Colorimetric Microdetermination of Bromhexine Drug in Aqueous Solution

A simple, accurate and sensitive method for determination of bromhexine hydrochloride drug in aqueous solution has been described. The procedure has been based on the reaction of this drug with an excess amount of p‐dimethylaminobenzaldehyde (DAB) in acidic medium (pH =1.6) and the presence of sodium dodecyl sulfate (SDS). The produced yellow color from this reaction has been followed spectrophotometrically at an absorbance maximum of 430 nm. Microgram amounts of bromhexine hydrochloride can be estimated with an accuracy of better than ±1.5% and a relative standard deviation of less than 3.5%. The method has been used for the determination of 0.41–82.5 μg.mL^?1 with a molar extinction coefficient of 4699.1–3602.3 L.mol^?1.cm^?1. An application of the developed procedure to bulk bromhexine hydrochloride and some of its pharmaceutical preparations has been carried out. The effect of the presence of some other surfactants and common pharmaceutical additives has been investigated. A comparison of the presented method with that in the absence of SDS and the standard method of the British Pharmacopoeia has been explored. The suggestion, according to the results, is to use the developed method as standard in pharmaceutical applications.     

Spectrophotometric Determination of Selected Antibiotics Using Prussian Blue Reaction

A simple, sensitive and accurate spectrophotometric method has been described for the determination of ampicillin(I), amoxicillin trihydrate(II) and cefazolin sodium(III). The procedure is based on the formation of Prussian Blue (PB) complex. The reaction between the acidic hydrolysis products of antibiotics (T = 60 °C) with mixture of Fe³⁺ and hexacyanoferrate(III) ions was evaluated for the spectrophotometric determination of the mentioned drugs. The maximum absorbance of the colored complex occurs at λ = 700 nm and the molar absorptivity is 3.0 × 10⁴ 1 mol^?1cm^?1. The effect of various parameters such as concentration of K₃Fe(CN)₆ and Fe³⁺, nature and amount of acids used, temperature and time of heating were investigated. Under optimum conditions the linear range of calibration graph was 2.0–12.0, 5.0–13.5 and 3.0–12.0 μg mL^?1 for ampicillin, amoxicillin and cefazolin, respectively. The relative standard deviation for the determination of 10 μg mL^?1 of antibiotics was about 0.5–1.5%. The proposed method was successfully applied to the determination of selected antibiotics from pharmaceutical preparations. The validity of the method was tested by the official methods and by the recovery studies of standard addition to pharmaceuticals.     

The Determination of Perphenazine by a New Simple Flow‐Injection Chemiluminescence Method

Abstract

A rapid and simple flow‐injection chemiluminescence (CL) method is described for the determination of perphenazine, which is based on the CL intensity that generated from the redox reaction of Ce (IV)-perphenazine in HNO₃ medium is proportional to the perphenazine concentration without any sensitizers. The proposed method allows the determination range within 1.0×10^?7–7.0 ×10^?5 g mL^?1 with a detection limit of 8.0×10^?8 g mL^?1, and it has been successfully applied to the determination of the perphenazine in pharmaceutical tablet compared well with the official method.     

A New Spectrophotometric Method for the Determination of Arsenic in Environmental and Biological Samples

Abstract

A simple and selective spectrophotometric method has been developed for the determination of trace amounts of arsenic using azure B as a chromogenic reagent. The proposed method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine. The liberated iodine bleaches the violet color of azure B and is measured at 644 nm. This decrease in absorbance is directly proportional to the As(III) concentration, and Beer's law is obeyed in the range 0.2–10 µg ml^?1 of As(III). The molar absorptivity, Sandell's sensitivity, detection limit, and quantitation limit of the method were found to be 1.12×10⁴ l mol^?1cm^?1, 6.71×10^?3 µg cm^?2, 0.02 µg ml^?1 and 0.08 µg ml^?1, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples.     

Flow Injection Chemiluminescence Determination Of Tetracyclines

Abstract

A fast and simple flow injection chemiluminescence method for the determination of trace amounts of tetracyclines is proposed based on the chemiluminescence of the KMnO₄ - TCs redox reaction in acidic medium in the presence of a sensitizer, OP. The response to the concentration of tetracyclines is linear in the range of 1.00 to 1000 μg mL^?1 with a relative standard deviation < 2.3 % for determination of 50.0 μg mL^?1 of each antibiotic (n = 11). The detection limits for tetracycline, oxytetracycline and chlortetracycline are 0.40, 0.52 and 0.60 μg mL^?1, respectively. The recommended method is suitable for automatic and continuous analysis and has been successfully tested for determination of tetracyclines in commercial formulations. The chemiluminescence intensity was found to be remarkably enhanced when in the presence of OP micellar system; possible reasons for this observed micellar induced enhanced chemiluminescence is given.     

