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Gadkariem EA, Ibrahim KE, Kamil NA, et al. A new spectrophotometric method for the determination of methyldopa. Saudi Pharm J. 2009;17(4):289-93doi: 10.1016/j.jsps.2009.10.005.
Gadkariem, E. A., Ibrahim, K. E., Kamil, N. A., Haga, M. E., & El-Obeid, H. A. (2009). A new spectrophotometric method for the determination of methyldopa. Saudi pharmaceutical journal : SPJ : the official publication of the Saudi Pharmaceutical Society, 17(4), 289-93. https://doi.org/10.1016/j.jsps.2009.10.005
Gadkariem, E A, et al. "A new spectrophotometric method for the determination of methyldopa." Saudi pharmaceutical journal : SPJ : the official publication of the Saudi Pharmaceutical Society vol. 17,4 (2009): 289-93. doi: https://doi.org/10.1016/j.jsps.2009.10.005
Gadkariem EA, Ibrahim KE, Kamil NA, Haga ME, El-Obeid HA. A new spectrophotometric method for the determination of methyldopa. Saudi Pharm J. 2009 Oct;17(4):289-93. doi: 10.1016/j.jsps.2009.10.005. Epub 2009 Nov 10. PMID: 23960712; PMCID: PMC3730969.
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Saudi Pharm J. 2009 Oct;17(4):289-93. doi: 10.1016/j.jsps.2009.10.005. Epub 2009 Nov 10.

A new spectrophotometric method for the determination of methyldopa.

Saudi pharmaceutical journal : SPJ : the official publication of the Saudi Pharmaceutical Society

E A Gadkariem, K E E Ibrahim, N A A Kamil, M E M Haga, H A El-Obeid

Affiliations

  1. University of Khartoum, Faculty of Pharmacy, P.O. Box 1996, Khartoum, Sudan.

PMID: 23960712 PMCID: PMC3730969 DOI: 10.1016/j.jsps.2009.10.005

Abstract

A new, simple and low cost spectrophotometric method for the determination of methyldopa in pharmaceutical preparations was developed. The method was based on the coupling of methyldopa with 2,6-dichloroquinone-4-chlorimide (DCQ). The absorbance maximum (λ max) of the resulted colored product was at 400 nm. Different buffers were used to determine the optimal pH for the reaction. About 1% w/v acetate buffer with pH 8.0 gave the optimal pH required for the reaction. Of the different solvents tried, water and ethanol were found to be the most suitable solvents. Beer's law was obeyed in concentration range of 4-20 μg/ml methyldopa. The correlation coefficient was found to be (r = 0.9975). The limit of detection and limit of quantification were 1.1 μg/ml and 3.21 μg/ml, respectively. The reaction ratio between methyldopa and DCQ was studied and found to be 1:3. The work included the study of the possible interference of hydrochlorothiazide found in combination with methyldopa tablets. The method was validated and results obtained for the assay of two different brands of methyldopa tablets were compared with the BP method (colorimetric). The repeatability and reproducibility of the developed method were evaluated and the obtained results quoted. The derivative formed as a result of the reaction of methyldopa with DCQ was isolated and its possible mechanistic pathway was suggested.

Keywords: 2,6-Dichloroquinone-4-chlorimide (Gibbs reagent); Methyldopa; Pharmaceutical preparations; Spectrophotometric analysis

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