Optimization of the spectrophotometric determination of mercury using copper(II) diethanoldithiocarbamate

1985 ◽  
Vol 50 (8) ◽  
pp. 1661-1672 ◽  
Author(s):  
Ernest Beinrohr ◽  
Katarina Blazseková ◽  
Ján Garaj
Keyword(s):  
Spectrophotometric Determination ◽  
Absorption Maximum ◽  
Ph Value ◽  
Rapid Determination ◽  
Analytical Signal ◽  
Aqueous Acetone ◽  
Determination Limit ◽  
Factors Affecting ◽  
Analytical Calibration

The work deals with the optimization of the conditions for the spectrophotometric determination of mercury using copper(II) diethanoldithiocarbamate [Cu((HOCH2CH2)2NCS2)2] (I). The determination is based on replacement of Cu2+ ions by Hg2+ ions in complex I in acidic aqueous acetone medium and measuring the decrease in the absorbance at the absorption maximum of complex I (λ = 440 nm). The statistical importance of the factors affecting the analytical signal (absorbance) was found by the analysis of variance. The analytical signal is affected most by the pH value, the concentration of Cu2+ ions, and the acetone content. The best results were obtained at pH ~ 2 and an acetone content of 15% (v/v). The analytical calibration curve is nonlinear. The determination limit is 50 μg Hg in 1 dm3. The method is useful for the rapid determination of mercury with a precision of ± 5% in colourless solutions not containing Cu2+ or Ag+ ions or strong oxidants.

Optimization of sol-gel based fibre-optic cholinesterase biosensor for the determination of organophosphorus pesticides

2000 ◽  
Vol 42 (7-8) ◽  
pp. 283-290 ◽  
Author(s):  
H.-C. Tsai ◽  
R.-A. Doong
Keyword(s):  
Fiber Optic ◽  
Ph Value ◽  
Rapid Determination ◽  
Organophosphorus Pesticides ◽  
Sol Gel ◽  
Neutral Red ◽  
Fluorescent Indicators ◽  
Low Leakage ◽  
Fiber Optic System

A sol-gel based fiber-optic biosensor with acetylcholinesterase as the biorecognition element has been developed for the rapid determination of organophosphorus pesticides. Nine fluorescent indicators, acridine, acridine orange, neutral red, DAPI, rhodamine B, fluorescein, umbelliferone, FITC on celite and FITC-dextran, have been examined to optimize the fiber-optic system. Results showed that acridine and FITCs were sensitive to the change of pH value caused by the enzyme-substrate catalysis reaction. However, the sensitivity of acridine was 260 times lower than that of FITCs. Higher toxicity of acridine to acetylcholinesterase than FITC was also observed. Moreover, the high-molecular-weight FITC-dextran showed low leakage rate when immobilizing using sol-gel technology, showing that the FITC-dextran was a suitable pH sensitive fluorescent indicator for the OPPs biosensor. The response of the fiber-optic biosensor to the substrate, acetylcholine, was highly reproducible (RSD=3.5%). A good linearity of acetylcholine in the range from 0.5 to 20 mM was also obtained (R2=0.98). Furthermore, a 30% inhibition can be achieved in 30min when 152 ppb paraoxon was added into the system. The results show the possibility for real-time determination of organophosphorus pesticides by using the biosensor developed in this study.

scholarly journals Rapid Spectrophotometric Determination of Phenoxazine

2010 ◽  
Vol 7 (2) ◽  
pp. 1001-1005
Author(s):  
Baghdad Science Journal
Keyword(s):  
Detection Limit ◽  
Spectrophotometric Determination ◽  
Acidic Medium ◽  
Absorption Maximum ◽  
Aqueous Samples ◽  
Economic Method ◽  
Beer's Law ◽  
Beer’S Law ◽  
The Stability

A rapid high sensitive and inexpensive economic method has been developed for the Determination of phenoxazine by using molecular spectrophotometry. The method is based on the oxidation of phenoxazine by potassium (meta)periodate in acidic medium. The oxidation conditions were selected to enhance the sensitivity and the stability of the pink colored species which shows an absorption maximum at 530 nm. The Beer’s law was obeyed for phenoxazine concentration range from 1 to 6 µg mL-1 with 0.003 µg mL-1 detection limit and provided variation coefficients between 0.4 to 1.7 %. This method was successfully applied for the determination of phenoxazine in aqueous samples

Spectrophotometric Determination of Carbaryl in Grains

1982 ◽  
Vol 65 (1) ◽  
pp. 32-34
Author(s):  
Kalapanda M Appaiah ◽  
Rasamsetti Ramakrishna ◽  
Kadari R Subbarao ◽  
Omprakash Kapur
Keyword(s):  
Spectrophotometric Determination ◽  
Absorption Maximum ◽  
Potassium Hydroxide ◽  
Oxidizing Agent ◽  
Spectrophotometric Measurement ◽  
The Relationship ◽  
Hydrolysis Of

