First Derivative Spectrophotometry Research Articles

Determination of triamterene and leucovorin in biological fluids by UV derivative-spectrophotometry and partial least-squares (PLS-1) calibration.

The resolution of binary mixtures of triamterene (TAT) and leucovorin (LV) by application of first-derivative spectrophotometry and by application of Partial Least Squares calibration (PLS-1) was performed. Triamterene is determined in presence of leucovorin directly in the absorption spectra at 358 nm, and leucovorin is determined in the first-derivative spectra at 305.6 nm, zero-crossing of the triamterene. The mean recovery values in urine samples were 102 and 97% for TAT and LV, respectively. Partial Least Squares calibration (PLS-1) multivariate calibration of spectrophotometric data, have been applied to the determination of these compounds in serum and in urine without pretreatment of the samples. The absorption spectra of samples of serum or urine, spiked with triamterene and/or leucovorin, were used to perform the optimization of the calibration matrices by PLS-1 method. Mean recovery values were of 107 and 108% for TAT and LV in serum samples, and 98 and 91% for TAT and LV in urine samples.

Direct Spectrophotometric Determination of Aluminum Oxide in Portland Cement and Cement Clinker

Abstract A spectrophotometric study of the complexation reaction between Al3+ and Quinizarin (QUIN) is carried out to ascertain the suitability of the complex formed for direct spectrophotometric determination of aluminum. The absorbance at 550 nm, due to the aluminum-QUIN complex, formed at pH 3.8, is recommended for the determination of aluminum content of portland cement and cement clinker. The proposed method is simple and rapid and possesses reasonable selectivity. Interference of iron (III), generally present in portland cement, is eliminated by addition of ascorbic acid. The results obtained for several SRMs, portland cement samples, and a variety of cement materials demonstrate that the proposed method allows precise and accurate determination of Al2O3 content over the concentration range 1.4 to 5.75 μg/mL of aluminum. The determination of Al can be carried out successfully in absence of a masking agent by using first-derivative spectrophotometry. Verification and use of control charts in spectrophotometric determination of Al is achieved. Record of verifier response during routine operation establishes that the method is being maintained in statistical control.

UV-Visible First-Derivative Spectrophotometry Applied to an Analysis of a Vitamin Mixture

A simple new experiment that uses UV-vis spectrophotometry to introduce undergraduate chemistry students to multicomponent analysis is presented and a method for the simultaneous determination of three vitamins using derivative spectrophotometry (zero-crossing method) is described. The methodology is simple and easy to apply and allows the determination of folic acid, pyridoxine, and thiamine over the concentration ranges 1.02-14.28, 1.00-16.00, and 6.00-20.00 μg mL-1, respectively. The resulting errors were nearly always less than 5%.

Quantitative analysis of metronidazole in intravenous admixture with ciprofloxacin by first derivative spectrophotometry.

Metronidazole in parenteral admixture with ciprofloxacin was analysed by first-derivative spectrophotometry using the zero-crossing technique of measurement. The procedure did not require prior separation steps. The method was found to be linear (r(2)>0.999) in the range of 2.5-10 microg ml(-1) for metronidazole in absence or presence (at constant concentration) of ciprofloxacin. The first-derivative method was applied for the analysis of intravenous admixture of metronidazole and ciprofloxacin and proved to be rapid, accurate and reproducible.

An insight into the solution equilibria of magnesium(II) with purpurin and spectrophotometric determination of magnesium

The complexation equilibria of magnesium(II) with purpurin (PURP) are studied spectrophotometrically as a function of pH in 50% (v/v) ethanol–water medium at 20°C. The uncharged complex formed at pH 9.5 allows precise and accurate determination of magnesium over the concentration range 0.8–4.3 μg ml −1. The molar absorptivity of the Mg–PURP complex at 540 nm and detection limit for Mg are 9.2×10 3 l mol −1 cm −1 and 75 ng ml −1, respectively. The proposed method is rapid and possesses reasonable selectivity. Under the optimum conditions, the use of first-derivative spectrophotometry has the advantage of high sensitivity than normal spectrophotometry and allows the determination of 0.2 μg ml −1 of magnesium. The validity of the method is examined by analysing several SRM Portland cement samples and a variety of cement materials of variable magnesia content.

