Simultaneous determination of ceftriaxone and streptomycin in mixture by 'ratio-spectra' 2nd derivative and 'zero-crossing' 3rd derivative spectrophotometry

Binary mixtures of antibiotics, ceftriaxone sulphate and streptomycin sodium, are assayed by 'ratio-spectra' 2nd derivative and 'zero-crossing' 3rd derivative spectrophotometry. Both procedures did not require any separation step and/or solving of equations. In the first method, calibration plots are linear up to 40mug/ml of ceftriaxone at 225, 241.5, 255.5, 255.5-241.5 and 225-241.5 nm (peak-to-peak), with r ranging from 0.9999 to 1.0000, and up to 30mug/ml of streptomycin at 206 nm, r 0.9998. Detection limits, at P = 0.05 level of significance: ceftriaxone, from 0.24 to 0.47 mug/ml (at the various wavelengths), streptomycin, 0.42 mug/ml. By the second method, lines of regression are linear up to 40 mug/ml of ceftriaxone, at 227.8 and 241.7 nm (r, 0.9999 and 1.0000) and up to 35 mug/ml of streptomycin (r, 0.9999). Detection limits were calculated to be 0.35 and 0.15 mug/ml for ceftriaxone and 0.27 mug/ml for streptomycin. Both methods were successfully applied to laboratory mixtures and to mixtures of commercial injections for these drugs.     

Simultaneous determination of tartrazine and sunset yellow by derivative spectrophotometry and ratio spectra derivative

Two methods for determining Tartrazine and Sunset Yellow in mixtures by first derivative spectrophotometry and by first derivative of the ratio spectra are described. The procedures do not require any separation step. By the first method, the measurements are obtained in the zero-crossing wavelengths and the calibration graphs are linear up to 20 microg/ml of Tartrazine and up to 40 microg/ml of Sunset Yellow. The determinations of Tartrazine and Sunset Yellow are also done by the first derivative of the ratio spectra. The methods are applied for determining both compounds in four commercial food products.     

First derivative of the ratio spectra method for resolving iodide and thiocyanate in binary mixtures

A new method is described to analyse the binary mixture of iodide (I(-)) and thiocyanate (SCN(-)) ions, using the first derivative of the ratio spectra obtained by mathematical treatment of the data. The method is based on the formation of mixed ligand complexes between benzohydroxamic acid (BHA), vanadium (V) and I(-) or SCN(-) and their extraction in ammonium quaternary salt dissolved in toluene. Calibration graphs for 2-9 mug/ml of I(-) and for 2-6 mug ml of SCN(-) were established by measuring the analytical signals at 376 nm for I(-) and at 400.6 nm for SCN(-). The method has been applied for determining both ions in waste water of an power station at ng/ml levels after a preconcentration step with C(18), without any separation step.     

A comparative study on various spectrometries with thin layer chromatography for simultaneous analysis of drotaverine and nifuroxazide in capsules

Three spectrophotometric methods including Vierordt's method, derivative, ratio spectra derivative, and thin layer chromatography (TLC)-UV densitometric method were developed for simultaneous determination of drotaverine HCl (DRT) and nifuroxazide (NIF) in presence of its impurity, 4-hydroxybenzohydrazide (4-HBH). In Vierordt's method, (E(1 cm)(1%)) values were calculated at 227 and 368 nm in the zero-order spectra of DRT and NIF. By derivative spectrophotometry, the zero-crossing method, drotaverine HCl was determined using the second derivative at 245 nm and the third derivative at 238 nm, while nifuroxazide was determined using the first derivative at 399 nm and the second derivative at 411 nm. The ratio spectra derivative spectrophotometry is basedon the measure of the amplitude at 459 nm for DRT and at 416 nm for NIF in the first derivative of the ratio spectra. Calibration graphs of the three spectrophotometric methods were plotted in the range 1-10 mug/ml of DRT and 2-20 mug/ml of NIF. TLC-UV densitometric method was achieved on silica gel plates using ethyl acetate : methanol : ammonia 33% (10 : 1 : 0.1 v/v/v) as the mobile phase. The Rf values were 0.74, 0.50, 0.30+/-0.01 for DRT, NIF and 4-HBH, respectively. On the fluorescent plates, the spots were located by fluorescence quenching and the densitometrical area were measured at 308 and 287 nm with linear range 0.2-4 mug/spot and 0.6-12 mug/spot for DRT and NIF, respectively. The proposed methods have been successfully applied to the commercial pharmaceutical formulation without any interference of excipients. Mean recoveries, relative standard deviations and the results of the proposed methods were compared with those obtained by applying the alternate methods.     

