Absorbance Ratio Method Research Articles

Spline-based Abel Transform (SAT) radial property reconstruction for noise and trapping correction: Application to axisymmetric sooting flames

In combustion research, optical diagnostics often necessitate Abel inversion to deconvolve the measurements of axisymmetric flames, especially to determine local soot temperature fields from integrated flame radiative emission measurements. However, traditional Abel inversion methods can considerably amplify experimental noise, especially towards the flame centerline. Although various strategies exist to mitigate this issue, they typically do not address the correction of signal trapping within the flame. The present paper introduces an adapted Abel inversion tool that combines resistance to experimental noise with a mechanism to correct signal trapping effects. The tool employs noise-free Abel inversion using piecewise spline functions. Its effectiveness is validated through numerical comparisons with conventional methods. The practical application is demonstrated in the measurement of soot temperature in a canonical laminar diffusion ethylene flame. This is achieved by using multi-wavelength line-of-sight attenuation (LOSA) and emission measurements. The tool corrects for the signal trapping effect in emission data by integrating extinction profiles, thus enabling a more precise soot temperature analysis. The current study also compares two techniques of temperature measurement based on thermal emission: traditional two-color pyrometry and a calibrated emission and absorption ratio method. The study further explores the effects of signal trapping, scattering contribution, and the absorption function ratio on soot temperature determination based on experimental profiles. The findings suggest that signal trapping and scattering contributions have a negligible impact on measurements at the wavelengths examined. However, the choice of absorption function ratio significantly influences the outcomes of two-color pyrometry, highlighting the advantage of the one color emission/absorption technique for the determination of sooting flames temperature measurements.

UV- Spectrophotometric technique- based method development and validation for simultaneous estimation of Ciprofloxacin HCl and Quercetin in bulk powder

Antibiotic resistance is increasing worldwide, especially among ocular pathogens and one of the major reasons for this severity is the formation of biofilm which causes antibacterial specialists like Ciprofloxacin HCl to be ineffective, but combining it with substances that inhibit quorum sensing, a process that leads towards the development of biofilm, such as Quercetin, in a single formulation is an effective way to treat these infections. Aiming to develop and approve a new analytical method for the simultaneous evaluation of ciprofloxacin HCl and quercetin in their mass powder, the current examination is expected to accomplish this. Two strategies—the simultaneous equation approach (I) and the absorbance ratio method (II)—were created and validated in accordance with ICH guidelines for specificity, selectivity, linearity, precision, and accuracy. Quercetin's and Ciprofloxacin HCl's absorbance maxima (λmax) were determined to be at 327 nm and 271 nm, respectively, with coefficient correlation values of 0.999 and 0.997. Their isosbestic point was noticed at a maximum wavelength of 283 nm. Both Ciprofloxacin HCl and Quercetin demonstrated linearity in the focus range from 1 µg/ml to 10 µg/ml when absorbances were measured at any of the aforementioned levels. It was discovered that the developed processes were exact and precise with less than 2% relative standard deviation (%RSD). %Recovery studies were found to be 98.62-101.15% for Ciprofloxacin HCl at 271nm, 99.34-100.94% for Quercetin at 327nm, 99.63-104.62%, and 101.23-102.64% for Ciprofloxacin HCl and Quercetin respectively at their isosbestic point. Because it was discovered to be simple, rapid, specific, selective, linear, exact, and based on absorptivity measurements, the established UV Spectrophotometric technique can be used for in vitro depiction and contemporaneous assessment of Ciprofloxacin HCl and Quercetin.

Simultaneous Analysis of Ezetimibe and Rosuvastatin by Q absorption Ratio Method

A Novel UV spectrophotometric method has been developed for the simultaneous estimation of ezetimibe and rosuvastatin based on Q absorption ratio method. The wavelengths of 234.8nm (lsosbestic point) and 242nm (λmax of rosuvastatin) were chosen as analytical wavelengths. The linearity was established in concentration range 2-40µg/mL for ezetimibe and rosuvastatin with correlation coefficient greater than 0.990. Analytical method validation was performed by following ICH guidelines. The % assay for ezetimibe and rosuvastatin in tablet formulation complied with acceptance criteria. The developed method thus can be used as a powerful quality control tool for simultaneous analysis of the drugs in bulk and in formulation by UV spectroscopy.