Simultaneous determination of phosphate and silicate in detergents and waters by first-derivative spectrophotometry

A first-derivative spectrophotometric method utilizing the zero-crossing measurement technique was developed for the simultaneous determination of phosphate and silicate in synthetic detergents and waters. Two procedures, based on the formation of phospho- and silicomolybdenum blue complexes in the presence of metol and ascorbic acid, were adopted to allow the simultaneous determination of both anions. The P concentration ranges and detection limits for the determination of phosphate in the presence of silicate utilizing the metol and ascorbic acid procedures were 0.12–1.7 and 0.07–1.2 μg mL−1 and 0.07 and 0.02 μg mL−1, respectively. The corresponding Si concentration ranges and detection limits for the determination of silicate in the presence of phosphate were 0.12–1.5 and 0.08–1.3 and μg mL−1 and 0.06 and 0.02 μg mL−1, respectively. The relative standard deviations (n = 10) were 0.86–2.8% for 0.43 μg mL−1 P and 0.5 μg mL−1 Si. The proposed procedures were evaluated by a statistical analysis of the analytical data.

Advantage of zero-crossing-point first-derivative spectrophotometry for the quantification of calcium oxalate crystalline phases by infrared spectrophotometry

The main component of urinary calculi in industrialized countries is calcium oxalate. Its detection in stones is easily performed by infrared spectrophotometry. However its two crystalline forms calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD), which are linked to different aetiologies, provide similar patterns, with overlapping vibrations leading to difficulties in differentiation and quantitation of both the phases in mixtures. Some minor but characteristic bands of each crystalline species are emphasized for analytical purposes. The method of zero-crossing-point first-derivative spectrophotometry was applied to calcium oxalate species quantitation and revealed to be easy, accurate, precise and very well adapted to routine laboratories.

Spectrophotometric Methods for the Simultaneous Determination of Metals in University Laboratories

Spectrophotometry is an analytical technique that is studied at the university level because of its ease of operation and low expense. Three different experimental methods of gradual difficulty are proposed for the application of this technique to the simultaneous determination of two metals. The techniques are applicable to the practice of all subdisciplines of experimental chemistry. These techniques are (1) absorption spectrophotometry, the determination of cobalt (II) and copper (II); (2) first-derivative spectrophotometry, the determination of chromium (III) and copper (II); and (3) first-derivative spectrophotometry using the zero-crossing method, the determination of copper (II) and mercury (II).

Direct spectrophotometric determination of aluminium oxide in Portland cement and cement clinker. An insight into the solution equilibria and analytical aspects of the aluminium–quinizarin system

A spectrophotometric study of the complexation reaction between Al3+ and quinizarin (QUIN) was carried out to ascertain the suitability of the complex formed for direct spectrophotometric determination of aluminium. The absorbance at 550 nm, due to the aluminium–QUIN complex, formed at pH 3.8, is recommended for the determination of the alumina content of Portland cement and cement clinker. The proposed method is simple and rapid and possesses reasonable selectivity. Interference of iron(III), generally present in Portland cement, is eliminated by addition of ascorbic acid. The results obtained for several SRM Portland cement samples and for a variety of cement materials demonstrate that the proposed method allows the precise and accurate determination of Al2O3 content over the concentration range 1.4–5.75 μg mL−1 of aluminium. The determination of Al can be carried out successfully in the absence of a masking agent by using first-derivative spectrophotometry. Verification and the use of control charts in the spectrophotometric determination of Al is achieved. The record of the verifier response during routine operation establishes that the method is being maintained in statistical control.

Determination of ipratropium bromide in vials using kinetic and first-derivative spectrophotometric methods

Two sensitive and accurate spectrophotometric methods are presented for the determination of ipratropium bromide (IPB). The first method, kinetic method, is based on the alkaline oxidation of IPB with KMnO 4. At a fixed time of 20 min, the formed manganate ion is measured at 608 nm. The concentration of IPB is calculated using the regression equation for the fixed-time method, at 20 min. The determination of IPB by fixed-concentration and rate-constant methods is feasible with regression equations obtained, but the fixed-time method was found to be more applicable. The second method uses first-derivative (D 1-) spectrophotometry for the determination of IPB at 254–268 nm. The applicability of the proposed methods was examined by analyzing Atrovent® unit dose vials and the percentage recoveries were 100.01±1.16, 100.02±0.97, for kinetic and D 1- methods, respectively.

