Simultaneous determination of carvedilol and ampicillin sodium by synchronous fluorimetry

The carvedilol and ampicillin sodium were simultaneously determined by the synchronous fluorimetry. With excitation wavelength at 254 nm, the maximum emission wavelengths of carvedilol and ampicillin sodium were at 357 and 426 nm, respectively. Because the emission spectra of carvedilol and ampicillin sodium were overlapped partially, carvedilol and ampicillin sodium cannot be determined directly by normal fluorimetric method. However, the synchronous fluorimetry can be used for determining both drugs simultaneously without separation procedure. The (Delta)(lambda) = 80 nm was used. Iso-propanol was selected as sensing reagent. Effects of pH, organic solvents and foreign ions on the determination of both drugs were studied. The linear relationship was obtained between the relative fluorescence intensity and concentration of carvedilol and ampicillin sodium in the range of 0.005-0.1 and 5.0-70.0 microg ml(-1), respectively. The linear regression equation of calibration graph for carvedilol is C = 0.000151F - 0.00210, and for ampicillin sodium is C = 0.0770F - 2.62. The correlation coefficient of linear regression equation is 0.9995 for carvedilol and 0.9998 for ampicillin sodium, respectively. The detection limit is 1 ng ml(-1) for carvedilol and 1 microg ml(-1) for ampicillin sodium. The relative standard deviations of carvidelol and ampicillin sodium are 2.47 and 1.61%, respectively. The recovery is from 96.0 to 103.0% for carcvedilol and from 98.0 to 105.0% for ampicillin sodium. This method was rapid, simple and highly sensitive for the determination of carvedilol and ampicillin sodium without pre-separation. The results obtained by this method agreed with those by the official methods. This method can be used for the determination of carvedilol and ampicillin sodium in the medicine dosage.     

Spectrophotometric determination of dapsone in pharmaceutical products using sodium 1,2-naphthoquinone-4-sulfonic as the chromogenic reagent

Spectrophotometric determination of dapsone is described. The dapsone reacts with sodium 1,2-naphthoquinone-4-sulfonic in pH 6.98 buffer solution to form a salmon pink compound, and its maximum absorption wavelength is at 525 nm, epsilon525=3.68 x 10(4) l mol(-1) cm(-1). The absorbance of dapsone from 0.40 to 10 microg ml(-1) obeys Beer's law. The linear regression equation of the calibration graph is C=0.2334 A + 0.01288, with a linear regression correlation coefficient of 0.9998, the detection limit is 0.24 microg ml(-1), and recovery is from 99.2 to 102.4%. Effects of pH, surfactant, organic solvents, foreign ions, and standing time on the determination of dapsone have been examined. This method is simple and can be used for the determination of dapsone in injection solution of dapsone. The results obtained by this method agreed with those by the official method (dead-stop titration method [The Chinese Pharmacopoeia, Pharmacopoeia Commission, Ministry of Health, vol. 2, fifth ed., PRC Chemical Industry Press, Beijing, 2000, p.720]).     

Spectrophotometric determination of procaine hydrochloride in pharmaceutical products using 1,2-naphthoquinone-4-sulfonic acid as the chromogenic reagent

Spectrophotometric determination of procaine hydrochloride is described. The procaine hydrochloride reacts with 1,2-naphthoquinone-4-sulfonic acid in pH 3.60 buffer solution to form a salmon pink compound, and its maximum absorption wavelength is at 484 nm, epsilon(484)=5.22 x 10(3).The absorbance for procaine hydrochloride from 0.30 to 100 microg ml(-1) obeys Beer's law. The linear regression equation of the calibration graph is C=19.23A-0.03, with a linear regression correlative coefficient is 0.9996, the detection limit is 0.28 microg ml(-1); recovery is from 98.0 to 105.2%. Effects of pH, surfactant, organic solvent, foreign ions, and standing time on the determination of procaine hydrochloride have been examined. This method is rapid and simple, and can be used for the determination of procaine hydrochloride in injection solution of procaine hydrochloride. The results obtained by this method agreed with those by the official method (dead-stop titration).     

