Determination In Pharmaceutical Preparations Research Articles

Spectrophotometric and fluorimetric determination of diazepam, bromazepam and clonazepam in pharmaceutical and urine samples

New spectrophotometric and fluorimetric methods have been developed to determine diazepam, bromazepam and clonazepam (1,4-benzodiazepines) in pure forms, pharmaceutical preparations and biological fluid. The new methods are based on measuring absorption or emission spectra in methanolic potassium hydroxide solution. Fluorimetric methods have proved selective with low detection limits, whereas photometric methods showed relatively high detection limits. Successive applications of developed methods for drugs determination in pharmaceutical preparations and urine samples were performed. Photometric methods gave linear calibration graphs in the ranges of 2.85–28.5, 0.316–3.16, and 0.316–3.16 μg ml −1 with detection limits of 1.27, 0.08 and 0.13 μg ml −1 for diazepam, bromazepam and clonazepam, respectively. Corresponding average errors of 2.60, 5.26 and 3.93 and relative standard deviations (R.S.D.s) of 2.79, 2.12 and 2.83, respectively, were obtained. Fluorimetric methods gave linear calibration graphs in the ranges of 0.03–0.34, 0.03–0.32 and 0.03–0.38 μg ml −1 with detection limits of 7.13, 5.67 and 16.47 ng ml −1 for diazepam, bromazepam and clonazepam, respectively. Corresponding average errors of 0.29, 4.33 and 5.42 and R.S.D.s of 1.27, 1.96 and 1.14 were obtained, respectively. Statistical Students t-test and F-test have been used and satisfactory results were obtained.

Trimipramine determination in pharmaceutical preparations with an automated multicommutated reversed-flow system

In this work an automated multicommutated flow methodology was implemented for the spectrophotometric determination of trimipramine in pharmaceutical preparations by oxidation with ammonium monovanadate in acidic medium. The developed procedure exploits a new approach for sample/reagent intermixing by combining binary sampling with flow-reversal. Rather than inserting the sample as a single continuous volume the intercalation of multiple small sample and reagent aliquots, under a time-based control, created multiple reaction interfaces that promoted reaction zone homogenisation even in limited dispersion conditions. Additionally, the reaction interfaces were reversed, increasing mutual zone penetration, which contributed to a faster reaction development while assuring a low dispersion pattern. A linear range of determination was verified for trimipramine concentrations between 1.0 and 18.0 μg ml −1 with a relative standard deviation ( n=10) lower than 1.69% and a sample throughput of about 26 samples per hour. The results were in agreement with those obtained by the reference procedure with relative deviations lower then 2.37%.

Simple determination of propranolol in pharmaceutical preparations by heavy atom induced room temperature phosphorescence

The applicability of heavy atom induced room temperature phosphorescence in real samples is demonstrated in this work. In this methodology only two reagents, potassium iodide as heavy atom salt and sodium sulphite as oxygen scavenger, were used to obtain phosphorescent signal of propranolol in solution. Thus a new simple, rapid and selective phosphorimetric method is proposed for propranolol determination in pharmaceutical preparations. The phosphorescence intensity was measured at 492 nm exciting at 294 nm. Phosphorescence was fully developed instantly, obtaining a linear concentration range between 0 and 500 ng ml −1 with a detection limit of 14.4 ng ml −1, an analytical sensitivity of 6.7 ng ml −1 and a standard deviation of 1.4% at a 300 ng ml −1 concentration level. The method has been successfully applied to the analysis of propranolol in an antidepressive pharmaceutical preparation and it was validated using standard addition methodology.

Drug-selective electrode for ketamine determination in pharmaceutical preparations and electrochemical study of drug with BSA

Ion-selective membrane electrode to the drug ketamine hydrochloride has been constructed using a modified PVC membrane which has ionic end-groups as ion-exchanger sites and which was cast using plasticized with ortho-nitrophenyloctyl ether ( o-NPOE) as plastisizer. This drug electrode show excellent Nernstian responses (59 mV per decade) in the concentration range 1×10 −5–1×10 −2 M with a detection limit of 5×10 −6 M. Response time was about 10 s for ketamine concentrations between 1×10 −5 and 1×10 −2 M. The response is not affected by pH between 4 and 8.5. Selectivity coefficients against various organic and inorganic cations were evaluated. The electrode was applied for determination of ketamine hydrochloride in pharmaceutical preparations using direct potentiometry. The drug electrode has also been used to study the interaction of bovine serum albumin (BSA) with ketamine in buffer solution (phosphate, pH 7). The saturated quantities of ketamine binding were 114, 32 and 25 mol/mol in 0.01, 0.02 and 0.1% of protein, respectively. The Hill equations were applied to obtain co-operative drug bindings to BSA at 27 °C.