Individual and simultaneous determination of uric acid and ascorbic acid by flow injection analysis

Flow injection methods for the individual and simultaneous determination of ascorbic acid and uric acid are proposed. A spectrophotometer and a miniamperometric detector are connected in sequence. The calibration graphs for uric acid obtained by measuring its absorbance at 293 nm and its current at +0.6 V are linear up to at least 80 and 70 mug/ml, respectively, with an rsd (n = 10) of 1 % for both methods at mid-range concentrations. The calibration graph for ascorbic acid with amperometric detection is linear up to 80 mg/l. with an rsd (n = 10) of 0.8% at 30 mg/l. The simultaneous determination of uric acid and ascorbic acid is based on measurement of the absorbance of uric acid at 393 nm and amperometric determination of both analytes at +0.6 V. The average relative errors of the analysis of binary mixtures of uric acid and ascorbic acid are 2.2 and 4.2%, respectively.     

Determination of pentachlorophenol by flow-injection analysis with spectrophotometric detection

Two FIA methods for the determination of pentachlorophenol, based on its oxidizing-condensation reaction with 4-aminoantipyrine in aqueous medium and spectrophotometric detection in the conventional and stopped-flow modes, are described. In both cases the calibration graphs are linear in the range from 1.0 to 60.0 mug/ml pentachlorophenol, with sampling rates of 48 and 28 samples/hr for triplicate analysis, respectively. Interferences from phenol and other chlorophenols have been evaluated. The stopped-flow method is particularly useful for determining pentachlorophenol in commercial formulations containing no more than 15% of other chlorophenols.     

Selective and sensitive spectrophotometric determination of copper(II) and benzoylperoxide with N-ethyl-2-naphthylamine

Spectrophotometric determinations of benzoylperoxide (BPO) and copper(II) were, respectively, investigated by using the colour reaction for N-ethyl-2-naphthylamine (NENA), BPO and copper(II) as a metal ion in various concentrations of acetonitrile-water mixed solution as acidic media. The calibration graphs were linear in the range of 0-200 mug BPO with apparent molecular coefficient (epsilon) of 8.5 x 10(3)M(-1) cm(-1) at 530 nm, and 0-2.4 mug per 10 ml copper(II) with epsilon = 1.72 x 10(5)M(-1) cm(-1) at 533 nm, respectively. Additionally, the FIA method for copper(II) was proposed with NENA-BPO. The calibration graph for FIA was linear in the range of 0-7.9 ng copper(II) per 5 mul at 533 nm. These proposed methods were selective and simple in comparison with previous methods such as cuproin kinetic reactions, especially the spectrophotometry for copper(II) with NENA-BPO was very specific, and the effect of foreign ions was negligible.     

Trace determination of zinc in standard alloys, environmental and pharmaceutical samples by fourth derivative spectrophotometry using 1-2-(thiazolylazo)-2-naphthol as reagent and ammonium tetraphenylborate supported on naphthalene as adsorbent

A highly sensitive, selective, economical and rapid method for the trace determination of zinc using fourth derivative spectrophotometry has been proposed with 1-2-(thiazolylazo)-2-naphthol (TAN) as an analytical reagent and ammonium tetraphenylborate (ATPB)-naphthalene as an adsorbent. Zn-TAN is quantitatively retained on ATPB naphthalene in the pH range 6.5-9.5. The calibration plot is linear in the concentration range 0.02-1.4 mug ml(-1) Zn of DMF solution. The sensitivity of the method as determined from the slope of the calibration plot is 2.640 (d(4)A/dlambda(4))/(mug ml(-1)). Nine replicate determinations of 5.0 mug of zinc in 5 ml of DMF give a mean signal height of 2.660 (peak to peak height between lambda(1)=597 nm and lambda(2)=585 nm) with a relative standard deviation of 1.1%. The various conditions have been optimized and the developed method has been used for the determination of zinc in standard alloys, environmental and pharmaceutical samples.     

