Determination of Potassium Guaiacolsulphonate In A Cough Syrup Using Second Derivative Spectrophotometry

Abstract

Potassium guaiacolsulphonate has been determined in a cough syrup by recording the second (D2) derivative absorption curve and taking D2 at 288 nn as a direct measure of its concentration. the mean percentage found from the labelled +SD was found to be 103.3+0.35. Added recovery experiments gave a mean percentage recovery of 100.3+0.24. the results were found to be in good agreement with those obtained using a spectro-fluorimetric method. the D2 method has been found to be reproducible with a relative standard deviation less than 1%.     

Spectrophotometric Method of Determination for Cycloserine Using Chlornil

Abstract

Cycloserine has been determined by a spectrophotometric method based on n → charge-transfer complex formation with chloranil. The method involves addition of cycloserine solution to chloranil reagent in borate buffer of pH 9; and heating at 65°C for 45 min. The complex formed exhibits absorption maximum of 348 nm; and A_max is linearly related to concentration over the range 2–8 μg/ml. The mean percentage found for the authentic sample is 100.32 ± 0.70. When applied to commercial capsules claimed to contain 250 mg each, the mean percentage found is 102.45 ± 1.05. These results have shown good agreement when compared with those obtained by the pharmacopoeial (B.P.) methods.     

Improved High Performance Liquid Chromatographic Method for the Determination of Some Corticosteroids

Abstract

A simple, selective and accurate high performance liquid chromatographic method for the determination of some pharmaceutically important corticosteroids has been developed. the suggested method uses a ultrasphere ODS column with acetonitrile-phosphate buffer (pH 8) as a mobile phase.

The mean percentage recovery ranged from 97.9 to 99.7, the proposed method was applied to the determination of the studied corticosteroids pro in some dosage forms. the statistical analysis of the results obtained were compared favourably with those given with the official method.     

Determination of Vitamin A in Presence of its Degradation Product by First - Derivative U.V.- Spectrophotometry

Abstract

A rapid spectrophotometric method for the determination of retinol palmitate (vitamin A) in the presence of its oxidative degradation product is presented. The method is based on the first-derivative measurement of the peak-trough amplitude at 288 – 336 nm. The mean percentage recovery for mixtures of vitamin A with their respective degradation product was 100(1.0). Graphs of log 0% versus time for vitamin A in 0.1 N hydrochloric acid/isopropanol was a straight line with a slope of ?0.0007 min^?1. The method has been succesfuly applied to monitor the vitamin stability.     

pH-Induced Difference Spectrophotometric Methods for Drug Analysis. I. Determination of Indomethacin

Abstract

On the basis of the spectral changes of indometnacin induced by changing the pH of the solvent medium, a method for its determination has been developed. The latter involves absorbance measurement of both acid and alkaline solutions of the compound at 260 nm: the difference between both values is linearly related to concentration in the range 0.4-1.4 mg/100 ml. The mean percentage recovery of authentic samples equal 100.1±0.42 (p=0.05). The method has been applied to the analysis of pharnaceutical preparations; the results obtained as compared to those of the official method indicate warranty of application in routine analysis.     

Azothia- and Azoxythiacrown Ethers as Ion Carriers. Part I. Cationic Response of Membrane Electrodes

13-Membered azothia- and azoxythiacrown ethers have been applied as ion carriers in ion-selective membrane electrodes. Their sensitivity and selectivity were studied towards alkali, alkaline earth, transition and heavy metal cations. It was found that membranes doped with the azoxythiacrown ether (A) show higher affinity towards Pb²⁺ than Cu²⁺ (log K_Cu,Pb ^pot = 1.7), whereas membranes with the azothiacrown ether (B) are more selective towards Cu²⁺ than Pb²⁺ (log K_Cu,Pb ^pot = -2.4). The discrimination of alkali and alkaline earth cations was found to be greater for B than for A. Electrodes with both ionophores suffered from strong interference by Ag⁺ and Hg²⁺. The relation between the carrier structure and electrode properties has been discussed.     