A novel spectrophotometric method for the determination of aminophylline in pharmaceutical samples in the presence of methanol

A rapid, simple and sensitive method for the determination of aminophylline (Ami) using sodium 1, 2-naphthoquine-4-sulfonate (NQS) and methanol is established in this paper. It is based on the fact that a russety product can be formed by the reaction between aminophylline (Ami) and sodium 1, 2-naphthoquine-4-sulfonate (NQS) in pH 13.00 buffer solution. When methanol is added to the solution, the sensitivity of the color development reaction between Ami and NQS is improved, and the color of the system of NQS-Ami becomes a salmon pink. Beer's law is obeyed in a range of 4.97-69.5 microg ml(-1) of Ami at the maximum absorption of 453 nm (epsilon=4.87 x 10(3) l mol(-1) cm(-1)). The linear regression equation of the calibration curve is A=0.14458+0.00832C (microg ml(-1)), with a linear regression correlation coefficient of 0.9944. The detection limit is 0.7 microg ml(-1) (3sigma/k), R.S.D. is 1.1% and the recovery rate is in range of 92.5-105%. Furthermore, this method has been successfully applied to the determination of Ami in pharmaceutical samples.     

Study of the sensitization of tetradecyl benzyl dimethyl ammonium chloride for the color development reaction between lysine and sodium 1,2-naphthoquinone-4-sulfonate and the determination of lysine in pharmaceutical and biological samples

A rapid, simple and sensitive method for the determination of lysine (Lys) using sodium 1,2-naphthoquinone-4-sulfonate (NQS) and tetradecyl benzyl dimethyl ammonium chloride (Zeph) is presented in this paper. The method is based on the russety product formed from Lys, NQS and Zeph in a buffer solution of pH 9.60, and the stoichiometric ratio of the product is 1:2:2. Beer's law is obeyed in a range of 0.09-18 microg ml(-1) of Lys at the maximum absorption of 474 nm (epsilon(474) is 8.1 x 10(5)l mol(-1)cm(-1)). The equation of linear regression is A=0.40427+0.06112C, with a linearly correlation coefficient of 0.9972. The limit of detection is 0.07 microg ml(-1), R.S.D. 0.8%, and average recovery rate in a range of 98.9-100.1%. This paper further optimizes the determination of Lys compared with the previous methods, and the reaction mechanism is studied intensively. The proposed method has been successfully applied to the determination of Lys in pharmaceutical and biological samples. The common components as nutritional additives in pharmaceuticals and other compounds in biological samples nearly do not interfere with the proposed method.     

Indirect determination of ampicillin sodium with sodium nitrate-ammonium thiocyanate-water system by extraction-flotation of cuprous thiocyanate

A novel method for indirect determination of ampicillin sodium by the extraction-flotation is proposed in this paper. It is indicated that the degradation of ampicillin sodium took place in the presence of 0.30 M sodium hydroxide in boiling water for 20 min. At pH 4.0, in the presence of ammonium thiocyanate, the thiol group of the degradation product of ampicillin sodium could reduce copper(II) to copper(I) due to the formation of the emulsion cuprous thiocyanate precipitation. By determining the residual amount of copper(II) in the solution and calculating the flotation yield of cuprous thiocyanate, the indirect determination of ampicillin sodium can be performed. When the concentration of cooper(II) was 5.0 μg/mL, a good linear relationship was obtained between the flotation yield of cuprous thiocyanate and the amount of ampicillin sodium in the range of 0.40～9.6 μg/mL. The linear equation is E = 4.1469 + 3.7949c with the correlation coefficient r = 0.9992, and the detection limit (3σ/K) of 0.37 μg/mL. Each parameter has been optimized and the reaction mechanism has been studied. The method has been successfully applied to the determination of ampicillin sodium in pharmaceutical, human plasma and urine samples. Analytical results obtained are satisfactory.     

Simultaneous determination of carvedilol and ampicillin sodium by first-derivative fluorometry in the presence of human serum albumin.

A sensitive and selective method for the simultaneous determination of carvedilol and ampicillin sodium (AS) in the presence of human serum albumin (HSA) is described. The maximum emission wavelengths of carvedilol and AS are at 357 nm and 426 nm with excitation at 254 nm, respectively. The first-derivative peaks of carvedilol and AS were at 337 nm and 398 nm, respectively. The linear-regression equations of the calibration graphs of carvedilol and AS were C = 0.0001H - 0.0063 and C = 1.530H - 43.84; the correlation coefficients were 0.9990 and 0.9986, respectively. The detection limits were 1 ng ml(-1) for carvedilol and 23 microg ml(-1) for AS, respectively. The effects of the pH, the stability of carvedilol and AS and foreign ions on the determination of carvedilol and AS were examined. The recoveries of carvedilol and AS were measured. This method is simple and can be used for the determination of carvedilol and AS in human serum and urine samples with satisfactory results.     