Rapid determination of zinc and iron in foods by flow-injection analysis with flame atomic-absorption spectrophotometry and slurry nebulization

A rapid method of determining zinc and iron in food by flame atomic-absorption spectrophotometry with slurry nebulization into an air-acetylene flame has been developed. A V-groove, clog-free Babington-type nebulizer, coupled to a single-line flow-injection analysis (FIA) system, was employed to introduce the slurry into the spray chamber. Under the FIA conditions described, an injection frequency of 120/hr is possible, with negligible carry-over and memory effects. The calibration graphs were obtained by using various concentrations (up to 0.1 g/ml) of white bean homogenate as standards, rather than solutions. The method has been applied to various kinds of foods, including grains, vegetables, fruits and sausage. Homogenization of semi-prepared samples to form slurries took only 4 min. Relative deviations between results by the slurry and solution methods for both elements averaged 2-3%. Detection limits by the slurry method were 0.3 mug/ml Zn and 0.6 mug/ml Fe.     

Determination of Ternary Mixtures of Vitamins by Ratio-Spectra Zero-Crossing Derivative Spectrophotometry

Abstract

The ratio-spectra zero-crossing first and third derivative spectrophotometry have been used for determining ternary mixtures of Vitamin 86, Vitamin B1 and Vitamin B12. The procedures are accurate, nondestructive and do not require solving of equations.

In both methods, calibration graphs are linear, with zero-intercept, up to 48 μg/ml of Vitamin B6, 64 μg/ml of Vitamin B1 and 60 μg/ml of Vitamin B12. Correlation coefficients range from 0.9999 to 1.0000.

Working wavelengths, 311, 272.5 and 215.5 nm, respectively, in the 1st-derivative mode and 300.5, 271.5 and 365 nm in the 3rd-derivative mode. Detection limits for each drug at p=0.01 level of significance were calculated to be 0.002, 0.009 and 0.004 μg/ml and 0.002, 0.004 and 0.001 μg/ml, in the first and third-derivative methods, respectively. Both methods apply favourably to either synthetic mixtures or commercial injections for these drugs.

An exhaustive statistical treatment of the experimental findings was performed to confirm the validity of the methods.     

Determination of diazepam and otilonium bromide in pharmaceuticals by ratio-spectra derivative spectrophotometry

Binary mixtures of diazepam and otilonium bromide are analyzed by ratio-spectra first- and second-derivative spectrophotometry. The procedures are accurate, non-destructive and do not require any separation step. Calibration graphs are linear with zero-intercept up to 50 μg/ml, r ranging from 0.9996 to 0.9999. Working wavelengths in the first- and second-derivative mode, respectively, are: diazepam 247 nm and 231 nm, otilonium bromide 262 nm and 226 nm. Limits of detection (LOD) are 0.30 and 0.12 μg/ml for diazepam and 0.063 and 0.30 μg/ml for otilonium bromide. The methods were successfully applied for determining the two drugs in laboratory mixtures and in pharmaceutical products. Received: 5 August 1996 / Revised: 16 September 1996 / Accepted: 18 September 1996     

Determination of diazepam and otilonium bromide in pharmaceuticals by ratio-spectra derivative spectrophotometry

Binary mixtures of diazepam and otilonium bromide are analyzed by ratio-spectra first- and second-derivative spectrophotometry. The procedures are accurate, non-destructive and do not require any separation step. Calibration graphs are linear with zero-intercept up to 50 μg/ml, r ranging from 0.9996 to 0.9999. Working wavelengths in the first- and second-derivative mode, respectively, are: diazepam 247 nm and 231 nm, otilonium bromide 262 nm and 226 nm. Limits of detection (LOD) are 0.30 and 0.12 μg/ml for diazepam and 0.063 and 0.30 μg/ml for otilonium bromide. The methods were successfully applied for determining the two drugs in laboratory mixtures and in pharmaceutical products. Received: 5 August 1996 / Revised: 16 September 1996 / Accepted: 18 September 1996     

Spectrophotometric multicomponent determination of sunset yellow, tartrazine and allura red in soft drink powder by double divisor-ratio spectra derivative, inverse least-squares and principal component regression methods

Double divisor-ratio spectra derivative (graphical method), classical least-squares and principal component regression (two numerical methods) methods were developed for the spectrophotometric multicomponent analysis of soft drink powders and synthetic mixtures containing three colorants without any chemical separation. The graphical method is based on the use of derivative signals of the ratio spectra using double divisor. In this method, the linear determination ranges were 2-8 mug ml(-1) sunset yellow, 4-18 mug ml(-1) tartrazine and 2-8 mug ml(-1) allura red in 0.1 M HCl. In the numerical methods, a training set was randomly prepared by using 18 samples containing between 0 and 8 mug ml(-1) of sunset yellow, 0-18 mug ml(-1) of tartrazine and 0-8 mug ml(-1) of allura red. The chemometric calibrations were calculated by using the prepared training set and its absorbances at seven points (from 375.0 to 550.0 nm) in the spectral region 325-584 nm. The proposed methods were validated by using synthetic ternary mixtures and applied to the simultaneous determination of three colorants in soft drink powders. The obtained results were statistically compared with each other.     

