Determination Of Micro Amounts Research Articles

Highly selective second order derivative spectrophotometry for simultaneous determination of nickel (ii) and cobalt (ii) using 2-ketobutyric acid thiosemicarbazone

A simple and highly selective second order derivative spectrophotometric method is proposed for the simultaneous determination of Ni(II) and Co(II) using 2-ketobutyric acid thiosemicarbazone (KBAT) as a sensitive complexing reagent. KBAT forms green and pink color complexes with nickel and cobalt at pH range of 8-11 and 5-10 respectively. Molar absorptivities of Ni-KBAT (1.55 × 104 L cm-1 mol-1 ) and Co-KBAT (1.03 × 104 L cm-1 mol-1 ) were obtained at 330 nm, under optimum pH of 9.5. Calibration graphs for the individual determination by second order derivative spectrophotometry were obtained. Beer’s law was obeyed at 369.8 nm for Ni(II) and 410 nm for Co (II) in the concentration ranges 0.30-2.34 μg mL-1 Ni and 0.33-2.65 μg mL-1. The zero crossing point at 369.8 nm for nickel and the amplitude measurement at 410 nm for cobalt were employed in the simultaneous determinations. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of nickel and cobalt in various steel alloys and biological sample.

Highly sensitive spectrophotometric methods for the determination of olanzapine

Highly sensitive and selective spectrophotometric methods (A and B) were developed for the determination of micro amounts of olanzapine (OLZ). Method A (direct method) is based on the oxidation of olanzapine with a known excess of iodine monochloride (ICl) in an acidic medium. Under the same condition, thymol blue was iodinated by unreacted ICl, and the absorbance of uniodinated thymol blue was measured at 536 nm. The decrease in ICl concentration is a measure of drug concentration. In method B (indirect method), oxidation of OLZ by a known excess of Ce(IV) in sulfuric acid medium followed by the reaction of unreacted Ce(IV) with leuco crystal violet (LCV) to crystal violet (CV), which is measured in an acetate buffer medium ( pH 4.9) at 580 nm. These methods obey the Beer’s law in the concentration range of 0.2-1.6 μg mL-1 (method A) and 0.1-1.4 μg mL-1 (method B). The developed procedures have been successfully applied to the determination of OLZ in pure and in dosage forms. The results exhibit no interference from the presence of excipients. The reliability of the methods was established by parallel determination of OLZ against the reference method.

Highly sensitive spectrophotometric methods for the determination of olanzapine

Highly sensitive and selective spectrophotometric methods (A and B) were developed for the determination of micro amounts of olanzapine (OLZ). Method A (direct method) is based on the oxidation of olanzapine with a known excess of iodine monochloride (ICl) in an acidic medium. Under the same condition, thymol blue was iodinated by unreacted ICl, and the absorbance of uniodinated thymol blue was measured at 536 nm. The decrease in ICl concentration is a measure of drug concentration. In method B (indirect method), oxidation of OLZ by a known excess of Ce(IV) in sulfuric acid medium followed by the reaction of unreacted Ce(IV) with leuco crystal violet (LCV) to crystal violet (CV), which is measured in an acetate buffer medium ( pH 4.9) at 580 nm. These methods obey the Beer's law in the concentration range of 0.2-1.6 µg mL-1 (method A) and 0.1-1.4 µg mL-1 (method B). The developed procedures have been successfully applied to the determination of OLZ in pure and in dosage forms. The results exhibit no interference from the presence of excipients. The reliability of the methods was established by parallel determination of OLZ against the reference method.

A highly sensitive spectrophotometric determination of micro amounts of vanadium(V) in environmental and alloy samples by using 3,4-dihydroxybenzaldehydeisonicotinoylhydrazone (3,4-DHBINH)

3, 4-Dihydroxybenzaldehydeisonicotinoylhydrazone was prepared, characterized with spectral analyses and used for developing a new method for the simple, sensitive and rapid spectrophotometric determination of vanadium(V) which gives maximum absorbance at wave length 360 nm. The metal ion gives a yellow colored complex with 3, 4-DHBINH in acetate buffer of pH 5.5 with 1:1 (metal:ligand) composition. The method obeys Beer's law in the range 0.5-5.3 microg mL(-1) of vanadium(V). The molar absorptivity and Sandell's sensitivity were found to be 1.29 x 10(4) L mol(-1) cm(-1) and 0.003949 microg cm(-2) respectively. The correlation co-efficient of the V(V)-3, 4-DHBINH complex was 0.992 which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD) as 0.424% (n = 5), and its detection limit 0.01677 microg mL(-1) of vanadium(V). The instability constant of the method was calculated by Asmus' method as 4.1666 x 10(-3). The interfering effect of various cations and anions were also studied. The proposed method was successfully applied to the determination of vanadium(V) in environmental samples (water and soil) tobacco leaves and alloy samples. The validity of the method was tested by comparing the results with those obtained using an atomic absorption spectrophotometer.

