Visible Spectrophotometric Methods for the Estimation of Ramipril in Single Component Pharmaceutical Formulations


Dashrathe G S *, Karajgi S R, Phadatare A T, Kalyane N V

Dept. of Pharmaceutical chemistry,  B.L.D.E.A.’S College of Pharmacy, Bijapur.

*Corresponding Author E-mail:



Two simple new visible spectrophotometric methods have been developed for determination of Ramipril, in single component pharmaceutical dosage forms. The methods were based on the formation of ion-pair complexes of the drug with dye Bromocresol Green (BCG) and Bromo Cresol purple (BCP), in acidic buffer solutions followed by their extraction in chloroform. Experiments were carried out to optimize the reaction conditions for complete colour formation. It was found that 5 ml BCG and BCP reagents and 5 ml of buffer solutions were optimum for the achievement of maximum colour intensity. BCG with Acid phthalate buffer of pH3 gave more absorbance at 415 nm this process was optimized (with BCP 405nm)The optical charactersic such as beer’s law, correlation coefficient, slope, Y intercept, and Molar absorptivity were calculated for all the methods and the analysis results of marketed formulations were in good agreement with their labeled claim. The recovery ranged from between 98 to 100 % for BCG and BCP which comply with official limits. The proposed methods were simple, sensitive, accurate and precise and can be successfully applied for the estimation of Ramipril. Results of the method were validated statistically and by recovery studies, this method was demonstrated to be adequate for routine analysis.


KEYWORDS: Ramipril, Bromocreol Green, Bromocresol Purple Visible Spectrophotometry.




Ramipril is a long-acting angiotensin-converting enzyme inhibitor and it is used in case of hypertension. It is described chemically as (2S,3aS,6aS)-1-[(2S)-2-[[(2S)-1-ethoxy-1-oxo-4phenylbutan-2-yl]amino]propanoyl]-3,3a,4,5,6,6a-hexahydro-2H-cyclopenta[d]pyrrole-2 carboxylic acid. Empirical formula is C23H32N2O5. Ramipril is official in I.P1. Literature survey reveals that a few spectrophotometric2-5, HPLC6, methods as alone or in combination with other drugs were reported for its analytical monitoring in formulation. Structural formula of Ramipril is given in fig. 1.



Materials and Methods:


Standerd drug Ramipril                       Bromocresol Green

Bromocresol purple                             Methanol (AR grade)

Chloroform (AR grade)                       double distilled water


Fig-1: Structural formula Ramipril



Elico double beam U.V. spectrophotometer with 1 cm matched quartz cells. All reagents used were of analytical grade. Following reagents and solutions were used.

1.        Preparation of buffer: pH 3 buffer solution was prepared as per IP by mixing appropriate quantities of 0.2 M potassium hydrogen phthalate.

Table-I: Optical Characteristics and Other Parameters



With BCG

With BCP

λmax (nm)



Beer’s Law limits (mcg/ml)



Molar absorptivity

31819.56 mol-1cm-1


Standard deviation



Coefficient of variation (%)




Table-II: Results of the Estimation of Ramipril In Tablets




Bromocresol Green

Bromocresol Purple


Claim (mg/cap)

Amount of pure drug added (mg)

Content Determined in Assay (mg)

% recovery

Content determined in Assay (mg)

% recovery










2.        Bromocresol Green Solution: 0.05% solution was prepared by dissolving 50mg bromocresol Green in 0.92 ml of 0.1 M NaOH and 20 ml of alcohol (95%) and made up to 100ml with methanol.

3.        Bromocresol Purple Solution: 0.05% solution was prepared by dissolving 50mg bromocresol Purple in 0.92 ml of 0.1 M NaOH and 20 ml of alcohol (95%) and made up to 100ml with methanol.

4.        Standard drug solutions

A. A stock solution of drug is prepared by dissolving accurately weighed 50 mg of pure Ramipril in 50 ml of methanol. So as to give the stock solution A of concentration 1 mg/ml.

B. 5 ml of stock solution-A was pipetted in to a 50 ml volumetric flask. And was diluted to 50 ml with methanol to give stock solution–B. of concentration 100 mcg/ml.

C. Sample solution (capsule): Twenty capsules were taken and average weight was calculated. Capsule powder equivalent to 100 mg of drug was weighed accurately and transferred to 100 ml volumetric flask. Methanol was added to the flask and the contents were shaken well for 10 minute and the volume was made up with methanol. This was filtered; rejecting the first few ml of filtrate, 5 ml of the filtrate was pipetted into 50 ml flask and was diluted to the mark. From this 5 ml was pipette into 25 ml flask, 5 ml of the reagent, 5 ml of buffer was added and the volume made up with chloroform.



Method I (Using Bromocresol Green):

From solution–B 2.5, 5, 7.5, 10, 12.5, 15 ml was pipetted in to 6 separate separating funnel, and 20 ml of chloroform, 5 ml of buffer and 5 ml of BCG (bromo cresol Green) were added. The contents were shaken for two minutes and the two phases were allowed to separate. The lower chloroform layer was collected in separate 50ml  volumetric flasks. The aqueous phase was further extracted two times with 10 ml portions of chloroform. The chloroform layer was combined and the volume was made up with chloroform so the concentration of the drug would be 5, 10, 15, 20, 25, 30, mcg/ml. the absorbance was measured at 415 nm against blank solution obtained in the same way omitting the drug. The amount of Ramipril present in the sample was computed from the calibration curve results are reported in tables I and II.


Method II (Using Bromocresol Purple)

Same procedure was followed by using BCP instead of BCG. The absorbance was measured at 405 nm against blank solution obtained in the same way omitting the drug The amount of Ramipril present in the capsule dosage form was computed from the calibration curve. The results are shown in tables I and II.



The proposed methods are colorimetric methods for determination of Ramipril from bulk powder and marketed formulations. These methods are very simple, accurate, and sensitive and give reproducible results. Proposed methods can be used for determination of Ramipril in bulk powder and formulations in a routine manner.



The proposed methods are simple, sensitive, accurate and economical for the routine estimation of Ramipril in bulk and in its tablet dosage form.



The authors wish to thanks Dr.Navnath Kalyane, Principal of B.L.D.E.A’S College of Pharmacy for providing laboratory facilities and Shreya life sciences, Aurangabad for providing Ramipril as gift sample.



1.        Indian pharmacopoeia, (2007), vol-II, Govt. Of India Ministry of Health and family Welfare, published by the Indian Pharmacopoeia commission, Ghaziabad, 477, 540.

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3.        Zambare Y. B. et al Simultaneous Estimation of Atorvastatin and Ramipril by First Derivative Spectrophotometric. method J Pharm Res, 2009;2(5):874-877.

4.        Abdellatef H. E. et al. Spectrophotometric and atomic absorption spectrometric determination of ramipril and perindopril through ternary complex formation with eosin and Cu(II). J Pharm Biomed Ana, 1999;18:1021–1027

5.        Patil P. R. et al. Simultanious Estimation of Ramipril and Amlodipine by UV Spectrophotometric method.   Res J Pharm Tech, 2009;2:304-07.

6.        Patel C. V. et al. validated Absorption Factor Spectrophotometric and RP-HPLC Method for the Determination of Ramipril and olmesartan medoxomil in Pharmaceutical formulations. Eurasian J Anal Chem, 2007;2,3:159.







Received on 17.02.2011          Modified on 08.03.2011

Accepted on 19.03.2011         © RJPT All right reserved

Research J. Pharm. and Tech. 4(5): May 2011; Page 823-824