Derivative Ratio Method Research Articles

Comparative Study for the Assay of Plant Derived Chemicals in Pharmaceutical Formulation Using Methods Dependent on Factorized Spectra.

Modern built-in spectrophotometer software supporting mathematical processes provided a solution for increasing selectivity for multicomponent mixtures. Simultaneous spectrophotometric determination of the three naturally occurring antioxidants-rutin(RUT), hesperidin(HES), and ascorbic acid(ASC)-in bulk forms and combined pharmaceutical formulation. This was achieved by factorized zero order method (FZM), factorized derivative method (FD1M), and factorized derivative ratio method (FDRM), coupled with spectrum subtraction(SS). Mathematical filtration techniques allowed each component to be obtained separately in either its zero, first, or derivative ratio form, allowing the resolution of spectra typical to the pure components present in Vitamin C Forte® tablets. The proposed methods were applied over a concentration range of 2-50, 2-30, and 10-100 µg/mL for RUT, HES, and ASC, respectively. Recent methods for the analysis of binary mixtures, FZM and FD1M, were successfully applied for the analysis of ternary mixtures and compared to the novel FDRM. All were revealed to be specific and sensitive with successful application on pharmaceutical formulations. Validation parameters were evaluated in accordance with the International Conference on Harmonization guidelines. Statistical results were satisfactory, revealing no significant difference regarding accuracy and precision. Factorized methods enabled the resolution of spectra identical to those of pure drugs present in mixtures. Overlapped spectra of ternary mixtures could be resolved by spectrum subtraction coupled FDRM (SS-FDRM) or by successive application of FZM and FD1M.

Synchronized determination of the novel heart failure combination therapy containing sacubitril calcium and valsartan by a validated spectrofluorimetric method

A sensitive and accurate spectrofluorimetric method was proposed for the determination of Sacubitril calcium and Valsartan simultaneously in binary mixture. The method was established on measuring the native fluorescence of Sacubitril calcium and Valsartan upon excitation at 240 nm in acetonitrile. The emission of Sacubitril calcium was measured at 615 nm. For the determination Valsartan a first derivative ratio method was employed to eliminate any spectral interference. The ratio emission spectra were achieved by dividing the emission spectra of various concentrations of Valsartan by the emission spectrum of Sacubitril calcium (100 ng/ml) then the first derivative of the obtained ratio emission spectra was recorded using the proper smoothing factor. The amplitude at 354.9 nm on the first derivative ratio emission spectrum was used to calculate the concentrations of Valsartan in presence of Sacubitril calcium. The method was linear over the concentration range 100–1000 ng/ml for both Sacubitril calcium and Valsartan. The mean accuracy values were found to be 99.32 ± 0.62 and 99.30 ± 0.70 for Sacubitril calcium and Valsartan, respectively. Statistical comparison between results obtained by the proposed method and a reported method for this drugs showed no significant difference. This developed method was used for the quantitative determination of Sacubitril calcium and Valsartan in both pure and pharmaceutical dosage form.

UV spectrophotometric methods for quantitative determination of masitinib; extraction of qualitative information

Masitinib is an orally administered selective tyrosine kinase inhibitor. It has emerged as a promising drug for multiple diseases including cancer and inflammation in either human or veterinary medicine. Five new and simple UV spectrophotometric methods were developed for its determination in bulk and in pharmaceutical tablets. These methods are based on measuring the absorbance of masitinib in either zero order or first, second, third or fourth derivative spectra. Measurements are optimized so as to minimize excipients' interferences. The methods are suitable for micro-analysis of masitinib. The proposed methods were validated according to the ICH-Q2(R1) guidelines and was successfully applied for determination of masitinib in laboratory prepared tablet. The presented methods are simple, fast, cost‐effective and suitable for routine pharmaceutical analysis. Moreover, two derivative spectrophotometric-based methods were developed for identification of masitinib, the derivative ratio method and log-A derivative method. The impact of the developed methods on the environment was assessed by both analytical Eco-Sale and the Green Analytical Procedure Index (GAPI). The present work proves how derivative spectrophotometry could greatly extract qualitative and quantitative information from UV spectra.

Simultaneous determination of enalapril maleate and nitrendipine in tablets using spectrophotometric methods manipulating ratio spectra.