Selective and sensitive extractive spectrophotometric determination of micro amounts of palladium(II) in spiked samples: using a new reagent N-ethyl-3-carbazolecarbaxaledehydethiosemicarbazone

N-Ethyl-3-cabazolecarboxaldehydethiosemicarbazone (ECCT) is proposed as a new, sensitive and selective complexing reagent for the separation and extractive spectrophotometric determination of palladium(II) at pH: 4.0 to form a yellowish orange colored 1:1 chelate complex, which is very well extracted in to n-butanol. The absorbance was measured at a maximum wavelength, 410 nm. This method obeys Beer's law in the concentration range 0.0-6.6 microg mL(-1) and the correlation coefficient of Pd(II)-ECCT complex is 0.998, which indicates an excellent linearity between the two variables with good molar absorptivity and Sandell's sensitivity, 1.647 x 10(4) l mol(-1)cm(-1), 6.49 x 10(-3) microg cm(-2), respectively. The instability constant of complex calculated from Edmond's method, 2.724 x 10(-5) was in good agreement with the value calculated from Asmus' method 2.624 x 10(-5), at room temperature. The precision and accuracy of the method is checked with calculation of relative standard deviation (n = 5), 0.839. Edmond's method was observed to be a more selective method in the presence of EDTA, oxalate and phosphate ions. The method was successfully applied for the determination of Pd(II) in water samples, synthetic mixtures and hydrogenation catalysts, employing an atomic absorption spectrometer for comparing these results.

Development and Evaluation of a Kinetic‐Spectrophotometric Method for Determination of Arginine

AbstractA kinetic method for the determination of micro quantities of amino acid arginine (Arg) is described in this paper. The catalytic activity of cobalt in the reaction of oxidation of purpurin (1,2,4‐trihydroxy‐antraquinone, PP) by hydrogen peroxide in alkaline buffer solution decreases in the presence of micro quantities of arginine, because of the formation of the complex. Operating conditions for the successful determination of arginine were optimized. The optimized conditions yielded a theoretical detection limit of 1.45 μg mL−1. Kinetic equations are proposed for the investigated process. The interference effects of certain foreign ions and amino acids upon the reaction rate were studied and removed in order to assess the selectivity of the method. The developed procedure was successfully applied to the determination of arginine in various pharmaceutical samples. The typical feature of this procedure is that determination can be carried out at room temperature and in a short analysis time. The newly developed method is simple, inexpensive and efficient for use in the analysis of a large number of samples.

Determination of Diclofenac Sodium in Commercial Pharmaceutical Formulations and Human Control Serum Using a Kinetic-Spectrophotometric Method

A kinetic method for the determination of micro quantities of diclofenac sodium (DS) is described in this paper. The method is based on a ligand-exchange reaction. The reaction was followed spectrophotometrically by monitoring the rate of appearance of the cobalt diclofenac complex at 376 nm. The optimum operating conditions regarding reagent concentrations and temperature were established. The optimized conditions yielded a theoretical detection limit of 1.29 microg ml(-1) based on the 3S(b) criterion. The interference effects of certain drugs, foreign ions and amino acids upon the reaction rate were studied in order to assess the selectivity of the method. The developed procedure was successfully applied to the rapid determination of diclofenac sodium in commercial pharmaceutical preparations and human control serum. The unique features of this procedure are that determination can be carried out at room temperature and the analysis time is short. The newly developed method is simple, inexpensive, and efficient for use in the analysis of a large number of samples.

