Charge Transfer Complexation Reaction Research Articles

Validated Spectrophotometric Methods Based on Charge Transfer Complexation Reactions for the Quantification of Antimalarial Drug: Chloroquine Phosphate in Pure and Dosage Forms

Validated Spectrophotometric Methods Based on Charge Transfer Complexation Reactions for the Quantification of Antimalarial Drug: Chloroquine Phosphate in Pure and Dosage Forms

Utilization of charge transfer complexation reaction for the spectrophotometric determination of acyclovir as antiviral drug in pharmaceutical formulations

Utilization of charge transfer complexation reaction for the spectrophotometric determination of acyclovir as antiviral drug in pharmaceutical formulations

Spectrophotometric studies of low-cost method for determination of ceftriaxone using a novel charge transfer acceptor, N-(2,4-dinitro-1-naphthyl)-p-toluenesulphonamide

BackgroundThis study reports a new, cost-effective and validated method for the determination of ceftriaxone (CFR). The method involved charge transfer (CT) complexation reaction of ceftriaxone (as n-electron donor) and N-(2,4-dinitro-1-naphthyl)-p-toluenesulphonamide {N-(2,4-DN1NL) PTS} as π-electron acceptor to form a complex. Ultraviolet, infrared and 1H NMR spectra of CFR, N-(2,4-DN1NL) PTS and adduct were then studied to predict the site of interaction between the donor and acceptor.ResultThe complex formed had deep golden-yellow colour, having a new absorption band at 440 nm. Molar absorptivity of 1.667 × 105 L M−1 cm−1 was obtained. The complexation reaction was completed at 30 °C optimal temperature within 10 min. Acetonitrile was found to be the best diluting solvent for optimal detector response and the complex was stable (absorbance unchanged) at room temperature for hours. At concentration of 1.708–11.956 µg mL−1, with low limits of detection of 0.143 µg mL−1, Beer’s law was observed. Between-day recovery statistics of CFR from quality control samples were 102.15 ± 0.062 (% RSD = 0.61, n = 12) over three days. The site of interaction of donor and acceptor molecules, as revealed through infrared (IR) and proton nuclear magnetic resonance studies (1H NMR) and the formation of charge transfer complex is through intermolecular hydrogen bonding between the amino group of the donor and the acidic proton of the acceptor. Common tablet excipients, as observed, did not interfere with the analytical method and no significant difference existed between the results of this new method and the high performance liquid chromatographic procedures (p > 0.05) documented in the USP. The new CT procedure described in this paper is not only simple but also fast, accurate and precise. Also, the reactions were carried out at room temperature compared to previously described procedures.ConclusionsThis novel method could therefore be adopted as a fast but cost-effective alternative for the qualitative and quantitative assessment of CFR in its pure and dosage form. It could find usefulness in on-the-spot detection of counterfeit drugs and in field inspections with reliable accurate results that compares with established methods.

Estimation of thiamine hydrochloride and sulphite using charge transfer complex reaction

A new spectrophotometric method is used for estimating Thiamine hydrochloride in its pure form and pharmaceutical formulations, the present method depends on the reaction between Thiamine hydrochloride and chrome azurol S to form a red complex which exhibit maximum absorption at 510 nm, the addition of Sulphite to the resulted red complex is bleaching it and this step was used for the determination of Sulphite which is considered an attacker of Thiamine hydrochloride, therefore, this method was developed for determination of Thiamine hydrochloride in presence of Sulphite. The linearity of the proposed method was obeyed Beer’s law from 2 to 48 and 0.04 to 2.4 ppm for Thiamine hydrochloride and Sulphite respectively. Also, the method sensitivity was measured by molar absorptivity values 5.9×104 l.mol-1.cm-1 and 1.68×104 l.mol-1.cm-1 for Thiamine hydrochloride and Sulphite respectively. The present method accuracy (average recovery) 100.06% and 100.04% the precision (RSD) of the method is ±0.98 - ±1.27% and ±0.76 - ±1.47 of Thiamine hydrochloride and Sulphite respectively. This method was applied for the estimation of B1 and SO32- in pharmaceutical preparations and various water samples respectively.