Room-temperature luminescence optosensings based on immobilized active principles actives: Application to nafronyl and naproxen determination in pharmaceutical preparations and biological fluids

This paper presents two easy and selective methods for determining the active principles nafronyl (NFL) and naproxen (NAP), using a flow-through fluorescence optosensor based on the on-line immobilization on a nonionic-exchanger (Silica Gel, Davisil™ and Amberlite XAD 7, respectively) solid support. The determination was performed in 5×10 −3 M HAc/NaAc buffer solution at pH 5 for NFL and 15×10 −3 M glycine/HCl buffer solution at pH 2.5 for NAP at a working temperature of 20 °C. The fluorescence intensities were measured at λ ex/em=294/336 nm and λ ex/em=332/354 nm for NFL and NAP, respectively. The response time for these optosensors were practically instant, obtaining a linear concentration range between 0 and 700.0 ng ml −1 with a detection limit of 20.8 ng ml −1, an analytical sensitivity of 10.1 ng ml −1 and a standard deviation of 1.27% at a 500 ng ml −1 concentration level for NFL and a linear concentration range between 0 and 200.0 ng ml −1 with the detection limit of 13.3 ng ml −1, an analytical sensitivity of 6.0 ng ml −1 and a standard deviation of 3.52% at a 100 ng ml −1 concentration level for NAP. The proposed methods were satisfactorily applied to real samples (three commercial formulations and urine samples). The effects of the possible interferences were evaluated in all cases.

Electrochemical behavior of thiamine on a self-assembled gold electrode and its square-wave voltammetric determination in pharmaceutical preparations.

The electrochemical behavior of thiamine on a self-assembled electrode of L-cysteine (Cys/SAM/Au) has been investigated and Cys/SAM/Au can be used to detect thiamine using square-wave voltammetry (SWV). At pH 11.40 Britton-Robinson buffer, thiamine exhibits a well-defined anodic peak on Cys/SAM/Au. Under the optimized conditions, the anodic peak current of SWV was linear with the content of thiamine in the range of 1.1 x 10(-8) - 2.2 x 10(-6) mol/L; the detection limit was 5.5 x 10(-9) mol/L. The method was successfully applied to the determination of thiamine in pharmaceutical preparations.

Flow‐Injection Analysis of Dopamine in Injections with a Periodate‐Selective Electrode

Dopamine determination in pharmaceutical preparations based on its oxidation with periodate (IO4−) using a new IO4−‐selective electrode under flow conditions is presented. An electrode with a tubular configuration, no internal reference solution, and a PVC (31.2%) membrane, with metaperiodate bis(triphenylphosphoranylidene)ammonium (1.3%) as ion exchanger and 2‐nitrophenyloctylether (67.5%) as mediator solvent, was used. Optimization procedures were directed at potentials versus dopamine readings instead of potential versus the remaining IO4−. This approach was achieved by selecting a 50‐cm reactor and an overall flow of 7 mL/min, and injecting 70 μL of dopamine standards in a 3.0 × 10−4 M IO4− solution. Under these conditions, a linearity range of 8.0 × 10−3 to 2.7 × 10−1 g/L, with a slope of 310.1 ± 7.4 mV L g−1 and a reproducibility of ±0.4 mV, were recorded (n = 8). Interference from common excipients was negligible. Under these conditions, analysis of dopamine injections (n = 12) presenting 200 mg/injection gave average and standard deviation values of 201.0 and 3.3 mg/injection, respectively. A simple and inexpensive flow‐injection analysis (FIA) manifold, with a good potentiometric detector, enabled the analysis of 200 samples/h without requiring pretreatment procedures. Comparison with the dopamine injection analysis in the United States Pharmacopoeia monograph showed good accuracy, with a relative deviation of −0.2%. © 2000 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 89: 876–884, 2000

Voltammetric and EQCM Studies on Selenium(IV) at Mercury, Gold and Glassy Carbon Electrodes in the Presence of Cu(II), Au(III), Pb(II) and Cd(II)