A fixed dose combination of enalapril maleate (EN) and nitrendipine (NT) achieved satisfactory blood pressure control rather than monotherapy. Four accurate spectrophotometric methods utilizing ratio spectra were developed and validated for the simultaneous determination of EN and NT in combined pharmaceutical dosage form (Eneas® tablets). The first method was first derivative ratio spectrophotometric method (1DD) where the amplitudes maxima were measured at 219.2nm and 233.4nm for the determination of EN and NT, respectively. The second method was ratio difference spectrophotometric method where EN and NT were estimated by measuring the amplitudes difference between 213nm and 225nm on the ratio spectrum of EN and between 241nm and 227nm on the ratio spectrum of NT. The third method was ratio subtraction followed by extended ratio subtraction, EN was determined at 210nm by subtraction of the constant values from the ratio spectrum then multiplication with the divisor (NT spectrum). An extended ratio subtraction method was then applied in order to determine NT at 235nm by using the zero-order spectrum of EN (10μg/ml) as a divisor. The fourth method was ratio subtraction coupled with constant multiplication methods. The zero- order absorption spectrum of the laboratory prepared mixture was divided by NT (12μg/ml) spectrum, subsequently, the value of the constant was multiplied by the divisor to obtain the original spectrum of NT, followed by its subtraction from the laboratory prepared mixture to get the spectrum of EN. EN and NT were determined at 210nm and 235nm, respectively. Linearity was ascertained over the concentration ranges of (1-11μg/ml) for EN and (2-14μg/ml) for NT, for the first and second methods and (2-13μg/ml) for EN and (3-20μg/ml) of NT, for the third and fourth methods. Application of the methods to the determination of the cited drugs in Eneas® tablets gave satisfactory results. Methods validation confirmed their accuracy and selectivity. Statistical comparison of the results with the reported one showed no significant difference, regarding precision and accuracy. Routine analysis of the cited drugs in quality control laboratories could be performed using the developed methods.

Determination of Rufinamide in the Presence of 1-[(2,6-Difluorophenyl)Methyl]-1H-1,2,3-Triazole-4 Carboxylic Acid Using RP-HPLC and Derivative Ratio Methods as Stability Indicating Assays to Be Applied on Dosage Form.

Rufinamide is a triazole derivative that is structurally dissimilar to other marketed antiepileptic drugs, has been assumed a marketing authorization, by the European Union and FDA, for use as a complementary therapy for seizures associated with Lennox-Gastaut syndrome. This work is concerned with development of two methods for determination of rufinamide (RUF) in presence of 1-[(2,6-difluorophenyl)methyl]-1H-1,2,3-triazole-4 carboxylic acid as its alkaline degradation product in dosage form. The first method was capable of determing RUF in the presence of its alkaline degradation product and in dosage form. Kromasil C8 column and mobile phase consisting of acetonitrile-water (50:50, v/v) were used and UV detection at 210 nm. In the second method, first derivative ratio spectrophotometry, RUF was determined by measuring peak amplitude at 269.5 nm over 5-30 μg/mL. The linearity range of RUF was 10-90 μg/mL for HPLC method covering its therapeutic range with r2 = 0.9999. Forced degradation under alkaline conditions was carried out, the degradation product was isolated and its structure was confirmed. Both methods were validated in accordance to ICH guidelines. Statistical analysis revealed no significant difference between obtained results and reported ones. The present study is useful for therapeutic drug monitoring and routine analysis of RUF in quality control laboratories. Kinetics of the alkaline degradation of RUF was studied by following the concentration of the remaining drug until complete degradation was achieved.

Three Simple and Economic Spectrophotometric Methods for Simultaneous Determination of Chitosan and Ascorbic Acid

Three simple, precise, and sensitive UV spectrophotometric methodshave been developed and validated for the determination of Chitosan (CH) in the presence of Ascorbic acid (AA) in a binary mixture. Method A is a derivative ratio method (1DD) that measures the peak amplitude of the first derivative for CH and AA at 207.2 and 282 nm; respectively. Method B is a ratio difference method (RDSM) that measures the peak amplitude difference of the ratio spectra (DP204.6- 202.9) and (DP268-230) for CH and AA; respectively. Method C is a mean centering of ratio spectra method (MCR) that measures CH and AA at 204.6 and 269.1 nm; respectively. Method A, B, and C were able to successfully determine the studied drugs in a concentration range of 0.5-9 mg/mL for CH and 2-20 mg/mL for AA. All results were statistically compared with the reported methods, where no significant difference was observed. The proposed methods were applied to the analysis of the studied drugs in pure and pharmaceutical formulations.