Validated spectrophotometric determination of maduramicin ammonium using three charge transfer complexation reactions

Direct spectrophotometric determination of Maduramicin ammonium (MAD) represents an analytical challenge since it is a weak UV-absorbing and lacking a strong chromophore. This work represents the first spectrophotometric determination of MAD as no direct spectrophotometric or colorimetric determination methods for MAD are available in the literature. The present study illustrates the development of three simple, rapid and inexpensive colorimetric methods for the routine quality control analysis of MAD based on the formation of colored charge transfer complexes with three electron acceptors namely p-chloranilic acid (p-CA), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and picric acid (PA). The color products of MAD with p-CA, DDQ and PA were measured at 519, 588 and 405nm respectively. The proposed methods were validated in terms of linearity, ranges, precision, accuracy, robustness and limits of detection and quantification. MAD was effectively determined over concentration ranges of 100-1000, 25-250 and 30-150μg/mL using p-CA, DDQ and PA, respectively with good linearity as shown by the values of correlation coefficients not less than 0.9991. The developed methods were successfully implemented in the assay of MAD powder pharmaceutical formulation for veterinary use.

Accelerated weathering studies of bioepoxy/ionic liquid blends: influence on physical, thermo-mechanical, morphology and surface properties

Ionic liquids are promising candidates with huge potential in combination with thermosetting polymers. However, the behavior of ionic liquid modified epoxy system towards outdoor environmental conditions are seldom reported. Therefore, it is interesting to study the effect of accelerated weathering on ionic liquid modified bioepoxy blends. In this work, bio-based epoxy resin and 1-Butyl-3-methylimidazolium chloride (BMIM[Cl]) ionic liquid blends were prepared by melt mixing method. The concentration of ionic liquid used was 0, 5, 10, 20, and 30 phr. The miscibility, morphology, thermo-mechanical, and surface hydrophilicity of the ionic liquid modified bioepoxy blends were studied before and after the accelerated weathering test. The miscibility of the blends was studied by Fourier transform infrared spectroscopy (FTIR). The FTIR results demonstrate the presence of charge transfer complexation reaction between ionic liquid and bioepoxy resin. The tensile strength and modulus were reduced while the elongation at break is increased with the addition of ionic liquid. On the other hand, the glass transition temperature and thermal stability of the bioepoxy blends were reduced with the addition of ionic liquid. The contact angle value increases with the incorporation of up to 10 phr ionic liquid, this is followed by a decrease. The interaction between the ionic liquid and bioepoxy resin has vanished after the weathering test. The elongation at break was reduced dramatically after the weathering test, especially for 20 and 30 phr blends. The thermal stability of the weathered samples is similar to that of the samples before weathering. While the Tg values of the blends are stable with respect to neat bioepoxy resin. On the other hand, the contact angle value of the bioepoxy blends increased after the weathering test due to the increased surface roughness after weathering.

Spectrophotometric Determination of Zolmitriptan in Pure Form and in Tablets Through Charge Transfer Complex Reaction