Flow injection spectrophotometric determination of boron in ceramic materials

A flow injection spectrophotometric method for the determination of boron in ceramic materials is described. The method is based on spectrophotometric measurement of the decrease in the pH produced by the reaction between boric acid and mannitol in the presence of an acid-base indicator. A bichannel FI (flow injection) manifold in which the sample solutions were injected into deionized water (at pH 5.4) and the stream was later merged with the reagent stream (a mannitol solution containing 1x10(-4) mol l(-1) bromocresol green at pH 5.4), was used. Transient signals were monitored at 616 nm. A theoretical model which describes the dependence between the absorbance values and boric acid concentration is presented. The model predicts a non linear dependence between the absorbance or increment in absorbance and the boric acid concentration. In contrast, the model predicts a linear dependence between the inverse of the absorbance values and the boric acid concentration. The calibration graphs (1/A vs mug ml(-1) B(2)O(3)) were linear over the range 1-30 mug ml(-1) of B(2)O(3). The relative standard deviations were 0.7 and 0.4% for 4 and 8 mug ml(-1) of B(2)O(3), respectively. The limit of detection was 0.02 mug ml(-1) of B(2)O(3) (3sigma criterium). The method was used to determine boron in nine ceramic materials with very different nominal boron compositions. The results were compared with those obtained using a potentiometric titration method as reference method. No significant differences (at 95% probability level) were found between the proposed and reference methods. The method is rapid, reliable, precise and free of interferences.     

Kinetic-spectrophotometric determination of Cu(II) and pyridine by use of the aerial oxidation of dimedone bisguanylhydrazone

The synthesis and analytical properties of dimedone bisguanylhydrazone (DIBG) are described for the first time. DIBG is oxidized by aerial oxygen and the reaction is catalysed by copper(II). The catalytic effect of copper(II) is increased by the presence of pyridine. Kinetic methods are described for determining trace amounts of copper(II) and pyridine. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 550 nm. The calibration graphs are linear in the range 0.6-9.5 mug for copper(II) and 0.2-8.8 mg for pyridine. The methods have been applied to the determination of copper in galena and of pyridine in piperidine and isoamyl alcohol. The kinetic parameters of the reaction have been determined.     

Preconcentration of trace cobalt with the ion pair of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and tetraphenylborate onto microcrystalline naphthalene or column method and its determination by derivative spectrophotometry

Cobalt-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-tetraphenylborate ion associated complex is quantitatively adsorbed on microcrystalline naphthalene in the pH range 3.5-9.5 from a fairly large volume of the aqueous samples (preconcentration factor ~30). After filtration, the solid mass consisting of the cobalt complex and naphthalene was dissolved with 5 ml of dimethylformamide (DMF) and the metal determined by first-derivative spectrophotometry. The cobalt-5-Br-PADAP complex can alternatively be quantitatively retained on ammonium tetraphenylborate-naphthalene adsorbent filled in a column (preconcentration factor 120) in the same pH range and determined similarly. The detection limit is 30 ppb (signal-to-noise ratio=2) and the calibration curve is linear over 0.3-8.0 mug of cobalt in 5 ml of the final DMF solution. Eight replicate determinations of 1.0 mug of cobalt gave a mean peak height of 0.208 (at 611.5 nm) with a relative standard deviation of 1.2%. The sensitivity of the method is 1.04 (dA/dnm) ml mug(-1) found from the slope of the calibration curve. The interference of a large number of anions and cations on the determination of cobalt has been studied and the optimized conditions developed were utilized for its trace determination in various standard alloys and biological samples.     