Abstract A method has been developed for determining carbaryl (1-naphthyl N-methyl carbamate) in grains, based on hydrolysis of carbaryl with methanolic potassium hydroxide to 1-naphthol, reaction with 4-aminophenazone in the presence of alkaline oxidizing agent, and spectrophotometric measurement at the absorption maximum at 475 nm. The relationship between absorbance and concentration is linear in the range of 0.5-20 μg/mL. The method can be applied to levels as low as 0.3 ppm carbaryl in grains.

Spectrophotometric Determination of Methomyl Residues in Selected Vegetables, Crains, and Soil

1977 ◽  
Vol 60 (5) ◽  
pp. 1093-1096
Author(s):  
Jois R Rangaswamy ◽  
Shimoga R Prakash ◽  
Yadathora N Vijayashankar
Keyword(s):  
Spectrophotometric Determination ◽  
Absorption Maximum ◽  
Acid Treatment ◽  
Sulfanilic Acid ◽  
Benzenesulfonic Acid ◽  
The Relationship

Abstract Methomyl (S-methyl-N-[(methylcarbamoyl) oxy] thioacetimidate) is converted to oxime and hydroxylamine by alkali and acid treatment, respectively. Hydroxylamine is oxidized with iodine in the presence of sulfanilic acid to yield p-diazoniumbenzenesulfonic acid which is coupled with α-naphthylamine to form a crimson p-benzenesulfonic acid-azo-α-naphthylamine with an absorption maximum at 520 nm. The relationship between absorbance and concentration of methomyl is linear in the range 0.5–10 μg. The method is sensitive and specific; 0.625 ppm methomyl can be determined in a 40 g sample of selected vegetables, grains, and soil.

scholarly journals USING AN ACTIVATED COPPER MICROELECTRODE FOR VOLTAMMETRIC DETERMINATION OF ALCOHOLS

2018 ◽  
Vol 13 (1) ◽  
pp. 22-32
Author(s):  
L. Yu. Martynov ◽  
T. V. Sitnikova ◽  
M. A. Lazov ◽  
I. Yu. Lovchinovsky ◽  
N. K. Zaitsev
Keyword(s):  
Photoelectron Spectroscopy ◽  
Analytical Signal ◽  
Copper Surface ◽  
Potential Range ◽  
Current Response ◽  
Optimal Conditions ◽  
Original Design ◽  
Factors Affecting ◽  
Naoh Solution

A method for fabricating a copper microdisk electrode of an original design based on 50 μm diameter wire sealed in borosilicate glass is described. The electrochemical properties of the copper microelectrode were studied by the method of steady-state voltammetry in a 2 M NaOH solution in the potential range from -1.1 to 0.8 V (versus saturated Ag/AgCl-electrode). In order to improve the electrochemical response a method for two-stage electrode activation based on a copper dissolution / redeposition procedure followed by polarization in an alkaline medium is suggested. Morphological and physico-chemical changes on copper surface after activation were examined by atomic force microscopy and X-ray photoelectron spectroscopy. After this procedure, the electrode showed a heterogeneous morphology with coarse texture and high roughness parameters, and a layer of catalytically active Cu(III) species was formed on copper surface. The best results were achieved with an activation time of 60 s and a polarization potential of -0.3 V. The effectiveness of the activation procedure was tested during the chronoamperometric determination of methanol, ethanol and ethylene glycol. Factors affecting the formation of the analytical signal of alcohols were studied, and optimal conditions of amperometric measurements were selected on their basis. Under optimal conditions, the metrological characteristics of the method were determined. The peak current response increases linearly with alcohols concentration over the range 0.01 - 0.45 M (0.04 - 3% v/v). The repeatability of the electrode response was evaluated as 3.8% (n = 10). The activated copper microelectrode was used for the determination of ethanol in pharmaceutical and other products.

scholarly journals SPECTROPHOTOMETRIC DETERMINATION OF ANTIOXIDANT SODIUM METABISULPHITE CONTENT IN PREPARED MEDICINAL FORMS OF VETERINARY MEDICINAL PRODUCTS

2020 ◽  
Vol 21 (2) ◽  
pp. 189-198
Author(s):  
H. Yu. Teslyar ◽  
M. Ya. Smolinska ◽  
I. Ya. Kotsyumbas ◽  
N. M. Chyhyn ◽  
N. G. Rohulia ◽  
...  
Keyword(s):  
Spectrophotometric Determination ◽  
Storage Time ◽  
Analytical Signal ◽  
Veterinary Drugs ◽  
Biologically Active Substances ◽  
Biologically Active ◽  
Optimal Conditions ◽  
Sodium Metabisulphite ◽  
Active Substances