Cyclic voltammetry (CV), adsorptive stripping voltammetry (AdSV) and electrochemical quartz crystal microbalance (EQCM) were employed to study the behavior of selenium(IV) at the mercury, gold and glassy carbon electrodes. Optimum measurement parameters and stock solution compositions were established. Selenium(IV) was studied in the presence of copper, gold, lead and cadmium ions. At the glassy carbon electrode, selenium and gold were found to be too slightly electroactive to be determinable. However, in view of the copious release of Se-Au in the EQCM experiment involving the gold electrode, a voltammetric procedure was developed to determine the two elements. Peak current intensities recorded in relation to a Se(IV)/Au(III) mixture concentration yielded a linear relationship over the concentration ranges 3–9 μg mL−1 Se in the presence of 10 μg mL−1 Au, over 3–6 μg mL−1 Au in the presence of 10 μg mL−1 Se, and over 4–10 μg mL−1 Se(IV) in the presence of 16 μg mL−1 Cu(II). Statistical analysis of the results obtained showed the procedures to be useful for determining Se(IV) and Au(III) at the glassy carbon electrode with a satisfactory accuracy and precision. In AdSV method a control growth mercury drop electrode (CGMDE) was used as the working electrode and 0.1 mol L−1 HClO4 solution containg Cu(II) as supporting electrolyte. This method was applied to selective Se(IV) determination in pharmaceutical preparations (tablets) after microwave digestion. The results obtained by AdSV were compared with those obtained by AAS method. Nickel nitrate was used as a modifier in AAS method. The procedure developed enables selenium to be determined quantitatively with a satisfactory accuracy and precision in multicomponent tablets with no need for isolating it from the matrix.

High-performance liquid chromatographic assay for the determination of paracetamol, pseudoephedrine hydrochloride and triprolidine hydrochloride

The different UV absorption characteristics of paracetamol, pseudoephedrine hydrochloride and triprolidine hydrochloride have been used to facilitate their determination in pharmaceutical preparations by HPLC. The method developed involves isocratic, reversed-phase chromatography. A ‘wavelength switching’ programme is preferred to the use of a compromise wavelength for all three compounds. This gives reasonable UV responses despite widely different UV characteristics and concentrations of drugs. The limits of quantitation are found to be within 200–700 μg ml −1 for paracetamol, 24–84 μg ml − for pseudoephedrine HCl and 1–4 μg ml − for triprolidine HCl. The method performs well in terms of precision and accuracy as indicated by linear regression analysis.

Electroanalytical study of sulphamerazine at a glassy-carbon electrode and its determination in pharmaceutical preparations by HPLC with amperometric detection

An electroanalytical study of the oxidation of sulphamerazine at a glassy-carbon electrode has been made by use of different voltammetric techniques. The limiting current is diffusion-controlled, at pH 7.0, for sulphamerazine in the concentration range 2.0 × 10 −5−1.0 × 10 −4 M. The limits of determination found for differential pulse voltammetry at a stationary electrode and at a rotating electrode were 5.9 × 10 −6 and 3.3 × 10 −6 M respectively. A reversed-phase HPLC method with amperometric detection for the analysis of sulphamerazine, sulphadiazine and phthalylsulphathiazole mixtures has been developed, and applied to a commercial pharmaceutical preparation.

Electroanalytical study of sulphadiazine at solid electrodes. Determination in pharmaceutical preparations

An electroanalytical study of the sulphadiazine oxidation process at solid electrodes using different voltammetric techniques was carried out. Limiting current is diffusion-controlled in the concentration range studied. dpv at a glassy carbon electrode allows the determination of sulphadiazine within the range 1.5 × 10 −5−6.0 × 10 −5 mol l −1. The dpv method was applied to determine sulphadiazine in a commercial pharmaceutical preparation.

Benzocaine Determination in Pharmaceutical Preparations

Abstract A new sensitive method for rapid and accurate determination of benzocaine via hydroxamic acid formation is described. The solution of hydroxylamine hydrochloride is reacted with benzocaine in alkaline medium to give corresponding hydroxamic acid (II) which forms the purple coloured complex with FeCl3 in acidic medium, having a maximum absorbance at 530 nm. The commonly present additives such as Tyrothricin, Propylene glycol, Glycerin do not show any interference except Quiniodochlor whose interference was eliminated by extracting it with alcohol and removal of waxy substances with a mixture of water and HCL (17.5 :2.5).

