First-order Derivative Spectrophotometry Research Articles

Determination of Astaxanthin in Haematococcus pluvialis by First-Order Derivative Spectrophotometry

A highly selective, convenient, and precise method, first-order derivative spectrophotometry, was applied for the determination of astaxanthin in Haematococcus pluvialis. Ethyl acetate and ethanol (1:1, v/v) were found to be the best extraction solvent tested due to their high efficiency and low toxicity compared with nine other organic solvents. Astaxanthin coexisting with chlorophyll and beta-carotene was analyzed by first-order derivative spectrophotometry in order to optimize the conditions for the determination of astaxanthin. The results show that when detected at 432 nm, the interfering substances could be eliminated. The dynamic linear range was 2.0-8.0 microg/mL, with a correlation coefficient of 0.9916. The detection threshold was 0.41 microg/mL. The RSD for the determination of astaxanthin was in the range of 0.01-0.06%; the results of recovery test were 98.1-108.0%. The statistical analysis between first-order derivative spectrophotometry and HPLC by T-testing did not exceed their critical values, revealing no significant differences between these two methods. It was proved that first-order derivative spectrophotometry is a rapid and convenient method for the determination of astaxanthin in H. pluvialis that can eliminate the negative effect resulting from the coexistence of astaxanthin with chlorophyll and beta-carotene.

Spectrophotometric simultaneous determination of Tenofovir disoproxil fumarate and Emtricitabine in combined tablet dosage form by ratio derivative, first order derivative and absorbance corrected methods and its application to dissolution study

Three simple, economical, precise, and accurate methods are described for the simultaneous determination of Tenofovir disoproxil fumarate (TE) and Emtricitabine (EM) in combined tablet dosage form. The first method is ratio derivative spectra, second is first-order derivative spectrophotometry and third is absorption corrected method. The amplitudes at 271.07 and 302.17nm in the ratio derivative method, 224.38 and 306.88nm in the first order derivative method were selected to determine Tenofovir disoproxil fumarate (TE) and Emtricitabine (EM), respectively, in combined formulation. Beer's law is obeyed in the concentration range of 3-21μ/ml for TE and 2-14μ/ml for EM for first two methods and range for third method was 6-30μ/ml of TE and 4-20μ/ml of EM. The percent assay for commercial formulation was found to be in the range 98.91%–101.72% for both the analytes by the proposed three methods. Absorption corrected method was successfully applied to carry out dissolution study of commercial tablet formulation by using USP II dissolution test apparatus. The methods were validated with respect to linearity, precision, and accuracy. Recoveries by proposed methods were found in the range of 99.06 %-101.34 % for both the analytes.

Competitive biosorption of Yellow 2G and Reactive Brilliant Red K-2G onto inactive aerobic granules: Simultaneous determination of two dyes by first-order derivative spectrophotometry and isotherm studies

This study focused on the competitive biosorption of Yellow 2G (Y2G) and Reactive Brilliant Red K-2G (RBR) by inactive aerobic granules in binary solutions. A first-order derivative spectrophotometric method for the simultaneous determination of Y2G and RBR in binary solutions was developed. Dubinin–Raduskevich (D–R) isotherm successfully predicted the biosorption of Y2G and RBR in both single and binary solutions. However, none of the tested binary adsorption isotherms could realistically represent the biosorption equilibrium data. Maximum biosorption capacity calculated from D–R isotherm for Y2G and RBR in single solution was 58.50 and 66.18 mg g −1, respectively; in binary solutions, for Y2G it decreased to 40.38 mg g −1, but for RBR it increased to 171.21 mg g −1, showing their synergism and antagonistic interactions. The FTIR results indicated the main functional groups on aerobic granules for biosorption of Y2G and RBR would be amine, hydroxyl, carboxyl and either.

Simultaneous Determination of the Textile Dyes in Industrial Effluents by First-Order Derivative Spectrophotometry

A first-order derivative spectrophotometric method for the simultaneous determination of three textile dyes, Procion Yellow HE4R, Procion Red HE7B and Remazol Black 5 (RB5), has been developed. The effects of pH, heating and ionic strength of the solution on the absorption spectra of the dyes were investigated. The wavelengths selected for the measures of the derivative signals of HE4R (395 nm), HE7B (604 nm) and RB5 (659 nm) presented these coefficients of linear correlation: 0.9978, 0.9992 and 0.9999, and these detection limits: 0.180, 0.317 and 0.0233 mg L(-1), respectively. The reliability and reproducibility of the method were tested and showed recovery values of 95.7 to 109%. The proposed method was applied for the determination of dyes in binary and ternary mixtures of textile effluents and showed an estimate of the loss of dyes for the effluents between 6.67 and 28.9%.