Simultaneous Determination of Cobalt(II) and Nickel(II) by Fourth-Order Derivative Spectrophotometric Method Using 2-Hydroxy-3-Methoxy Benzaldehyde Thiosemicarbazone

A simple and new simultaneous fourth derivative spectrophotometric method is proposed for the analysis of a two-component system containing cobalt(II) and nickel(II) without separation using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent reacts with cobalt(II) and nickel(II) at pH 6.0, forming soluble brown and yellow colored species, respectively. Cobalt(II) and nickel(II) present in themixture are simultaneously determined without solving the simultaneous equations bymeasuring the fourth derivative amplitudes at 468.5 nm and 474.5 nm, respectively. The derivative amplitudes obey Beer's law at 468.5 nm and 474.5 nm for Co(II) and Ni(II) in the range 0.059–3.299 μg mL−1 and 0.058–3.285 μg mL−1 respectively. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of cobalt in biological samples, nickel in plant samples, and in some alloy steels and soil sample.

Determination of Micro Amounts of Nucleic Acids Based on Shifting the Aggregate‐Monomer Equilibrium of Fluorescent Dye

A sensitive spectrofluorimetric method for the determination of nucleic acids based on shifting the aggregate‐monomer equilibrium of the fluorescent dye phenosafranine (PF) was proposed. Formation of aggregate induced by the pre‐micellar aggregation of an anionic surfactant, sodium dodecyl sulfate (SDS), was observed. The possibility of using the in situ–formed aggregate as a fluorescent probe for nucleic acids was also studied. The results showed that the fluorescence intensity of the system increased dramatically when nucleic acids were added to the solution. The fluorescence enhancement effect was thought to be based on the nucleic acid‐modulated shift of the aggregate‐monomer equilibrium of PF in the anionic surfactant solution. Intercalation of the monomer in nucleic acids caused the dissociation of the aggregate and led to a very high fluorescence enhancement. It seemed that the aggregate molecules acted as a source of monomer molecules ready for interaction with nucleic acids. A linear dependence of fluorescence intensity enhancement on the concentration of fish sperm DNA (fsDNA) over the range 0.04–20 µg/mL fsDNA allowed sensitive quantification of fsDNA by a simple fluorescence method. The detection limit was 17 ng/mL and the RSD was 1.2% for 2 µg/mL fsDNA (n=7). Furthermore, calibration graphs for calf thymus DNA (ctDNA) and yeast RNA were also obtained.

Determination of Microamounts of Proteins by Resonance Light Scattering with Copper Phthalocyanine Tetrasulfonic Acid

Based on the strong enhancement effect of proteins on the resonance light scattering of copper phthalocyanine tetrasulfonic acid, a method for the determination of microamounts of proteins has been developed. Under the experimental conditions (2.0×10−6 mol/L copper phthalocyanine tetrasulfonic acid, pH 2.60, ionic strength 0.001 mol/L NaCl), the linear range of this assay is 0.06–4.0 µg/mL for bovine serum albumin (BSA), 0.1–2.0 µg/mL for human serum albumin (HSA), 0.0–2.0 µg/mL for human γ‐IgG, and 0.2–6.0 µg/mL for ovalbumin. The detection limits (3δ) are 16.8 ng/mL for BSA, 23.4 ng/mL for HSA, 37.6 ng/mL for human γ‐IgG, and 48.3 ng/mL for ovalbumin, respectively. This method has been applied to the analysis of total proteins in human serum samples collected from the hospital, and the results were in good agreement with those reported by the hospital.

Diazotised p-Nitroaniline Reagent for the Determination of Trace Amounts of Salbutamol Sulphate in Aqueous Solution– Application to Pharmaceutical Preparations

A simple, rapid and sensitive spectrophotometric method for the determination of micro amounts of salbutamol sulphate in aqueous solution has been developed. The method is based on the coupling of salbutamol sulphate with diazotised p-nitroaniline in basic medium to form a coloured mono azo dye which is stable, water- soluble and exhibits maximum absorption at 488 nm. Beer’s law is obeyed over the range 10–120 µg of salbutamol sulphate in a final volume of 25 ml, i.e., 0.4–4.8 ppm with a molar absorptivity of 3.13×10 4 l.mol. -1 cm -1 , a relative error of +1.80 to –3.40% and a relative standard deviation of +5.70 to +1.65%, depending on the concentration level. The proposed method does not require temperature control or solvent extraction and the method has been successfully applied to the determination of salbutamol sulphate in different types of pharmaceutical preparations, tablets and syrup.