Simultaneous Determination of Luliconazole and Salicylic Acid by Simultaneous Equation Method and Absorbance Ratio Method

The simultaneous determination of Luliconazole and Salicylic Acid in pharmaceutical formulations holds significant importance for ensuring therapeutic efficacy and patient safety. This research focuses on developing an accurate and efficient method using UV-Visible spectrophotometry, specifically the Simultaneous Equation Method (SEM) and Absorbance Ratio Method (ARM), to quantify these active ingredients in topical creams. The study begins with the preparation of stock solutions and selection of the analytical wavelength, with 298 nm chosen in reference to the isobestic point at 230 nm. Cream samples containing 10 mg Luliconazole and 30 mg Salicylic Acid are prepared, sonicated, and filtered for analysis. The UV method is validated in accordance with ICH guidelines, encompassing linearity, precision, LOD, LOQ, specificity, robustness, and accuracy. Calibration curves show excellent linearity within the concentration range of 5-30 µg/ml for both compounds. Intra-day and inter-day precision studies exhibit low % RSD values, indicating the reliability and reproducibility of the method. LOD and LOQ values demonstrate the sensitivity of the method, enabling detection and quantification at trace levels. Specificity is confirmed through overlay spectra and comparisons of analyte responses. Robustness is assessed by varying temperature and concentration, demonstrating the method's resilience to minor changes. Accuracy is evaluated through the standard addition method, yielding recoveries within acceptable limits. The proposed UV method is successfully applied to the analysis of Luliconazole and Salicylic Acid in commercial cream samples, with assay results confirming its accuracy and suitability for routine quality control.

Simultaneous Analysis of Cilnidipine and Nebivolol by Absorbance Correction Method and Q Absorption Ratio Method

Two novel UV spectrophotometric methods have been developed for the simultaneous estimation of cilnidipine (CIL) and nebivolol hydrochloride (NBV) in combined dosage form. Method I was based on absorbance correction principle while method II was Q absorption ratio method. For absorbance correction method, λmax of CIL 242.6nm was chosen as λ1, as NBV shows nil absorbance at this wavelength and 280.6nm, the λmaxof NBV was chosen as λ2 , as both the drugs showed satisfactory absorbance at this wavelength. Beer’s law was obeyed in the concentration range of 4-48μg/mL and 4-100μg/mL for cilnidipine and nebivolol hydrochloride respectively with correlation coefficients (r2) greater than 0.990. For Q absorption ratio method, 275nm (Isosbestic point) and 280.6nm (λmax of NBV) were chosen as the two wavelengths for analysis. Beer’s law was obeyed in the concentration range of 4-48μg/mL and 4-100μg/mL for cilnidipine and nebivolol hydrochloride, respectively with correlation coefficients (r2) greater than 0.990. The developed methods were validated as per ICH guidelines. The % assays of cilnidipine and nebivolol hydrochloride in tablet dosage form were found to be 97% and 102%, respectively by absorbance correction method and 95% and 105% by Q absorption ratio method, which were within acceptance limits. The developed methods can thus serve as powerful quality control tools for simultaneous determination of cilnidipine and nebivolol hydrochloride in bulk and in combined dosage form.

Simultenious Estimation of Sodium Benzoate and Caffeine in Soft Drinks by UV Spectroscopy

A simple spectrophotometric methods have been developed for the simultaneous estimation of sodium benzoate and caffeine from the food products Method-I simultaneous equation method involves the measurement of absorbance at two wavelengths 224nm (λ max of sodium benzoate) and 274nm (λ max of caffeine) using Water as diluent. Method – II Absorption ratio method involves the measurement of absorbance at two wavelengths 274nm (λ max of caffeine) and 241nm (λ max of Isobestic point). The method was validated as per ICH guideline rules in terms of accuracy (recovery study), precision, ruggedness, robustness and the validation parameters were within acceptable limits. The percentage recovery at various concentration levels varied from 99.5 to 100.6% for sodium benzoate and 99.3 to 98.3% for caffeine. Two popular soft drink brands were purchased from supermarket and evaluated for sodium benzoate and caffeine by simultaneous equation method and Q-absorption ratio method. The amount of sodium benzoate and caffeine found in sample 1is 150µg/ml and139µg/ml and in sample 2 is 179µg/ml and 190µg/ml respectively.

Simultaneous Equation, Absorbance Ratio and First Order Derivative Methods for the Estimation of Atorvastatin Calcium and Fenofibrate in Solid Dosage Form

Simultaneous Equation, Absorbance Ratio and First Order Derivative Methods for the Estimation of Atorvastatin Calcium and Fenofibrate in Solid Dosage Form

Chemometric Methods for Simultaneous Determination of Candesartan Cilexetil and Hydrochlorothiazide in Binary Combinations.