Flow injection chemiluminescence analysis of some penicillins by their sensitizing effect on the potassium permanganate-glyoxal reaction.

A new chemiluminescence method using flow injection is described for the determination of four penicillins, namely: phenoxymethylpenicillin potassium, amoxicillin, ampicillin, and ampicillin sodium. The method is based on sensitizing effect of these drugs on the chemiluminescence reaction of potassium permanganate in sulfuric acid with glyoxal. The different experimental parameters affecting the chemiluminescence intensity were carefully studied and incorporated into the procedure. The method allows the determination of 0.1-1.0 microg/ml phenoxymethylpenicillin potassium, 0.1-1.0 microg/ml amoxicillin, 0.1-1.0 microg/ml ampicillin, and 0.1-1.0 microg/ml ampicillin sodium. The method was successfully applied to the determination of four penicillin antibiotics in pharmaceutical preparations.     

Determination of dextran sulfate sodium with crystal violet by triple-wavelength overlapping resonance Rayleigh scattering

A triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS) method was developed to detect dextran sulfate sodium (DSS) with crystal violet (CV). At pH 10.0 Britton Robinson buffer solution medium, the interaction of CV with DSS occurred which greatly enhanced the RRS intensity with the new RRS peaks appearing at 340, 501 and 671 nm and all these three peaks enhanced with the increase of DSS concentration in the range of 0.04-2.5 microg ml(-1) and the detection limit for the three single peaks was 0.024, 0.027, and 0.027 microg ml(-1), respectively, whereas that of the TWO-RRS method was 0.013 microg ml(-1). The TWO-RRS method was found to have much better flexibility and high sensitivity than the single-wavelength method. In this paper, the interaction conditions were optimized. The affecting factors and characteristics of RRS for the interaction of DSS with CV were investigated and a sensitive method for the determination of trace amounts of DSS using the TWO-RRS method was developed.     

Spectrofluorimetric determination of Er (III) with diantipyrylmethane

The optimum fluorescence conditions for erbium (III) are obtained by irradiating this lanthanide at 435 nm in 0.04 microg ml(-1) diantipyrylmethane solution at pH = 8 (lambdaem = 510 nm). The method proposed is satisfactory for the determination of erbium (III) in the range of 0.001 to 1 microg ml(-1). The relative standard deviation 0.02 microg ml(-1) Er (III) in 0.04 microg ml(-1) diantipyrylmethane solution is 1.1%. The effect of other rare earths upon the intensity of the fluorescence emitted by erbium (III) is discussed.     

Study on fluorescence property of carvedilol and determination of carvedilol by fluorimetry

The property of carvedilol in acid-alkaline medium was studied by spectrofluorimetry. Effects of organic solvents on carvedilol fluorescence spectra were examined and the reason was discussed. A simple, rapid and high sensitive fluorimetric method for the determination of carvedilol in medicine is developed. The measurement of relative fluorescence intensity was carried out at 356 nm with excitation at 254 nm. Effects of pH, standing time and foreign ions on the determination of carvedilol have been examined. A linear relationship was obtained between the relative fluorescence intensity and concentration of carvedilol in the range of 0.50-270 ng ml(-1). The linear regression equation of the calibration graph is C = 0.000543F - 0.002 (C is concentration (microg ml(-1)) and F is relative fluorescence intensity in the equation), with a correlation coefficient of linear regression of 0.9998 and relative standard deviation of 2.31%. The detection limit of this method is 0.19 ng ml(-1), and recovery is from 98.70 to 102.1%. This method can be used for determination of carvedilol in tablet. The results obtained by this method agreed with those by the official method.     