EXTRACTIVE SPECTROPHOTOMETRIC DETERMINATION OF IRON (II) USING AN ION ASSOCIATION COMPLEX FORMATION

Spectrophotometric determination of micro amount of iron has been developed using a solvent extraction of an ion association complex of ferrous ion. The method is dependent on the formation of an ion associate complex of iron (II) with ethylene diamine disuccinic acid as a primary ligand and cetyl trimethyl ammonium bromide (CTMA) as counter ion, which is extracted into 1.2- dichloroethane (DCE). The complex is formed at pH = 5.0-7.0 and the iron concentration can be determined by measuring the absorbance directly in the organic phase. The apparent molar absorptiviy is 1.73 x 105 L mol-1 cm-1 and Sandell sensitivity is 0.32 mg cm-1, free from interferences. The proposed method was applied to the determination of iron in water, fruit juice, wine, food minerals and pharmaceutical formulations.

Simultaneous preconcentration flotation-separation and spectrophotometric determination of thorium, lanthanum and yttrium in some geological and enviromental samples

The extraction and preconcentration of a metal complex via surfactant-mediated phase separation was studied. A sensitive, selective and low-cost methodology for the determination of micro amounts of thorium, lanthanum and yttrium ions, using Eriochrome Cyanine R (ECR) with a flotation step prior to spectrophotometric determination was developed. The precipitate in the scum layer was quantitatively collected, stripped with 4 ml of 3% HCl and measured spectrophotometrically at 540 nm for Th(IV) and at 650 nm for both La(III) and Y(III). The stripping of Th(IV), La(III) and Y(III) from the scum layer was carried out in one step with different mineral acids. The stripping efficiency was found to be quantitative in the case of HCl. An excess amount of ECR was used to eliminate the interfering effects of various foreign species. The proposed procedure was applied to the determination of Th(IV), La(III) and Y(III) spiked in natural water samples and in some ore samples. Additionally, the mechanism of flotation of the metal chelate was proposed to be due to a physical interaction between the metal chelate and the oleic acid surfactant through the Van der Waals force.

Near-infrared fluorimetric determination of nucleic acids by shifting the ion-association equilibrium between tetracarboxy aluminum phthalocyanine and tetra- N-hexadecylpyridiniumyl porphyrin

A new method was developed for determination of micro amounts of nucleic acids based on near-infrared (near-IR) fluorescence recovery, employing a two-reagent system which is composed of an anionic tetracarboxy aluminum phthalocyanine (AlC 4Pc) and a cationic tetra- N-hexadecylpyridiniumyl porphyrin (TC 16PyP). The fluorescence of the AlC 4Pc, with the maximum emission wavelength at 701 nm, could be quenched by TC 16PyP at its proper concentration, but recovered by adding nucleic acids. Under optimal conditions, the recovered fluorescence is proportional to the concentration of nucleic acids. The calibration graphs are linear over the range of 1–200 ng mL −1 for fish sperm DNA (FS DNA) and 2–400 ng mL −1 for calf thymus DNA (CT DNA). The corresponding detection limits are 0.59 ng mL −1 for FS DNA and 0.82 ng mL −1 for CT DNA, respectively. Four synthetic and three real nucleic acid samples were determined with satisfactory results.

Differential-Kinetic Determination of Microamounts of Thorium in Soils

Microamounts of thorium in soils can be determined by a differential-kinetic method based on the kinetic properties of the complex of thorium with 1,2-cyclohexanediaminetetraacetic acid (ThDCTA). The thorium content was determined spectrophotometrically upon decomposition of this complex in 0.1 M HNO3 in the presence of Arsenazo III. The method involves anion-exchange isolation of Th from solution obtained by degradation of the soil material; it allows thorium determination in the presence of a number of impurities, which poses less stringent requirements on thorium separation from these impurities.

Application of artificial neural networks in multivariable optimization of an on-line microwave FIA system for catalytic kinetic determination of iridium(III).

