https://www.kau.edu.sa/Files/130/Researches/60281_31089.pdf

Part 1. Spectrophotometric determination of trace mercury (II) in dental-unit wastewater and fertilizer samples using the novel reagent 6-hydroxy-3-(2-oxoindolin-3-ylideneamino)-2-thioxo-2H-1,3-thiazin-4(3H)-one and the dual-wavelength β-correction spectrophotometry

Two simple, rapid and reliable methods for the determination of four antihistamines based on the measurement of the chloride of their hydrochlorides are described. In the titrimetric method, the chloride content of each drug is determined by titrating with mercury(II) nitrate using diphenylcarbazone-bromothymol blue as indicator. In the spectrophotometric method, to a fixed concentration of mercury(II)-diphenylcarbazone complex different amounts of drug are added and the decrease in absorbance of mercury(II)-diphenylcarbazone complex, consequent to the replacement of diphenylcarbazone of the complex by the chloride of the drug, was measured at 540 nm. The stoichiometry of the reaction that forms the basis for titrimetry is assessed. Different variables affecting the color formation in spectrophotometry were studied and optimized. At the wavelength of maximum absorption, Beer's law is obeyed in the 0-100 microg ml(-1) range. The molar absorptivity and Sandell sensitivity are calculated. The proposed methods were applied for the analysis of pharmaceutical formulations containing these drugs. Statistical treatment of the experimental results indicates that the procedures are precise and accurate. Excipients used as additives in pharmaceutical formulations did not interfere in the proposed procedures as shown by the recovery studies.

Titrimetric and spectrophotometric assay of some antihistamines through the determination of the chloride of their hydrochlorides

Spectrophotometric determination of some histamine H1-antagonists drugs in their pharmaceutical preparations.

The study of a number of diphenhydramine-dye systems was carried out in order to determine the most suitable precipitate for the turbidimetric determination of diphenhydramine using flow injection (Fl). The reagent selected was Bromophenol Blue. The chemical and Fl variables were optimised. The calibration graph was linear over the concentration range 50–230 p.p.m. of diphenhydramine hydrochloride. A number of interfering substances were also investigated.

Determination of diphenhydramine hydrochloride by flow injection with Bromophenol Blue and turbidimetric measurement

In this article, a simple, selective and sensitive spectrophotometric method for the direct determination of trace amounts of Hg2+ in aqueous samples was performed, based on complexation reaction between Hg2+ and 2,4,7-triamino-6-phenylpteridine (triamterene) with maximum absorbance at 415 nm. The important analytical parameters and their effects on the reported system were investigated. Beer's law was found to obey for Hg2+ in the concentration range 0.1–4.2 μg/mL with molar absorptivity of 5.32 × 104 l mol−1 cm−1 and Sandell's sensitivity of 8.532 ng cm−2. The interference effect of some anions and cations on the determination was described. Most importantly, the method was applied for determination of trace amount of Hg2+ in water samples, biological, plant leaves and soil samples with satisfactory results. The performance of the proposed method was evaluated in terms of student's t-test and variance ratio F-test, which indicated the significance of proposed method over the reference method.

Highly sensitive and selective spectrophotometric detection of trace amounts of Hg2+ in environmental and biological samples based on 2,4,7-triamino-6-phenylpteridine

A spectrophotometric method is proposed for the determination of diphenhydramine in pharmaceutical preparations. The method is based on an addition-compound formation between diphenhydramine and the tetrabromophenolphthalein ethyl ester in 1,2-dichloroethane. Beer’s law is obeyed over the range of 2.0×10−6–1.0×10−5M of diphenhydramine at 594 mμ. Optimum conditions are described. The effect of diverse substances and the composition of the colored species were also investigated.

Spectrophotometric Determination of Diphenhydramine in Pharmaceutical Preparations

A new rapid, sensitive and selective method is proposed for the spectrophotometric determination of a trace of mercury (II) by solvent extraction. The method is based on the formation of an ion-pair complex between the tribromo-mercury(II) complex anion and the dyestuff cation obtained by oxidation of variamine blue B. The optimum pH range for the color reaction is 2.5–4. The blue complex can be extracted into nitrobenzene and has a maximum absorption at 605 mμ in the organic solvent. Beer’s law holds in the range 3.2×10−6−2.2×10−5 M of mercury(II) in the aqueous layer before the extraction, with a molar absorptivity of 4.03×104 mol−1cm−1 l at 605 mμ. The color reaction is instantaneous and the complex remains stable 15 mintes in the nitrobenzene layer. Of the 22 cations and 11 anions examined, tin(II), tin(IV), antimony (III), iodide, cyanide, and thiocyanate showed serious interferences.

Masahiro Tsubouchi

Papers

Spectrophotometric Determination of Diphenhydramine in Pharmaceutical Preparations

Spectrophotometric determination of mercury (II) by solvent extraction with variamine blue B.