Simple, accurate, precise, and cost-effective chemometric techniques for the measurement of candesartan cilexetil and hydrochlorothiazide in synthetic mixtures were improved and validated. H-point standard addition, Q-absorption ratio, and correction absorbance spectrophotometric techniques were utilized for the simultaneous determination of both medicines in real pharmaceutical formulations. A new calibration approach was implemented based on chemical H-point standards. This approach was developed to resolve significantly overlapping spectra of two analytes and provide direct correction of both proportional and constant errors caused by the matrix of the sample. The first method of simultaneous determination of candesartan cilexetil and hydrochlorothiazide was carried out using the H-point standard addition method at wavelengths 239 and 283. For the ratio of the absorption at two selected wavelengths, one of which is the isoabsorptive point and the other being the maximum of one of the two components, the second method absorption ratio method was utilized. In distilled water, the isoabsorptive point of candesartan cilexetil and hydrochlorothiazide occurs at 258 nm. λ max of hydrochlorothiazide is 273 nm, which is the second wavelength used. Lastly, the absorbance correction method was implemented. This approach is based on absorbance correction equations and uses distilled water as the solvent for the examination of both medicines. In NaOH/EtOH solvent, the absorbance maxima of candesartan cilexetil and hydrochlorothiazide are 250 nm and 340 nm, respectively. For both wavelengths, candesartan cilexetil and hydrochlorothiazide exhibited linearity over a concentration range of 1-46 μg/ml and 1-44 μg/ml, respectively, for H-point standard addition. The Q-absorption ratio approach provides linearity over the concentration ranges of 1-46 μg/ml at 273 nm for candesartan cilexetil and 1-29 μg/ml for hydrochlorothiazide, 1-46 μg/ml at 258 nm for candesartan cilexetil, and 1-44 μg/ml for hydrochlorothiazide. For hydrochlorothiazide, the linearity for the correction absorbance method was obtained throughout a concentration range of 1-46 μg/ml at wavelengths 250 and 340 nm and 1-44 μg/ml at wavelength 250 nm. The results of the analysis have been statistically and empirically supported by recovery studies. All methods yielded recoveries in the range of 96 -102% for both medications. The LOD ranged from 0.46 -0.94 μg/mL for hydrochlorothiazide and from 1.26 -2.40 μg/mL for candesartan cilexetil. The approaches were then used to quantify candesartan cilexetil and hydrochlorothiazide in pharmaceutical tablets.

Development and Validation of UV Absorbance Ratio Method for the Simultaneous Estimation of Nebivolol and Valsartan in Bulk Drugs and Pharmaceutical Dosage Form

A simple, robust, precise, UV spectroscopic method has been developed for the simultaneous estimation of Nebivolol and Valsartan in bulk and tablet dosage forms. In this paper the estimation of those drugs was carried out by simultaneous equation method. This method is based on measurement of absorption at 281nm and 251nm i.e, λmax of Nebivolol and Valsartan respectively. The linearity observed for Nebivolol is in the range of 5-25 μg/ml and for Valsartan is in the range of 5-80 μg/ml. The accuracy of methods was assessed by recovery studies and was found to be within the range of 99.28%-99.26% for both Nebivolol and Valsartan. The developed methods were validated with respect to linearity, accuracy (recovery), and precision. The method can be employed for estimation of pharmaceutical formulations with no interference from any other excipients and diluents. The results were validated as per ICH guidelines.

A brief Review on Q-absorption Ratio Method in UV-Spectrophotometry

This present work carries a brief review on Q-Absorption ratio method in UV-spectrophotometry. Absorption ratio method is used for the ratio of the absorption at two selected wavelengths one of which is iso-absorptive point and other being the λmax of one of the two components. The aim of this article is to give brief idea about various method developed using Q-Absorption ratio methodon combined dosage forms. It shows selection of wavelength, linearity study and choosing solvent for give combine dosage form. This study also gives brief idea about practical and industrial application of Q-Absorption ratio method.