A new rapid, selective and sensitive on-line microwave flow injection-kinetic method was developed for spectrophotometric determination of micro amounts of Ir(III), based on its catalytic effect on the m-acetylchlorophosphonazo (CPA-mA) and KIO(4) reaction in NaOH media. An on-line microwave oven was employed to accelerate the reaction. The reaction was followed spectrophotometrically by measuring the decrease of the absorbance of CPA-mA at 580 nm. The effect of five variables for the determination of Ir(III) was optimized by means of a multilayer artificial neural network using extended delta-bar-delta (EDBD) algorithms. Under the optimum experimental conditions, Ir(III) could be determined in the range 0.060-0.60 micro gZZZ;mL(-1) with detection limit of 0.02 micro gZZZ;mL(-1) and the sampling frequency of 34 h(-1). The proposed method was applied to the determination of micro amounts of Ir(III) in refined ore and secondary alloy with the recoveries from 91.4% to 109%.

Micro Determination of Ammonia by a Kinetic Spectrophotometric Method

A simple and sensitive kinetic spectrophotometric method is described for the determination of micro amounts of ammonia. The method is based on the inhibiting effect of ammonia on the oxidation rate of aqua ethylenediamine-tetraacetate chromium(III) [Cr(HEDTA)(H2O)] with N-bromo succinimide (NBS) to yield chromium(VI). The reaction was followed spectrophotometrically by measuring the rate of change in absorbance with time at 365 nm, which is the maximum absorption wavelength of chromium(VI). Using the recommended procedure, ammonia can be determined up to 153 µg ml−1 with a linear calibration graph and a detection limit of 0.09 µg ml−1. The method was successfully applied to the determination of ammonia in waste water samples. Recovery experiments for the analyzed samples were 97–100% with relative standard deviation, Sr (%) of ≤ 2.9% indicating high accuracy and precision of the proposed method. The interference of various cations and anions in the determination of ammonia was investigated.

Sensitive and Selective Spectrophotometric Determination of Hg(II), Ni(II), Cu(II) and Co(II) Using Iminodibenzyl and 3-Chloroiminodibenzyl as New Reagents and Their Applications to Industrial Effluents and Soil Samples

Iminodibenzyl (IDB) and 3-chloroiminodibenzyl (Cl-IDB) are proposed as a new class of spectrophotometric reagents for the determination of micro amounts of mercury(II), nickel(II), copper(II) and cobalt(II) in the presence of 3-methyl-2-benzothiazoline hydrazone hydrochloride hydrate (MBTH) or 4-aminoantipyrine (AAP) as electrophilic coupling reagents. The reaction is carried out in neutral aqueous medium. The blue colour formed shows maximum absorbance at 660 nm using MBTH and 630 nm with AAP. The methods obey Beer's law. The molar absorptivity and Sandell's sensitivity show different values with different metals and reagents. The blue colour can also be extracted quantitatively which can be exploited as an efficient extractive spectrophotometric technique for the separation of metal ion from other interfering species. As many as 15 cations and 12 anions and/or complexing agents listed do not interfere. Both the methods have good reproducibility and can be satisfactorily applied in the determination of metals in industrial effluents and soil samples.

Kinetic determination of lysine in pharmaceutical sample

Akinetic method for the determination of micro quantities of the amino acid lysine (Lys) is described in this paper. The catalytic activity of cobalt in the reaction of the oxidation of purpurin (1,2,4-trihydroxyanthraquinone PP) by hydrogen peroxide in alkaline buffer solution decreases in the presence of micro quantities of lysine, because of the formation of a complex.1,2 The experimental conditions for the successful determination of lysine were optimized. The relative error ranges from 7.7 to 1.9% in the concentration range from 0.118 to 23.520?g cm-3. The detection limit is 0.023?g cm-3. Kinetic equations are proposed for the investigated process. The effects of certain foreign ions and amino acids on the reaction rate were determined in order to assess the selectivity of the method. The method was applied to the determination of lysine in a pharmaceutical sample Riborn-P (Medecon?Belgrade).

Colorimetric determination of tocopheryl acetate (vitamin E) in pure form and in multi-vitamin capsules

A simple, accurate and sensitive method for the determination of micro amounts of vitamin E (V E) in pure form and in multi-vitamin capsules is described. The method is based on the reduction of tetrazolium blue in slightly alkaline medium by vitamin E after extraction from aqueous EDTA medium with petroleum ether and transesterification. The oxidation reduction reaction occurs after 10 min of heating in a water bath at 90±2°C, leading to the formation of a highly coloured formazan derivative. Different variables affecting the colour development were investigated and optimized. Absorbance measurements were made at 526 nm and the calibration graph was linear for 0.2–11.0 μg/ml of (V E) with relative precision of about 0.7–1.5% when the standard additions method is used.