Colorimetric and Bromometric Determination of Pirbuterol Hydrochloride

Abstract

Two proposed methods are reported for the quantitation of pirbuterol hydrochloride, namely, (i) colorimetric and (ii) titrimetric methods. The colorimetric method is based on coupling betweem diazotized sulphanilamide and pirbuterol hydrochloride. Under the optimum conditions studied, the coupling product exhibits a maximum at 440 nm. Linear relation between absorbance, A, and concentration of pirbuterol hydrochloride is in the range 5–40 μgml^?1. The mean percentage obtained for capsules (Exirel^R ?15 mg) was 100.8 ± 0.7 whereas mean percentage recovery obtained for the authentic drug was 100.5 ± 0.8.

The titrimetric procedure involves bromination of authentic pirbuterol in acid medium and residual titration of excess bromine. The stoichiometry of the reaction was investigated and infra-red analysis, of the bromoderivative was carried out. When applied to capsules the bromometric method gave mean percentage of 100.18 ± 2.25.     

Quantitative Densitometric Determination of Theophylline

Abstract

A method for identification and quantification of theophylline in certain dosage forms, that employs TLC-scanner is reported. the method is applied for theophylline either as raw material or in certain dosage forms admixed with other medicamenta. Samples were extracted with methanol, separated and measured in situ on silica gel G plates at about 270 nm using TLC-scanner. the mean recovery (six determinations) was 99.9± 0.57. the developed procedure has been found to be simple, rapid and precise and its application to various dosage forms was demonstrated and yields comparable results with UV measurement after location, scraping and elution from the plates.     

First Derivative Spectrophotometric Determination of Phenytoin

Abstract

The first derivative curve (D₁) of absorption spectrum of Phenytoin in buffer pH 10 develos negative peaks at 244, 263 and 270 nm. D₁ at 244 nm was found linearly related to concentration over a range 0.4 ? 1.4 mg per 100 ml and highly reproducible (C.V. %=0.62). Tablets and capsules have been analyzed using D₁ at 244 nm and the mean percentage found were 99.7 ± 0.81 and 103.3 ± 0.44, respectively. The B.P. method gave 100.9 and 103.8 %, respectively.     

Differential Pulse Polarographic Determination of Moxifloxacin Hydrochloride in Pharmaceuticals and Biological Fluids

Abstract

A simple, fast, sensitive and fully validated differential pulse polarographic (DPP) method for the determination of trace amounts of moxifloxacin in pharmaceutics, serum and urine is reported. Moxifloxacin exhibited irreversible cathodic peak over the pH 5.00–11.00 in Britton–Robinson (B–R) buffer. At pH 10.00 (the analytical pH), a well‐defined peak at ?1.61 V versus saturated calomel electrode was obtained. The current has been characterized as being diffusion‐controlled process. The diffusion current constant (i_d) was 1.48±0.12 and the current–concentration plot was rectilinear over the range from 5×10^?7 to 1×10^?4 M with correlation coefficient (n=10) of 0.995.

The proposed method was applied to commercial tablets and average percentage recovery was in agreement with that obtained by spectrophotometric comparison method. The method was extended to the in vitro determination of moxifloxacin in spiked human serum and urine.     

Voltammetric Determination of Rosiglitazone in Pharmaceutical Preparations and Human Plasma

Abstract

The voltammetric behavior of rosiglitazone was studied using direct current (DC_t), differential pulse (DPP), and alternating current (AC_t) polarography. The drug manifests cathodic waves over a pH range of 2–11.2. In Britton‐Robinson buffer (BRb; pH 4), the diffusion current–concentration relationship was found to be rectilinear over a range of 4–24 µg · mL^?1 and 0.1–16 µg · mL^?1 using DC_t and DPP modes, respectively, with minimum limits of detection (LOD) of 0.15 µg · mL^?1 and 0.07 µg · mL^?1 using the DC_t and DDP modes, respectively. The diffusion‐current constant (I _d) was 6.63±0.03 (n=5). The proposed method was successfully applied to the determination of the studied compound both in pure form and in formulations. The mean percentage recoveries in tablets were 100.09±1.18 and 100.85±0.88 (n=5) using DC_t and DPP modes, respectively. Furthermore, the proposed method, adopting the DPP mode, was applied to the determination of rosiglitazone in spiked human plasma and the obtained mean percentage recoveries were 99.14±3.29 (n=4).     