Apert syndrome (AS) a type of acrocephalosyndactyly is a rare congenital disorder with autosomal dominant mode of transmission that consists of craniofacial synostosis, midfacial hypoplasia and bilateral limb syndactyly. Patients present in early childhood for multiple surgeries which make it imperative to know about various anaesthetic implications like difficult airway ventilation, airway hyper reactivity, associated congenital anomalies, increased airway secretions and deranged temperature thermoregulation associated with this syndrome. The patient should be thoroughly evaluated preoperatively and managed accordingly. We discuss the successful management of a three and a half years old male child two simple, rapid and selective colorimetric methods were developed for the determination of zolmitriptan (ZMT) in pure form and pharmaceutical preparations. These methods are based on the directly formation of charge-transfer complexes between ZMT and m-nitrophenol (MNP) in aqueous medium (ZMT: MNP, 1:1) and 2,4-dinitrophenol (DNP) in ethanol:water (80:20). The developed method involves formation of coloured complexes (1:1) of ZMT with MNP and DNP. The yellow formed complexes were quantitatively measured at 400 and 440 nm for ZMT-MNP and ZMT-DNP, respectively. Beer's law was obeyed in the concentration ranges of 3.0–260 μg/mL for MNP and 3.5–120 μg/mL for DNP. Limit of detection and limit of quantitation for MNP were calculated as 0.58 and 1.75 μg/mL, respectively, and for DNP were 0.32 and 0.97 μg/mL, respectively. The method was validated with respect to accuracy, robustness and selectivity. The proposed method has been successfully applied for the determination of ZMT in tablets.

Spectrophotometric, Thermodynamic and Density Functional Studies of Charge Transfer Complex Between Benzhydryl Piperazine and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone

The charge transfer complex of benzhydryl piperazine as donor with the π-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinone has been studied spectrophotometrically in acetonitrile medium at different temperatures. On mixing the donor with acceptor, a reddish brown colored charge transfer complex is formed. Electronic absorption spectra of the complex show charge transfer bands at 587, 546 and 457 nm. The molecular composition of the complex was studied by applying Job’s continuous variation and spectrophotometric titration methods. These results support the formation of the complex in a 1:2 ratio. The Benesi–Hildebrand equation has been applied to compute the formation constant and molecular extinction coefficient. Thermodynamic parameters of the charge transfer complexation reaction (standard entropy, standard enthalpy and standard Gibbs free energy) have been calculated. The results of the spectrophotometric study demonstrated that the charge transfer complex formation is endothermic. The computational studies of the charge transfer complex were performed by using the Gaussian 09 W package of programs. The bond lengths, bond angles, dihedral angles, Mulliken atomic charges, molecular electrostatic potential maps and characterization of the highest occupied molecular orbital and lowest unoccupied molecular orbital surfaces of charge transfer complex were computed.

Spectrophotometric methods based on charge transfer complexation reaction for the determination of some antifungal drugs in pure and dosage forms

Charge transfer complexes of some antifungal drugs fluconazole (FLU), sertaconazole nitrate (SER) and miconazole nitrate (MCO) as electron donor with the σ-acceptor iodine (I2) and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), p-chloranilic acid (p-CLA) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π-acceptors in acetonitrile were investigated. The formation of the colored charge-transfer complexes were utilized in the development of simple, rapid and accurate spectrophotometric methods for the analysis of the cited drugs in pure forms and pharmaceutical formulations at 365 nm for MCO and SER using I2 method, at 460 nm for FLU and SER using DDQ method, at 535 and 530 nm for FLU and SER, respectively, using p-CLA method and at 842 nm for MCO and SER using TCNQ method. The optimum experimental conditions have been studied carefully and optimized. Beer’s law was obeyed over the concentration ranges of 2.0–28, 10–240 and 2.0–160 µg mL−1 for MCO, FLU and SER, respectively, with good correlation coefficients (0.9996–0.9999). Molar absorpitivity, Sandell sensitivity, relative standard deviation, limit of detection and quantification were calculated. The obtained data refer to high accuracy and precision of the proposed method. The obtained results were confirmed by inter and intra-day accuracy and precision with percent recovery of 99.1–100%, 99.3–101% and 99.1–101% for MCO, FLU and SER, respectively. These data were compared with those obtained using official methods for the determination of the cited drugs. The proposed methods were applied successfully for simultaneous determination of the cited drugs in their pharmaceutical formulations with good accuracy and precision and without interferences from common additives. KEY WORDS: Fluconazole, Sertaconazole nitrate, Miconazole nitrate, Charge transfer complexes, Spectrophotometry, Pharmaceutical formulations Bull. Chem. Soc. Ethiop. 2016, 30(3), 333-346.DOI: http://dx.doi.org/10.4314/bcse.v30i3.2

