Spectrophotometric determination of certain antidepressants in pharmaceutical preparations

Simple and reproducible spectrophotometric methods have been developed for determination of sertraline, fluoxetine, and venlafaxine in pharmaceutical preparations. The methods are based on the reactions between the studied drug substances and ion-pair agents (bromothymol blue, bromocresol green, or bromophenol blue) to produce yellow-colored ion-pair complexes in acidic buffers. After extracting in chloroform, the ion-pair complexes are spectrophotometrically determined at the optimum wavelength. Optimizations of the reaction conditions were carried out. Beer's law was obeyed within the concentration range from 1 to 15 microg/mL. The molar absorptivity, Sandell sensitivity, and detection and quantification limits were also determined. The developed methods were applied successfully for the determination of these drugs in some available commercial preparations. The results were compared statistically with those obtained from reported high-performance liquid chromatography methods.     

Atomic absorption spectroscopic, conductometric and colorimetric methods for determination of some fluoroquinolone antibacterials using ammonium reineckate

Three accurate, rapid and simple atomic absorption spectrometric (AAS), conductometric and colorimetric methods were developed for the determination of gatifloxacin (GTF), moxifloxacin (MXF) and sparfloxacin (SPF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink coloured complexes were determined either by AAS or colorimetrically at lambda(max) 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone. The optimizations of various experimental conditions were described. Optimum concentration ranges for the determination of GTF, MXF and SPF were 5.0-150, 40-440 microg mL(-1) and 0.10-1.5 mg mL(-1) using atomic absorption (AAS), conductometric and colorimetric methods, respectively. Detection and quantification limits are ranges from 1.5 to 2.3 microg mL(-1) using AAS method or 30-45 microg mL(-1) using colorimetric method. The proposed procedures have been applied successfully to the analysis of these drugs in pharmaceutical formulations and the results are favourably comparable to the reference methods.     

Atomic absorption spectroscopic, conductometric and colorimetric methods for determination of fluoroquinolone antibiotics using ammonium reineckate ion-pair complex formation

Three accurate, rapid and simple atomic absorption spectrometric, conductometric and colorimetric methods were developed for the determination of norfloxacin (NRF), ciprofloxacin (CIP), ofloxacin (OFL) and enrofloxacin (ENF). The proposed methods depend upon the reaction of ammonium reineckate with the studied drugs to form stable precipitate of ion-pair complexes, which was dissolved in acetone. The pink coloured complexes were determined either by AAS or colorimetrically at lambdmax 525 nm directly using the dissolved complex. Using conductometric titration, the studied drugs could be evaluated in 50% (v/v) acetone in the range 5.0-65, 4.0-48, 5.0-56 and 6.0-72 microg ml-1 of NRF, CPF, OFL and ENF, respectively. The optimizations of various experimental conditions were described. The results obtained showed good recoveries of 99.15 +/- 1.15, 99.30 +/- 1.40, 99.60 +/- 1.50, and 99.00 +/- 1.25% with relative standard deviations of 0.81, 1.06, 0.97, and 0.69% for NRF, CPF, OFL, and ENF, respectively. Applications of the proposed methods to representative pharmaceutical formulations are successfully presented.     

Spectrophotometric determination of some anti-tussive and anti-spasmodic drugs through ion-pair complex formation with thiocyanate and cobalt(II) or molybdenum(V)

Two rapid, simple and sensitive extractive specrophotometric methods has been developed for the determination of anti-tussive drugs, e.g., dextromethorphan hydrobromide (DEX) and pipazethate hydrochloride (PiCl) and anti-spasmodic drugs, e.g., drotaverine hydrochloride (DvCl) and trimebutine maleate (TM) in bulk and in their pharmaceutical formulations. The proposed methods depend upon the reaction of cobalt(II)-thiocyanate (method A) and molybdenum(V)-thiocyanate ions (method B) with the cited drugs to form stable ion-pair complexes which extractable with an n-butnol-dichloromethane solvent mixture (3.5:6.5) and methylene chloride for methods A and B, respectively. The blue and orange red color complexes are determined either colorimetrically at lambdamax 625 nm (using method A) and 467 or 470 nm for (DEX and PiCl) or (DvCl and TM), respectively (using method B). The concentration range is 20-400 and 2.5-50 microg mL-1 for methods A and B, respectively. The proposed method was successfully applied for the determination of the studied drugs in pure and in pharmaceutical formulations applying the standard additions technique and the results obtained in good agreement well with those obtained by the official method.     

