Keywords : Spectrophotometry


Spectrophotometric Assay of Sulphamethoxazole in Pure and Pharmaceutical Dosage Forms by Diazotization and Coupling Reaction

Salim A. Mohammed; Hind A. Zamel

Rafidain Journal of Science, 2017, Volume 26, Issue 1, Pages 111-121
DOI: 10.33899/rjs.2017.139119

A simple, rapid, accurate and sensitive spectrophotometric method has been developed for the quantitative determination of sulphamethoxazole (SMX) in both pure form and its pharmaceutical preparations. The proposed method is based on the diazotization of SMX with sodium nitrite in hydrochloric acid medium to form a diazonium salt, which is coupled with γ-resorsolic acid (2,6-dihydroxybenzoic acid) in alkaline medium of sodium hydroxide to form a stable and water-soluble azo dye exhibited maximum absorption at 432 nm against reagent blank. Beer’s law is obeyed over the concentration range of 5 to 300 μg of SMX /20 mL (0.25-15 ppm) with a good determination coefficient (R2=0.9984) and apparent molar absorptivity 3.34×104 l.mol-1.cm-1. The limit of detection (LOD) and limit of quantification (LOQ) are 0.0584 and 0.1752 μg mL−1, respectively. The recoveries and relative standard deviations in tablets and oral suspension formulations are found as 96.6 to 99.04% and 1.6 to 3.0%, respectively, depending on the concentration level. The method is suitable for the determination of SMX in the presence of other excipients that are usually present in dosage forms. The composition of the resulting product has also been worked out and it is found to be (1:2)SMX: γ-resorsolic acid. This procedure is applied successfully to the analysis of SMX in pharmaceutical preparations (tablets and oral suspension) without prior separation but with acceptable errors.

Sensitive and Selective Spectrophotometric Assay of Lead in Aqueous Solution

Dheeya J. Yacoob

Rafidain Journal of Science, 2014, Volume 25, Issue 1, Pages 69-81
DOI: 10.33899/rjs.2014.86073

A sensitive and selective spectrophotometric method for the determination of lead (II) in aqueous solution using zincon reagent has been developed. The pinkish red coloured complex was formed at pH 9.5 which shows maximum absorption at 543 nm. Beer's law is obeyed in the range 0.04 –1.2 ppm with a molar absorbtivity of 9.84 x 104 l.mol -1cm-1. The established stoichiometry is l:l ligand: metal. The method seems to be selective through the study of cationic and anionic interferences, easy, rapid, accurate, reproducible, and the complex is stable for 24 hours. The optimum conditions and the applications of the method have been studied for the assay of lead in different water samples.

Spectrophotometric Determination of Tellurium (IV) with Chrome Azurol S: Application to Sea Water and Synthetic Alloys

Wadala A. Bashir; Ghaida K. Hanna; Sadallah T. Sulaiman

Rafidain Journal of Science, 2013, Volume 24, Issue 11, Pages 10-22
DOI: 10.33899/rjs.2013.80278

The detailed investigation of a sensitive spectrophotometric method for the determination of trace amounts of tellurium (IV) is described. The method is based on the reaction of tellurium (IV) with chrome azurol S in the presence of cetylpyridinium chloride hydrate surfactant at a final pH of 3.1 to form a pink coloured chelate absorbing maximum at 525 nm. Beer’s law is obeyed over the range (5-50) µg/25 ml, with a molar absorptivity of (2.5 ×104) l.mol-1.cm-1 and a coefficient of determination (r2) of 0.9997. Sandell’s sensitivity index is (5.104×10-3) µg.cm-2, a relative error of (0.8-0.2%) and a relative standard deviation of (0.2 to ±1.8) %, depending on the concentration levels in the calibration curve. The method has been applied successfully to determine Te (IV) in sea water and some synthetic alloys.