Utilitization of Charge Transfer Complexation Reaction for the Spectrophotometric Determination of Vardenafil HCl and Yohimbin HCl in Pharmaceutical Formulations

Utilitization of Charge Transfer Complexation Reaction for the Spectrophotometric Determination of Vardenafil HCl and Yohimbin HCl in Pharmaceutical Formulations

Spectrophotometric and spectroscopic studies on charge transfer complexes of the antifungal drug clotrimazole

Clotrimazole (CLZ) is an imidazole derivative that is therapeutically used as an antifungal drug. The routine control analysis of CLZ requires rapid, reliable, accurate and precise methods for the quantification of the drug in its pharmaceutical formulations. Spectrophotometric methods are presented for the determination of the antifungal agent that are based on the charge transfer complexation reaction of CLZ with the π-acceptors tetracyanoethylene (TCE) and 7,7′,8,8′-tetracyanoquinodimethane (TCNQ). The formation of coloured complexes was quantitated at 396nm and 842nm for CLZ-TCE and CLZ-TCNQ, respectively, which enabled the development of simple and accurate spectrophotometric methods for the analysis of CLZ in pure drug substances and its pharmaceutical products. Under the optimum reaction conditions, linear relationships with appreciable correlation coefficients (0.9985–0.9994) were found between the absorbance at the relevant maxima and the concentrations of CLZ in the range of 5.00–35.00μgmL−1 for CLZ-TCE and 1.00–25.00μgmL−1 for CLZ-TCNQ. The molar absorptivities and Sandell's sensitivity values were also statistically evaluated. The proposed methods were successfully applied to analyze CLZ in topical creams and sterile solutions with mean recovery percentages in the range of 99.60–100.20%, which indicated no interference from the inactive ingredients. Furthermore, the charge transfer complexes of CLZ were also characterized by FT-IR spectroscopy.

Method Development for Quantification of Loratidine and Alverine Citrate by Visible Spectrophotometry

The present work describes on two colorimetric methods based on charge transfer complex reaction of loratidine (LRT) and alverine citrate (ALV) with chloranilic acid in chloroform. The methods were developed on Perkin Elmer LAMBDA 25 UV –VIS spectrophotometer with 1cm quartz cells. The methods were optimised to achieve maximum colour intensity and validated for reliability. The coloured complexes showed maximum absorbance at 538 nm for LRT and 540 nm for ALV. The absorbances were found to increase linearly with increase in concentration which was emphasised by the calculated regression coefficients (0.9998-0.9999). Linearity of standard plot was in the order of 100-700 and 80-560µg/ml for LRT and ALV, respectively. The molar absorptivity, sandells sensitivity, LOD, LOQ and other validation parameters have been assessed extensively and all the parameters seem to comply with the acceptance criteria. The proposed methods were proved to be more accurate, simple, precise and rapid by statistical validation, recovery studies and could be appropriate to employ in regular laboratory analysis.

Validated spectrophotometric methods for determination of sodium valproate based on charge transfer complexation reactions