Development and Validation of Simultaneous Estimation of Canagliflozin and Metformin by Q Absorbance Ratio Method in its API and Tablet Formulation

A simple, precise and sensitive UV spectrophotometric method has been developed for the estimation of Canagliflozin and metformin in bulk and pharmaceutical dosage Form by Q Absorbance ratio method. Absorbance uses the ratio of absorbance at two selected wavelengths, one which is an iso absorptive point and other is the λmax of one of the two components. From the overlay spectra of two drugs, it is evident that Canagliflozin and Metformin show an isoabsorptive point at 260nm. The second wavelength used is 235nm which is λmax of Meformin HCl. Beer’s law was obeyed in range of 2-10µg/ml for both Canagliflozin and Metformin HCl. The correlation coefficient was found to be nearer to 0.9990 at both the wavelength for Canagliflozin and Metformin HCl. The result of interday and intraday precision shows standard deviation less than 2% for three concentration and three replicates. The accuracy found to be between 98% - 102%. The LOD and LOQ were found to be within the Linearity Range. The purposed method was novel and can apply for the determination of Canagliflozin and Metformin HCl in Tablet Dosage Form. The method was successfully validated as per the ICH guidelines.

Simultaneous Estimation of Luliconozole and Methyl Paraben in Pharmaceutical Formulation by UV Spectroscopy using Absorption Ratio Method

For the simultaneous quantification of luliconazole (LUZU) and methyl paraben (MP) in formulation, a straightforward, precise UV spectrophotometric approach was developed and validated. The method was developed using absorbance ratio method. For luliconazole and methyl paraben, the absorbance was measured at 297 nm and 274 nm, respectively. The method was discovered to be linear, sensitive, exact and accurate. ICH guidelines were followed in developing the procedure. Keywords: Q- absorbance ratio method, methyl paraben, luliconazole, and UV spectrophotometric method.

Two methods for determination of a binary mixture of Amlodipine besylate and Atorvastatin calcium using dual-wavelength spectrophotometry

Two simple, clear, and accurate spectrophotometric methods based on two-wavelength selections, were developed for the simultaneous determination of Amlodipine besylate (AML) and Atorvastatin calcium (ATO) in tablet dosage forms. The ratio difference method uses amplitudes between 238 and 288 nm. The measured amplitudes for the parameters: linear range 4-40 μg/ml; precision for AML is 100.22±0.7856, repeatability is 0.9122, precision for ATO is 100.12±0.6439, repeatability is 0.8968. The absorption ratio method using two wavelengths is 221 and 238 nm. The absorption rate method for parameters: linear range 4-40 μg/ml; precision for AML is 100.6±0.9562, repeatability is 1.0124, precision for ATO is 100.86±0.8596, repeatability is 1.1045. Both quantitative methods showed that AML and ATO could be quantified in their mixtures without any extraction at all. The absorption ratio method exhibited quick, simple applicability to both laboratory and commercial drug mixtures.

Simultaneous Estimation of Metformin and Teneligliptin in Pharmaceutical Formulation by Using UV Spectroscopy

Three new UV spectrophotometric methods namely simultaneous equation, absorbance ratio and dual wavelength methods were developed and validated for simultaneous estimation of Metformin and Teneligliptin in bulk drug and tablet formulation which were simple, rapid, sensitive, precise and accurate. In simultaneous equation method, absorbance was measured at 233nm for Metformin and 241nm for Teneligliptin. In absorbance ratio method, absorbance was measured at 244nm for Metformin and 233nm for Teneligliptin. In dual wavelength method, two wavelengths were selected for each drug, the absorbances was measured at 225 and 251nm for Metformin and 240 and 221nm for Teneligliptin. Developed methods were validated according to ICH guidelines including parameters viz., specificity, linearity and range, precision, accuracy, limit of detection and limit of quantification. All the three methods showed linear response in the concentration range of 2-10µg/mL for Metformin and 0.5-2.5µg/mL for Teneligliptin with a low correlation coefficient. Results of method validation parameters follows ICH guideline acceptable limits. Methods were found to be simple, rapid, sensitive, economical and hence can be useful for simultaneous estimation of Metformin and Teneligliptin in pure drug and commercial tablet formulation for routine quality control analysis.