Uv Spectrophotometric Methods for Determination of Sofosbuvir in Pure Form and Pharmaceutical Dosage Forms in Presence of Its Alkaline Degradate

Aims: Two spectrophotometric methods were developed and validated for the determination of sofosbuvir in presence of its alkaline degradate.
 Study Design: Ratio difference and ratio derivative methods were assisted for determination of sofosbuvir in presence of its alkaline degradate, laboratory-prepared mixtures and in tablet dosage forms.
 Place and Duration of Study: Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy (Girls), Al - Azhar University, between December 2019 and January 2020.
 Methodology: Two analytical methods were achieved and validated for the quantitative determination of Sofosbuvir in presence of its alkaline degradate. The first method was ratio difference (RD) method, where the UV absorption spectra of different concentrations of sofosbuvir were divided by the spectrum of a certain concentration (15 µg mL-1) as a devisor of its alkaline degradate to get the ratio difference spectra. Afterwards, the peak amplitudes difference between 253.7 and 243.5 nm were measured. The second method was the ratio derivative (1DR) method, where the first derivative of the ratio spectra (1DR) was obtained and its amplitude was measured at 247 and 268 nm. Good linearity was obtained over the concentration range of 3-15 µg mL-1 for the proposed methods. The proposed procedures were adopted for the selective determination of intact Sofosbuvir in presence of up to 80% of its degradation product. Sofosbuvir was exposed to different conditions as alkaline, acidic and oxidative degradation.
 Results: The proposed methods were developed and validated with good linearity range of 3-15 µg mL-1 for both methods, and also with good accuracy and precision. And the obtained results were statistically compared to those obtained by the reported method.
 Conclusion: Sofosbuvir was successfully determined by the proposed ratio difference and ratio derivative methods in bulk powder, laboratory prepared mixtures and tablet dosage form with good accuracy and precision. The methods were validated according to ICH guidelines. The results obtained were compared with those of the reported method and were found to be in good agreement.

Simultaneous micro-determination of eplerenone and torsemide in their combined tablets using HPTLC-Dual wavelength spectrodensitometric and spectrophotometric methods

Sudden death is common in patients with Congestive heart failure, occurring at a rate of six to nine times that of the general population. Day by Day, new combined therapies of more advanced drug generations are involved in treatment. Recently, the Eplerenone/ Torsemide binary therapy is displacing the older Spironolactone/ Frusemide treatment trend of heart disease because it proved better tolerability and potency. This necessitates fast development of analytical methods that are capable of simultaneous determination of such important drug mixture. In this study, validated analytical methods have been established for simultaneous quantitation of eplerenone (EPL) and torsemide (TOR). One of the methods represents the first high-performance thin-layer chromatographic (HPTLC) attempt for EPL-TOR simultaneous estimation. A mixture of ethyl acetate -methanol- chloroform (8:2:1, v/v/v) was applied as mobile phase. EPL and TOR were well resolved and scanned at 242 nm (at hRF 77) and 288 nm (at hRF 36), respectively. Other proposed methods include solvent-induced difference, derivative ratio and ratio subtraction (complemented with isosbetstic point) spectrophotometric methods that were adopted as faster, simpler and more economic alternatives for the routine analysis of the increasingly used binary EPL-TOR medication, especially in the developing countries. Both HPTLC and spectrophotometric methods successfully determined both drugs without interference from one another. All methods were validated as per ICH guidelines. In the HPTLC method, calibration plots were linear between 50–600 and 35–800 ng/band for EPL and TOR, respectively. The spectrophotometric methods proved excellent linearity in the range of 3–25 and 3–30 μg/mL for EPL and TOR, respectively. Within all the proposed methods, ratio subtraction spectrophotometric method was the most sensitive one for EPL (LOD = 0.75 μg/mL). Regarding TOR, direct spectrophotometry achieved the lowest LOD (0.71 μg/mL). The high accuracy, simplicity and low cost of the proposed methods recommend their application in the industrial analysis of EPL and TOR combined dosage forms. A full comparison with the reported techniques shows the privileges of the suggested analytical procedures.

