Spectrophotometric methods for the determination of lansoprazole and pantoprazole sodium sesquihydrate.
Department of Analytical Chemistry, Faculty of Pharmacy, Cairo University, Egypt.
Spectrophotometric procedures for determination of two irreversible proton pump inhibitors, lansoprazole (I) and pantoprazole sodium sesquihydrate (II) are presented. Two methods were based on charge transfer complexation reaction of these drugs, where they act as n-donors, with either pi acceptor 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and with sigma acceptor as iodine. A third method was also investigated depending on ternary complex formation with eosin and copper (II). The colored products were quantified spectrophotometrically using absorption bands at 457 nm for DDQ (method A) at 293 and 359 nm for iodine (method B) and at 549 nm using ternary complex formation (method C), for both drugs. The molar combining ratio and the optimum assay conditions were studied. These methods determined the lansoprazole in concentration ranges from 10 to 90, 1.48 to 6.65 and 3.69 to 16.61 microg ml(-1) with mean percentage recovery 99.63% for DDQ, 99.71%, 99.18% for iodine and 99.76% for ternary complex and with relative standard deviation 0.11, 0.24, 0.13 and 0.36%, respectively. For pantoprazole, the concentration ranges were 10-60, 17.7-141.6 and 4.3-25.9 microg ml(-1) with mean percentage recovery 99.51, 98.97, 99.84 and 99.46% and relative standard deviation 0.53, 1.21, 0.65, 0.81% for the three mentioned methods, respectively. Investigation of the formed complexes was made with respect to its composition, molar ratio of the reaction, association constant K(C)AD, molar absorptivity epsilon(lambda)AD and free energy change deltaG for methods (A) and (B). The proposed methods have been applied successfully to the analysis of the cited drugs either in pure form or in pharmaceutical formulations, with good accuracy and precision, compared statistically with those given by the reported methods. They are recommended for quality control and routine analysis.
J AOAC Int. ;91 (6):1309-17 19202791
Spectrofluorometric determination of olanzapine and fluphenazine hydrochloride in pharmaceutical preparations and human plasma using eosin: application to stability studies.
University of Mansoura, Faculty of Pharmacy, Department of Analytical Chemistry, 35516 Mansoura, Egypt.
A simple, rapid, and sensitive spectrofluorometric method has been developed for the determination of olanzapine (OLZ) and fluphenazine hydrochloride (FPZ HCI). The proposed method is based on the quantitative quenching effect of the studied drugs on the native fluorescence of eosin at pH 3.4 and 3.2 for OLZ and FPZ HCI, respectively. The fluorescence was measured at 547 nm after excitation at 323 nm. The fluorescence-concentration plots were rectilinear over the range of 0.05-1.0 and 0.10-1.0 microg/mL, with lower detection limits of 1.8 x 10(-3) and 1.2 x 10(-3) microg/mL, for OLZ and FPZ HCI, respectively. The proposed method was successfully applied to the analysis of commercial tablets and ampules containing the drugs, and the results were in good agreement with those obtained with reference methods. The proposed method was further applied to the determination of OLZ in spiked human plasma. The mean recovery was 98.62 +/- 0.24%(n = 4). The method was also used for stability studies of FPZ HCI upon oxidation with hydrogen peroxide, and the kinetics of the reaction were studied. A proposal for the reaction pathway was postulated.
J AOAC Int. ;90 (1):142-6 17373444
Simultaneous estimation of pantoprazole and domperidone in pure powder and a pharmaceutical formulation by high-perfomance liquid chromatography and high-performance thin-layer chromatography methods.
Department of Pharmaceutical Chemistry, Shree S.K. Patel College of Pharmaceutical Education and Research, Ganpat Vidyanagar, Kherva, Mehsana-382711, Gujarat, India. email@example.com
This paper describes validated high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC) methods for the simultaneous estimation of pantoprazole (PANT) and domperidone (DOM) in pure powder and capsule formulations. The HPLC separation was achieved on a Phenomenex C18 column (250 mm id, 4.6 mm, 5 pm) using 0.01 M, 6.5 pH ammonium acetate buffer-methanol-acetonitrile (30 + 40 + 30, v/v/v, pH 7.20) as the mobile phase at a flow rate of 1.0 mL/min at ambient temperature. The HPTLC separation was achieved on an aluminum-backed layer of silica gel 60F254 using ethyl acetate-methanol (60 + 40, v/v) as the mobile phase. Quantification was achieved with ultraviolet (UV) detection at 287 nm over the concentration range 400-4000 and 300-3000 ng/mL with mean recovery of 99.35+/-0.80 and 99.08+/-0.57% for PANT and DOM, respectively (HPLC method). Quantification was achieved with UV detection at 287 nm over the concentration range 80-240 and 60-180 ng/spot with mean recovery of 98.40+/-0.67 and 98.75+/-0.71% for PANT and DOM, respectively (HPTLC method). These methods are simple, precise, and sensitive, and they are applicable for the simultaneous determination of PANT and DOM in pure powder and capsule formulations.
