Colorimetric Determination of Sympathomimetic Amines Methyldopa and Noradrenaline

1985 ◽  
Vol 68 (1) ◽  
pp. 91-95
Author(s):  
Mohamed I Walash ◽  
Abed Abou Ouf ◽  
Fatma B Salem
Keyword(s):  
Alkaline Solution ◽  
Dosage Forms ◽  
Colorimetric Determination ◽  
Sympathomimetic Amines ◽  
Chromogenic Reagent ◽  
Beer's Law ◽  
Beer’S Law ◽  
Orange Color

Abstract The chromogenic reagent p-dimethylaminocinnamaldehyde (PDAC) is introduced for the determination of the sympathomimetic amines methyldopa and noradrenaline. The method is based on measurement of the orange color developed when the alkaline solution of methyldopa and noradrenaline is allowed to react with PDAC at pH 5.0. The color developed obeys Beer's law in the concentration range 0.1-1.5 mL of 2 x 103M solution of noradrenaline and methyldopa. The results are compared with those obtained with another chromogenic reagent, pdimethylaminobenzaldehyde (PDAB). Determinations on dosage forms of the drugs, using PDAC and PDAB reagents, agreed well with results of determinations by official pharmacopoeia! methods.

scholarly journals Determination of Two Antibacterial Binary Mixtures by Chemometrics-Assisted Spectrophotometry

2007 ◽  
Vol 90 (1) ◽  
pp. 128-141 ◽  
Author(s):  
Abd El-Maaboud I Mohamed ◽  
Osama H Abdelmageed ◽  
Ibrahim H Refaat
Keyword(s):  
Binary Mixtures ◽  
Colorimetric Method ◽  
Correlation Coefficients ◽  
Dosage Forms ◽  
Considerable Degree ◽  
Zero Crossing ◽  
First Derivative ◽  
Beer's Law ◽  
Beer’S Law

Abstract Simple chemometrics-assisted spectrophotometric methods are described for determination of 2 antibacterial binary mixtures. The mixtures are composed of norfloxacin in combination with tinidazole and erythromycin (as ethylsuccinate ester or stearate salt) in combination with trimethoprim. The normal UV absorption spectra of each pair of drugs in the studied mixtures, in the range of 200-400 nm, showed a considerable degree of spectral overlapping: 77.5% for the norfloxacintinidazole mixture and 84.3% for the erythromycintrimethoprim mixture. Resolution of the norfloxacintinidazole mixture and trimethoprim in the presence of erythromycin was accomplished successfully by using zero-crossing first derivative (1D), classical least-squares (CLS) regression analysis, and principal component regression (PCR) analysis methods. In addition, an alternative simple and accurate colorimetric method was developed for the determination of erythromycin in the presence of trimethoprim using 2,4-dinitrophenylhydrazine. All variables affecting the development of the colored chromogen were studied and optimized, and the product was measured at 526-529 and 538-542 nm for erythromycin stearate and erythromycin ethylsuccinate, respectively. For zero-crossing, first derivative technique Beer’s law was obeyed in the general concentration range of 250 μg/mL for norfloxacin, tinidazole, and trimethoprim with good correlation coefficients (0.9994-0.9996). Overall limits of detection (LOD) and quantification (LOQ) ranged from 0.59 to 2.81 and 1.96 to 9.33 μg/mL, respectively. The obtained results from CLS and PCR were compared with those obtained from a 1D spectrophotometric method. With the exception of erythromycin, overall recoveries in the average range of 97.33-103.0% were obtained with a considerable degree of accuracy when the suggested methods were applied to analysis of synthetic binary mixtures, some commercial dosage forms such as tablets and oral suspension without interference from the commonly encountered excipients and additives. For the colorimetric method, Beer's law was obeyed in the general concentration range of 7.21-28.84 μg/mL erythromycin with good correlation coefficients (0.9980-0.9996). Overall LOD and LOQ ranged from 0.73 to 1.65 and 2.43-5.49 μg/mL, respectively. Erythromycin derivatives were determined in the commercial dosage form, without interference from trimethoprim-encountered excipients and additives. The obtained results, with both chemometric and colorimetric methods, have been compared with those obtained from reported methods, and proper F- and t-values were observed, indicating no significant difference between the results of the suggested methods and reported method(s). The good percentage recoveries and proper statistical data obtained proved the efficiency of the proposed procedures for the determination of the studied drugs in their binary mixtures as well as in the commercial dosage forms with quite satisfactory precision.

