HPLC determination of phenylpropanolamine in pharmaceutical OTC preparations

A convenient HPLC method to determine phenylpropanolamine (PPA) in addition to phenylephrine (PE) and chlorpheniramine (CPA) in commercially available over-the-counter (OTC) preparations has been developed. Sample solutions were prepared by dilution with water or methanol followed by filtration and direct injection into the HPLC system. The mobile phase was a mixture of methanol-acetonitrile-acetic acid (0.1 M)-triethylamine (20:20:60:0.6, v/v/v/v) containing sodium heptanesulfonate (0.5 mM) as an ion pair. The separation was achieved on a reversed-phase ODS column with detection wavelength set at 254 nm. The compounds showed good linearity in the range 2.5-1000 micro M with detection limits ranged from 0.13 to 0.48 micro M. PE, caffeine and CPA were well separated when present together with PPA. The method was applied to the determination of PPA in pharmaceutical preparations including hard and soft capsules.     

Simultaneous determination of dextropropoxyphene napsylate, caffeine, aspirin and salicylic acid in pharmaceutical preparations by reversed-phase HPLC

The official compendial method for the determination of dextropropoxyphene napsylate, caffeine, aspirin and salicylic acid involves a lengthy extraction by gas chromatography and spectrophotometry. The analytical scheme reported here provides a fast, sensitive, and stability-indicating reversed-phase HPLC assay for all these components concurrently. The total elution time is 10 min. The accuracy of the method has been tested on commercial products. The method can easily detect low levels of salicylic acid.     

An HPLC assay for the determination of ketoconazole in common pharmaceutical preparations

An HPLC method is described using octadecylsilica (3 microns) with an acetonitrile phosphate buffer mobile phase containing diethylamine which is capable of separating ketoconazole [(+/-)-cis-1-acetyl-4-(4[2-(dichlorophenyl)-2- (1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl)pi perazine] from four related compounds, (R049223, R063600, R053165 and R039519) and from excipients in tablets, cream and shampoo. The method was validated using an external calibration method for tablets, shampoo and creams and a standard addition method for cream. The limits of detection for the related compounds in the presence of ketoconazole are also reported.     

Comparison of second derivative-spectrophotometric and reversed-phase HPLC methods for the determination of prednisolone in pharmaceutical formulations.

Second derivative-spectrophotometric and high-performance liquid chromatographic methods for the determination of prednisolone in pharmaceutical formulations have been developed. Determination of prednisolone in tablets was conducted by using a second-order derivative UV spectrophotometric method at 250 nm (n = 5). Standards for the calibration graph ranging from 5.0 to 35.0 microg/ml were prepared from stock solution. The proposed method was accurate, with 98% recovery value, and precise, with a coefficient of variation (CV) of 1.38. These results were compared with those obtained by an exclusively developed isocratic reversed-phase high-performance liquid chromatography (HPLC) method. An isocratic reversed-phase Bondapak C(18) column with acetonitrile-citrophosphate buffer (pH 5; 45:55 v/v) mobile phase was used and UV detector was set to 241 nm using 11 alpha-hydroxyprogesterone as an internal standard. Calibration solutions used in HPLC were in the range from 2 to 300 microg/ml. Results obtained by derivative UV spectrophotometric method were comparable to those obtained by HPLC method, as far as analysis of variance (ANOVA) test, F(calculated), 0.762 and F(theoretical), 3.89, results were concerned.     

Development and validation of a reversed-phase column liquid chromatographic method for the determination of five cephalosporins in pharmaceutical preparations

A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters microBondapak C18 column (250 x 4.6 mm id, 10 pm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)-acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30-300, 3-30, and 15-120 microg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations.     