Spectrophotometric Determination of Bismuth with Alizarine Red S and Cetylpyridinium Chloride - Application to Water Samples, Urine and Veterinary Preparation

Salim A. Mohammed; Mohammed M. Mohammed

Rafidain Journal of Science, 2013, Volume 24, Issue 9, Pages 52-63
DOI: 10.33899/rjs.2013.78759

A simple, accurate, sensitive and reliable method for spectrophotometric determination of Bismuth(III) is developed. The method is based on the reaction of bismuth (III) with alizarine red S (ARS) and cetylpyridinium chloride (CPC) in the presence of Triton X-100 at pH 3 to form a pink, water soluble ternary complex which shows a maximum absorption at 507 nm with a molar absorptivity of 1.4 x104 L.mol-1cm-1. The calibration curve is linear in the concentration range 5– 150 μg of bismuth (III) in a final volume of 20mL (i.e. 0.25-7.5 μg mL-1) with a determination coefficient of (R2) (0.9974). The limit of detection (LOD) and the limit of quantification (LOQ) are 0.0671 and 0.2235 g.mL-1, respectively. Under optimum conditions, the stoichiometry of the reaction between bismuth (III), alizarine red S and cetylpyridinium chloride is found to be 1:3:6, respectively. The recoveries are obtained in the range of 98.8- 102.1% and a relative standard deviation (RSD) of ± 0.93 to ±3.07% depending on the concentration level. The proposed method has been applied successfully to the determination of bismuth (III) in various samples such as, natural waters, urine and veterinary preparation

Spectrophotometric Determination of Cerium (III) with Arsenazo III: Application to Sea Water and Synthetic Alloys

Sadallah T. Sulaiman; Ghaydaa K. Hanna; Wadala A. Bashir

Rafidain Journal of Science, 2013, Volume 24, Issue 5, Pages 37-50
DOI: 10.33899/rjs.2013.74510

The detailed investigation of a sensitive and selective spectrophotometric method for the determination of trace amounts of cerium is described. The method is based on the reaction of cerium(III) with arsenazo ш in the presence of sodium dodecyl sulphate surfactant at pH 3.0 to form a blue-greenish coloured chelate absorbing maximum at 653 nm. Beer’s law is obeyed over the range (5-70) µg /25 ml, with a molar absorptivity of (4.99×104) l.mol-1.cm-1 and the coefficient of determination (r2) is 0.9994, Sandell’s sensitivity index is (28.08×10-4) µg.cm-2, a relative error of (0.0-0.2%) and a relative standard deviation of (0.0 to +2.1)%, depending on the concentration levels in the calibration curve. The method has been applied successfully to determine cerium in sea water and some synthetic alloys.

Improved Spectrophotometric Determination of Bismuth (III) with Bromopyrogallol Red in Mixed Surfactants-Application to Waters and Veterinary Preparation

Enas S. Thunoon; Najih H. Shekho

Rafidain Journal of Science, 2013, Volume 24, Issue 3, Pages 39-52
DOI: 10.33899/rjs.2013.71038

A simple and sensitive spectrophotometric method for the determination of trace amounts of bismuth is established. The method is based on the reaction of bismuth with bromopyrogallol red at pH 3 in the presence of a mixture of cetylpyridinium chloride and triton X-100 surfactants to form a blue coloured complex which shows maximum absorbance
at 644 nm. A plot of absorbance with bismuth concentration gives a straight line indicating that Beer,s law has been obeyed over the range 3-150 µg/25 ml, i.e., 0.12-6 ppm with a molar absorptivity of 3.3×104 l.mol-1.cm-1 and Sandell,s sensitivity index of 0.006
µg.cm-2. The interfering effect of a number of common captions and anions in the presence of comosite mixture (NaF and tartaric acid) and ascorbic acid as masking agents has been studied. The effect of common excipients has also been examined. The method has been applied successfully to the determination of bismuth in water samples and a veterinary preparation.

Photometric Assay of Nitrite in Various Samples

Ammar M. Bilal; Wadala A. Bashir

Rafidain Journal of Science, 2013, Volume 24, Issue 2, Pages 60-83
DOI: 10.33899/rjs.2013.67483

The assay is based on the reaction of nitrite in acidic medium with
m-nitroaniline to form the corresponding diazonium ion which is coupled with
N-(1-naphthyl)ethylenediamine to form a stable purplish azo dye that shows maximum absorption at 530 nm. Beer's law is obeyed over the concentration range 0.04-1.0 ppm. The molar absorptivity is (4.6x104l.mol-1.cm-1), and Sandell's sensitivity index of (0.1 ng. cm-2).
The proposed method has been applied to the determination of nitrite in meat, water and soil.