Spectrophotometric determination of carvedilol in pharmaceutical formulations through charge-transfer and ion-pair complexation reactions.
Departamento de Farmácia Industrial, Universidade Federal de Santa Maria, Campus, Santa Maria, Brazil. firstname.lastname@example.org
Simple extraction-free spectrophotometric methods have been developed for the determination of carvedilol (CAR). The methods were based either on charge-transfer reaction of the drug with the sigma-acceptor iodine, in acetonitrile, or on ion-pair formation with the acidic sulphophthalein dyes bromothymol blue (BTB) and bromocresol green (BCG), in chloroform. The obtained complexes showed absorbance maxima at 363, 411 and 414 nm, respectively for iodine, BTB and BCG. Beer's law validation, accuracy, precision, and other aspects of analytical merit are presented in the text. The proposed methods were applied for the determination of CAR in tablets and compounded capsules. The results were in good agreement with those obtained by an established UV spectrophotometric method.
Anal Sci. 2006 Jul ;22 (7):983-8 16837750
Department of Chemistry, Aligarh Muslim University, Aligarh 202002, Uttar Predesh, India. email@example.com
A kinetic spectrophotometric method has been developed which is based on the oxidation of pantoprazole with Fe(III) in sulfuric acid medium. Fe(III) subsequently reduces to Fe(II), which is coupled with potassium ferricyanide to form Prussian blue. The reaction is followed spectrophotometrically by measuring the increase in absorbance with time (1-8 min) at 725 nm. The initial rate method is adopted for constructing the calibration graph, which is linear in the concentration range of 5-90 microg ml(-1). The regression analysis yields the calibration equation, nu = 3.467 x 10(-6)+ 4.356 x 10(-5)C. The limits of detection and quantitation are 1.46 and 4.43 microg ml(-1), respectively. The proposed method was optimized and validated both statistically and through recovery studies. The experimental true bias of all samples is <+/-2.0%. The method has been successfully applied to the determination of pantoprazole in pharmaceutical preparations.
Reversed-phase high performance liquid chromatographic method for the determination of lansoprazole, omeprazole and pantoprazole sodium sesquihydrate in presence of their Acid-induced degradation products.
National Organization for Drug Control and Research, Cairo,Egypt. firstname.lastname@example.org
A simple sensitive, selective and accurate reversed-phase high performance liquid chromatographic method was developed and validated for the quantitative determination of lansoprazole, omeprazole and pantoprazole sodium sesquishydrate in the presence of their acid-induced degradation products. The three compounds were monitored at 280 nm using Nova-Pak C(18) column and a mobile phase consisting of 0.05 M potassium dihydrogen phosphate : methanol : acetonitrile (5 : 3 : 2 v/v/v). Linearity ranges were 2-20 microg ml(-1), 2-36 microg ml(-1) and 0.5-20 microg ml(-1) for lansoprazole, omeprazole and pantoprazole, respectively. The corresponding recoveries were 100.61+/-0.84%, 100.50+/-0.80% and 99.78+/-0.88%. The minimum detection limits were 0.55, 0.54 and 0.03 microg ml(-1) for lansoprazole, omeprazole and pantoprazole, respectively. The method could be successfully applied to the determination of pure, laboratory prepared mixtures and pharmaceutical dosage forms. The results obtained were compared with the reported methods for lansoprazole and pantoprazole or the official U.S.P method for omeprazole.
Development and application of spectrophotometric methods for the determination of citalopram hydrobromide in dosage forms.