Determination of Nebivolol Hydrochloride and Hydrochlorothiazide in Tablets by First-Order Derivative Spectrophotometry and Liquid Chromatography

Two simple and accurate methods for analysis of nebivolol hydrochloride (NEB) and hydrochlorothiazide (HCTZ) in their combined dosage forms were developed using first-order derivative spectrophotometry and reversed-phase liquid chromatography (LC). NEB and HCTZ in their combined dosage forms (tablets) were quantified using first-derivative responses at 294.6 and 334.6 nm in the spectra of their solutions in methanol. The calibration curves were linear in the concentration range of 8-40 microg/mL for NEB and 10-60 microg/mL for HCTZ. LC analysis was performed on a Phenomenex Gemini C18 column (250 x 4.6 mm id, 5 microm particle size) in the isocratic mode with 0.05 M potassium dihydrogen phosphate-acetonitrile-methanol (30 + 20 + 50, v/v/v; pH 4) mobile phase at a flow rate of 1 mL/min. Detection was made at 220 nm. Both of the drugs and the internal standard (ezetimibe) were well resolved with retention times of 5.1 min for NEB, 2.9 min for HCTZ, and 8.2 min for ezetimibe. The calibration curves were linear in the concentration range of 1-14 microg/mL for NEB and 0.3-28 microg/mL for HCTZ. Both methods were validated and found to be accurate, precise, and specific, and results were compared statistically. Developed methods were successfully applied for the estimation of NEB and HCTZ in their combined dosage forms.

Simultaneous Determination of Nickel and Copper by H-Point Standard Addition MethodFirst-Order Derivative Spectrophotometry in Plant Samples After Separation and Preconcentration on Modified Natural Clinoptilolite as a New Sorbent

For the simultaneous determination of nickel(ll) and copper(ll) in plant samples, a rapid and accurate method was developed. In this method, solid-phase extraction (SPE) and first-order derivative spectrophotometry (FDS) are combined, and the result is coupled with the H-point standard addition method (HPSAM). Compared with normal spectrophotometry, derivative spectrophotometry offers the advantages of increased selectivity and sensitivity. As there is no need for carrying out any pretreatment of the sample, the spectrophotometry method is easy, but because of a high detection limit, it is not so practical. In order to decrease the detection limit, it is suggested to combine spectrophotometry with a preconcentration method such as SPE. In the present work, after separation and preconcentration of Ni(ll) and Cu(ll) on modified clinoptilolite zeolite that is loaded with 2-[1-(2-hydroxy-5-sulforphenyl)-3-phenyl-5-formaza-no]-benzoic acid monosodium salt (zincon) as a selective chromogenic reagent, FDS-HPSAM, which is a simple and selective spectrophotometric method, has been applied for simultaneous determination of these ions. With optimum conditions, the detection limit in original solutions is 0.7 and 0.5 ng/mL, respectively, for nickel and copper. The linear concentration ranges in the proposed method for nickel and copper ions in original solutions are 1.1 to 3.0 x 10(3) and 0.9 to 2.0 x 10(3) ng/mL, respectively. The recommended procedure is applied to successful determination of Cu(ll) and Ni(ll) in standard and real samples.

First-order Derivative Spectrophotometry for the Determination of Vitamin C in Medicament

Abstract A novel method for the determination of vitamin C(Vc) is proposed in this article. After the reaction with Folin-Ciocalteau reagent at ambient temperature, Vc solution was scanned at 750—1100 nm, and its first-order derivative spectrum were obtained from the original spectrum. The values of derivative selected at 995 nm were used for determination. It was proved that Vc could quickly react with Folin-Ciocalteau reagent within 5 min and the product was quite stable for a long time. The conditions required for this method is not very complicated, its precision and accuracy are similar to those of the iodometric titration described in Chinese Pharmacopoeia, and the limit of detection is 0.312 μg/mL. The determination of the results of vitamin C tablet, pill, and injection demonstrates that this method has wide pharmaceutical applications.