Determination of Candesartan Cilexetil in Tablet Dosage Forms and Dissolution Testing Samples by First Derivative UV Spectrophotometric Method

Abstract

This article describes the development and validation of a first derivative UV quantitative analytical method for determination of candesartan cilexetil in tablet dosage forms. A signal at 270.1 nm of the first derivative spectrum (ID_270.1) was found adequate for quantification. The limit of quantification was 3.06 µg/ml. The linearity between ID_270.1 nm and concentration of candesartan cilexetil in the range of 6.00–32.00 µg/ml presented a correlation coefficient of (r²) = 0.9990. The mean recovery percentage was 100.97 and 99.23% for candesartan cilexetil standard solution and candesartan standard cilexetil solution with excipients, respectively. The intraday and interday accuracy of the assay was 98.60% and 99.10% respectively. The intraday and interday variability was below 2.0%.

The proposed method is accurate, precise, sensitive, and selective and can be used in quality control laboratories for its intended purpose.     

Analysis of levofloxacin in pharmaceutical preparations by high performance thin layer chromatography

A new simple, precise, rapid, and selective high‐performance thin layer chromatography (HPTLC) method has been developed for the analysis of levofloxacin in pharmaceutical formulations. The method uses lamotrigine as an internal standard. The stationary phase was silica gel 60F₂₅₄ prewashed with methanol; water‐methanol‐n‐butanol‐ammonia solution 5 + 5 + 5 + 0.4 (v/v) was used as mobile phase. Detection and quantification were performed densitometrically at λ = 298 nm. The linear range of the analysis was 0.8–3.0 μg and the percentage recovery was 99.90%.     

Analysis of 4-Tert-Butylpyrocatechol in Styrene by Solid Phase Extraction and High Performance Liquid Chromatography

Abstract

A solid phase extraction procedure has been developed to isolate and preconcentrate 4-tert-butylpyrocatechol and its oxidation products from etyrene. The eluted amount of 4-tert-butylpyrocatechol from the cartridges was determined by reversed phase HPLC, External calibration method was used in the concentration range between 3 and 80 ppm of 4-tert-butylpyrocatechol and mean recovery was found to be 97 % with a relative standard deviation of 3.4%.     

Simultaneous determination of levofloxacin hemihydrate and ambroxol hydrochloride in tablets by thin-layer chromatography combined with densitometry

This paper describes the application of thin-layer chromatography (TLC) combined with densitometry to simultaneous determination of levofloxacin hemihydrate (LEV) and ambroxol hydrochloride (AMB) in bulk and tablets. The separation was achieved on aluminum sheet of silica gel 60 F ₂₅₄ using chloroform: methanol: toluene: ammonia (10: 6: 3: 0.8 v/v/v/v) as mobile phase. Quantification was carried out densitometrically at 245 nm. This system was found to give compact spots for LEV (R _f value of 0.4) and AMB (R _f value of 0.7). The calibration curves for LEV and AMB was found to be linear between 9960–16600 ng/spot (r ² = 0.999) and 600–1000 ng/spot (r ² = 0.999), respectively. The mean percentage recoveries from tablets for LEV and AMB were 99.45% and 99.58%, respectively. The TLC-densitometry method has many advantages, such as simplicity, reasonable sensitivity, rapidity, and low cost, and it can be successfully used in routine analysis of both these drugs in tablet formulations.     

Simultaneous estimation of levodopa,carbidopa and 3‐oxymethyldopa in rat plasma using HPLC‐ECD

The aim of study was to develop a suitable analytical method for simultaneous estimation of levodopa, carbidopa and 3‐O‐methyl dopa in rat plasma. Chromatographic separation of plasma samples was achieved using a reverse‐phase C₁₈ column. The mobile phase used consisted of a mixture of methanol and phosphate buffer (10 mM , pH 3.50) in the ratio of 90:10 v/v. All analytes were estimated by electrochemical detection at +800 mV. The developed method has been validated as per the standard guidelines. Precision study results were found to be satisfactory, with percentage relative standard deviation for repeatability and intermediate precision <3.96 and 6.56%, respectively, for all analytes detected in rat plasma. The developed method in rat plasma was found to be simple, rapid, accurate, precise and specific. The proposed method has been successfully applied for analysis of rat plasma samples obtained during an oral pharmacokinetic study of sustained release pellets of levodopa and carbidopa in rats. Copyright © 2016 John Wiley & Sons, Ltd.     