Simultaneous Estimation of Sacubitril and Valsartan Combination of Drug in Tablet Dosage Form Using Hydrotropy by UV Spectrophotometry

Sacubitril/valsartan, traded under the brand name Entresto between others, is a fixed-dose combination medication for use heart failure. Sacubitril is a neprilysin inhibitor (A prodrug) and is used in combination with valsartan to reduce the risk of cardiovascular events in patients with chronic heart failure. It is anti - hypertensive drug. Valsartan is an Angiotensin Receptor Blocker (ARB) that may be used to treat a variety of cardiac conditions including hypertension, diabetic nephropathy and heart failure. Two UV-spectrophotometric methods have been developed and validated for simultaneous estimation of Sacubitril and Valsartan in a tablet dosage form. The first method employed solving of simultaneous equations based on the measurement of absorbance at two wavelengths, 226.0 nm and 254.0 nm, 𝜆max for Sacubitril and Valsartan, respectively. The second method was absorbance ratio method, which involves formation of Q-absorbance equation at 240 nm (isoabsorptive point) and also at 254 nm (𝜆max of Valsartan). The methods were found to be linear between the range of 4-12 𝜇g/mL for Sacubitril and 2-10 𝜇g/mL for Valsartan using Methanol as solvent. The mean percentage recovery was found to be 96.68%and 101.89% for the simultaneous equation method and 100.2% and 104.53% for the absorbance ratio method, for sacubitril and valsartan respectively. It could be concluded from the results obtained in the present investigation that the two methods for simultaneous estimation of sacubitril and valsartan in tablet dosage form are simple, rapid, accurate, precise and economical and can be used, successfully, in the quality control of pharmaceutical formulations and other routine laboratory analysis. The reviewed highlights various analytical techniques such as high-performance liquid chromatography (HPLC), ultra- performance liquid chromatography (UPLC), UV Spectroscopy, high per-formance thin layer chromatography (HPTLC), liquid chromatography coupled to tandem mass spectrometry (LC- MS), RP-HPLC and other chromatographic method used. The combination of these drugs with different method was examine and the commonly use of the drugs in hypertensive.

Validated Spectrophotometric Methods for Simultaneous Determination of Atorvastatin Calcium and Olmesartan Medoxomil in Their Pharmaceutical Formulation.

Few spectrophotometric methods have been developed for the simultaneous determination of atorvastatin calcium (ATO) and olmesartan medoxomil (OLM). This work aimed to develop and validate five simple spectrophotometric methods for the simultaneous estimation of ATO and OLM in their tablet form. Method I applied the area under curve (AUC) based on the measurement of areas between 241 and 261 nm for ATO, and 248 and 263 nm for OLM. Method II applied second derivative spectrophotometry where the analytical amplitudes at 246.5 and 235 nm were chosen for the estimation of ATO and OLM, respectively. Method III applied the ratio difference (RD) method based on the measurement of amplitude difference (ΔP) within ratio spectra; ΔP (240-260 nm) was directly related to ATO concentration, and ΔP (262-240 nm) was directly related to OLM concentration. Method IV depended on the absorbance ratio method in which the wavelength at the iso-absorptive point (λISP) and the maximum absorbance wavelength (λmax), 277 and 255.5 nm, respectively, were used to calculate OLM concentration, while ATO concentration was determined from the zero-order UV spectra at 300 nm. Method V utilized a dual wavelength (DW) technique where ΔA between 247.5 and 262 nm was directly related to ATO concentration, and ΔA between 216 and 238 nm was directly related to OLM concentration. The results of the assays indicated good mean % recovery ± SD as well as good agreement with the reported method. Five simple and rapid spectrophotometric methods were developed, validated, and successfully applied for simultaneous estimation of ATO and OLM tablets. None of the developed methods has previously been reported for simultaneous determination of ATO and OLM.

Q-ABSORBANCE RATIO, DERIVATIVE SPECTROPHOTOMETRIC AND H-POINT STANDARD ADDITION METHODS FOR SIMULTANEOUS DETERMINATION OF PRIDINOL MESYLATE, AND DICLOFENAC SODIUM IN PHARMACEUTICAL FORMULATION.

     Three methods for simultaneous estimation of diclofenac sodium and pridinol mesylate have been developed. First method is the application of the Q–analysis (absorbance ratio) method, the wavelengths selected were 265nm (isosbestic point) and 285nm (λmax of diclofenac sodium) with 258nm (λmax of pridinol mesylate). The linearity ranges for diclofenac sodium and pridinol mesylate were 8-64 μg/ml and 14-56 μg/ml, respectively. The second technique is based on the second derivative spectrophotometric method at zero crossing wavelengths. The linearity ranges for diclofenac sodium and pridinol mesylate were (4.0-40.0) μg/ml and (4.0-30.0) μg/ml, respectively. The third method is the H-Point Standard addition method (HPSAM) depending upon the zero and second-order derivative signals for diclofenac sodium and pridinol mesylate were applied pairs of wavelengths, 250.37and 266.34 nm; with 224.18 and 235.10 nm, respectively.