Determination of amitriptyline,imipramine and orphenadrine in antidepressant drugs by potentiometry,spectrophotometry and atomic absorption spectrometry

Methods are described for the determination of amitriptyline, imipramine and orphenadrine in some antidepressant drugs. They are based on a prior reaction with ammonium reineckate to form 11 water-insoluble drugreineckate ion-pair complexes. These complexes are (i) used as ion-exchangers in liquid-membrane electrodes responsive to the drug cations, (ii) extracted with nitrobenzene or dissolved in acetonitrile and spectrophotometrically measured at 525 nm and (iii) dissolved in 90% acetone followed by nebulization in an air-acetylene flame for atomic absorption spectrometric measurements of Cr at 358.6 nm. The reaction and monitoring conditions are optimized to permit determination of as little as 10 g/ml of the drugs. Determination of the drugs in some pharmaceutical preparations shows an average recovery of 98.8% of the nominal and a mean standard deviation of 0.8%. The results compare favorably with data obtained by the United States and British Pharmacopoeia methods.     

Extractive-spectrophotometric determination of disopyramide and irbesartan in their pharmaceutical formulation

Picric acid, bromocresol green, bromothymol blue, cobalt thiocyanate and molybdenum(V) thiocyanate have been tested as spectrophotometric reagents for the determination of disopyramide and irbesartan. Reaction conditions have been optimized to obtain coloured comoplexes of higher sensitivity and longer stability. The absorbance of ion-pair complexes formed were found to increases linearity with increases in concentrations of disopyramide and irbesartan which were corroborated by correction coefficient values. The developed methods have been successfully applied for the determination of disopyramide and irbesartan in bulk drugs and pharmaceutical formulations. The common excipients and additives did not interfere in their determination. The results obtained by the proposed methods have been statistically compared by means of student t-test and by the variance ratio F-test. The validity was assessed by applying the standard addition technique. The results were compared statistically with the official or reference methods showing a good agreement with high precision and accuracy.     

Spectrophotometric determination of hyoscine butylbromide and famciclovir in pure form and in pharmaceutical formulations

A simple, rapid, and extractive spectrophotometric method was developed for the determination of hyoscine butylbromide (HBB) and famciclovir (FCV) in pure and pharmaceutical formulations. These methods are based on the formation of yellow ion-pair complexes between the basic nitrogen of the drug and four sulphonphthalein acid dyes, namely; bromocresol green (BCG), bromothymol blue (BTB), bromocresol purple (BCP) and bromophenol blue (BPB) in phthalate buffer of pH range (3.0-3.5). The formed complexes were extracted with chloroform and measured at 420, 412, 409 and 415nm for HBB and at 418, 412, 407 and 414nm for FCV using BCG, BTB, BCP and BPB, respectively. The analytical parameters and their effects on the reported systems are investigated. Beer's law was obeyed in the range 1.0-20mugmL(-1) with correlation coefficient (n=6)>/=0.9997. The molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated. The composition of the ion pairs was found 1:1 by Job's method in all cases and the conditional stability constant (K(f)) of the complexes have been calculated. The free energy changes (DeltaG) were determined for all complexes formed. The proposed methods have been applied successfully for the analysis of the studied drugs in pure and pharmaceutical formulations with percentage recoveries ranges from 99.84 to 100.26. The results were in good agreement with those obtained by the official methods.     

Spectrophotometric microdetermination of nefopam, mebevrine and phenylpropanolamine hydrochloride in pharmaceutical formulations using alizarins

Simple and rapid spectrophotometric procedures have been established for quantitation of nefopam hydrochloride (NF) mebevrine hydrochloride (MB) and phenylpropanolamine hydrochloride (PP). The procedures are based on the reaction between the examined drugs (NF, MB and PP) and alizarin (I), alizarin red S (II), alizarin yellow G (III) and quinalizarin (IV) producing ion-pair complexes which can be measured at the optimum wavelength. The optimization of the reaction conditions is investigated. Beer's law is obeyed in the concentration ranges 0.5-30.0 microg ml(-1). The molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. The correlation coefficient was > or =0.9988 (n=6) with a relative standard deviation (R.S.D.) of < or =1.3, for six determinations of 20 microg ml(-1). The methods are successfully applied to the determination of NF, MB and PP in their pharmaceutical formulations.     