On the metal ion selectivity of PNP-lariat ether—an insight from density functional theory calculations

The complexes of Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺, and Ca²⁺ metal cations with [N₃P₃R₄O(CH₂CH₂O)₄] (R?=?H(1), NMe₂(2), NC(NMe₂)₂(3)) PNP-lariat ethers were systematically studied in the gas phase by using density functional theory (DFT) B3LYP-D3/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) method. The gas phase cation affinities were calculated to span the wide range between 64.2 and 496.1 kcal mol^?1 in order K⁺?<?Na⁺?<?Li⁺?<?Ca²⁺?<?Mg²⁺?<?Be²⁺. The structural and electronic properties of 1–3 and their complexes were investigated and effects of electron-donor substituents were analyzed. The electron-donor substituents were found to promote the cation affinity. Sidearm coordinative interaction with the crown ether-complexed metal ion has been noticed. The nature of the metal–ligand interactions was investigated using Bader’s Quantum theory of atoms in molecule. It has been found that the Be²⁺–N bonds are partly covalent in nature while other coordinate bonds are of the electrostatic nature. The electron density at the bond critical points was found to be consistent with cation affinity. Natural bond orbital analysis was performed on the optimized geometries. The results showed that the stabilization interaction energies are caused by the donation of O/N lone pair electrons to the LP* orbitals of the metal cations. The amount of charge transfer follows the cation affinity order. The largest charge transfer and associated second-order perturbation stabilization energy were observed for Be²⁺ complexes.

     

Determination of uranium and thorium in natural waters by ICP-OES after on-line solid phase extraction and preconcentration in the presence of 2,3-dihydro-9,10-dihydroxy-1,4-antracenedion

An on-line solid phase extraction method, linked to inductively coupled plasma optical emission spectrometry (ICP-OES), has been examined using octadecyl-bonded silica cartridge for determination of low levels of uranium and thorium in aqueous samples. 2,3-dihydro-9,10-dihydroxy-1,4-anthracenedion forms a hydrophobic complex with cations and the resulted complex was retained on SPE. The retained complex was eluted using an acidic solution and introduced into ICP for determination. Various effective parameters and chemical variables such as sample pH, amount of ligand (as a complexing agent), sampling and eluting flow rates and concentration of the eluent were optimized. Under optimal conditions, calibration curves with dynamic linear ranges of 1–200 μg/L (r ₂ = 0.9999) and 1–500 μg/L (r ₂ = 0.9994) for U and Th were obtained, respectively. Detection limits based on three times of standard deviations of blank by 6 replicates were 0.69 μg/L and 0.84 μg/L for U and Th, respectively. Sample throughput was 10 samples/h. The interference effects of several metal ions on percentage of recovery of U and Th were also studied. The method was applied to the recovery and sequential determination of these actinide elements in different water samples.     

Amperometric and Conductimetric Methods for Simultaneous Determination of Captopril and Bendroflumethiazide

Abstract

The mixture of captopril (antihypertensive) and bendroflumethiazide (diuretic) was assayed using conductimetric and amperometric methods. Each method was applied for the analysis of laboratory-made sample mixtures in authentic and dosage forms. For captopril, the amperometric and conductimetric methods gave mean percent recoveries of 100.2 ± 1.2 and 99.6 ± 1.2, respectively. These results have shown good agreement when compared with other methods in the literature. When applied to bendroflumethiazide the conductimetric method gave percent recovery of 98.5 ± 1.6 which agreed closely with the spectrophotometric pharmacopoeial method.

The pK₁ for captopril was determined potentiometrically at room temperature (25°C) in aqueous medium. The calculated value, based on Henderson equation was 3.78.     

New Spectrophotometric Method for Azithromycin Determination

Abstract

Azithromycin (AZT), an antibiotic belonging to the family of macrolides, can be analyzed by a new spectrophotometric method based on the formation of an ion pair between this drug and an inorganic complex of (Mo(V)–thiocyanate) followed by its extraction with dichloroethane. This ion‐association complex shows an orange color and exhibits a maximum absorbance at 469 nm. The experimental conditions of the reaction were studied and optimized. The calibration graph was linear (r=0.9996) over the range 10^?6 M–10^?5 M of AZT. This simple and validated method has been successfully applied to the determination of azithromycin in pharmaceutical formulations with a mean relative standard deviation of 1.07% and mean recovery of 99.66%. The common excipients present in azithromycin formulations did not interfere in its determination. This new spectophotometric method has been applied successfully to illustrate the dissolution profiles of original tablets and generic compounds; hence, it could be employed in routine quality control of azithromycin in pharmaceutical dosage forms.