Development and validation of a reversed-phase ion-pair high-performance liquid chromatographic method for the determination of risedronate in pharmaceutical preparations

A stability indicating, reversed-phase ion-pair high-performance liquid chromatographic method was developed and validated for the determination of risedronate in pharmaceutical dosage forms. The determination was performed on a BDS C₁₈ analytical column (250 mm × 4.6 mm i.d., 5 μm particle size); the mobile phase consisted of 0.005 M tetrabutylammonium hydroxide and 0.005 M pyrophosphate sodium (pH 7.0) mixed with acetonitrile in a ratio (78:22, v/v) and pumped at a flow rate 1.00 mL min⁻¹. The ultraviolet (UV) detector was operated at 262 nm. The retention times of magnesium ascorbyl phosphate, which was used as internal standard and risedronate were 4.94 and 5.95 min, respectively. The calibration graph was ranged from 2.50 to 20.00 μg mL⁻¹, while detection and quantitation limits were found to be 0.48 and 1.61 μg mL⁻¹, respectively. The intra- and inter-day percentage relative standard deviations, %R.S.D., were less than 5.9%, while the relative percentage error, %E_r, was less than 0.4%. The method was applied to the quality control of commercial tablets and content uniformity test and proved to be suitable for rapid and reliable quality control.     

A simple method for simultaneous determination of basic dyes encountered in food preparations by reversed-phase HPLC

The present method utilizes a simple pretreatment step, cleanup on polyamide SPE cartridges, and HPLC resolution on reversed-phase C18 for the detection of the three basic nonpermitted dyes encountered in food matrixes. Polyamide cartridges were chosen because both acidic and basic dyes can be cleaned up due to their amphoteric nature. Analysis was performed on a reversed-phase C18 micro-Bondapak column using the isocratic mixture of acetonitrile-sodium acetate with a flow rate of 1.5 mL/min and a programmable lambda(max) specific visible detection to monitor colors, achieving higher sensitivity and expanded scope to test multicolor blends. All the colors showed linearity with the regression coefficient, from 0.9983 to 0.9995. The LOD and LOQ ranged between 0.107 and 0.754 mg/L and 0.371 and 2.27 mg/L or mg/kg, respectively. The intraday and interday precision gave good RSDs, and percentage recoveries in different food matrixes ranged from 75 to 96.5%. The study demonstrates that the use of a combination of a simple SPE cleanup and HPLC resolution with UV-Vis end point detection was successful in screening the presence of these three basic nonpermitted dyes individually or in blend, in a variety of food matrixes.     

Simultaneous determination of acetaminophen and dextropropoxyphene napsylate in pharmaceutical preparations by reverse phase HPLC

The method reported provides a fast, sensitive, accurate and reproducible reverse-phase HPLC assay for acetaminophen and dextropropoxyphene simultaneously. The total elution time is < 5 min. The method is stability-indicating since it can also determine p-aminophenol, a degradation product of acetaminophen, in a concentration as low as 0.005% of the acetaminophen concentration.     

Gravimetric method for the determination of diclofenac in pharmaceutical preparations

A gravimetric method for the determination of diclofenac in pharmaceutical preparations was developed. Diclofenac is precipitated from aqueous solution with copper(II) acetate in pH 5.3 (acetic acid/acetate buffer). Sample aliquots had approximately the same quantity of the drug content in tablets (50 mg) or in ampules (75 mg). The observed standard deviation was about +/- 2 mg; therefore, the relative standard deviation (RSD) was approximately 4% for tablet and 3% for ampule preparations. The results were compared with those obtained with the liquid chromatography method recommended in the United States Pharmacopoeia using the statistical Student's t-test. Complete agreement was observed. It is possible to obtain more precise results using higher aliquots, for example 200 mg, in which case the RSD falls to 1%. This gravimetric method, contrary to what is expected for this kind of procedure, is relatively fast and simple to perform. The main advantage is the absolute character of the gravimetric analysis.     