scholarly journals Spectrophotometric Stability-Indicating Methods for the Determination of Leflunomide in the Presence of Its Degradates

2006 ◽  
Vol 89 (6) ◽  
pp. 1524-1531 ◽  
Author(s):  
Samah S Abbas ◽  
Lories I Bebawy ◽  
Laila A Fattah ◽  
Heba H Refaat
Keyword(s):  
Dosage Forms ◽  
Derivative Spectrophotometry ◽  
Reaction Conditions ◽  
Pharmaceutical Dosage Forms ◽  
First Derivative ◽  
Beer's Law ◽  
First Derivative Spectrophotometry ◽  
Colored Product ◽  
Beer’S Law

Abstract Five simple and sensitive methods were developed for the determination of leflunomide (I) in the presence of its degradates 4-trifluoromethyl aniline (II) and 3-methyl-4-carboxy isoxazole (III). Method A was based on differential derivative spectrophotometry by measuring the △1D value at 279.5 nm. Beer's law was obeyed in the concentration range of 2.0020.00 μg/mL with mean percentage accuracy of 100.07 1.32. Method B depended on first-derivative spectrophotometry and measuring the amplitude at 253.4 nm. Beer's law was obeyed in the concentration range of 2.0016.00 μg/mL with mean percentage accuracy of 98.42 1.61. Method C was based on the reaction of degradate (II) with 2,6-dichloroquinone-4-chloroimide (Gibbs reagent). The colored product was measured at 469 nm. Method D depended on the reaction of degradate (II) with para-dimethyl aminocinnamaldehyde (p-DAC). The absorbance of the colored product was measured at 533.4 nm. Method E utilized 3-methyl-2-benzothiazolinone hydrazone in the presence of cerric ammonium sulfate with degradate (II). The green colored product was measured at 605.5 nm. The linearity range was 40.00-280.00, 2.40-24.00, and 30-250 μg/mL with mean percentage accuracy of 100.75 1.21, 100.13 1.45, and 99.74 1.39 for Methods CE, respectively. All variables were studied to optimize the reaction conditions. The proposed methods have been successfully applied to the analysis of leflunomide in pharmaceutical dosage forms and the results were statistically compared with that previously reported.

Colorimetric Determination of Propoxur and Its Residues in Vegetables

1983 ◽  
Vol 66 (1) ◽  
pp. 105-107 ◽  
Author(s):  
Kalapanda M Appaiah ◽  
Omprakash Kapur ◽  
Krishnarajpet V Nagaraja
Keyword(s):  
Absorption Maximum ◽  
Potassium Hydroxide ◽  
Colorimetric Determination ◽  
Diaminodiphenyl Sulfone ◽  
Beer's Law ◽  
Beer’S Law ◽  
Hydrolysis Of

Abstract A method has been developed for the determination of propoxur (o-isopropoxyphenyl N-methylcarbamate) based on the hydrolysis of propoxur with methanolic potassium hydroxide to its phenol and coupling with diazotized 4,4-diaminodiphenyl sulfone. The orange complex formed has an absorption maximum at 500 nm and obeys Beer’s law in the range 0.25-5.0 μg/mL. The method can be applied to levels as low as 0.5 ppm propoxur from vegetables.

