Lories I. Bebawy

Spectrophotometric determination of fluoxetine and sertraline using chloranil, 2, 3 dichloro-5, 6 dicyano benzoquinone and iodine

Spectrophotometric procedures are presented for the determination of two commonly used antidepressant drugs, fluoxetine (I) and sertraline hydrochloride (II). The methods are based mainly on charge transfer complexation reaction of these drugs with either pi acceptors chloranil and 2, 3 dichloro-5, 6-dicyanoquinone (DDQ) or sigma acceptor iodine. The colored products are quantified spectrophotometrically at 550, 450 and 263 nm for fluoxetine and at 450, 455 and 290 nm for sertraline in chloranil, DDQ and iodine methods, respectively. The molar combining ratio and the optimum assay conditions were studied. The methods determine the cited drugs in concentration ranges of 8-640, 16-112 and 7.5-60 microg/ml with mean percentage recoveries of 99.83, 99.76 and 100.00% and R.S.D. of 1.24, 0.95 and 1.13% in fluoxetine and ranges of 16-160, 15-105 and 6-48 microg/ml with mean percentage recoveries of 100.39, 99.78 and 99.69% and R.S.D. of 1.02, 0.81 and 0.57% in sertraline for chloranil, DDQ and iodine methods, respectively. A more detailed investigation of the complex formed was made with respect to its composition, association constant K(AD)c, molar absorptivity xiAD(A) and free energy change deltaG. The proposed methods were applied successfully to the determination of the cited drugs either in pure or dosage forms with good accuracy and precision. The results were compared statistically with those given by the reported methods.

Fluorimetric determination of some antibiotics in raw material and dosage forms through ternary complex formation with terbium (Tb3

A highly sensitive and specific fluorimetric method was developed for the determination of cefazolin sodium I, cefoperazone sodium II, ceftriaxone sodium III, and cefixime IV. The proposed method involves the formation of ternary complex with Tb(3+) in the presence of Tris buffer. The quenching of the terbium fluorescence due to the complex formation was quantitative for the four studied drugs. The effect of pH, concentration of Tris buffer and terbium were studied. The formation of the complex was highly dependent on the pH. The optimum pH was found to be pH 8 for cefazolin sodium I, ceftriaxone sodium III, cefixime IV and pH 10 for cefoperazone sodium II. The optimum concentration for Tb(3+) was found 1 ml of 10(-4) M solution and for Tris buffer 1 ml of the prepared solution. Under the described conditions, the proposed method was applicable over the concentration range 8.79 x 10(-6)-7.91 x 10(-5), 9.7 x 10(-6)-4.49 x 10(-)5, 6.10 x 10(-6)-2.50 x 10(-5), and 4.92 x 10(-6)-2.95 x 10(-5) mol with mean percentage accuracy of 99.79+/-0.24, 98.97+/-1.25, 100.05+/-0.79, and 100.15+/-0.54 for I, II, III, and IV, respectively. The proposed method was applied successfully for the determination of studied drugs in bulk powder and in pharmaceutical formulations. The results obtained by applying the described method were statistically analyzed and compared with those obtained by applying the official method. The proposed method was used as stability indicating method for the determination of the studied drugs in the presence of their degradation products.

Determination of some antihistaminic drugs by atomic absorption spectrometry and colorimetric methods

Atomic absorption spectrometry (AAS) and colourimetric methods have been developed for the determination of pizotifen (I), ketotifen (II) and loratadine (III). The first method depends on the reaction of the three drugs (I); (II) and (III) with cobalt thiocyanate reagent at pH 2 to give ternary complexes. These complexes are readily extracted with organic solvent and estimated by indirect atomic absorption method via the determination of the cobalt content in the formed complex after extraction in 0.1 M hydrochloric acid. It was found that the three drugs can be determined in the concentration ranges from 10 to 74, 12 to 95 and 10 to 93 microg ml(-1) with mean percentage recovery of 99.71+/-0.87, 99.70+/-0.79 and 99.62+/-0.75%, respectively. The second method is based on the formation of orange red ion pairs as a result of the reaction between (I); (II) and (III) and molybdenum thiocyanate with maximum absorption at 469.5 nm in dichloromethane. Appropriate conditions were established for the colour reaction. Under the proposed conditions linearity was obeyed in the concentration ranges 3.5-25, 5-37.5 and 2.5-22.5 microg ml(-1) with mean percentage recovery of 99.60+/-0.41, 100.11+/-0.43 and 99.31+/-0.47% for (I): (II) and (III), respectively. The third method depends on the formation of radical ion using 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). The colour formed was measured at 588 nm for the three drugs (I); (II) and (III), respectively. The method is valid in concentration range 10-80 microg ml(-1) with mean percentage recovery 99.75+/-0.44, 99.94+/-0.72 and 99.17+/-0.36% for (I); (II) and (III), respectively. The proposed methods were applied to the analysis of pharmaceutical preparations. The results obtained were statistically analysed and compared with those obtained by applying the official and reference methods.