Generic nonextractive spectrophotometric method for determination of 4-quinolone antibiotics by formation of ion-pair complexes with beta-naphthol

This paper describes the development of a generic spontaneous nonextractive spectrophotometric method for determination of 13 pharmaceutically important 4-quinolone antibiotics. The method was based on the formation of yellow-colored water-soluble ion-pair complexes between 2% (w/v) beta-naphthol reagent and each of the studied drugs in sulfuric acid medium at room temperature. The formed ion-pair chromogens have maximum absorption peaks in the range of 365-391 nm. The concentrations of the reagents and the experimental conditions affecting the reaction were optimized. Under the optimum conditions, linear relationships with good linear coefficients (0.9987-0.9995) were found between the absorbance and concentration of the investigated drugs in the range of 10-350 microg/mL. The assay limits of detection and quantitation were 1-9.9 and 3.4-32.9 microg/mL, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. The proposed method was successfully applied to the analysis of the investigated drugs in pure and pharmaceutical dosage forms with good accuracy and precision; the percentages of label claim ranged from 97.8-102.8 +/- 0.35-1.60%. The results obtained by the proposed spectrophotometric method were comparable with those obtained by the official or reported methods. The proposed method is superior to all the previously reported ion-pair formation-based methods in terms of simplicity because it did not involve extraction procedures for the ion-pair complex. Therefore, this method might be recommended for routine use in quality control laboratories for analysis of the investigated 4-quinolone antibiotics in their pure forms, as well as in pharmaceutical dosage forms.     

Spectrophotometric determination of some histamine H1-antagonists drugs in their pharmaceutical preparations

Two rapid, simple and sensitive extractive specrophotometric methods has been developed for the determination of three histamine H1-antagonists drugs, e.g., chlorphenoxamine hydrochloride (CPX), diphenhydramine hydrochloride (DPH) and clemastine (CMT) in bulk and in their pharmaceutical formulations. The first method depend upon the reaction of molybdenum(V) thiocyanate ions (Method A) with the cited drugs to form stable ion-pair complexes which extractable with methylene chloride, the orange red color complex was determined colorimetrically at lambda(max) 470nm. The second method is based on the formation of an ion-association complex with alizarin red S as chromogenic reagents in acidic medium (Method B), which is extracted into chloroform. The complexes have a maximum absorbance at 425 and 426nm for (DPH or CMT) and CPX, respectively. Regression analysis of Beer-Lambert plots showed a good correlation in the concentration ranges of 5.0-40 and 5-70microgmL(-1) for molybdenum(V) thiocyanate (Method A) and alizarin red S (Method B), respectively. For more accurate analysis, Ringbom optimum concentration ranges were calculated. The molar absorptivity, Sandell sensitivity, detection and quantification limits were calculated. Applications of the procedure to the analysis of various pharmaceutical preparations gave reproducible and accurate results. Further, the validity of the procedure was confirmed by applying the standard addition technique and the results obtained in good agreement well with those obtained by the official method.     

Spectrofluorimetric study of the charge-transfer complexation of certain fluoroquinolones with 7,7,8,8-tetracyanoquinodimethane

Simple, rapid and sensitive spectrofluorimetric methods are described, for the first time, for the determination of ciprofloxacin (CIP), norfloxacin (NOR), pefloxacin (PEF) and fleroxacin (FLE). The methods are based on the charge-transfer (CT) reaction of these drugs as n-electron donors with 7,7,8,8-tetracyanoquinodimethane (TCNQ) as pi-electron acceptor. TCNQ was found to react with these drugs to produce intensely transfer reaction complexes and the fluorescence intensity of the complexes was enhanced in 21-35 fold higher than that of the studied fluoroquinolones itself. The formation of such complexes was also confirmed by both infrared and ultraviolet-visible measurements. The different experimental parameters that affect the fluorescence intensity were carefully studied. At the optimum reaction conditions, the drug-TCNQ complexes showed excitation maxima ranging from 277 to 284 nm and emission maxima ranging from 451 to 458 nm. Rectilinear calibration graphs were obtained in the concentration range of 0.03-0.9, 0.04-1.2, 0.04-1.3 and 0.08-2.4 microg ml(-1) for CIP, NOR, PEF and FLE, respectively. The developed methods were applied successfully for the determination of the studied drugs in their pharmaceutical dosage forms with a good precision and accuracy compared to official and reported methods as revealed by t- and F-tests.     

Tetrabutylammonium bromide/thenoyltri-fluoroacetone/mibk extraction for aas determination of cobalt, nickel, and manganese in copper ores and concentrates

An extraction-AAS method of determination of Co, Ni, and Mn in metallurgical copper materials containing considerable amounts ofCu, Fe, Pb, Zn, and Al has been developed. Good selectivity of group separation of Co, Ni, and Mn has been achieved by (a) the use of tetrabutylammonium bromide to improve extractability of HTTA complexes by ion-pair formation, and (b) the masking of major elements with sodium thiosulphate and sulphosalicylic acid. The extracts are stable for at least 3 weeks.     