Rapid determination of chromium(VI) in electroplating waste water by use of a spectrophotometric flow injection system

A new rapid and sensitive FI method is reported for spectrophotometric determination of trace chromium(VI) in electroplating waste water. The method is based on the reaction of Cr(VI) with sodium diphenylamine sulfonate (DPH) in acidic medium to form a purple complex (lambda(max) = 550 nm). Under the optimized conditions, the calibration curve is linear in the range 0.04-3.8 microg ml(-1) at a sampling rate of 30 h(-1). The detection limit of the method is 0.0217 microg ml(-1), and the relative standard deviation is 1.1% for eight determinations of 2 microg ml(-1) Cr(VI). The proposed method was applied to the determination of chromium in electroplating waste water with satisfactory results.     

Separation of rutin nona(H-) and deca(H-) sulfonate sodium by ion-pairing reversed-phase liquid chromatography

Ion-pairing reversed-phase liquid chromatography (RPLC) was used to separate two polysulfonates, rutin nona(H-) sulfonate sodium and rutin deca(H-) sulfonate sodium, which have very similar chemical structures. The final product always contained both of them when one of the compounds was synthesized. Baseline separation was achieved on a C8-bonded silica column at ambient temperature. The eluent was acetonitrile-15 mM phosphate buffer solution containing 20 mM TBA (pH 6.0) (46:54, v/v). The calibration plot was linear in the concentration range 0.5-200 microg ml(-1) for both analytes. The limits of detection (LODs; 254 nm) were 0.03 microg ml(1-) for rutin nona(H-) sulfonate sodium and 0.04 microg ml(-1) for rutin deca(H-) sulfonate sodium. Three batches of rutin deca(H-) sulfonate sodium were analyzed using the assay; the results showed that the analytical performance is really satisfactory.     

Study of methanol catalyzed reaction between sodium 1,2-naphthoquine-4-sulfonate and hydroxyl ion and its application in the determination of methanol

A novel and simple spectrophotometric method for the direct determination of methanol with 1,2-naphthoquinone-4-sulfonate (NQS) is developed in this paper. It is based on the fact that methanol can catalyze the reaction between 1,2-naphthoquinone-4-sulfonate and hydroxyl ion to form 2-hydroxy-1,4-naphthoquinone in buffer solution of pH 13.00. Beer's law is obeyed in a range of 0.26-15.8 mg/ml at the maximal absorption wavelength of 454 nm. The equation of linear regression is A = 0.01998 + 0.05944C (mg/ml), with a linear regression correlation coefficient of 0.9977. The detection limit is 0.25mg/ml (3sigma/k), while R.S.D. is 2.0% and the recovery rate is in a range of 96.5-103%. The detailed mechanism for the formation of the products is proposed and discussed.     

Quantitative analysis of rabeprazole sodium in commercial dosage forms by spectrophotometry

The main aim of this work is to develop and validate two spectrophotometric methods for the quantitative analysis of rabeprazole sodium in commercial dosage forms. Method A is based on the reaction of drug with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of ammonium cerium(IV) nitrate in acetic acid medium at room temperature to form red-brown product which absorbs maximally at 470 nm. Method B utilizes the reaction of rabeprazole sodium with 1-chloro-2,4-dinitrobenzene (CDNB) in dimethyl sulfoxide (DMSO) at 45+/-1 degrees C to form yellow colored Meisenheimer complex. The colored complex has a characteristic band peaking at 420 nm. Under the optimized reaction conditions, proposed methods are validated as per ICH guidelines. Beer's law is obeyed in the concentration ranges of 14-140 and 7.5-165 microg ml(-1) with linear regression equations of A=6.041 x 10(-4)+1.07 x 10(-2)C and A=1.020 x 10(-3)+5.0 x 10(-3)C for methods A and B, respectively. The limits of detection for methods A and B are 1.38 and 0.75 microg ml(-1), respectively. Both methods have been applied successfully for the estimation of rabeprazole sodium in commercial dosage forms. The results are compared with the reference UV spectrophotometric method.     