Simultaneous Determination of N-Butylscopolamine and Oxazepam in Pharmaceutical Formulations by First-Order Digital Derivative Spectrophotometry

A simple method has been developed for the simultaneous determination of N-butylscopolamine bromide and oxazepam in pharmaceutical formulations using first-order digital derivative spectrophotometry. Acetonitrile was selected as the solvent in which both compounds showed well-defined bands. Both analytes showed good stability in this solvent when solutions of the analytes were exposed to light and temperatures between 20 degrees and 80 degrees C. The simultaneous determination of both drugs was performed by the zero-crossing method at 226.0 and 257.0 nm for N-butylscopolamine and oxazepam, respectively. The linear range of determination was found to be 2.5 x 10(-7) to 8.0 x 10(-5) mol/L for N-butylscopolamine and 7.1 x 10(-8) to 8.0 x 10(-5) mol/L for oxazepam. A very good level of repeatability (relative standard deviation) of 0.2% was observed for N-butylscopolamine and oxazepam. The ingredients commonly found in pharmaceutical formulations do not interfere. The proposed method was applied to the determination of these drugs in pharmaceutical formulations (capsules).

Individual and Simultaneous Spectrophotometric Determination of Dapsone and Metoclopramide HCl in Pharmaceutical Dosage Forms and Synthetic Binary Mixtures

A rapid, sensitive and selective spectrophotometric method has been developed for the quantitative determination of dapsone (DAP) and metoclopramide hydrochloride (MCP) in both pure and dosage forms. Individual and simultaneous methods are based on the diazo coupling reaction of these drugs with benzoylacetone (BAC) in alkaline medium. The resulting azo dyes exhibit maximum absorption at 437 and 411 nm with a molar absorptivity of 4.14x10(4) and 2.97x10(4) l mol-1 cm-1 for DAP and MCP, respectively. Simultaneous determination of DAP and MCP was developed utilizing first-order digital derivative spectrophotometry. All variables have been optimized. No interferences were observed from drug excipients and the validity of the methods was tested against reference methods.

Pyrocatechol violet as a marker to characterize liposomal membrane permeability using the chelation and the first-order derivative spectrophotometry

Pyrocatechol violet (PV), a chelating agent for cupric ions was used to characterize liposomal membrane permeability. After cupric ions were added to PV liposomes, free PV turned into its chelate (PV-Cu), and encapsulated PV kept stable since liposomal membranes prevented metal ions from permeating. After the light scattering background of liposomes and the absorbance of PV were eliminated by the first-order derivative spectrophotometric method, PV-Cu i.e. free PV in liposome suspensions could be determined without separation. The released PV from liposomes could also be determined. Because PV release is relevant to liposomal membrane permeability, PV becomes a marker to characterize the membrane permeability. This new method was simple, rapid, sensitive, and was used to measure the temperature-dependent liposomal membrane permeability in this paper. Dipalmitoylphosphatidylcholine (DPPC) and soybean lecithin liposomes showed the peaks of release at 40 °C and 39 °C, respectively.

First-order UV-derivative spectrophotometry in the analysis of omeprazole and pantoprazole sodium salt and corresponding impurities

The first-order UV-derivative spectrophotometry, applying zero-crossing method was developed for the determination of omeprazole (OM), omeprazole sulphone (OMS), pantoprazole sodium salt (PANa), and N-methylpantoprazole (NPA) in methanol–ammonia 4.0% v/v, where the sufficient spectra resolutions of drug and corresponding impurity were obtained, using the amplitudes 1D 304, 1D 307, 1D 291.5 and 1D 296.5, respectively. Method showed good linearity in the ranges (μg ml −1): 1.61–17.2 for OM; 2.15–21.50 for OMS; 2.13–21.30 for PANa and 2.0–20.0 for NPA, accuracy and precision (repeatability and reproducibility). The experimentally determined values of LOD (μg ml −1) were 1.126; 0.76; 0.691 and 0.716 for OM, OMS, PANa and NPA, respectively. The obtained values of 2.91% w/w for OMS and 3.58% w/w for NPA in the presence of their parent drug, by applying the method of standard additions, point out the usage of the proposed method in stability studies. Zero-crossing method in the first-order derivative spectrophotometry showed the impurity–drug intermolecular interactions, due to the possible intermolecular hydrogen bonds, confirmed by divergences of experimentally obtained amplitudes for impurities OMS and NPA in comparison to expected values according to regression equations of calibration graphs.