scholarly journals On the determination of reducing corticosteroids

1955 ◽  
Vol 53 (2-3-4) ◽  
pp. 503-508
Author(s):  
Luiz Augusto de Abreu ◽  
Regina Raposo de Abreu
Keyword(s):  
Human Urine ◽  
Guinea Pigs ◽  
Adrenal Glands ◽  
Colorimetric Determination ◽  
Beer's Law ◽  
Beer’S Law ◽  
Made In

1. The authors preconize the use of Folin-Ciocalteu's reagent in the colorimetric determination of reducing cortcosteroids. 2. The reaction follows Beer's law in the range 0-50 μg of 11-desoxycorticosterone. 3. Determinations made in human urine and adrenal glands of rats and guinea pigs are comparable with results obtained by other methods.

Colorimetric Determination of Diazepam in Pharmaceutical Preparations

1975 ◽  
Vol 58 (5) ◽  
pp. 875-878 ◽  
Author(s):  
Tulsidas R Baggi ◽  
Surinder N Mahajan ◽  
Griddaluru Ramana Rao
Keyword(s):  
Colorimetric Method ◽  
Pharmaceutical Preparations ◽  
Colorimetric Determination ◽  
Pyridoxine Hydrochloride ◽  
Yellow Solution ◽  
Beer's Law ◽  
Beer’S Law ◽  
Pure Drug ◽  
Solvent Blank

Abstract A colorimetric method is presented for the estimation of diazepam as the pure drug and in formulations. Diazepam is hydrolyzcd with 6N HC1 to 2-methyIamino-5-chlorobenzophenone, which is extracted with chloroform to give a yellow solution whose absorbance is measured at 410 nm against a solvent blank. The color obeys Beer's law in the concentration range of 0–30 μg/ml. In 5 determinations, recovery was 99.0±1.9%. The method is applicable to pure diazepam and its formulations for oral and parenteral use. No interferences were observed from pyridoxine hydrochloride and commonly used preservatives, vehicles, and colors.

scholarly journals Colorimetric and Titrimetric Methods for Determination of Some Cephalosporins in their Pure and Dosage Forms.

2000 ◽  
Vol 68 (3) ◽  
pp. 263-273 ◽  
Author(s):  
Hisham E. Abdellatef ◽  
Abdalla A. Shalaby ◽  
Heba M. Elsaid ◽  
Magda M. Ayad
Keyword(s):  
Colorimetric Method ◽  
Dosage Forms ◽  
Operating Conditions ◽  
Titrimetric Method ◽  
Beer's Law ◽  
Beer’S Law ◽  
Good Percentage ◽  
Good Agreement ◽  
Mechanism Of The Reaction

Two colorimetric and titrimetric procedures are developed for determination of some cephalosporins, namely, cefotaxime sodium (CFT), cehroxime sodium (CFU) and ceftazidime pentahydrate (CFZ). The first method, a colorimetric method, was based on the reaction of these cited drugs with 4-chloro-7-nitrobenzofurazan (NBD-Cl), in the presence of 5x10-3 M borax, with the formation of stable colored chromogens with maximum absorbance in the range of 409 - 414 nm. All variables affecting the development of the colour have been investigated and the conditions were optimized. The method obeys Beer's law over concentration ranges of 19.09 - 95.49, 17.85 - 124.98 and 63.66 - 254.66 µg ml-1 of CFT, CFU and CFZ, respectively. Obedience to Beer's law permitted the successful application of the proposed method for the assay of cefuran, cefumax and fortum vials. The results obtained reveal good percentage recoveries, which are in good agreement with those obtained by the official methods. In the second method, the titrimetric method, the conditions for the oxidimetric titration of cephalosporins have been studied. The titration takes place because of catalytic quantities of KBr, which give rise to an intermediate that can be hydrolyzed to the sulfoxide. The operating conditions are described and a hypothesis is put forward concerning the mechanism of the reaction.