Determination of lamivudine and zidovudine in binary mixtures using first derivative spectrophotometric, first derivative of the ratio-spectra and high-performance liquid chromatography-UV methods

Three methods are presented for the simultaneous determination of lamivudine and zidovudine. The first method depends on first derivative UV spectrophotometry, with zero-crossing and peak-to-base measurement. The first derivative amplitudes at 265.6 and 271.6 nm were selected for the assay of lamivudine and zidovudine, respectively. The second method depends on first derivative of the ratio-spectra by measurements of the amplitudes at 239.5 and 245.3 nm for lamivudine and 225.1 and 251.5 nm for zidovudine. Calibration graphs were established for 1-50 μg/ml for lamivudine and 2-100 μg/ml for zidovudine. In the third method (HPLC), a reversed-phase column with a mobile phase of methanol:water:acetonitrile (70:20:10 (v/v/v)) at 0.9 ml/min flow rate was used to separate both compounds with a detection of 265.0 nm. Linearity was obtained in the concentration range of 0.025-50 μg/ml for lamivudine and 0.15-50 μg/ml for zidovudine. All of the proposed methods have been extensively validated. These methods allow a number of cost and time saving benefits. The described methods can be readily utilized for analysis of pharmaceutical formulations. There was no significant difference between the performance of all of the proposed methods regarding the mean values and standard deviations. The described HPLC method showed to be appropriate for simultaneous determination of lamivudine and zidovudine in human serum samples.     

Determination of gentamycin by synchronous derivative fluorimetry

Use of synchronous first-derivative fluorimetry for determination of gentamycin is described. Gentamycin reacts with acetylacetone and formaldehyde in pH 5.6 HOAc/NaOAc buffer solution to form N-gentamyl-2,6-dimethyl-3,5-diacethyl-1,4-dihydropyridine[I] which is a fluorescent substance. Spectra of [I] and the reagent blank can be separated with synchronous derivative fluorimetry, and gentamycin can be determined directly. The synchronous spectral peaks of [I] and the reagent blank are at 434 and 411 nm, respectively. The first-derivative peak of [I] is at 425 nm. Effects of pH, foreign ions, buffer system, and heating time on the determination of gentamycin have been examined. The linear regression equation of the calibration graph is C=0.0513H-0.0416, with a correlation coefficient of linear regression of 0.9978. C means total potency of gentamycin: U ml(-1); H means peak height in the linear regression equation calibration graph. The linear range for the determination of gentamycin is from 0.00 to 3.00 U ml(-1). Recovery is from 95.06 to 112.0%, R.S.D. of 3.8%. The results determined by the fluorimetric method agreed roughly with those by the microbiological method. The method is simple and has low detection limit.     

Manual and fia methods for the determination of cadmium with malachite green and iodide

A sensitive and rapid spectrophotometric method for the determination of cadmium is described, based on the formation of a blue complex at pH 4 between the anionic iodide complex of cadmium(II) and Malachite Green; the colour is stabilized with poly(vinyl alcohol). The calibration graph for measurement at 685 nm is linear over the range 1-50 mug of cadmium per 25 ml of final solution, with a relative standard deviation of +/-1.7% for 1 mug/ml cadmium. The molar absorptivity is 6.1 x 10(4) 1.mole(-1).cm(-1). The method can be successfully adapted for FIA, the peak height being proportional to the cadmium concentration over the range 0.1-3 mug/ml; a two-channel manifold is used and an improvement in selectivity is obtained. The use of a gradient tube is demonstrated to give a good calibration for Cd(II) over the range 2 x 10(-2) -2 x 10(-6)M.     

Automated determination of sulphite and sulphur dioxide by cool flame molecular emission spectrometry after reduction to hydrogen sulphide with sodium tetrahydroborate III

An automated method for the determination of sulphite and sulphur dioxide by cool flame molecular emission spectrometry is described. The method is based on the reduction of both compounds to hydrogen sulphide with sodium tetrahydroborate III. The sample which is mixed with NaBH(4) is acidified with 6M hydrochloric acid and carried by a continuous-flow stream into a gas-liquid separator where the evolved hydrogen sulphide is swept by nitrogen into a cool, hydrogen-nitrogen-entrained air flame. The intensity of the blue diatomic S(2) emission generated is measured at 384 nm. The proposed method has a detection limit for sulphite of 0.029 mug/ml and relative standard deviations of 1.2 and 1.5% for 1 and 5 mug/ml respectively. The calibration graph is linear up to 24 mug/ml sulphite and samples can be analysed at a rate of about 40/hr. The method has been applied to the determination of SO(2) in air and sulphite in wines.