Analytical Laboratory, Bio Fine Pharmaceuticals (Pvt.) Ltd., Multan, Pakistan. email@example.com
Study was carried out to develop two simple, fast, accurate and sensitive spectrophotometric methods (A and B) for the determination of citalopram hydrobromide in commercial tablet formulations. In method A, UV spectrophotometer determined the contents of citalopram hydrobromide in tablets at 240 nm in methanol solvent. The linear range was 5-40 microg ml-1 with molar absorptivity 1.4x10(4) l mol-1 cm-1. While the method B based on the reaction of citalopram base as n-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone as pi-acceptors to give highly colored complex species that absorb maximally at 590 nm. Beer's law was obeyed in the concentration limit of 10-250 microg ml-1 with molar absorptivity 3.3x10(3) l mol-1 cm-1 for citalopram hydrobromide. The limits of detection and limit of quantification was calculated and found to be 5.2 microg ml-1 and 17.4 microg ml-1 respectively. The proposed methods were found to be rapid, accurate, precise and sensitive for the determination of citalopram hydrobromide in commercial tablet formulations with out interferences from common additives encountered.
Pharmazie. 2005 Mar ;60 (3):197-200 15801672
Initial-rate method for the determination of pantoprazole in pharmaceutical formulations using 1-fluoro 2,4-dinitrobenzene.
Analytical Research Laboratory, Department of Chemistry, Aligarh Muslim University, Aligarh, UP, India. firstname.lastname@example.org
A simple and selective kinetic spectrophotometric method for the determination of pantoprazole in pharmaceutical preparations is described. The procedure is based upon a kinetic investigation of the reaction of the drug with 1-fluoro-2,4-dinitrobenzene in DMSO at room temperature. The absorbance of the coloured product was measured at 420 nm. The plot of the logarithm of the initial rate of the reaction vs. the logarithm of molar concentration of pantoprazole is linear over the range 10-20 microg x ml(-1). The procedure retains its accuracy in the presence of a large excess of its degradate, sulfenic acid, which is prepared by degradating the pure drug in borate buffer of pH 8 at room temperature for seven days. The results are validated statistically and through recovery studies. The method has been successfully applied to the determination of pantoprazole in commercial tablets. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.
Department of Chemistry, Faculty of Science, Mansoura University, 34517 Dumyat, Egypt. email@example.com
Adsorption and reduction of pantoprazole were investigated by cyclic and square-wave voltammetry on a hanging mercury drop electrode in Britton-Robinson buffers at pH 2.0-11.0. The reduction process gave rise to a single peak within the entire pH range. Study of the variation of the reduction signal with solution variables such as pH and concentration of pantoprazole and instrumental variables such as accumulation time and potential, frequency, pulse height and pulse amplitude, has resulted in optimization of the reduction signal for analytical purposes. The voltammetric procedure was applied successfully to give a rapid and precise assay of pantoprazole in a tablet dosage form.
Differential pulse anodic voltammetric determination of pantoprazole in pharmaceutical dosage forms and human plasma using glassy carbon electrode.
Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, 06100 Ankara, Turkey. firstname.lastname@example.org
Pantoprazole is used as an anti-ulcer drug through inhibition of H(+), K(+)-adenosine 5(')-triphosphatase in gastric parietal cells. It reduces the gastric acid secretion regardless of the nature of stimulation. The use of differential pulse voltammetry for the determination of pantoprazole in pharmaceutical dosage forms and human plasma using a glassy carbon electrode has been examined. The best voltammetric response was reached for a glassy carbon electrode in Britton-Robinson buffer solution of pH 5.0 submitted to a scan rate of 20.0 mVs(-1) and a pulse amplitude of 50.0 mV. This electroanalytical procedure was able to determine pantoprazole in the concentration range 6.0 x 10(-6)-8.0 x 10(-4)M. Precision and accuracy of the developed method was checked with recovery studies. The limit of detection and limit of quantitation were found to be 4.0 x 10(-7) and 9.0 x 10(-7)M, respectively. Rapidity, precision, and good selectivity were also found for the determination of pantoprazole in pharmaceutical dosage forms and human plasma. For comparative purposes high-performance liquid chromatography with a diode array and UV/VIS detection at 290.0 nm determination also was developed.
First-order UV-derivative spectrophotometry in the analysis of omeprazole and pantoprazole sodium salt and corresponding impurities.