scholarly journals VALIDATED SPECTROPHOTOMETRIC METHOD TO DETERMINE VARDENAFIL AND SILDENAFIL IN PHARMACEUTICAL FORMS USING POTASSIUM IODIDE AND POTASSIUM IODATE

2017 ◽  
Vol 9 (10) ◽  
pp. 65 ◽  
Author(s):  
Amir Alhaj Sakur ◽  
Shaza Affas
Keyword(s):  
Potassium Iodide ◽  
Spectrophotometric Method ◽  
Molar Absorptivity ◽  
Dosage Forms ◽  
Potassium Iodate ◽  
Average Recovery ◽  
Beer's Law ◽  
Beer’S Law ◽  
Good Agreement

Objective: To develop and validate simple, sensitive, precise and free of organic solvents method for the determination of sildenafil (SIL) and vardenafil (VAR) in bulk and pharmaceutical formulation.Methods: The method is based on the reaction of studied drugs with a mixture of potassium iodide and potassium iodate in an aqueous medium at (25±2 °C) to form yellow coloured triiodide ions (I3-) within 45 min. The reaction is followed spectrophotometrically by measuring the absorbance at 288, 351 nm and 285, 351 nm for sildenafil and vardenafil respectively.Results: The effects of analytical parameters on the reported systems were investigated. Beer's law of SIL was obeyed in the range of (0.4-12) μg ml-1and (0.6-16) μg ml-1. Molar absorptivity was found to be (67.659 ×103) lmol/cmand (37.955×103) lmol/cm at 288 nm, 351 nm respectively. Beer's law of VAR was obeyed in the range of (0.2-13) μg/mland (0.5-40) μg/ml. Moreover, molar absorptivity’s were found to be (68.719 ×103) l mol-1 cm-1and (26.691×103) l mol-1 cm-1 at 285 nm, 351 nm respectively.Conclusion: The proposed method has been applied to determine the components in dosage forms with an average recovery of 98.15% to 103.45% and the results have been found in good agreement with those results obtained by the reference methods.

Spectrophotometric Method for Determination of Cephalexin in Its Dosage Forms

1992 ◽  
Vol 75 (6) ◽  
pp. 994-998 ◽  
Author(s):  
Ila T Patel ◽  
Muljibhai B Devani ◽  
Tushar M Patel
Keyword(s):  
Spectrophotometric Method ◽  
Dosage Forms ◽  
Oral Suspension ◽  
Specific Method ◽  
Reaction Conditions ◽  
Beer's Law ◽  
Beer’S Law ◽  
Official Procedure

Abstract A simple, rapid, and specific method was developed for determination of cephalexin and its dosage forms. The method is based on the reaction of cephalexin with acetylacetone-formaldehyde reagent to give a yellow chromophore measurable at 400 nm. The color is stable for 3 h. Beer's law is valid within a concentration range of 10-100 μg/mL for cephalexin. All variables were studied to optimize the reaction conditions. The method is specific for amino β-lactam antibiotics. Non-amino β-lactam antibiotics do not interfere. No interference was observed in the presence of common pharmaceutical adjuvants. The validity of the method was tested by analyzing cephalexin tablets, capsules, and oral suspension. Good recoveries were obtained for these preparations. The results were comparable with those obtained by the official procedure

COLORIMETRIC DETERMINATION OF CRUDE POWDERED MYRRH, PURIFIED MYRRH EXTRACT, OILY FRACTION, AND ITS DIFFERENT PHARMACEUTICAL DOSAGE FORMS

2002 ◽  
Vol 35 (2) ◽  
pp. 183-197 ◽  
Author(s):  
Mohamed H. Abdel-Hay ◽  
Amal Saleh ◽  
E. S. H. El Ashry ◽  
N. Rashed ◽  
Osama Salama
Keyword(s):  
Dosage Forms ◽  
Colorimetric Determination ◽  
Pharmaceutical Dosage Forms
Sign in / Sign up

Export Citation Format

Share Document