Simultaneous Determination of Dapsone and Pyrimethamine by Derivative Spectrophotometry in Pharmaceutical Formulations

A simple and fast method was developed for the simultaneous determination of dapsone and pyrimethamine by first-order digital derivative spectrophotometry. Acetonitrile was used as a solvent to extract the drugs from the pharmaceutical formulations, and the samples were subsequently evaluated directly by digital derivative spectrophotometry. The simultaneous determination of both drugs was performed by the zero-crossing method at 249.4 and 231.4 nm for dapsone and pyrimethamine, respectively. The best signal-to-noise ratio was obtained when the first derivative of the spectrum was used. The linear range of determination for the drugs was from 6.6 x 10(-7) to 2.0 x 10(-4) and from 2.5 x 10(-6) to 2.0 x 10(-4) mol/L for dapsone and pyrimethamine, respectively. The excipients of commercial pharmaceutical formulations did not interfere in the analysis. Chemical and spectral variables were optimized for determination of both analytes. A good level of repeatability, 0.6 and 1.7% for dapsone and pyrimethamine, respectively, was observed. The proposed method was applied for the simultaneous determination of both drugs in pharmaceutical formulations.

Zero- and First-Order Derivative Spectrophotometry for Individual and Simultaneous Determinations of Copper(II) and Palladium(II) Using an Oxazolidine Derivative as a New Reagent.

A new oxazolidine derivative was synthesized as a reagent for individual and simultaneous determinations of Cu(II) and Pd(II) using zero- and first-order derivative spectrophotometry. 5-Imino-3-(p-methoxyphenyl)-2-methyloxazolidin-4-thione (PMOX) formed colored complexes with these metal ions in aqueous and micellar media containing cetylpyridi-nium bromide. The first-derivative spectra of these complexes permitted a simultaneous determination of Cu(II) and Pd(II) in concentration intervals 0.27 - 2.35 and 0.43 - 4.26 μg ml 1 at zero-crossing wavelengths of 412 and 376 nm, respectively. The influence of the experimental conditions, the ionization constant of the reagent and the stoichiometry of the complexes are reported. The methods were free from any interference of a large number of other metal ions. A critical evaluation of the proposed methods was performed by a statistical analysis of the experimental data. The methods have been applied to determine copper in steel, aluminum-, and nickel-base alloys and to the determination of palladium in activated charcoal.

Rapid, selective, direct and derivative spectrophotometric determination of titanium with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone

A simple and sensitive spectrophotometric method is developed for the determination of titanium in aqueous medium. The metal ion forms a reddish brown coloured complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range 1–7. The complex shows two absorption maxima, one at 430 nm and the other at 500 nm. The reagent shows appreciable absorbance of 430 nm and negligible absorbance at 500 nm at pH 1.5. Beer's law is obeyed in the range 0.09 to 2.15 μg ml −1 of titanium(IV). The molar absorptivity and the Sandell's sensitivity of the method are 1.35 × 10 4 1 mol −1 cm −1 and 0.0049 μg cm −2, respectively. A method for the determination of titanium by first-order derivative spectrophotometry is also proposed. The methods have been employed successfully for the determination of titanium in several alloy and steel samples.

Simultaneous determination of copper, mercury and lead by first-order derivative spectrophotometry using dithizone as reagent

A first-order derivative spectrophotometric method has been developed for the simultaneous determination of copper, mercury and lead at μg/L levels using dithizone as reagent. The procedure involves the simultaneous extraction of these elements by dithizone in chloroform from weakly alkaline solutions. Linear calibration curves were obtained in the ranges 0.5–10 (Cu), 1–10 (Hg) and 1–10 (Pb) μg present in 40 ml of aqueous phase with detection limits of 5 μg/L (Cu) and 20 μg/L (Hg and Pb). The R.S.D.s for 100 μg/L of copper, mercury and lead were 2.5, 2.6 and 3.1% respectively, for 5 determinations. The method is applicable for the determination of copper and lead in marine sediment samples with good precision and accuracy.

Digital Derivative Spectrophotometric Determination of Micro Amounts of Iron with 1,10-Phenanthroline

Abstract Digital first-order derivative spectrophotometry was applied to the determination of iron with 1,10-phenanthroline. Under the recommended conditions, a linear relationship was confirmed between the first-derivative value and the iron concentration. The present method gives accurate results for iron, ranging from 1.6×10−7 to 8×10−5 mol dm−3 (8.9 μg dm−3–4.5 mg dm−3). The relative standard deviations for the determination of 4.8×10−5, 4.8×10−6, and 4.8×10−7mol dm−3 of iron(III) were 0.37, 0.38, and 0.93%, respectively. The effects of 63 diverse ions were examined. The present method was applied to the determination of iron in practical samples, i.e., river water, waste water and sea water.