Institute of Analytical Chemistry, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Yugoslavia. email@example.com
The first-order UV-derivative spectrophotometry, applying zero-crossing method was developed for the determination of omeprazole (OM), omeprazole sulphone (OMS), pantoprazole sodium salt (PANa), and N-methylpantoprazole (NPA) in methanol-ammonia 4.0% v/v, where the sufficient spectra resolutions of drug and corresponding impurity were obtained, using the amplitudes 1D(304), 1D(307), 1D(291.5) and 1D(296.5), respectively. Method showed good linearity in the ranges (microg ml(-1)): 1.61-17.2 for OM; 2.15-21.50 for OMS; 2.13-21.30 for PANa and 2.0-20.0 for NPA, accuracy and precision (repeatability and reproducibility). The experimentally determined values of LOD (microg ml(-1)) were 1.126; 0.76; 0.691 and 0.716 for OM, OMS, PANa and NPA, respectively. The obtained values of 2.91% w/w for OMS and 3.58% w/w for NPA in the presence of their parent drug, by applying the method of standard additions, point out the usage of the proposed method in stability studies. Zero-crossing method in the first-order derivative spectrophotometry showed the impurity-drug intermolecular interactions, due to the possible intermolecular hydrogen bonds, confirmed by divergences of experimentally obtained amplitudes for impurities OMS and NPA in comparison to expected values according to regression equations of calibration graphs.
Other papers by authors:
Effects of industrial formulations of Bacillus thuringiensis on the biology of Musca domestica L.(Diptera : Muscidae).
Plant Protection Department, Faculty of Agriculture, Ain Shams University, Cairo, Egypt.
The effects of two industrial formulations of Bacillus thuringiensis (Bactimos and Vectobac) on larval and adult stages of Musca domestica L. were assessed in the laboratory. Biocides concentrations of 0.4% to 2% were tested on larvae, while the concentrations of 1% and 2% were tested on adults and were given to the flies in their diet. Larval mortality ranged between 38% and 53% and between 55% and 71% for bactimos and Vectobac respectively. Pupation rates decreased from 91% in the control group down to 47% and 29% for Bactimos and Vectobac respectively. Moreover, adult emergence rates decreased 3-4 folds in groups treated with the highest biocide concentrations. The effect on adult mortality was relatively lower, as control adults showed 4% mortality whereas those treated with Bactimos and Vectobac experienced 17-28% and 32-44% mortality respectively. In addition, biocides treatment induced a dramatic decrease in female fecundity from 273 eggs/female in the control to 118-180 eggs/female treated siblings. These findings indicate that Bactimos and Vectobac possess both direct and indirect harmful effects on Musca domestica.
Botany Department, Faculty of Science, Suez Canal University, Ismailia, Egypt. firstname.lastname@example.org
Ballota undulata, Ballota kaiseri, and Ballota saxatilis are very rare (and endemic--B. kaiseri), threatened species growing in St. Catherine Protectorate, southern Sinai, Egypt. They are subjected to a number of threats that have caused populations to decline in both number and size. For the long-term survival of these species, an appropriate conservation strategy for the maintenance of their genetic variation should be developed. This study measures genetic diversity within and among populations of these Ballota species and determines the conservation implications of the results. The genetic analyses demonstrated that the three Ballota species maintain relatively high levels of genetic diversity (He = 0.195-0.317) and that most of the their genetic diversity was found within populations (GST = 0.045-0.099). Indirect estimates of historical gene flow for B. undulata and B. saxatilis were relatively high (Nm(W)= 5.25 and 3.37, respectively) but suggest that there is somewhat less gene movement among B. kaiseri populations (Nm(W)= 2.29). The levels of genetic diversity maintained within populations of the three Ballota species indicate that an appropriate sampling design for ex situ safeguarding should capture the majority of the genetic diversity found within these taxa.
Department of Analytical Chemistry, Faculty of Pharmacy, Cairo University, 23 El-ahrar St., Cairo, Egypt.
Two spectrophotometric methods for the determination of imipramine in presence of iminodibenzyl as an impurity are described. The first method is a ratio-spectra first derivative spectrophotometry, the signals were measured at 240.2 nm for imipramine. Calibration graph was found linear in the range 5-30 microg ml(-1). The second method is based on the reaction of imipramine base, being an electron donor, with p-chloranilic acid, being pi acceptor, to form a purple colored charge transfer complex. The absorbance was measured at 520.5 nm without interference with iminodibenzyl. Both methods are rapid, simple and do not require any preliminary separation or treatment of the samples. Furthermore, the two methods were applied to pharmaceutical dosage form.
