and validation of a sub-minute analytical enantioselective high performance liquid chromatographic separation for a folic acid precursor in normal phase mode”, J. Chromatography, A 1269, pp. 242-254, (2012). 

[4]      B.C. Nelson, K.E. Sharpless and L.C. Sander, “ Quantitative determination of folic acid in multivitamin–multielement tablets using liquid chromatography/ tandem mass spectrometry.”, J. Chromatogr. A, 1135, pp. 203–211, (2006).

[5]      D.E. Breithaupt, “ Determination of folic acid by ion-pair RP-HPLC in vitamin fortified fruit juices after solid-phase extraction.”, Food Chem., 74, pp.  521–525, (2001).

[6]      M.S.A. Pradoa, C.A. Silva, M.F. Tavaresa and K.D. Altria, “Determination of folic acid in tablets by microemulsion electrokinetic chromatography.”, J. Chromatogr. A, 1051, pp.291–296, (2004).

[7]      M.J. Akhtar, M.A. Khan and I. Ahmad, “ High-performance liquid chromatographic determination of folic acid and its photodegradation products in the presence of ribofl avin”,  J. Pharm Biomed Anal., 16, pp. 95–99, (1997).

[8]      H.X. Guo, Y.Q. Li, L.F. Fan, X.Q. Wu, M.D. Guo, “Voltammetric behavior study of folic acid at phosphomolybdic-polypyrrole film modified electrode”, Electrochim Acta, 51, pp. 6230–6237, (2006).

[9]      J. Amezdelpozo, A. Costagarica, A. Mirandaordieres and  P.Tunonblanco , “Phase-selective alternatingcurrent adsorptive stripping voltammetry of folic acid on a mercury thin-film electrode”, Electroanalytes, 4, pp. 87–92,(1992).

[10]   A.C. Le Gall, C. Vandenberg, “Determination of folic acid in sea water using adsorptive cathodic-stripping voltammetry”, Anal. Chim. Acta, 282, pp.459–70,(1993).

[11]   D.B. Luo, “Determination of folic acid by adsorptive stripping voltammetry at the static mercury drop electrode”, Anal. Chim. Acta., 189, pp.277–283,(1986).

[12]   S.W. Szczepaniak and M. Ren, “Adsorptive stripping-voltammetric determination of folic acid in pharmaceutical preparations”,Electroanalytes, 6 , pp. 505–507, (1994).

[13]   J.L. Manzoori , A. Jouyban, M. Amjadi, and J. Soleymani, “ Spectrofluorimetric determination of folic acid in tablets and urine samples using 1, 10-phenanthroline-terbium probe”, Luminescence, 26(2),pp.106–111, (2011).

[14]   A. Pathak and S.J. Rajput, “Simultaneous determination of a ternary mixture of doxylamine succinate, pyridoxine hydrochloride, and folic acid by the ratio spectra-zero-crossing, double divisor-ratio spectra derivative, and column high-performance liquid chromatographic methods ”, J. AOAC Int., 91(5), pp.1059–1069, (2008).

[15]   P. Nagaraja, R.A. Vasantha, and H.S. Yathirajan, “Spectrophotometric determination of folic acid in pharmaceutical preparations by coupling reactions with iminodibenzyl or 3-aminophenol or sodium molybdate–pyrocatechol.”, Anal. Biochem., 307(2), pp.316–321, (2002).

[16]   K. V. S. S. Murty, C. S. P. Sastry and B. G. Rao , “Spectrophotometric determination of aromatic amines using catechol and iodine”, J. Ind. Chem. Soc., 59, pp. 1107–1109, (1982).

[17]   M.N. Reddy, N. Viswanadham, and C.S.P. Sastry, “Spectrophotometric methods for the determination of folic acid”, Ind. Drugs, 21, pp.460–462, (1984).

[18]   F. Buhl, and U. Hachula, “Spectrophotometric determination of folic acid and other reductants using a couplet redox complexation reaction with cerium (IV) and arsenazo III”, Chemia Analiyczna, 36, pp. 27–34, (1991).

[19]   M.Q. Al-Abachi and R.S.Al-Abaidi, “Spectrophotometric assay of folic acid in pharmaceutical tablets via oxidative coupling.”,  Iraqi J. of Sci., 45(1), pp.24-29, (2004). 

[20]   D. L. Massart,  B. G. M. Vandeginste, S. N. Deming, Y. Michotte and L. Kaufman, “Chemometrics: Data Handling in Science and Technology”, Elsevier, Amsterdam, Vol. 2, (1988).

[21]   IUPAC, “Analytical Chemistry Division. Nomenclature, symbol, units and their usage in spectrochemical analysis. II. Data interpretation.”, Spectrochim. Acta. B, 33, pp.241-246, (1978).

[22]   B.C. Karlsson, A.M. Rosengren, P.O. Andersson and  I.A. Nicholls, “The spectrophysics of warfarin: Implications for protein binding.”, J. Phys. Chem., Part B, 111, pp. 10520–10528, (2007).

[23]   D.S. Foster, “photometric and fluorometric  methods of analysis metals”, part 1, John Wiley & Sons, Inc. ; New York , pp.750,(1978).

[24]   L. G. Hargis , “Analytical chemistry: Principles and techniques”, Prentice-Hall, Inc., Englewood Cliffs, New Jersey, Ch. 23,pp. 549-568, (1988).

[25]   C. Rossotti, H. Rossotti, “The Determination of stability Constant”, McGraw – Hill book company, Inc, USA, pp.23-78, (1961).

[26]   P.Atkins, J.De Paula, “Physical Chemistry”, 8 th Edn. W. H. Freeman and Company, pp.212, (2006).  

[27]   J. Hine, “Physical Organic Chemistry”, 2nd ed., McGraw-Hill, New York, pp. 486-487, (1962). 

[28]   F. Khan, and L. Tantuvay,” Thermodynamics in  [Mn(II)-antibiotics-bacitracin] mixed system: a polarographic approach.”, J. Pharm. Biomed. Anal., 27, pp. 933-944, (2002).

[29]   A. A. Al-sarawy,” Potentiometric and thermodynamic studies of 4-sulfamethoxazoleazo-3 -methyl-2pyrazolin-5-one and its metal complexes.,”,Chem. Pap., 58( 2), pp.109-112, (2004).

[30]   E. G. Akgemci and T. Atalay ,” Determination of thermodynamic parameters of some complexes of 9ethyl-3-carbazolecarboxaldehyde 4-phenyl-3-thiosemicarbazone.”, Turk. J. Chem., 24(1), pp.89-94, (2000).

[31]   J.N. Miller and J.C. Miller, Statistics and chemometrics for analytical chemistry, 5th Ed., Pearson Education Limited, Harlow, England, pp.107-149, (2005).

[32]   British Pharmacopoeia, H.M. Stationery Office, London, UK, 1, pp.575, (2013).