Colorimetric and Atomic Absorption Spectrometric Determination of Some Heterocyclic Nitrogenous Compounds of Pharmaceutical Interest

Abstract

Simple spectroanalytical methods are proposed for the determination of five heterocyclic nitrogenous compounds. The suggested methods depend upon the formation of the ion-pair complexes of the studied compounds with ammonium reineckate followed by colorimetric and atomic absorption measurement of the complexes solutions. The proposed methods were applied to the determination of some pharmaceutical dosage forms containing the studied compounds. Results obtained were in agreement with those obtained by official and compendium methods.     

Spectrophotometric methods for the determination of the antidepressant drug paroxetine hydrochloride in tablets

Simple, sensitive, and accurate visible spectrophotometric methods are described for the determination of paroxetine hydrochloride (PA) in tablets. Among them, the first 3 methods are based on the ion-pair complexes of PA formed with bromothymol blue (BTB), bromophenol blue (BPB), and bromocresol green (BCG) in aqueous acidic buffers. The complex species extracted into chloroform were quantitatively measured at 414 nm with BTB and BCG and at 412 nm with BPB. Beer's law was obeyed over the concentration ranges of 2-20, 2-16, and 2-16 microg/mL, respectively. The fourth method described is based on a coupling reaction between PA and 7-chloro-4-nitrobenzofurazon (NBD-Cl) in borate buffer, pH 8.5, in which a yellow reaction product that was measured at 478 nm was formed. The Beer's law range for this method was 2-10 microg/mL. The last method developed describes the interaction of PA base, as an n-electron donor, with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as a pi-acceptor, in acetonitrile to give blue-colored TCNQ- radical anion with absorption maxima at 750 and 845 nm. Measured at 845 nm, the absorbance-concentration plot was rectilinear over the range of 1.5-15 microg/mL. The new methods developed were successfully applied to the determination of PA in tablets without any interference from common tablet excipients. The results of the methods were in good agreement with those obtained with an official liquid chromatographic method. This report describes first colorimetric methods for the determination of PA.     

Spectrophotometric determination of gatifloxacin in pure form and in pharmaceutical formulation

Simple, rapid, and extractive spectrophotometric methods were developed for the determination of gatifloxacin (GT) in bulk and pharmaceutical dosage form. These methods are based on the formation of yellow ion-pair complexes between the basic nitrogen of the drug and three sulphonphthalein acid dyes, namely; bromocresol green (BCG), bromocresol purple (BCP), bromophenol blue (BPB) and bromothymol blue (BTB) in phthalate buffer pH 3.0, 3.4 and 3.2, using BCG, BCP and (BPB or BTB), respectively. The formed complexes were extracted with chloroform and measured at 415, 417, 412 and 414 nm for BCG, BPB, BCP and BTB, respectively. The analytical parameters and their effects on the reported systems are investigated. The reactions were extremely rapid at room temperature and the absorbance values remains unchanged at 48 h for all reactions. Beer's law was obeyed in the ranges 2.0-20, 2.0-14 and 2.0-16 microg mL(-1) for BCG, BCP and (BPB or BTB), respectively. The composition of the ion pairs was found 1:1 by Job's method. Beer's law validation, accuracy, precision, limits of detection, limits of quantification. The proposed methods have been applied successfully for the analysis of the drug bulk form and its dosage form. The results were in good agreement with those obtained by the official and reported methods.     

Synthesis,characterization, and crystal structures of two novel ion-pair complexes based on benzene-1,2-dithiolate ligand

Two novel ion-pair complexes, [IBzPy][Ni(Bdt)₂] (I) and [IBzDMPy][Ni(Bdt)₂] (II) (IBzPy = 1-(4-iodobenzyl)pyridinium, IBzDMPy = 1-(4-iodobenzyl)-3,5-dimethyl-pyridinium, and Bdt = benzene-1,2-dithiolate), have been synthesized and characterized by elemental analysis, IR, cyclic voltammetry, and X-ray single-crystal structure determination. The crystal structure determination reveals that the central Ni atoms in complexes I and II are in slightly distorted square-planar coordination environment. The cyclic voltammetric studies show that there are two oxidation peaks for complexes I and II, which are attributed to Ni(IV/III) and Ni(III/II) redox couples.     