Department of Analytical Chemistry, Faculty of Pharmacy, Cairo University, 23 El-ahrar St, Cairo, Egypt.
Two methods are described for the determination of zolpidem hemitartrate in presence of its degradation product. The first method was a TLC-UV densitometric one in which the mobile phase methanol: water (20:80) was used for developing the TLC plates. The R(f) of zolpidem hemitartrate was found to be 0.29+/-0.01 and that of its degradation product was 0.59+/-0.01. Linearity range was 0.5-4 microg/spot with mean recovery percentage (99.98+/-0.988)%. The second method was an HPLC method. HPLC was performed on a Bondapack C(18) column. The mobile phase was composed of a mixture of acetonitrile-0.01 M KH(2)PO(4)(40:60). The pH was adjusted to 3.5+/-0.1. Flow rate was 1.2 ml/min. Calibration graphs were linear in the range of 0.5-5 microg/ml with UV detection at 245 nm. Both methods have been successfully applied to pharmaceutical formulations. The results obtained were statistically compared with those obtained by applying the reported methods.
National Organization for Drug Control and Research (NODCAR), 6 Hussen Kamal el Deen, Ben-el-sariat, Dokki, 12311, Giza, Egyp. email@example.com
Four stability-indicating methods were developed for the determination of sumatriptan succinate in the presence of its degradation products. The first method depends on the quantitative densitometric evaluation of thin-layer chromatography of sumatriptan succinate in the presence of its degradation products without any interference. Cyclohexane-dichloromethane-diethylamine (50:40:10 v/v/v) was used as a mobile phase and the chromatogram was scanned at 228 nm. This method determines sumatriptan succinate in the concentration range l-8 microg per spot with mean percentage recovery 100.52+/-1.23%. The second and third methods depend on the use of first-derivative (D(1)) and second-derivative (D(2)) spectrophotometry at 234 and 238 nm, respectively. These methods determine the drug in the concentration range 1.25-10 microg x ml(-1) with mean percentage recovery 99.91+/-1.01% and 99.96+/-1.13% for (D(1)) and (D(2)), respectively. The fourth method depends on the use of ratio derivative spectrophotometric technique. The amplitude in the first derivative of the ratio spectra at 235 nm was selected to determine the cited drug in the presence of its degradation products. Calibration graph is linear in the concentration range 1.25-10 microg x ml(-1) with mean percentage recovery 100.19+/-1.19%. The suggested methods were successfully applied for determining sumatriptan succinate in bulk powder, laboratory-prepared mixtures and pharmaceutical dosage forms (Imigran tablet) with good accuracy and precision. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the reported method.
National Organization For Drug Control and Research (NODCAR), 6 Hussen Kamal el Deen, Ben-el-sariat, Dokki, Giza, Egypt. firstname.lastname@example.org
Two stability-indicating methods were developed for the determination of doxazosin mesylate (I) and celecoxib (II) in the presence of their degradation products. The first method depends on the use of first derivative spectrophotometry (D(1)) at 256, 269 nm for (I) and (II), respectively. This method determines (I) and (II) in concentration ranges of 0.8-12 and 1-20 microg ml(-1) with mean percentage accuracies of 99.21+/-0.88 and 99.59+/-1.67% for (I) and (II), respectively. The second method depends on the quantitative densitometric evaluation of thin-layer chromatography of (I) and (II) in the presence of their degradation products without any interference. Methylisobutyl ketone-glacial acetic acid-water (20:10:10) was used as a mobile phase for (I) and cyclohexane-dichloromethane-diethyleamine (50:40:10) for (II). The chromatograms were scanned at 248 and 253 nm for (I) and (II), respectively. This method determines (I) and (II) in concentration ranges of l-4 microg per spot for both drugs with mean percentage accuracies of 100.19+/-0.95 and 99.91+/-1.95% for (I) and (II), respectively. The suggested methods were used to determine doxazosin mesylate and celecoxib in bulk powder, laboratory-prepared mixtures and pharmaceutical dosage forms (cardura tablet and celebrex capsule). The results obtained by applying the proposed methods were statistically analysed and compared with those obtained by the reported methods.
Determination of fat-soluble vitamins in oil matrices by multidimensional high-performance liquid chromatography.