This work presents the development, validation and application of four simple and direct spectrophotometric methods for determination of sodium valproate (VP) through charge transfer complexation reactions. The first method is based on the reaction of the drug with p-chloranilic acid (p-CA) in acetone to give a purple colored product with maximum absorbance at 524nm. The second method depends on the reaction of VP with dichlone (DC) in dimethylformamide forming a reddish orange product measured at 490nm. The third method is based upon the interaction of VP and picric acid (PA) in chloroform resulting in the formation of a yellow complex measured at 415nm. The fourth method involves the formation of a yellow complex peaking at 361nm upon the reaction of the drug with iodine in chloroform. Experimental conditions affecting the color development were studied and optimized. Stoichiometry of the reactions was determined. The proposed spectrophotometric procedures were effectively validated with respect to linearity, ranges, precision, accuracy, specificity, robustness, detection and quantification limits. Calibration curves of the formed color products with p-CA, DC, PA and iodine showed good linear relationships over the concentration ranges 24–144, 40–200, 2–20 and 1–8μg/mL respectively. The proposed methods were successfully applied to the assay of sodium valproate in tablets and oral solution dosage forms with good accuracy and precision. Assay results were statistically compared to a reference pharmacopoeial HPLC method where no significant differences were observed between the proposed methods and reference method.

Use of picric acid and iodine as electron acceptors for spectrophotometric determination of lansoprazole through a charge-transfer complexation reaction

This article describes the development of two simple and selective spectrophotometric methods for the determination of lansoprazole (LAN), an irreversible proton pump inhibitor, in both pure drug and capsule formulations. The methods are based on the formation of charge-transfer (CT) complexes between LAN an electron donor and either picric acid or iodine as an electron acceptor. The intensely coloured products formed were quantified based on the absorption bands at 410nm for picric acid (method A) and 360nm for iodine (method B). The accuracy and precision of the methods were evaluated on intra-day and inter-day bases. Beer's law is obeyed in the concentration ranges of 2–32 and 0.8–12.0μg/ml LAN for method A and method B, respectively. The molar absorptivity values, limits of detection (LOD) and limits of quantification (LOQ) have also been reported. The reaction stoichiometry for both methods was evaluated by Job's method of continuous variation and was found to be 1:1 (LAN: picric acid and LAN: iodine). The proposed methods were successfully applied to the determination of LAN in capsules with good accuracy and precision and without a detectable interference from common excipients. A statistical comparison of the methods revealed that there is no significant difference between the official method and the proposed methods.

SPECTROPHOTOMETRIC METHODS FOR THE ESTIMATION OF DULOXETINE HYDROCHLORIDE IN BULK AND IN PHARMACEUTICAL DOSAGE FORM

Three simple, accurate, sensitive and economical spectrophotometric methods have been developed and subsequently validated for determination of duloxetine hydrochloride in bulk and pharmaceutical formulation. Method A is an extractive spectrophotometric method based on formation of ion-pair complexes of duloxetine hydrochloride with Solochrome Black T, to form pink colored chromogen, which showed a maximum absorption at 512 nm, and obeys Beer’s law in the concentration range of 2-10 μg/mL. Method B is based on the formation of charge transfer complexation reactions of duloxetine hydrochloride with picric acid to form a yellow colored chromogen, which showed maximum absorption at 420 nm and obeys Beer’s law in the concentration range of 5-25 μg/mL. Method C is a UV spectrophotometric method using isopropyl alcohol as solvent, in which absorption maxima was at 290 nm, Beer’s law obeyed in the concentration range of 5-30 μg/mL. The validation of the above methods was done and the results demonstrated that, the procedures were accurate, precise and reproducible. So, the proposed methods can be applied for the routine analysis of duloxetine hydrochloride in bulk drug and in its tablet dosage form.

Validated spectrophotometric methods for the determination of bifonazole in pharmaceuticals by charge transfer complexation

Two simple and selective visible spectrophotometric methods were developed for assay of bifonazole in pure drug and in its pharmaceutical formulation. The developed methods were based on the charge transfer complexation reaction of bifonazole with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (CAA) for method A and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) for method B, resulting in the formation of colored complex. The colored reaction products were quantitated spectrophotometrically at 517nm and 457nm for bifonazole-CAA and bifonazole-DDQ complexes, respectively. The complexes obeyed Beer’s law in the concentration range of 50.00–400.00 and 5.00–50.00μgmL−1 with molar absorptivities at 0.0956×104 and 0.6953×104Lmol−1cm−1 for method A and method B, respectively. The proposed procedures were successfully applied for the quantitative determination of bifonazole in its pharmaceutical formulation. The solid charge transfer complexes of bifonazole with each of the π-acceptor reagent were also synthesized and characterized by FT-IR spectroscopy.