Assessment of Aliskiren Hemifumarate and Amlodipine Besylate in combined Tablet Dosage form by Three Simple UV Spectrophotometric Methods

Background: For a cardiovascular patient's blood pressure to be effectively controlled, more than one drug is required. When coupled with amlodipine besylate (AMLO), a calcium channel blocker, Aliskiren hemifumarate (ALI) is the 1st nonpeptide, low molecular mass, orally active transition state rennin inhibitor to efficaciously normalize blood pressure and cardiac ailments.
 Objective: Three innovative, easy, sensitive, exact, and accurate UV spectrophotometric approaches, including simultaneous equation method (SEM), absorbance ratio method (ARM) and 1st derivative (zero-crossing) spectroscopic approach (FDR), were created and authenticated by validation for synchronized estimation of ALI and AMLO in tablet formulation.
 Materials and Methods: The SEM was used to measure the absorbance of both medicines at 237 and 280 nm. ALI and AMLO were calculated using 237 and 271 nm, respectively, in the ARM. ALI and AMLO, on the other hand, used the FDR technique to transform UV spectra to first derivative spectra, with the first derivative signal captured at 237 and 254 nm, respectively. The wavelength interval (Δλ) was kept at 2 and the scaling factor was kept at 1 when transforming zero-order spectra using the first derivative approach. Validation of the proposed processes was done in compliance with the “International Conference on Harmonization” (ICH) recommendations. Results: SEM and ARM both showed a linear outcome in the range of 1-50 µg/ml for ALI and AMLO. FDR, on the other hand, was shown to be more sensitive and linear between 0.5 and 50 µg/ml for both medications. The results of the method validation parameters were within the allowed ranges of the ICH guidelines.
 Conclusion: The proposed procedures were shown to be relatively quick, sensitive, simple, and cost-effective, and can thus be used for scheduled quality control analysis of ALI and AMLO in the mixed tablet.

Q-Absorbance Ratio Spectrophotometric Method for the Simultaneous Estimation of Metformin Hydrochloride and Voglibose in Tablet Dosage form

A new, simple, accurate, precise and reproducible UV-Spectrophotometric method is being developed for the simultaneous estimation of Metformin Hydrochloride and Voglibose in tablet dosage form. The stock solutions were prepared in methanol. The λmax for Metformin Hydrochloride and Voglibose were found to be248 nm and 287nm respectively. The Metformin Hydrochloride and Voglibose obeyed Beer’s law in concentration range of 8-16µg/ml and 4-20µg/ml respectively. Results of analysis of absorbance ratio method were analysed and validated for various parameters according to ICH guidelines for accuracy, precision, linearity, robustness, LOD and LOQ. The proposed method is highly sensitive, precise and accurate, therefore can be used for intended purpose.

A VALIDATED STABILITY INDICATING UV-SPECTROPHOTOMETRIC SIMULTANEOUS ESTIMATION OF ROSUVASTATIN CALCIUM AND FENOFIBRATE IN BULK AND PHARMACEUTICAL FORMULATION

Objective: The present work deals with the development and validation of the absorbance ratio method for the estimation of rosuvastatin calcium and fenofibrate in bulk and pharmaceutical formulation. Studied forced degradation characteristics of bulk and pharmaceutical formulation as per stability guidelines. Methods: The bulk and pharmaceutical formulation studied by the absorbance ratio method. It is the ratio of absorbances at two selected wavelengths. One wavelength is the isoabsorptive point and another wavelength is λ max of one of the components. From the overlay spectra of the two drugs, ROS and FEN showed the isoabsorptive point at 249.5 nm. The second wavelength used was 287 nm, which was the λ max of FEN. Results: The drugs obeyed Beer's law and showed a good correlation. The correlation coefficient for the ROS was 0.999 and for FEN 0.999. The RSD for intraday precision was 0.57 for ROS and 0.057 for FEN. The interday precision was 0.05 for ROS and 0.03for FEN, respectively. The detection limit and quantification limit were found to be 0.048 and 0.14 μg/ml for ROS and 0.069 and 0.21μg/ml for FEN, respectively. More degradation was found in acid hydrolysis and photostability degradation. Conclusion: A simple, precise, accurate, validated, stability-indicating method for simultaneous estimation of rosuvastatin calcium and fenofibrate in bulk and pharmaceutical formulation has been developed.