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Acta Pol Pharm. ;69 (2):213-23 22568035
Simple, sensitive and selective spectrophotometric methods for the determination of atenolol in pharmaceuticals through charge transfer complex formation reaction.
Department of Chemistry, University of Mysore, Manasagangotri, Mysore 570006, Karnataka, India.
Three rapid, selective and sensitive spectrophotometric methods have been proposed for the quantitative determination of atenolol (ATN) in pure form as well as in its pharmaceutical formulation. The methods are based on charge transfer complexation reaction of ATN as n-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,4-dinitrophenol (DNP) and 2,4,6-trinitrophenol (picric acid; PA) as pi-acceptors to give highly colored radical anion species. The colored products were quantified spectrophotometrically at 590 nm with DDQ (method A) and at 420 nm with both DNP (method B) and PA (method C). Under the optimized experimental conditions, Beer's law is obeyed over the concentration ranges of 3-48, 2-24 and 1.5-18 μg/mL ATN for method A, method B and method C, respectively. The molar absorptivity, Sandell sensitivity, limits of detection and quantification are also reported. The effects of reaction medium, reaction time and reagent concentration on the sensitivity and stability of the complexes formed have been examined. The proposed methods were successfully applied to the determination of ATN in pure form and 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 and the results showed no significant difference between the reference and proposed methods with regard to accuracy and precision. Further, the accuracy and reliability of the methods were confirmed by recovery studies via standard addition technique.
Talanta. 2009 Nov 15;80 (1):151-7 19782205
Utility of certain sigma- and pi-acceptors for the spectrophotometric determination of ganciclovir in pharmaceutical formulations.
Chemistry Department, Faculty of Science, Zagazig University, Zagazig 44519, Egypt. email@example.com
Studies were carried out, for the first time, to investigate the charge-transfer reactions of ganciclovir as n-electron donor with the sigma-acceptor iodine and various pi-acceptors: 7,7,8,8-tetracyanoquinodimethane; tetracyanoethylene; 2,3-dichloro-5,6-dicyano-1,4-benzoquinone; p-chloranilic acid; 2,3,5,6-tetrabromo-1,4-benzoquinone; 2,3,5,6-tetrachloro-1,4-benzoquinone and 2,4,7-trinitro-9-fluorenone. The formation of the colored charge-transfer complexes was utilized in the development of simple, rapid and accurate spectrophotometric methods for the analysis of ganciclovir in pure form as well as in its pharmaceutical formulation (capsules). Different variables affecting the reactions were studied and optimized. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9993-0.9998) were found between the absorbance and the concentration of ganciclovir in the range of 2.0-240 microg mL(-1). For more accurate analysis, Ringbom optimum concentration range was found to be between 5.0 and 225 microg mL(-1). The limits of detection ranged from 0.36 to 2.45 microg mL(-1) and the limits of quantification ranged from 1.20 to 8.17 microg mL(-1). A Job's plot of the absorbance versus the molar ratio of ganciclovir to each of acceptors under consideration indicated (1:1) ratio. The proposed methods were applied successfully for simultaneous determination of ganciclovir in capsules with good accuracy and precision and without interferences from common additives. The recovery percentages ranged from 99.45+/-0.73% to 100.35+/-1.40%. The results were compared favourably with the reported method.
Anal Chem Insights. 2008 ;3 :31-43 19609388
Optimized and validated spectrophotometric methods for the determination of enalapril maleate in commercial dosage forms.
Department of Chemistry, Aligarh Muslim University, Aligarh (U.P.) 202 002, India. firstname.lastname@example.org
Four simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of enalapril maleate in pharmaceutical formulations. The first method is based on the reaction of carboxylic acid group of enalapril maleate with a mixture of potassium iodate (KIO(3)) and iodide (KI) to form yellow colored product in aqueous medium at 25 +/- 1 degrees C. The reaction is followed spectrophotometrically by measuring the absorbance at 352 nm. The second, third and fourth methods are based on the charge transfer complexation reaction of the drug with p-chloranilic acid (pCA) in 1, 4-dioxan-methanol medium, 2, 3-dichloro 5, 6-dicyano 1, 4-benzoquinone (DDQ) in acetonitrile-1,4 dioxane medium and iodine in acetonitrile-dichloromethane medium. Under optimized experimental conditions, Beer's law is obeyed in the concentration ranges of 2.5-50, 20-560, 5-75 and 10-200 microg mL(-1), respectively. All the methods have been applied to the determination of enalapril maleate in pharmaceutical dosage forms. Results of analysis are validated statistically.
Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt.
Three simple, rapid and sensitive spectrophotometric procedures were developed for the analysis of cephapirin sodium (1), cefazoline sodium (2), cephalexin monohydrate (3), cefadroxil monohydrate (4), cefotaxime sodium (5), cefoperazone sodium (6) and ceftazidime pentahydrate (7) in pure form as well as in their pharmaceutical formulations. The methods are based on the reaction of these drugs as n-electron donors with the sigma-acceptor iodine, and the pi-acceptors: 2,3-dichloro-5,6-dicyano-p-benzo-quinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). Depending on the solvent polarity, different coloured charge-transfer complexes and radicals were developed. Different variables and parameters affecting the reactions were studied and optimized. The obtained charge-transfer complexes were measured at 364 nm for iodine (in 1,2-dichloroethane), 460 nm for DDQ (in methanol) and 843 nm for TCNQ (in acetonitrile). Ultraviolet-visible, infrared and (1)H-nuclear magnetic resonance techniques were used to study the formed complexes. Due to the rapid development of colours at ambient temperature, the obtained results were used on thin-layer chromatograms for the detection of the investigated drugs. Beer's plots were obeyed in a general concentration range of 6-50, 40-300 and 4-24 mug ml(-1) with iodine, DDQ and TCNQ, respectively, with correlation coefficients not less than 0.9989. The proposed procedures could be applied successfully to the determination of the investigated drugs in vials, capsules, tablets and suspensions with good recovery; percent ranged from 96.47 (+/-1.14) to 98.72 (+/-1.02) in the iodine method, 96.35 (+/-1.62) to 98.51 (+/-1.30) in the DDQ method, and 95.98 (+/-0.78) to 98.40 (+/-0.87) in the TCNQ method. The association constants and standard free energy changes using Benesi-Hildebrand plots were studied. The binding of cephalosporins to proteins in relation to their molar absorptivities was studied.
Talanta. 1998 Aug ;46 (6):1357-62 18967264
Foods and Drugs Laboratories, School of Chemistry, College of Science and Technology, Andhra University, Visakhapatnam 530 003, India.
Simple, selective and sensitive spectrophotometric methods are described for the determination of pentoxifylline, based on the haloform reaction with a known and excess of standard iodine solution under alkaline conditions. The excess of iodine is determined at pH 3.0 with metol-isoniazid (lambda(max)=620 nm; method A) or wool fast blue BL (lambda(max)=540 nm, method B). All the variables have been optimised and the reaction mechanisms presented. Regression analysis of Beer's law plots showed good correlation in the concentration ranges 4.0-24.0 and 0.4-2.4 mg ml(-1) for methods A and B respectively. No interferences were observed from excipients and the validity of the methods was tested by analysing pharmaceutical formulations. Recoveries were 99.0-100.0%. The concentration measurements were reproducible within a relative standard deviation of 1.0%.
Talanta. 1985 Mar ;32 (3):189-93 18963823
Department of Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain.
A spectrophotometric method for the détermination of trace amounts of Nb(V) based on the formation of a ternary complex with Bromopyrogallol Red (L) and cetylpyridinium bromide (CPB) in 1M hydrochloric acid/15% dimethylformamide medium has been developed. The ternary 1:2:2 Nb-L-CPB complex is formed. The absorbance maximum is at 645 nm, the molar absorptivity being (4.00 +/- 0.04) x 10(4) l.mole(-1).cm(-1). The relative standard deviation is 1.9% and Beer's law is obeyed up to 1.4 mug of Nb(V) per ml. The application of the method to the determination of Nb in pyrochlore-bearing rocks is described. A possible mechanism of interaction of the surfactant with the Nb-L complex is discussed.
Anal Sci. 2007 Sep ;23 (9):1103-7 17878586
Spectrophotometric determination of spermine and related compounds using o-hydroxyhydroquinonephthalein and manganese(II).