Application of π receptors to the spectrophotometric determination of naftidrofuryl oxalate in pure form and its pharmaceutical preparation

Three different spectrophotometric methods are developed for the determination of naftidrofuryl oxalate (NAF) in pure form and its pharmaceutical preparation. The methods are based on charge transfer complexation reactions of NAF as n-electron donor with either p -chloranilic acid (PCA) or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or tetracyano ethylene (TCNE) as π-receptors to give highly colored anion radicals species. The colored products were quantified spectrophotometrically at 515, 588 and 396 nm in PCA, DDQ and TCNE methods, respectively. Under the optimized experimental conditions, Beer's law is obeyed over the concentration ranges of 75.0-300.0, 25.0-150.0 and 15.0- 50.0 μg/mL NAF for PCA, DDQ and TCNE methods, respectively. The proposed methods were applied successfully to the determination of NAF in pure form and its commercial tablets with good accuracy and precision. Statistical comparison of the results was performed using Student's t-test and F-ratio at 95% confidence level, showing that there is no significant difference between the reference and the proposed methods with regard to accuracy and precision. Further, the validity of the proposed methods was confirmed by standard addition technique.

Spectrophotometric determination and thermodynamic studies of the charge transfer complexation of emedastine difumarate with some π-acceptors

Spectrophotometric procedures were presented for the determination of antihistaminic drug, emedastine difumarate. The methods are based on the charge transfer complexation reaction of the drug with π-acceptors; 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), chloranilic acid (CA) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). Different charge-transfer complexes and colored radical anions were obtained. The formations of the colored complexes were utilized in the development of simple, rapid and accurate spectrophotometric methods for the analysis of emedastine in drug substance and products. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9996–0.9999) were found between the absorbance at the relevant maxima and the concentrations of emedastine in the range of 0.8–200μgmL−1. The limits of detection ranged from 0.06 to 0.76μgmL−1. The molar absorptivities and association constants for the colored complexes were evaluated using the Benesi–Hildebrand equation. The free energy change (ΔG°) and the enthalpy of formation (ΔH°) as well as the entropy (ΔS°) were also determined. The methods were successfully applied to analyze the drug formulation with mean recovery percentages±RSD% of 100.04±0.59–100.22±0.72. The results were compared favorably with the official and reported methods.

Spectrophotometric Determination of Valsartan using p-Chloranilic Acid as π-Acceptor in Pure and in Dosage Forms

The aim of this work was to develop a simple, sensitive and extraction free spectrophotometric method for the quantitative estimation of valsartan in both pure and in pharmaceutical preparations. The developed method is based on the charge transfer complexation reaction between valsartan (VRT) as n- electron donor and pchloranilic acid (p-CA) as π-acceptor. VRT reacts with p-CA in methanol to produce a bright pink colored complex with a maximum absorption at 530 nm. Beer's law was obeyed in the concentration range of 5-50 µg/mL. The linear regression equation of the calibration graph is A = 0.0081+0.0092C with a regression coefficient (r) of 0.9976 (n = 7). The molar absorptivity is calculated to be 2.06 × 10 3 L mol –1 cm –1 and the Sandell sensitivity is 0.1025 μg cm –2 . The limits of detection (LOD) and quantitation (LOQ) values are calculated according to ICH guidelines. The method developed is successfully applied to the determination of VRT in dosage forms.

Spectrophotometric Determination of Domperidone in its Pharmaceutical Formulation Through Charge Transfer Complexation Reactions

Spectrophotometric Determination of Domperidone in its Pharmaceutical Formulation Through Charge Transfer Complexation Reactions