Simultaneous Determination of Naphazoline Nitrate and Tetramethylthionine Base in Eye Drops by First-Derivative UV Spectrophotometry

ABSTRACT A rapid first-derivative spectrophotometric method for the simultaneous determination of naphazoline nitrate and tetramethylthionine base in eye drops by using zero-crossing measurements is described. Solutions of this drug combination in water were analysed by measurement of the amplitudes at 257.2 and 247.5 nm, respectively. Good linearity, accuracy, precision and selectivity were found, and the method is proposed for routine quality control purposes.

UV-spectrophotometric determination of ampicillin sodium and sulbactam sodium in two-component mixtures

A simple spectrophotometric method is used for the resolution of the binary mixtures of ampicillin sodium and sulbactam sodium. In aqueous solution, zero-order spectra are subject to interference, so first-derivative spectrophotometry was used to enhance the spectral details allowing the determination of ampicillin sodium from the signal at the zero-crossing point for sulbactam sodium at 268 nm. In 0.1 N sodium hydroxide, sulbactam sodium was determined from the absorbance at 260 nm with negligible contribution from ampicillin sodium. Also, sulbactam sodium was determined without interference using first- and second-derivative spectra in 0.1 N sodium hydroxide at 276 nm (peak-height) and 262–284 nm (peak-to-peak), respectively. The method is rapid, simple, does not require a separation step and allows the determination of each drug without interference from the other. The proposed method has been applied successfully to the assay of these drugs in mixtures and in commercial injections.

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 μg of cobalt in 5 ml of the final DMF solution. Eight replicate determinations of 1.0 μg 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 (d A/d nm) ml μg −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.

Zero-Crossing Derivative Spectrophotometric Determination of Mercury(II) And Palladium(II) with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1-3-thiazolidine and Cetyltrimethylammonium Bromide

A method is proposed for the simultaneous determination of mercury(II) and palladium(II) by first-derivative spectrophotometry based on the absorption spectra of their complexes with 5-(3,4-Methoxyhydroxyphenylmethylene)-2-thioxo-1,3-thiazolidine [5-(3,4-methoxyhydroxybenzylidene) rhodanine]. Zero-crossing measurement technique is found suitable for the measurement of the first-derivative value at the specified wavelengths. Mercury(II) (0.4-1.4 μg ml−1) and palladium(II) (0.08 - 1.8 μg ml−1) in different ratios have been determined simultaneously. A critical evaluation of the proposed method is performed by statistical analysis of the experimental data.

Determination of piroxicam and its major metabolite 5-hydroxypiroxicam in human plasma by zero-crossing first-derivative spectrophotometry

A zero-crossing first-derivative spectrophotometric method for the determination of piroxicam and its major metabolite 5-hydroxypiroxicam (5-HP) in human plasma is described. This technique permits the quantification of compounds with closely overlapping spectral bands without any separation step. The method consists of direct extraction of the less-ionised forms of piroxicam and 5-hydroxypiroxiam with pure diethyl ether. First derivative values at 343.5 and 332.5 nm for piroxicam and 5-HP, respectively, were obtained. The absolute recovery of the method was found to be 89.4% for piroxicam and 90.3% for 5-HP. Calibration graphs are linear ( r better than 0.9998), with zero-intercept, in the concentration range 0.5–12.0 μg ml −1 for both compounds. The limits of quantification attained according to the IUPAC definition were 0.29 and 0.27 μg ml −1 for piroxicam and 5-HP, respectively. The results obtained by the proposed method were in good agreement with those found by the high-performance liquid chromatographic method (HPLC).