Kanako Miyachi, Kenzo Moriyama, Takako Yamaguchi, Hiroshi Tominaga, Shinichiro Kamino, Yoshikazu Fujita
Department of Hospital Pharmacy School of Medicine, Kinki University, Osaka, Japan. email@example.com
A simple and highly sensitive spectrophotometric method for the determination of spermine (Spm) was established based on the ternary complex formation reaction of Spm with o-hydroxyhydroquinonephthalein (QP) as a xanthene dye and manganese(II) as a metal ion in the presence of a dispersion agent. The apparent molar absorptivity at 555 nm and the relative standard deviation of the proposed method were 1.4 x 10(5) dm(3) mol(-1) cm(-1) and 0.50%(n = 10), respectively. In the method for flow-injection analysis (FIA), which employs a single-channel flow manifold system, a good linear relationship was observed over the 2 - 20 pg microl(-1) range of Spm by direct injection.
Anal Sci. 2007 May ;23 (5):601-4 17495409
Spectrophotometric determination of oxalate ion with N,N'-diethyl-N,N'-[[4,4'-dihydroxy-1,1'-binaphthalene]-3,3'-diyl]bisbenzamide and copper(II).
Osaka University of Pharmaceutical Sciences, Osaka, Japan.
A simple and rapid spectrophotometric method for the determination of oxalate ion was established by the fading of a colored complex between N,N'-diethyl-N,N'-[[4,4'-dihydroxy-1,1'-binaphthalene]-3,3'-diyl]bisbenzamide and copper(II). Beer's law was obeyed in the concentration range of 0.1 - 2.0 microg cm(-3) for oxalate ion, with an effective molar absorptivity at 533 nm and the relative standard deviation being 8.0 x 10(3) dm(3) mol(-1) cm(-1) and 1.0%(n = 5), respectively. This proposed method has excellent reproducibility, and was applied to recovery tests of oxalate ion in tap water and human urine; the results were satisfactory. This is suggested that the method is based on the reaction of copper(II) to copper(I) with oxalate ion.
Anal Sci. 2006 May ;22 (5):757-61 16770058
Department of Studies in Chemistry, University of Mysore, India.
The proposed work describes a simple spectrophotmetric as well as a titrimetric method to determine sulfur dioxide. The spectrophotometric method is based on a redox reaction between sulfur dioxide and iodine monochloride obtained from iodine with chloramine-T in acetic acid. The reagent iodine monochloride oxidizes sulfur dioxide to sulfate, thereby reducing itself to iodine. Thus liberated iodine will also oxidize sulfur dioxide and reduce itself to iodide. The obtained iodide is expected to combine with iodine to form a brown-colored homoatomictriiodide anion (460 nm), which forms an ion-pair with the sulfonamide cation, providing exceptional color stability to the system under an acidic condition, and is quantitatively relatd to sulfur dioxide. The system obeys Beer's law in the range 5 - 100 microg of sulfur dioxide in a final volume of 10 ml. The molar absorptivity is 5.03 x 10(3) l mol(-1)cm(-1), with a relative standard deviation of 3.2% for 50 microg of sulfur dioxide (n = 10). In the titrimetric method, the reagent iodine monochloride was reduced with potassium iodide (10%) to iodine, which oxidized sulfur dioxide to sulfate, and excess iodine was determined with a thiosulfate solution. The volume difference of thiosulfate with the reagent and with the sulfur dioxide determined the sulfur dioxide. Reproducible and accurate results were obtained in the range of 0.1 - 1.5 mg of sulfur dioxide with a relative standard deviation of 1.2% for 0.8 mg of sulfur dioxide (n = 10).
Spectrophotometric determination of carbinoxamine maleate in pharmaceutical formulations by ternary complex formation with Cu(II) and eosin.
Department of Chemistry, Faculty of Science, Aleppo University, Syria.
A simple and sensitive spectrophotometric method was developed for the determination of carbinoxamine maleate in pharmaceutical formulations. The method is based on the formation of a ternary complex, extractable with chloroform, between copper(II), eosin, and carbinoxamine maleate. The absorption spectra of the ternary complexes shows, under optimum conditions, a maxima at 538 nm, with apparent molar absorptive 6.1690 x 10(4) mol(-1) cm(-1), Sandell's sensitives 6.75 x 10(-3) microg cm(-2), and linearity in the concentration range 0.75-10.0 microg ml(-1). The method can be achieved with high accuracy (recovery values, 100 +/- 2%) and precision (with standard deviation 0.029-0.155 and relative standard deviation 3.87-1.55%). The method was again successfully applied, with high accuracy and good precision, for the determination of carbinoxamine maleate in various pharmaceutical formulations (syrup, drops, and tablets).