Utility of p-chloranilic Acid and 2,3 Dichloro-5,6-dicyano p-Benzoquinone (DDQ) for the Spectrophotometric Determination of Triamterene

Microbiological and spectrophotometric methods for the determination of tioconazole: A comparative thermodynamic study

Two sensitive microbiological and charge transfer spectrophotometric methods have been developed for the quantitative determination of the antifungal drug, tioconazole, in its pure form and pharmaceutical preparations. The microbiological assay was based on the agar disk diffusion method by measuring the diameter of the inhibition zones related to different concentrations of tioconazole. The spectrophotometric method relied on charge transfer complex formation between tioconazole as an n-donor and chloranilic acid as a π-acceptor at room temperature. The formed complex was measured at λ_max = 530 nm. The molar absorptivity and the formation constant of the formed complex were determined using different models, including the Benesi-Hildebrand, Foster-Hammick-Wardley, Scott, Pushkin-Varshney-Kamoonpuri, and Scatchard equations. Different thermodynamic parameters associated with the complex formation, including the free energy change (ΔG°), the standard enthalpy (ΔH°), and the standard entropy change (ΔS°), were evaluated. The two methods were validated in conformity with ICH-recommended guidelines and employed successfully for the quantification of tioconazole in both pure form and pharmaceutical formulations.

Ultra-Performance Liquid Chromatographic and Densitometric Methods for Sensitive Determination of Xipamide and Triamterene in Pure and Pharmaceutical Dosage Forms

BACKGROUND

Validated UPLC method and TLC densitometric method were prescribed for determination of antihypertensive components. Objectives: To establish and validate rapid and accurate Ultra performance liquid chromatographic (UPLC) and TLC densitometric methods for determination of Xipamide and Triamterene in pure and dosage forms.

METHODS

The first method; UPLC method, depended on using Agilent Zorbax Eclipse Plus C8 (50 mm × 2.1 mm, 1.8 μm), as the column, mobile phase composed of (acetonitrile-water) (70 + 30, v/v) adjusted by acetic acid to obtain (pH 3), 0.2 mL/min flow rate and UV detection at 231.4 nm. The second method was a thin layer chromatography (TLC) densitometric method, separation was achieved by using toluene-methanol-ethyl chloride-acetic acid (7 + 2 + 1 + 0.2, v/v/v) as the mobile phase, pre coated silica gel plates as the stationary phase and UV detection at 300.0 nm.

RESULTS

The obtained results were validated and statistically compared with official and reported methods. The obtained results showed high accuracy and reproducible results with excellent mean recoveries for both drugs.

CONCLUSIONS

The UPLC method showed shorter retention time for both Xipamide (0.88 min) and Triamterene (0.63 min), lower detection limit less than 0.055 µg/mL for both drugs with high selectivity, decreased injection volume (1 µL) and lower flow rate other than any HPLC method. Both proposed methods were sensitive, selective, and effectively applied to pure and dosage forms (Epitens®).

HIGHLIGHTS

Unprecedented sensitive, rapid, and reproducible UPLC and TLC methods were developed for selective determination of mixture of Xipamide and Triamterene with LOD less than 0.076 µg/mL for both drugs.