Polarographic determination of loratadine in pharmaceutical preparations

Loratadine, a potent antihistamine drug, is not directly electroreducible at a dropping mercury electrode; however, by means of a nitration procedure it is possible to obtain a nitro-loratadine derivative which has been identified as 4-(8-chloro-7-nitro-5,6-dihydro-11 H-benzo-[5,6]-cyclohepta-[l,2-b]-pyridin-l l-ylidene)-1-piperidine carboxylic acid ethyl ester. The electrochemical reduction of this derivative at different pHs and concentrations using polarography and cyclic voltammetry was studied. The derivative exhibits a differential pulse polarographic peak due to the reduction of the nitro group. This peak was used in order to develop an analytical procedure for determining loratadine in pharmaceutical dosage forms.

The recovery study shows adequate accuracy and precision for the developed assay and the excipients do not interfere in the determination.     

Kinetic determination of codeine in pharmaceutical preparations

A kinetic method for the determination of codeine, based on its inhibitor action on the catalytic decomposition of hydrogen peroxide by cobalt(II), is presented. It has been found that the effect of codeine is most pronounced in the presence of 5% v/v ethylene glycol. The reaction is followed photometrically. Codeine can be determined in concentrations ranging from 0.80×10^–5 M to 2.4×10^–5 M. The method has been applied to the determination of codeine in pharmaceutical preparations.     

Polarographic determination of chlorquinaldol in pharmaceutical preparations

A polarographic method for chlorquinaldol (5,7-dichloro-2-methyl-8-hydroxyquinoline) determination, based on the main cathodic wave, has been developed in acidic medium and it has been applied to pharmaceutical preparations. The obtained results show good accuracy; the relative standard deviation is ± 0.013.     

Spectrofluorimetric determination of clioquinol in pharmaceutical preparations

Summary The absorption spectrum of the nitrate radical (NO₃) in aqueous solution and the kinetic of the reactions with Cl^– and OH^– have been determined using laser-spectrometric techniques. The maximum absorption was found at 635 nm with a decadic absorption coefficient of =(530±110) l/mol·cm. At 298 K rate constants of k₁=(1.0±0.2)·10⁷ l/mol·s for the reaction with chloride and of k₂=(8.2±0.9)·10⁷ l/mol·s for the reaction with hydroxide were obtained.     

Spectrofluorimetric determination of fluoroquinolones in pharmaceutical preparations

Simple, rapid and highly sensitive spectrofluorimetric method is presented for the determination of four fluoroquinolone (FQ) drugs, ciprofloxacin, enoxacin, norfloxacin and moxifloxacin in pharmaceutical preparations. Proposed method is based on the derivatization of FQ with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 9.0 to yield a yellow product. The optimum experimental conditions have been studied carefully. Beer's law is obeyed over the concentration range of 23.5-500 ng mL(-1) for ciprofloxacin, 28.5-700 ng mL(-1) for enoxacin, 29.5-800 ng mL(-1) for norfloxacin and 33.5-1000 ng mL(-1) for moxifloxacin using NBD-Cl reagent, respectively. The detection limits were found to be 7.0 ng mL(-1) for ciprofloxacin, 8.5 ng mL(-1) for enoxacin, 9.2 ng mL(-1) for norfloxacin and 9.98 ng mL(-1) for moxifloxacin, respectively. Intra-day and inter-day relative standard deviation and relative mean error values at three different concentrations were determined. The low relative standard deviation values indicate good precision and high recovery values indicate accuracy of the proposed methods. The method is highly sensitive and specific. The results obtained are in good agreement with those obtained by the official and reference method. The results presented in this report show that the applied spectrofluorimetric method is acceptable for the determination of the four FQ in the pharmaceutical preparations. Common excipients used as additives in pharmaceutical preparations do not interfere with the proposed method.     

Colorimetric determination of pyridoxine in pharmaceutical preparations

Summary The USP method for the determination of pyridoxine hydrochloride in pharmaceutical preparations has been modified to increase the stability of the colour, the speed of determination and the sensitivity. The reaction is carried out in propan-2-ol medium instead of water triethanolamine is used as the buffer, and iodine is used as oxidant when necessary. The colour is stable for about 45 min, the sensitivity of the reaction is greatly increased and the method takes only about a fifth of the time of the USP method.