Spectrophotometric Microdetermination of Some Pharmaceutically Impor tant Aminoquinoline Antimalarials, as Ion-Pair Complexes

 A simple, rapid, accurate and sensitive spectrophotometric method for the microdetermination of some pharmaceutically important aminoquinoline antimalarials, namely amodiaquine dihydrochloride (I), chloroquine phosphate (II) and primaquine phosphate (III) is described. The method is based on the interaction of these drugs with calmagite indicator to give highly coloured ion-pair complexes which exhibit maximum absorption at 663, 665 and 666 nm, respectively, Beer’s law is obeyed in the concentration ranges 1.0–25.0, 1.0–28.0 and 1.0–33.0 μg/ml for the drugs I, II and III, respectively. For more accurate analysis, the Ringbom optimum concentration ranges are 2.5–22.5, 2.0–26.0 and 3.0–30.0 μg/ml, respectively. The apparent molar absorptivities were calculated. Statistical treatment of the experimental results indicates that the method is sufficiently accurate and precise. The accuracy of the method is indicated by the recovery (99.8±1.4%) and the precision by the relative standard deviation (>1.5%). The proposed method has been applied to the determination of these drugs in certain formulations, with results that compared favourably with those obtained by the official methods. Received November 2, 1998. Revision February 29, 2000.     

Study of fluorescence characteristics of the charge-transfer reaction of quinolone agents with bromanil

A spectrofluorimetric method was discussed for the determination of three antibacterial quinolone derivatives, ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CIP) through charge-transfer complexation (CTC) with 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, TBBQ). The method was based on the reaction of these drugs as n-electron donors with the pi-acceptor TBBQ. TBBQ was found to react with these drugs to produce a kind of yellow complexes and the fluorescence intensities of the complexes were enhanced by 29-36 times more than those of the corresponding monomers. UV-vis, (1)H NMR and XPS techniques were used to study the complexes formed. The various experimental parameters affecting the fluorescence intensity were studied and optimized. Under optimal reaction conditions, the rectilinear calibration graphs were obtained in the concentration range of 0.021-2.42 microg mL(-1), 0.017-2.63 microg mL(-1) and 0.019-2.14 microg mL(-1) for OFL, NOR and CIP, respectively. The methods developed were applied successfully to the determination of the subject drugs in their pharmaceutical dosage forms with good precision and accuracy compared to official and reported methods as revealed by t- and F-tests.     

Spectrophotometric study of the charge-transfer and ion-pair complexation of methamphetamine with some acceptors

The charge-transfer (CT) complexes of methamphetamine (MPA) as a n-donor with several acceptors including bromocresolgreen (BCG), bromocresolpurple (BCP), chlorophenolred (CPR), picric acid (PIC), and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) have been studied spectrophotometrically in chloroform solutions in order to obtain some information about their stoichiometry and stability of complexation. The oscillator strengths, transition dipole moments and resonance energy of the complex in the ground state for all complexes have been calculated. Vertical ionization potential of MPA and electron affinity of acceptors were determined by ab initio calculation. The acceptors were also used to utilize a simple and sensitive extraction-spectrophotometric method for the determination of MPA. The method is based on the formation of 1:1 ion-pair association complexes of MPA with BCG, BCP and PIC in chloroform medium. Beer's plots were obeyed in a general concentration range of 0.24-22 microg ml(-1) for the investigated drug with different acceptors. The proposed methods were applied successfully for the determination of MAP in pure and abuse drug with good accuracy and precision.     

Spectrophotometric quantification of fluoxetine hydrochloride: Application to quality control and quality assurance processes

Simple and rapid spectrophotometric methods have been developed for the microdetermination of fluoxetine HCl. The proposed methods are based on the formation of ion-pair complexes between fluoxetine and bromophenol blue (BPB), bromothymol blue (BTB), bromocresol green (BCG), and bromocresol purple (BCP) which can be measured at optimum λ_max. Optimization of reaction conditions was investigated. Beerșs law was obeyed in the concentration ranges of 0.5–8.0 μg mL⁻¹, whereas optimum concentration as adopted from the Ringbom plots was 0.7–7.7 μg mL⁻¹. The molar absorptivity, Sandell sensitivity, and detection limit were also calculated. The most optimal and sensitive method was developed using BCG. The correlation coefficient was 0.9988 (n = 6) with a relative standard deviation of 1.25, for six determinations of 4.0 μg mL⁻¹. The proposed methods were successfully applied to the determination of fluoxetine hydrochloride in its dosage forms and in biological fluids (spiked plasma sample) using the standard addition technique.