Spectrophotometric determination of aminomethylbenzoic acid using sodium 1,2-naphthoquinone-4-sulfonate as the chemical derivative chromogenic reagent

A new method has been established for the determination of aminomethylbenzoic acid using sodium 1,2-naphthoquinone-4-sulfonate as the chemical derivative chromogenic reagent. This method is based on the formation of a pink compound from the reaction of aminomethylbenzoic acid and sodium 1,2-naphthoquinone-4-sulfonate. The nucleophilic substitution reaction proceeds quantitatively in pH 12.0 buffer solution. The stoichiometric ratio of the reaction, maximum absorption wavelength and the value of epsilon(430) were 1:1, 430 nm, and 2.87 x 10(3)L mol(-1)cm(-1), respectively. Beer's law was obeyed in the range of 0.80-80 mg/L of aminomethylbenzoic acid. The data have been filled to a linear regression equation A=0.03183+0.01658C (mg/L), with a correlation coefficient of 0.9996. The detection limit is 0.11 mg/L, R.S.D. is 0.54%, and average recovery is over 99.6%. This paper further improves the determination of aminomethylbenzoic acid compared to the previous methods. The kinetic property and reaction mechanism have also been discussed. This proposed method has been successfully applied to the determination of aminomethylbenzoic acid in injection of aminomethylbenzoic acid with satisfactory results.     

A facile spectrophotometric method for cobalt determination using alpha-benzilmonoxime in sodium dodecylsulfate micellar solutions.

Alpha-benzilmonoxime in sodium dodecylsulfate micellar media has been used for the spectrophotometric determination of cobalt at pH 9.0. The linear range of calibration is 0.05-1.50 microg cm(-3) of cobalt at 380 nm with molar absorptivity of 3.72 x 10(4) dm3 mol(-1) cm(-1), which is about 1.5-times greater than that of the alpha-benzilmonoxime extraction based method. The relative standard deviations, recoveries, detection limit and effects of diverse ions on the determination of cobalt were studied. These analytical results were satisfactory. The method was successfully applied to the determination of cobalt in the various samples.     

Fluorimetric trace determination of cerium(III) with sodium triphosphate

Sodium triphosphate acts as a specific reagent for enhancing the fluorescence intensity of cerium(III). The purpose of this study was to investigate the spectrofluorimetric determination of trace amounts of Ce(III) in sodium triphosphate solution. The excitation and emission wavelengths are 303.5 nm and 353 nm respectively. Optimum sodium triphosphate concentration is found to be 0.074 g l(-1) at room temperature. The fluorescence varies linearly with the concentration of cerium(III) in the range 0.001-45 mug ml(-1). The detection limit is 9.4 x 10(-4)mug ml(-1). The relative standard deviations for 30 mug ml(-1) and 0.05 mug ml(-1) Ce(III) in 0.074 g l(-1) sodium triphosphate solution are 1.1% and 0.72% respectively. Quenching effects of other lanthanides and some inorganic anions are described. This method is a direct and rapid analytical method for the determination of Ce(III) in rare earth mixtures and cerium concentrates.     

Determination of nickel with 2-(2-quinolylazo)-5-diethylaminoaniline as a chromogenic reagent.

A sensitive, selective and rapid method for the determination of nickel based on a rapid reaction of nickel(II) with 2-(2-quinolylazo)-5-diethylaminoaniline (QADEAA) has been developed. In the presence of pH = 6.0 ammonia-ammonium chloride buffer solution and sodium dodecyl sulfonate (SDS) medium, QADEAA reacts with nickel to form a violet complex having a molar ratio of 1:2 (nickel to QADEAA). The molar absorptivity of the complex is 1.38 x 10(5) l mol(-1) cm(-1) at 595 nm. Beer's law is obeyed in the range of 0.01-0.4 microg/ml. This method had been applied to the determination of nickel with good results.     

The determination of trace lead in Chinese medicinal herbs by flow injection analysis in polyethyleneglycol medium

In this work, a new flow injection analysis (FIA) for the determination of Pb(2+) in Chinese medicinal herbs was developed. In the buffer solution of borax-NaOH (pH 10.5), Pb(2+) reacted with 2-[(5-bromo-2-pyridyl)-azo]-5-(diethyl-amino)phenol (5-Br-PADAP) to form a complex. The experimental results showed that the sensitivity was enhanced in the presence of polyethyleneglycol-800 (PG-800). The main factors affecting the determination were investigated in detail. Under the optimum conditions, the linear range and detection limit is 0.0-0.3microg/mL and 1.5ng/mL (correlation coefficient r=0.9996), respectively. The linear regression equation is A=-0.005+0.60c (microg/mL). The sample throughout is 10h(-1). Foreign substrates effects were also investigated. The proposed method has been successfully applied to the determination of lead in reference material, goldthread and lepidium seed.