Spectrophotometric determination of some n-donating drugs using DDQ

Abstract A simple sensitive spectrophotometric method is described for determination of six drugs with different n-donating groups. These drugs are azithromycin (I), ketoconazole (II), clotrimazole (III), clozapine (IV), oxamniquine (V), and pimozide (VI). The method depends on the interaction of these compounds with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) as π acceptor to form highly colored reaction product. The analytical wavelength chosen is 588 nm which gives maximum sensitivity. Optimum conditions for the reaction were determined and the mean percentage recoveries were 99.79 ± 0.65, 100.44 ± 1.03, 100.12 ± 0.66, 99.60 ± 0.8,99.74 ± 0.65 and 100.29 ± 0.79 for I, II, III, IV, V and VI, respectively. Study of the reaction product showed that charge transfer complex (CT) primarily formed dissociates to give radical anion with λmax at 429 nm. The effect of basic properties of the studied drugs, on the production of radical anion, was illustrated by determining the yield percentage and confirmed thr...

Application of TLC-densitometry, first-derivative UV-spectrophotometry and ratio derivative spectrophotometry for the determination of dorzolamide hydrochloride and timolol maleate

Three methods are described for the simultaneous determination of dorzolamide hydrochloride (DORZ) and timolol maleate (TIM) in ophthalmic solutions. The first method is based on application of thin layer chromatographic separation of both drugs followed by the densitometric measurements of their spot areas. After separation on silica gel GF(254) plates, using methanol-ammonia 25% (100:1.5 v/v) as the mobile phase, the chromatographic zones corresponding to the spots were scanned at 253 and 297 nm, respectively. The calibration function was established in the ranges of 2-18 microg for DORZ and 0.5-4.5 microg for TIM. The second method depends on first derivative ultraviolet spectrophotometry, with zero-crossing measurement method. The first derivative values D(1) at 250.2 and 312.5 nm were selected for the assay of DORZ and TIM, respectively. Calibration graphs follow Beers law in the range 10-64 and 2.5-16 microg ml(-1), respectively. The third method is based on ratio first derivative spectrophotometry. The signals in the first derivative of the ratio spectra at 244 and 306.2 nm were selected to determine DORZ and TIM in the mixture and calibration graphs are linear in the range of 5-40 and 5.0-17.5 microg ml(-1), respectively. The proposed methods were successfully applied to the determination of these compounds in synthetic mixtures and in pharmaceutical preparations. The proposed methods are simple, rapid and suitable for quality control application.

Determination of astemizole, terfenadine and flunarizine hydrochloride by ternary complex formation with eosin and lead(II)

A simple and sensitive spectrophotometric method has been established for the determination of astemizole(I), terfenadine(II) and flunarizine hydrochloride(III) based on ternary complex formation with eosin and lead(II). The method does not involve solvent extraction. The colour of the produced complex is measured at 547.5 nm for (I) and (III), while (II) is measured at 540.7 nm. Appropriate conditions were established for the colour reaction and for the eosin: Pb(II): drug ratio to obtain maximum sensitivity. Under the proposed conditions, the method is applicable over concentration range of 4.1-37.6, 11.8-47.2 and 2.4-19.1 microg x ml(-1) with mean percentage recovery of 99.20+/-0.63, 99.76+/-0.39 and 99.60+/-0.47% for (I), (II) and (III), respectively. The suggested method was applied for determination of (I), (II) and (III) in pharmaceutical preparations. Through the use of a non-ionic surfactant (methylcellulose), prior extraction of the drugs was unnecessary. The results obtained demonstrated that the method is equally accurate, precise and reproducible as the official or reported methods. For the purpose of enhancing the sensitivity, a fluorescence quenching method for determination of the studied drugs via ternary complex formation was also investigated. The detection limit for the studied drugs (I), (II) and (III) was 0.94-7.1 microg x ml(-1) with mean percentage recovery of 99.84+/-0.29, 99.24+/-0.36 and 99.34+/-0.26%, respectively. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by official or reference methods. Unlike other reported ion-pair techniques, the suggested methods have the advantage of being applicable for the determination of the three drugs in their pharmaceutical dosage forms without prior extraction. They are recommended for quality control and routine analysis where time, cost effectiveness and high specificity of analytical techniques are of great importance.