Sensitive Spectrophotometric Determination of Benzoylperoxide with N,N,N′,N′-Tetramethyl-p-phenylenediamine

Abstract

A highly sensitive spectrophotometric determination of benzoylperoxide (BPO) based on the color developing reaction between N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) and BPO in the presence of cerium(IV) in weakly acidic media is proposed. The calibration graph is linear in the range 0–6000 ng BPO per 10 ml with an apparent molar absorptivity of 4.73 × 10⁵ 1 mol^?1 cm-1 at 612 nm. The proposed method is about 50-fold more sensitive than N-ethyl-2-naphthylamine (NENA), and application to assays of flour is described.     

3,4-Dihydroxybenzoic Acid As A Reagent for the Spectrophotometric Determination of Titanium

Abstract

The reaction between titanium(IV) and 3,4-dihydroxybenzoic acid in aqueous media results in an intensely colored complex which is stable for at least 8h. It allows the spectrophotometric determination of titanium in silicate rocks. The proposed method, in pH 4.0–6.0, shows a molar absorptivity of 1.43.10⁴ L.mole^?1.cm^?1 at 380 nm. Beer's Law is obeyed up to 3.0 μg/mL of titanium(IV). The interference of iron(III) can be eliminated by reduction to iron(II) with hydroxylamine hydrochloride. The method was applied to the determination of titanium in various standard rocks and the results indicated that the accuracy and precision are satisfatory.     

Indirect Flow-Injection Analysis of Ascorbic Acid by Photochemical Reduction of Methylene Blue

Abstract

Ascorbic acid was determined indirectly by spectrophotometry at 666 nm based on the photochemical reduction of methylene blue using flow-injection analysis. The carrier stream was 12.7 μgml^?1 methylene blue in phthalate-HCl buffer solution at pH 3.2. The reactor was irradiated with a 500-Watt halogen lamp to facilitate the development of the photochemical reaction. The system allows determination of ascorbic acid in the range 0.18–6.12 μgml^?1 with relative standard deviations of 2.09 and 0.31% for 1.97 and 4.92 μgml^?1 samples, respectively, and a sampling frequency of 50–55 h^?1. The proposed method was applied successfully to the determination of ascorbic acid in vitamin C tablets.     

Application of the Coupled Redox and Complexation Reactions to Flow Injection Spectrophotometric Determination of Promazine

Abstract

A flow injection (FI) spectrophotometric method is proposed for the determination of promazine hydrochloride. The method is based on the coupled redox - complexation reactions which proceed in the promazine-iron(III) and 1,10-phenantroline system. A linear calibration graph was obtained between 2–12 ppm of promazine hydrochloride with a sampling rate of 163 samples h^?1. The proposed method was applied to the determination of promazine in pharmaceuticals.     

Kinetic Spectrophotometric Determination of Traces of Manganese(II) by Its Catalytic Effect on Oxidation of 4‐Hydroxycoumarin with Potassium Permanganate in River Water Samples

Abstract

A new kinetic method for determination of traces of manganese(II) based on its catalytic effect on the oxidation of 4‐hydroxycoumarine with KMnO₄ at pH=1.35 and at a temperature of 25°C was proposed. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of the dye at 525 nm. The calibration graph is linear in the range 20–200 ng/cm³. The effects of certain foreign ions upon the reaction rate were determined for assessment by the selectivity of the method. The proposed method has been applied for determination of manganese(II) in river water samples with satisfactory results.     