Simultaneous determination of dextromethorphan HBr and bromhexine HCl in tablets by first-derivative spectrophotometry

A rapid, simple and direct assay procedure based on first-derivative spectrophotometry, using a zero-crossing and peak-to-base measurement at 234 and 324 nm, respectively, has been developed for the specific determination of dextromethorphan HBr and bromhexine HCl in tablets. Calibration graphs were linear with the correlation coefficients of 0.9999 for both analytes. The limit of detections were 0.033 and 0.103 μg ml −1 for dextromethorphan HBr and bromhexine HCl, respectively. A HPLC method has been developed as the reference method. The results obtained by the first-derivative spectrophotometry were in good agreement with those found by the HPLC method.

First-derivative spectrophotometric determination of ponceau 4R, sunset yellow and tartrazine in confectionery products

A first-derivative spectrophotometric method was developed for quantitative determination of synthetic organic dyes, Ponceau 4R (E124), Sunset Yellow (E110) Tartrazine (E102), which are used in food products under governmental regulations all over the world because of their toxicity and carcinogenity. In this study, Ponceau 4R with Sunset Yellow, and Tartrazine with Sunset Yellow, were simultaneously determined in their binary mixtures by first-derivative spectrophotometry. The method was applied to different sugar confectionery products. Recoveries were 93.8–101.2%, 92.1–107.9% and 94.9–99.2% for Ponceau 4R, Sunset Yellow and Tartrazine, respectively. The results were also compared by an independent method, thin layer chromatography (TLC). A t-test indicates that the differences obtained via the present methods and TLC were insignificant at the 95% confidence level. In addition, the present method is very rapid, economical and accurate.

Application of the bivariate spectrophotometric method for the determination of metronidazole, furazolidone and di-iodohydroxyquinoline in pharmaceutical formulations

The bivariate calibration algorithm was applied to the spectrophotometric determination of metronidazole, furazolidone and di-iodohydroxyquinoline in pharmaceutical dosage forms. The results obtained were compared with the results of derivative spectrophotometry. The statistical evaluation of method bias was carried out, and it was shown that the proposed procedure may be competitive with commonly used first-derivative spectrophotometry. The advantage of the bivariate calibration is its simplicity, and the fact that there is no need to use the derivatization procedures.

Determination of Triamcinolone Acetonide in Ointment by UV Derivative Spectrophotometry and High Performance Liquid Chromatography

Triamcinolone acetonide in ointment was determined by first-derivative ultraviolet spectrophotometry and by high performance liquid chromatography. The UV derivative spectrophotometric method eliminated the interference of the ointment excipients when the determination was made at 274 nm, Δλ = 4 nm, scan speed of 300 nm/min, and ordinate settings ±0.050. The correlation coefficient and the relative standard error of the estimate were, respectively, 0.9999 and 0.39%. The coefficient of variation and the recovery average were 0.48 and 99.77%, respectively. The chromatographic methods were standardized using a LiChrospher® 100 RP-18 (5μm) in LiChroCART® (125-4) column, UV detection at 254 nm and mobile phases consisting of: (1) acetonitrile-water (35:65 v/v) and (2) methanol-water-96% acetic acid (55:44:1 v/v), apparent pH 3.0. The peak area response versus concentration was linear at a concentration range from 10.0 to 100.0 μg/mL. The correlation coefficients and the relative standard errors of the estimate were 0.9995, 1.84% and 0.9998 and 1.14% for methods 1 and 2, respectively. The coefficients of variation and the recovery averages were 0.66%, 99.84% and 0.60%, 99.36% for methods 1 and 2, respectively.

Simultaneous determination of tartrazine and sunset yellow in cosmetic products by first-derivative spectrophotometry

A spectrophotometric method for the simultaneous determination of Tartrazine (TT) and Sunset Yellow (SY) in cosmetic products has been developed. An extraction process was carried out using methylene chloride and the colouring matters were measured in the aqueous phase formed, the other components of the sample remaining in the organic phase. The applicable concentration ranges were 0.5–10 ug/ml TT and 0.5–12 μg/ml SY. The detection limits were 26 and 11 ng/ml and the relative standard deviations were 1.0 and 0.9% for TT and SY, respectively. The method was applied to the determination of both compounds in cosmetics.