Spectrophotometric determination of clobetasol propionate, halobetasol propionate, quinagolide hydrochloride, through charge transfer complexation

Two spectrophotometric procedures are described for the determination of clobetasol propionate(I), halobetasol propionate(II) (corticosteroids) and quinagolide hydrochloride(III) (prolactin inhibitor). For corticosteroid drugs, the procedures are based on the formation of phenyl hydrazones of the corticosteroids which are subsequently subjected to charge transfer complexation reaction with either 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as pi-acceptor or with iodine as sigma-acceptor. Prolactin inhibitor was reacted directly with the previous reagents. The molar ratios of the reactants were established and the experimental conditions were studied giving maximum absorption at 588 and 290 nm with DDQ and iodine methods, respectively for the three drugs. The concentration ranges were 20-150,50-300, and 20-80 microg ml(-1) in DDQ method for (I), (II), and (III), respectively and 13-20,15-40, and 8-32 microg ml(-1) in iodine method for (I), (II) and (III), respectively.

Stability-Indicating Method for the Determination of Meloxicam and Tetracaine Hydrochloride in the Presence of their Degradation Products

Abstract Sensitive, spectrophotometric and densitometric methdos are described for the determination of meloxicam I and tetracaine hydrochloride II in the presence of their degradation products. Meloxicam was determined in the presence of its degradation products (5-methyl-2-aminothiazole) III and benzothiazine carboxylic acid IV by two methods. These methods are the first derivative Spectrophotometry at 338 nm and TLC densitometric method at 365nm. The methods were applicable over the concentration range of 5–20μg.m−1 and 2–10μg with mean accuracies of 99.66±0.91% and 99.99±0.70% respectively.

Stability-Indicating Method for the Determination of Some Cephalosporines in the Prescence of Degradation Products

Abstract A rapid and convenient spectrophotometric method is described for the quantitative determination of some of Cephalosporines Cefadroxil, I Cephradine II and Cefaclor III. The proposed method depends upon the conversion of these compounds to the corresponding piperazine-2,5 dione derivatives by heating in an alkaline sorbitol-zinc ion solution for 10—25 minutes at 90°C and subsequent treatment of these derivatives with 0.1 N sodium hydroxide to obtain highly absorbing products with λmax at 345 nm for I & II and at 334 nm for III using zero order absorption curve. Using first derivative spectrum (D1) for III the λmax is at 362 nm. The method was found to be free of the interference from polymerization and other degradation products. Its application to assess the stability of the Cephalosporines was demonstrated. Verification of Beers Law showed lincarity at concentrations of 12.5-87.5 μg ml−1, 12.5-125 μg ml−l and 6.7-66.7 μg ml−1 for I, II and III respectively with mean accuracies 100.37 ± 0.72%, ...

Spectrophotometric and HPLC Determination of Linezolid in Presence of Its Alkaline-Induced Degradation Products and in Pharmaceutical Tablets

Abstract In this work three sensitive stability-indicating methods for the determination of linezolid in the presence of its alkaline-induced degradation products are developed. The first method depends on the oxidative coupling reaction of linezolid with 3-methyl benzothiazoline-2-one hydrazone (MBTH) hydrochloride in the presence of ferric chloride in an acid medium. The resulting stable colored products showed absorption λmax at 627 nm. The second method is based on alkaline hydrolysis of linezolid to yield the degradation product which reacts with haematoxylin reagent in the presence of boric acid to give a reddish violet chromogen at λmax 557 nm. The third method is based on (HPLC) resolution efficiency in the determination of linezolid in the presence of its alkaline induced degradation product. The percentage recoveries for the proposed methods were 99.54 ± 0.58, 99.84 ± 0.78, and 100.02 ± 0.49 within the concentration range of 1.6–12 µg mL−1, 10–60 ng mL−1 and 5–40 µg mL−1, respectively. The proposed methods were applied successfully for the determination of intact drug in bulk powder, laboratory prepared mixtures containing different percentages of degradation product and pharmaceutical dosage forms. The results of the analysis were found to agree statistically with those obtained with the reported method. Furthermore, the methods were validated and also assessed by applying the standard addition technique.