The Applications of Al- Chrome Azurol S Color Reaction to Assay Mishraq Alum Purity and Fluoride in Tablet

Hanan H. Ahmad; Farha K. Omar

Rafidain Journal of Science, 2011, Volume 22, Issue 6, Pages 60-72
DOI: 10.33899/rjs.2011.6530

In the present research, a spectrophotometric method is suggested as an alternative to the gravimetric method used to find mishraq alum purity. The method is based on the complex formation between aluminium ion and either Chrome Azurol S (CAS) or Eriochrome cyanine R (ECR) to give colored products suitable for the determination of aluminium. The same reaction has been applied to the determination of fluoride in tablet, depending on the bleaching effect of fluoride on the formed aluminium colored complex. Statistical comparison of method has given satisfactory results

Spectrophotometric Determination of Chlorocresol via Nitrosation Reaction – Application to Pharmaceutical Preparations (Creams)

Widad E. Hassan; Nief R. Ahmed

Rafidain Journal of Science, 2009, Volume 20, Issue 6, Pages 66-73
DOI: 10.33899/rjs.2009.39987

A spectrophotometric method for the determination of pure chlorocresol and in a number of its pharmaceutical preparations (creams) has been developed that offers advantages of simplicity, sensitivity and stability. The proposed method was based on the formation of a nitroso derivative of chlorocresol. The colored product have maximum absorption at 424 nm. Beer's law is obeyed over the concentration range of (2-26) ppm, with a molar absorptivity of 0.417×104 l.mol-1.cm-1. Relative standard deviation of the method was better than ±1.8% and the average recovery was 99.2%. The proposed method has been successfully applied to the determination of chlorocresol in pure form and in pharmaceutical preparations (creams).

Indirect Spectrophotometric Method for the Determination of Mefenamic Acid in Pharmaceutical Formulations*

Zainab M. Al-mufty; Nief R. Ahmed

Rafidain Journal of Science, 2009, Volume 20, Issue 6, Pages 39-47
DOI: 10.33899/rjs.2009.39959

A simple, sensitive and accurate spectrophotometric method for the determination of mefenamic acid in pure form and in some pharmaceutical formulations was developed. The method is based on the oxidation of mefenamic acid by iron(III), and subsequent complexation of iron(II) with o-phenanthroline, forming a red-colored complex (ferroin) having the maximum absorbance at 510 nm. Beer's law is obeyed in the concentration range of 0.4-2.0 μgml, the molar absorptivity and Sandell's sensitivity are 2.9×104 L.mol-1.cm-1 and 8.3 ng.cm-2, respectively and the relative standard deviation (RSD) is less than 2.0 (n=10). The limits of detection and quantitation are 0.065 and 0.195 μg.ml-1,respectively. The method is applied successfully to determination of mefenamic acid in some pharmaceutical formulations (capsules and tablets). The common excipients do not interfere with the proposed method. A statistical comparison of these results with those of official method using (t and F) values at 95% confidence level shows good agreement and indicates no significant difference in the precision and the present method has good validity.

Spectrophotometric Determination of 1-Naphthylamine - Application to Sea and River Waters

Dawood H. Mohammed; Sameer A. Rahim

Rafidain Journal of Science, 2009, Volume 20, Issue 3, Pages 84-91
DOI: 10.33899/rjs.2009.40239

The present work includes a detailed investigation of a new spectrophotometric method for the determination of 1-naphthylamine. The method is based on oxidative coupling reaction of the compound with catechol in the presence of potassium chromate as oxidant in acidic medium to form a stable purple–red coloured product which shows maximum absorption at 530 nm. The molar absorptivity is 3685 l.mol-1.cm-1. Beer's law is obeyed over the range of (1- 60) ppm. The method is applied to the recovery of 1-naphthylamine from sea and river water.