Simultaneous Quantification of Diaveridine and Sulfadimidine by Derivative and Ratio Derivative UV Spectroscopy

Derivative spectrophotometry for two sulfa drugs (Diaveridine and sulfadimidine) was carried out for their simultaneous quantification in their binary mixtures. The optimum conditions were studied. The zero crossing wavelengths for Diaveridine (DV) in presence of sulfadimidine (SDM) were 235, 273, 242, 258, 244 nm, 238 and 289, 224 nm for 1st, 2nd, 3rd and 4th derivatives, respectively. The linear range for DV was 2.5-35.0 μg/mL and that for SDM was 1.0-25.0 μg/mL. LODs for DV were 2.32, 2.50, 0.76 and 1.89 μg/mL with LOQs 7.73, 8.33, 2.55 and 6.31 μg/mL for 1st, 2nd, 3rd and 4th derivatives, respectively. LODs for SDM were 3.19, 2.59, 3.22 and 2.29 μg/mL with LOQs of 10.62, 8.63, 10.73 and 7.64 μg/mL for 1st, 2nd, 3rd and 4th derivatives, respectively. Moreover, ratio derivative method (1DD) was used for the quantification of both drugs; ranging from 10.0-25.0 μg/mL for both drugs. 1DD values were measured at 223 and 254 nm, for diaveridine and sulfadimidine, respectively. The obtained results were compared statistically by the Paired t-test and the variance ratio F-test.

Evaluation of the Efficiency of Smart Stability-Indicating Spectrophotometric Methods Based on Mathematical and Statistical Processing of the Obtained Results Via Different Manipulating Pathways

Background: Smart different stability-indicating spectrophotometric methods have been established for the assay of chlordiazepoxide and clidinium bromide without the intervention of alkaline degradate of clidinium via various and different manipulating pathways without previous separation steps. Objective: The specificity of the established methods was inspected by analysing mixtures of cited drugs in the existence of the alkali-induced degradation product. Methods: These methods were employed either on scanned zero-order absorption spectra using absorbance subtraction, dual wavelength and Q-absorbance ratio or the amplitudes of the ratio spectra of zero-order absorption spectra like amplitude modulation and by derivative techniques to the ratio spectra as a derivative ratio method. In addition, the absorbance of the recovered zero-order absorption spectra was applied by successive ratio subtraction coupled with constant multiplication. Finally, the pathway depends on the amplitudes of the derivative spectra, successive derivative subtraction coupled with constant multiplication. The ranges of linearity were (1-12µg/mL) for chlordiazepoxide and (3- 12µg/mL) for clidinium bromide. Results: The outcomes achieved by the prospective methods were in consent with those of the official and reported methods when statistically compared using student’s t test, F-test and one-way ANOVA where no significant difference was detected with suitable precision, proving the absence of any important difference in accuracy and precision between them. They were confirmed in accordance with International Conference on Harmonization guidelines. Conclusion: The established methods can be considered as alternative methods for the routine determination of this fixed dose combination with minimum sample preparation.

Simultaneous determination of Nebivolol hydrochloride and Valsartan in their binary mixture using different validated spectrophotometric methods.

Five simple, sensitive, accurate and precise spectrophotometric methods were developed for the simultaneous determination of Nebivolol hydrochloride (NEB) and Valsartan (VAL) in their binary mixtures and in pharmaceutical dosage form. The methods included Ratio Difference, First Derivative ratio, Mean Centering of ratio spectra, Bivariate and H-Point Standard additions method. The calibration curves were linear over the concentration range of 10-70μg/ml and 20-60μg/ml for NEB and VAL, respectively for Ratio Difference and First Derivative ratio method and over the concentration range of 10-70μg/ml and 10-60μg/ml for NEB and VAL, respectively for Mean Centering of ratio spectra, Bivariate and H-Point Standard additions method. These methods were examined by analyzing synthetic mixtures of the studied drugs and they were utilized to determine the studied drugs in their commercial pharmaceutical preparation. All methods were validated as per ICH guidelines and accuracy, robustness, repeatability and precision were found to be within the acceptable limits. The results of the proposed methods were compared to the results of reported methods with no significant difference between them.