Fluorescence properties of domperidone and its determination in pharmaceutical preparations

The native fluorescence characteristics of domperidone in various solvents and at different pH values are reported. The fluorophore is the benzo-1,3-diazolin-2-one group which is also present in the analogous benperidol, droperidol and pimozide molecules from which domperidone is derived; the substituent may therefore be considered as a relatively strong fluorophore; its excitation and emission maxima are little influenced by pH variation. Domperidone can be determined in pharmaceutical preparations by its native fluorescence in ethanol (λ ex = 283 nm ;λ em = 324 nm) and in 0.01 M HCl (λ ex = 284 nm;λ em = 329 mn) with a detection limit of 0.01 μg ml -1.

Reversed-phase High-performance Liquid Chromatographic Investigation of Levodopa Preparations II: Levodopa Determination

A reversed-phase high-performance liquid chromatographic procedure with UV detection at 280nm is presented for levodopa determination in pharmaceutical preparations. The method is fast and specific for levodopa in the presence of its most likely impurities and degradation products.

Determination of Pharmaceutical Preparations by Gas Chromatography. V. Determination of Chlorpheniramine Maleate and dl-Methylephedrine Hydrochloride using a Nitrogen Selective RbCl-Alkali Flame Ionization Detector

Determination of Pharmaceutical Preparations by Gas Chromatography. V. Determination of Chlorpheniramine Maleate and dl-Methylephedrine Hydrochloride using a Nitrogen Selective RbCl-Alkali Flame Ionization Detector

GLC Determination of Hexadiphane in Pharmaceutical Preparations

AbstractA specific, rapid, and sensitive GLC method for purity control of hexadiphane and its determination in pharmaceutical preparations is described. The method utilizes an extraction of the free base, followed by GLC on a 0.5% OV-17 column at isothermal temperature for 6 min and then the temperature was programmed. Results from this method and from a titrimetric method were compared, and no significant differences were found.

Determination of Pharmaceutical Preparations by Gas Chromatography. II. Determination of β-Hydroxybutylic Acid-p-phenetidide, Ethoxybenzamide and Caffeine in Antipyretic Preparations

β-Hydroxybutyric acid-p-phenetidide (B), ethoxybenzamide (EB), and caffeine in antipyretic preparations were determined by gas-liquid chromatography with hydrogen flame ionization detector on a 2-m column of 1.3% Epon resin at 165°. B was changed to trimethylsilyl derivative by using a silyl reagent consisting of hexamethylidisilazane and trimethylchlorosilane. EB was slightly affected by using hexamethyldisilazane : trimethylchlorosilane (8 : 2) directly. Then the reagent was diluted withte trahydrofuran : chloroform (1 : 1) mixture and the effect can be eliminated. Determination was made successfully by the internal standard method using phenanthrene.

Determination of Pharmaceutical Preparations by Gas Chromatography. III. Determination of Acetylsalicylic Acid, Phenacetin and Caffeine

Acetylsalicylic acid, phenacetin, and caffeine in antipyretic preparations were determined by gasliquid chromatography with hydrogen flame ionization detector on 2-m column of 8% SE-52, at 170°. Acetylsalicylic acid was changed to trimethylsilyl derivative at room temperature by using hexamethyldisilazane and trimethylchlorosilane. Determination was made successfully by the internal standard method using dibutyl phthalate.

Determination of Pharmaceutical Preparations by Gas Chromatography. IV. Determination of Al-acetylsalicylic Acid Preparations

Aluminium-acetylsalicylic acid (Asp-Al), phenacetin, caffeine, and acetaminophen were determined by gas-liquid chromatography with hydrogen flame ionization detector on a 2-m column of 10% QF-1, at 170°. i) For Asp-Al, phenacetin, and caffeine preparations, mixture of these three was added to 40 ml of 0.5% sodium fluoride solution (0.2N HCl) at room temperature. After 20 min, only Asp-Al was decomposed to acetylsalicylic acid, and acetylsalicylic acid, phenacetin, and caffeine were extracted with chloroform. The solvent was evaporated from the extract on a water bath and the cooled residue was silanized. ii) For Asp-Al, AA and caffeine preparations, AA and caffeine were extracted with chloroformacetone (1 : 1) mixture, and the residue which contains Asp-Al was added to 40 ml of 0.5% sodium fluoride solution (0.2N HCl) at room temperature. After 20 min, acetylsalicylic acid was extracted with chloro-form. This chloroform solution was mixed with the former chloroform-acetone solution, and this was evaporated on a water bath. The cooled residue was silanized. Determination was made successfully by the internal standard method using dipropyl phthalate.