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Kolorimetrische Bestimmung von Pyridoxin in pharmazeutischen Präparaten

Zusammenfassung Die USP-Methode zur Bestimmung von Pyridoxinhydrochlorid in pharmazeutischen Präparaten wurde modifiziert, um die Beständigkeit der Farbe, die Geschwindigkeit der Bestimmung und deren Empfindlichkeit zu verbessern. Statt in Wasser wird die Reaktion in Propan-2-ol durchgeführt, wobei Triethanolamin als Puffer und Jod — wenn nötig — als Oxydationsmittel verwendet werden. Die Farbe ist ungefähr 45 min beständig, die Empfindlichkeit der Reaktion stark verbessert und die zur Durchführung der Methode erforderliche Zeit beträgt etwa ein Fünftel im Vergleich zur USP-Methode.

     

Polarographic determination of chlorhexidine in pharmaceutical preparations

The electroreduction of chlorhexidine has been studied by d.c, a.c. and pulse polarography. Polarograms of the drug recorded from ammonium acetate buffers exhibit a single well-defined wave. The current is diffusion-controlled and proportional to the concentration. The reduction wave is due to an irreversible 8-electron reduction of the four> C=NH groups in the molecule to amino groups. The drug is strongly adsorbed on the electrode surface over a considerable potential range. Hence, the drug can be determined by polarography in the presence of other weaker surfactants often present in pharmaceutical formulations. Procedures have been proposed for pulse-polarographic determination of the drug in antiseptic cream and liquids. The proposed method is simple and accurate and does not involve time-consuming separation of the drug from insoluble constituents present in the sample.     

Development and validation of a rapid reversed-phase HPLC method for the determination of insulin from nanoparticulate systems

A reversed-phase high-performance liquid chromatographic (HPLC) method has been developed and validated for the determination of insulin in nanoparticulate dosage forms. Its application for the development and characterization of insulin-loaded nanoparticulates composed of polyelectrolytes has also been carried out. A reversed-phase (RP) C18 column and gradient elution with a mobile phase composed of acetonitrile (ACN) and 0.1% aqueous trifluoroacetic acid (TFA) solution at a flow rate of 1 mL/min was used. Protein identification was made by UV detection at 214 nm. The gradient changed from 30:70 (ACN:TFA, v/v) to 40:60 (v/v) in 5 min followed by isocratic elution at 40:60 (v/v) for a further five minutes. The method was linear in the range of 1-100 microg/mL (R2 = 0.9996), specific with a good inter-day and intra-day precision based on relative standard deviation values (less than 3.80%). The recovery was between 98.86 and 100.88% and the detection and quantitation limits were 0.24 and 0.72 microg/mL, respectively. The method was further tested for the determination of the association efficiency of insulin to nanoparticulate carriers composed of alginate and chitosan, as well as its loading capacity for this protein. Encapsulant release under simulated gastrointestinal fluids was evaluated. The method can be used for development and characterization of insulin-loaded nanoparticles made from cross-linked chitosan-alginate.     

UV-densitometric method for the determination of estrogens and androgens in pharmaceutical preparations

Summary UV Densitometric Method for the Determination of Estrogens and Androgens in Pharmaceutical Preparations A convenient method for the determination of estradiol benzoate/testosterone propionate and of ethynylestradiol/methyltestosterone mixtures from ampoules and lingualets, is described. The procedure is simple since the method involves direct reading from the thin-layer plate, avoiding thus the elution of the spot.After TL Chromatographie separation of active substances, densitometric measurements were performed with a HPTL scanner at 254 nm, whereby good and precise results were obtained. The standard deviation was found to range from 0.022 to 0.183, whereas the relative standard deviation ranged from 0.93 to 2.7%.The results obtained show that the method is applicable to routine analysis.