Spectrophotometry analysis for simultaneous determination of the new antiviral drug combination: Daclatasvir/sofosbuvir in their pure form and pharmaceutical preparation

Daclatasvir and Sofosbuvir are recently co-formulated as antiviral combination for treatment of hepatitis C virus (HCV). Several spectrophotometry methods were developed and validated for determination of the partially overlapped spectra of Daclatasvir and Sofosbuvir with simple data manipulation. Daclatasvir can be directly determined at 316.0 nm with in a linear range of 2.5–25.0 μg/mL. Three approaches were applied for determination of Sofosbuvir; the first is using dual wavelength method at which the absorbance difference between 350.0nm and 270.0nm was recorded and absorption subtraction method where the two drugs have an isosbestic point at 272.0nm. The second approach is derivative spectroscopy using first derivative method, Sofosbuvir can be determined at 253.0nm at which Daclatasvir showed a zero crossing point. The third approach is manipulation of ratio spectra using ratio difference method at which the overlapping spectra of Sofosbuvir divided by a divisor from Daclatasvir where the difference in peak amplitude measured at 257.0nm and 228.0 nm. Ratio derivative method was also applied at which the first derivative corresponding to each ratio spectrum was recorded then the amplitude values were measured at 270.0nm. In these methods Sofosbuvir showed linearity in the range of 10.0–80.0 μg/mL. These methods were validated according to ICH guidelines and was successfully applied to pharmaceutical formulation and showed nonsignificant difference when compared to a well established published method.

An Empirical Algorithm using Derivative Difference for Estimating Chlorophyll-A in Case-II Water

Water quality management includes measurement of quantity and quality. The abundance of phytoplankton in water body represents the physical condition and chemical constituents. As Chlorophyll-a exists in all types of phytoplankton, naturally the choice for water quality measurement is estimation of Chl-a concentration. The Chl-a concentration is estimated using various spectral reflectance algorithms such as single band regression, band ratio, three-band ratio, four-band ratio etc have been developed and is being used. Subsequently, the first order derivative ratio and second order derivative ratio methods are also used in some studies. Though such algorithms provide water quality measures, new algorithms are being introduced to improve estimation accuracy. In this paper, a new algorithm ‘Derivative Difference’ is proposed. It is based on the Chlorophyll concentration variation with shape of reflectance spectrum. The derivative data represents the slope of the reflectance data at different wavelength. The difference in derivative values at selected two different wavelengths were correlated with measured values to estimate Chl-a concentration. Obtained results were compared with the values obtained from band ratio method and derivative ratio methods. The algorithm is found to be better in some conditions.

Ratio spectrum derivative quantitative analysis of propranolol and diazipam in combind pharmaceutical mixtures

Two new spectrophotometric methods were developed for the simultaneously estimation of DZP and PRO using the first ratio derivative method (DD1) and the second ratio derivative (DD2). The two methods were succeeded to the estimation of both drugs with a range of concentrations from (5-50 µg.ml-1), depending on Peak to baseline, peak area, peak to peak at specific wavelengths for each compound. The analytical results and of the estimate of The DZP and PRO showed that Rec% values ranged from 95.04-104.97% and 96.30-104.69, and RSD% were between 0.00948-4.87736 % and 0.1163-3.37655%, for the first and second ratio derivative respectively. The method has been successfully applied to the estimation of both PRO and DZP in its pharmaceuticals forms.