Colorimetric Determination of Ampicillin and 6-Aminopenicillanic Acid Using Acenaphthenequinone as a Chromophoric Reagent

Abstract

A colorimetric method for the determination of ampicillin (Amp.) and 6-aminopenicillanic acid (6-APA) are described, based on the reaction of these drugs with acenaphthenequinone in basic media to give a highly intense red coloured product. The latter exhibits an absorption maximum at 610 nm with apparent molar absorptivities of 2.83 and 1.45 × 10⁴ l. mol^?1 cm^?1 and Sandell sensitivities of 0.013 and 0.015 μg cm^?2 for Amp. and 6-APA, respectively. The optimum concentration ranges are 0.4-10 and 0.4-14 μg ml^?1 for Amp. and 6-APA, respectively. For more accurate results, Ringbom optimum concentration ranges are 1–8.5 and 1–12 μg ml^?1 for Amp. and 6-APA, respectively. Statistical analysis indicated that there was no significant difference between the results obtained by the described method and those of the official methods. The mean recoveries percentage were found to be 99.5 × 1.1% for pharmaceutical formulations and 99.1 × 1.6% for serum and urine samples. The method is selective for the determination of Amp. or 6-APA in the presence of their degradation products, additives and excipiences that are normally encountered in dosage forms. The proposed method was applied successfully to the determination of Amp. in pharmaceutical formulations. Also, applicability of the proposed method to human serum and urine is presented and the validity assessed by applying the standard addition technique.     

Determination of Poisonous Trace Element Thallium(I) by Kinetic Catalytic Reaction

Abstract

A effective and simple determination of poisonous trace element thallium(I) by means of kinetic catalytic reaction is proposed. The method is based on a catalytic effect of thallium(I) on a luminol-hydrogen peroxide system. Three different kinds of surfactants, cetrimonium bromide (CTMAB), sodium dodecyl sulphate (SDS), and Tween-80, are also investigated to improve the detection sensitivity. In optimum conditions, a highly selective and sensitive method for detecting trace thallium(I) has been established. The detection limit is 0.0073 µg · mL^?1, the relative standard deviation for six determinations of 0.04 µg · mL^?1 thallium(I) is less than 4.0%, and the linear range of determination is 0.02–0.1 µg · mL^?1.     

Direct automatic determination of free acidity in oils by flow-injection analysis

An automatic method is proposed for the determination of free acidity. It uses the same reagents as the manual standard method (potassium hydroxide and phenolphthalein as indicator) and is based on peak-height measurements in the low concentration range (0.15–0.81%) and peak-width measurements or flow-injection titrations for higher concentrations. The sampling frequency is 60 h^-1. The results obtained by the proposed method are in good agreement with those obtained by the conventional standard method.     

Spectrophotometric Determination of Cadmium(II) Using p,p′‐Dinitro‐SYM‐Diphenylcarbazid in Aqueous Solutions

Abstract

A sensitive and selective spectrophotometric method is proposed for the rapid determination of cadmium(II) using, p,p′‐dinitro‐sym‐diphenylcarbazid, directly in aqueous solution. The reaction between cadmium(II) and p,p′‐dinitro‐sym‐diphenylcarbazid occurs immediately in strong basic media (0.02 N sodium hydroxide solution). The complex shows a maximum of absorption at 630–640 nm, and the absorbance remains stable for at least 24 h. The method allows the cadmium determination over the range 0.5–6.0 µg mL^?1, with a molar absortivity of 2.05×10⁴ L mol^?1 cm^?1 and features a detection limit of 0.13 ppm. The interferences caused by several ions [Ca(II), K(I), Ba(II), Al(III), Pb(II), Zn(II), Cl^?1, NO₃ ^?, SO₄ ^2?], which are present in most of environmental samples, were determined. The validation of the spectrophotometric method was done by recovery test of cadmium(II) in tap water and sea water. The results show that the proposed method has been successfully applied to the determination of cadmium(II) in water samples.     

FLOW - Injection Determination of Traces of Sulfide by the Brilliant Green - Sulfide Reaction with Spectrophotometry Detection

Abstract

A flow injection system is proposed for the rapid and sensitive determination of trace amounts of sulfide based on the addition reaction of sulfide with Brilliant Green at pH 7 and 25 C°. The effect of important parameters, such as reagent concentration, pH, reagent flow rate, sample volume, temperature and length of the reaction coil are reported. Sulfide in the range of 40 - 2000 ng·ml^?1 can be determined at a rate of 40 ± 5 samples per hour. The limit of detection was obtained as 2.0 ng of sulfide. The relative standard deviation for the determination of 100 ng·ml^?1 of sulfide is 0.8%. A system is proposed for elimination of potential interferences. The method was applied to the determination of sulfide in synthetic samples and in spring water.     