Study of efficiency and spectral resolution for mathematical filtration technique using novel unlimited derivative ratio and classical univariate spectrophotometric methods for the multicomponent determination-stability analysis

Six simple, sensitive and selective spectrophotometric methods based on mathematical filtration technique are presented for concurrent determination of aceclofenac (ACE) and paracetamol (PAR) in presence of their degradation products, namely; diclofenac sodium (DIC) and 4-aminophenol (4-AP), respectively without preliminary physical separation procedures. This technique consists of several consecutive steps applied on built-in spectrophotometer software utilizing zero and/or derivative and/or ratio spectra of the studied components. These methods, namely, dual wavelength (DW), induced dual wavelength (IDW), derivative subtraction (DS) coupled with constant multiplication (CM), ratio difference method (RD), constant center method (CC) and the novel introduced unlimited derivative ratio method (UDD). This novel method has a very powerful competence for the analysis of the challengeable mixtures lacking zero crossing point. The linearity, accuracy and precision ranges of these methods were determined and validated as per ICH guidelines. Moreover, the specificity was checked by analyzing synthetic mixtures of both drugs. These methods were applied for the determination of the cited drugs in pharmaceutical formulation and a statistical comparison of the obtained results was made with each other and with those of reported spectrophotometric method. The comparison of the results of pure powder form showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Novel spectrophotometric and factor-based multivariate calibration-prediction techniques for determination of two inhibitors of hepatitis C-virus and hepatocellular carcinoma in pure, human urine, and human plasma.

Novel univariate and multivariate factor-based calibration-prediction techniques were validated for simultaneous ultraviolet spectrophotometric determination of ribavirin (RIV), daclatasvir (DAV), sofosbuvir (SOV), and sorafenib (SON) which are co-administered for treatment of hepatocellular carcinoma (HCC) that results from Hepatitis C-virus (HCV) infection in their commercial products and in biological fluids. Determination of these compounds is essential owing to their pharmacotherapeutic benefits. Due to spectral overlapping of RIV, DAV, SOV, and SON, univariate extended derivative ratio (EDR) method and multivariate partial least-squares (PLS) and principal component regression (PCR) methods were used for constructing the calibration curves. The extended derivative ratio (EDR) absorption maxima at 215 nm and minima at 310.5 nm was used for determination of RIV and DAV, respectively and absorption maxima at 240.3 nm and minima at 284.5 nm for determination of SOV and SON, respectively. The linearity was established over the range of 6-42 μg mL-1, 4-16 μg mL-1, 10-70 μg mL-1, and 3-9 μg mL-1 for RIV, DAV, SOV and SON with correlation coefficient (r2) of 0.9997, 0.9997, 0.9999 and 0.9997, respectively. This method was effectively applied to pure, pharmaceutical preparations and to spiked human urine and plasma. PLS and PCR models were established for the determination of the studied drugs in the range of 6-42, 4-16, 10-70 and 3-9 μg mL-1 for RIV, DAV, SOV, and SON, respectively. Furthermore, updating the PLS model (PLS model update) were allowed for the determination of these drugs in spiked human urine, plasma and drug-dissolution test of their tablets. The obtained results were compared to official and reported method showing that there were no significant differences. The results of applying PLS and PCR models for evaluation of RIV, DAV, SOV, and SON in human urine samples as real samples were also encouraging. It is expected that the suitable features of the proposed method make it helpful for biological and clinical applications.

UV-ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF DAPOXETINE HYDROCHLORIDE AND SILDENAFIL CITRATE IN TABLET DOSAGE FORM

Objective: The objective of this research was to develop and validate a simple ultraviolet (UV) spectrophotometric method for simultaneous determination of sildenafil citrate and dapoxetine hydrochloride in a pharmaceutical formulation.Methods: Two simple UV spectrophotometric methods have been developed for simultaneous determination of sildenafil citrate and dapoxetine hydrochloride. For both methods, stock solutions were prepared in methanol followed by the further required dilutions with methanol. Proposed dual-wavelength method and ratio derivative method, the wavelength of maximum absorption for sildenafil citrate and dapoxetine hydrochloride was 292 nm and 231 nm, respectively.Results: In both methods, the linearity range lies between 10 and 60 μg/ml for sildenafil citrate and 2–12 μg/mL for dapoxetine hydrochloride with their respective wavelengths. By dual-wavelength method, the percentage of sildenafil citrate and dapoxetine hydrochloride was found to be 101.3% and 100.3%, respectively.Conclusion: Result obtained in this research work clearly indicated that both these methods were found to be accurate, precise, stable, and robust as indicated by low values of percentage relative standard deviation. Thus, the present study gives an excellent method for the determination of both the drugs in combined tablet formulation.

UV-ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR SIMULTANEOUS ESTIMATION OF DAPOXETINE HYDROCHLORIDE AND SILDENAFIL CITRATE IN TABLET DOSAGE FORM

Objective: The objective of this research was to develop and validate a simple ultraviolet (UV) spectrophotometric method for simultaneous determination of sildenafil citrate and dapoxetine hydrochloride in a pharmaceutical formulation.Methods: Two simple UV spectrophotometric methods have been developed for simultaneous determination of sildenafil citrate and dapoxetine hydrochloride. For both methods, stock solutions were prepared in methanol followed by the further required dilutions with methanol. Proposed dual-wavelength method and ratio derivative method, the wavelength of maximum absorption for sildenafil citrate and dapoxetine hydrochloride was 292 nm and 231 nm, respectively.Results: In both methods, the linearity range lies between 10 and 60 μg/ml for sildenafil citrate and 2–12 μg/mL for dapoxetine hydrochloride with their respective wavelengths. By dual-wavelength method, the percentage of sildenafil citrate and dapoxetine hydrochloride was found to be 101.3% and 100.3%, respectively.Conclusion: Result obtained in this research work clearly indicated that both these methods were found to be accurate, precise, stable, and robust as indicated by low values of percentage relative standard deviation. Thus, the present study gives an excellent method for the determination of both the drugs in combined tablet formulation.

Development and Validation of Spectrophotometric Methods for the Determination of Amoxicillin trihydrate and Dicloxacillin sodium in Their Binary Mixture

Three sensitive and cost-effective spectrophotometric methods are introduced for the determination of amoxicillin and dicloxacillin in their binary mixtures with minimum sample pretreatment, with or without the presence of their common impurity; 6-aminopenicillanic acid (6-APA). In this work, dicloxacillin is determined by dual wavelength, derivative ratio and isoabsorptive spectrophotometric methods. However, amoxicillin is determined by direct UV spectrophotometry at 273.6 nm and by the first derivative ratio spectrophotometric method (DD method). For method (A); the dual wavelength method, the wavelengths selected for the determination of dicloxacillin were 223.6 and 237 nm. Method (B); the isoabsorptive spectrophotometric method, comprises measuring the total content of the mixture at their isoabsorptive point (230.4 nm), and then the content of dicloxacillin can be calculated by subtraction. Method (C) is the first derivative of ratio spectra for the determination of amoxicillin (using 8 μg/mL of dicloxacillin as a divisor at 231 nm) and dicloxacillin (using 20 μg/mL of 6-APA as a divisor at 234.6 nm) in presence of their common impurity; 6-APA. Statistical comparison of the results obtained from the suggested methods with those of the reported HPLC method showed no significant difference with respect to accuracy and precision. The developed methods can be used for quality control analysis of the studied drugs in laboratories lacking HPLC qualifications.Kay words: Amoxicillin, Dicloxacillin, Dual wavelength, Isoabsorptive point, First derivative ratio

Two Derivative Spectrophotometric Methods for the Simultaneous Determination of 4-AminoAntipyrine in Presence of Its Acidic Products

Simple, economic and sensitive mathematical spectrophotometric methods were developed for the estimation 4-aminoantipyrine in presence of its acidic product. The estimation of binary mixture 4-aminoantipyrine and its acidic product was achieved by first derivative and second derivative spectrophotometric methods by applying zero-crossing at (valley 255.9nm and 234.5nm) for 4-aminoantipyrine and (peak 243.3 nm and 227.3nm) for acidic product. The value of coefficient of determination for the liner graphs were not less than 0.996 and the recovery percentage were found to be in the range from 96.555 to 102.160. Normal ratio spectrophotometric method 0DD was used 50 mg/l acidic product as a divisor and then measured at 299.9 nm with correlation coefficient 0.998 and limit of detection 0.04098. ratio derivative methods 1DD and 2DD; are based on measuring the first derivative and second derivative for normal ratio spectrum at (peak 290.7 nm and valley 310 nm) for 1DD and (peak 286, valley 301 and peak 316nm) for 2DD the correlation coefficient for linearity graph not less than 0.997 and the recovery percentage were found to be in the range from 99.64 to 100.11.