Flow-Injection Chemiluminescent Determination of Piroxicam Using Tris (2,2′-bipyridyl) Ruthenium(II)—Potassium Permanganate System

Abstract

A rapid and sensitive chemiluminescence method using flow-injection has been developed for the determination of an analgesic agent drug, piroxicam. The method is based on the chemiluminescence reaction of piroxicam with an acidic potassium permanganate and Ru(bipy)₃ ²⁺. The chemiluminescence intensity is greatly enhanced when quinine sulfate is used as a sensitizer. After optimization of the different experimental parameters, a calibration graph was obtained over a concentration range of 3.0 × 0^?8–3.0 × 0^?5 mol L^?1 with the detection limit of 1.0 × 0^?8 mol L^?1. The relative standard deviation is 1.5% (n = 11) for the determination of 8.0 × 10^?7 mol L^?1 piroxicam. The proposed method was successfully applied to commercial tablets, spiked serum, and urine samples.     

An Improved Solid Phase Spectrophotometry Method for the Determination of Aromatic Esters

Abstract

A method based on Solid Phase Spectrophotometry was developed for the determination of methyl benzoate. Hydroxamic acid formed by the reaction between the above and hydroxylamine, reacts with V(V) and oxalate yielding a violet compound, which is sorbed on an anion-exchange resin. The absorbance of the resin phase at 546 and 750 nm is measured directly. The calibration graph is linear for the 4.8–23 μM concentration range. RSD is shown as 3.7%, with a detection limit of 0.09 mg. 1^?1. This method has been applied to the determination of aromatic esters in brandies.     

Study of Spectrophotometric Determination of Amoxicillin Using Sodium 1,2‐Naphthoquinone‐4‐Sulfonate as the Chemical Derivative Chromogenic Reagent

Abstract

A simple and sensitive spectrophotometric method is described for determination of amoxicillin. The method is based on a nucleophilic substitution reaction to measure the pink compound produced by the reaction of amoxicillin with sodium 1,2‐naphthoquinone‐4‐sulfonate in pH 9.00 buffer solution. The stoichiometric ratio of the compound is 1:1, and its maximum absorption wavelength is at 468 nm, ε=3.91×10³ L · mol^?1 · cm^?1. The Beer's law is obeyed in the range of 0.8–120 µg · mL^?1 of amoxicillin. The linear regression equation is A=0.041239+0.22128 C, with 0.9994 of a linear regression correlation coefficient. The detection limit is 2.0 µg · mL^?1, and average recovery is over 98.5%. This paper further optimizes the determination of amoxcillin compared to the previous methods, and the kinetic property and reaction mechanism are studied intensively. This proposed method has been successfully applied to the determination of amoxicillin in tablets and capsules. The results obtained by this method agreed well with those by the official method high pressure liquid chromatography (HPLC).     

On the Effect of Hydrogen Peroxide on the Flow‐Injection Determination of Platinum Based on Luminol Chemiluminescent Reaction

Abstract

A flow‐injection chemiluminescent (CL) method for the determination of trace amounts of Pt(IV) based on the oxidation reaction of luminol in alkaline solution is proposed. The effect of Pt(IV) on the oxidation of luminol was studied in the absence and in the presence of hydrogen peroxide. The positive effect of hydrogen peroxide as well as chloride ions on the sensitivity of measurements was observed. The developed method is characterized by a low limit of detection of Pt (LOD=0.06 ng mL^?1) and good reproducibility (RSD=2.2%). The addition of hydrogen peroxide to the reaction medium resulted in decreasing of platinum detection limit to 0.03 ng mL^?1.     

Flow injection chemiluminescence determination of isoniazid with electrogenerated hypochlorite

A flow-injection chemiluminescence method for the determination of isoniazid based on the sensitizing effect of isoniazid on the chemiluminescence generating luminol-hypochlorite reaction is described. The hypochlorite was electrogenerated on-line by constant current electrolysis, thus, eliminating instability of hypochlorite solution prepared from commercially available sodium hypochlorite. The calibration graph is linear in the range 1 × 10^–8 to 1 × 10^–6 g mL^–1, and the detection limit is 6 × 10^–9 g mL^–1. The relative standard deviation for determination of 5 × 10^–8 g mL^–1 is 2.8%. The proposed method has been successfully applied to the determination of isoniazid in pharmaceutical preparations.