An analytical method for the quantitative determination of antioxidant sodium metabisulphite in veterinary drugs has been proposed by spectrophotometric method. Based on the literature data, the optimal conditions of the analytical reaction were selected experimentally. The dependence of the value of the analytical signal on the temperature of the reaction medium, concentration of p-rosaniline and duration of the reaction was investigated to establish the optimal conditions of the analytical reaction and obtain a stable analytical signal. The stability of the colored analytical form in time was also checked and the linear dependence of the value of the analytical signal on the concentration of sodium metabisulphite was investigated. The analytical reaction at room temperature is optimal. The maximum analaytical signal is achieved by carrying out the analytical reaction for 10 minutes and then practically does not change for an hour. To achieve the maximum analytical signal, it is necessary to use a 20-fold excess of dye relative to sodium metabisulphite. The analytical signal remains stable only for the first hour, then gradually begins to decrease. Metrological characteristics of the method of determination of metabisulphite in veterinary drugs are calculated, the limits of spectrophotometric determination are 0.33 – 2.50 μg/ml. The correctness of the developed method was checked on model solutions by the method of "introduced-found" method of comparison in the presence of various biologically active substances that are part of drugs together with sodium metabisulphite. The content of sodium metabisulphite in veterinary drugs of domestic and foreign production at different intervals of their storage time was established. It is shown that the content of sodium metabisulphite in drugs decreases during their storage time, until complete disappearance, which directly affects the content of the active substance, because in the absence of antioxidant oxidative processes with biologically active substances begin to take place.

Spectrophotometric Determination of Hydralazine Hydrochloride Tablets Using Ninhydrin

1983 ◽  
Vol 66 (6) ◽  
pp. 1455-1457
Author(s):  
Manesh C Dutt ◽  
Tju-Lik Ng ◽  
Lian-Tun Long
Keyword(s):  
Spectrophotometric Determination ◽  
Absorption Maximum ◽  
Room Temperature ◽  
Mass Spectrometric ◽  
Dilute Solutions ◽  
Ultraviolet Spectrophotometry ◽  
Buffer Solution ◽  
Colored Product ◽  
Hydralazine Hydrochloride

Abstract A method is described for the assay of hydralazine HC1 in tablets, based on the colored product formed by the reaction between hydralazine and ninhydrin. The reaction is conducted at room temperature in a pH 3 buffer solution and the colored product is measured spectrophotometrically at the absorption maximum at 442 nm. Under the stipulated conditions, this reaction is highly specific for hydralazine and is not affected by other drugs which may be used in combination with hydralazine. Results of infrared and mass spectrometric studies suggested that the colored product is a hydrazone. Ultraviolet spectrophotometry also showed that dilute solutions of hydralazine degrade rapidly in the presence of alcohols.

Selective determination of tantalum in ores by extraction with N-phenylbenzohydroxamic acid in toluene

1990 ◽  
Vol 55 (7) ◽  
pp. 1686-1690 ◽  
Author(s):  
José Aznarez ◽  
Juan Carlos Vidal ◽  
Cecilia Vaquero
Keyword(s):  
Hydrochloric Acid ◽  
Acid Solution ◽  
Aqueous Phase ◽  
Spectrophotometric Determination ◽  
Absorption Maximum ◽  
Good Accuracy ◽  
Molar Absorptivity ◽  
Selective Determination ◽  
Accuracy And Precision

A method for tantalum(V) spectrophotometric determination in a non-aqueous phase is proposed. Tantalum(V) is extracted with N-phenylbenzohydroxamic acid into toluene from a 5M hydrochloric acid solution. The colour is then developed by addition of 4-(2-pyridylazo)-resorcinol (PAR) solution in N,N-dimethylformamide and pyridine to an aliquot of the extracted phase. The Ta(V)-PAR complex gives an absorption maximum at 547 nm with a molar absorptivity of 3.88 ± 0.04 . 104 l mol-1 cm-1. The method has been applied to the selective determination of tantalum in ores with good accuracy and precision.

Spectrophotometric Determination of Carbofuran Residues in Water

1980 ◽  
Vol 63 (2) ◽  
pp. 200-201
Author(s):  
Swadesh K Handa
Keyword(s):  
Nitric Acid ◽  
Spectrophotometric Determination ◽  
Spectrophotometric Method ◽  
Absorption Maximum ◽  
Colored Compound

Abstract A spectrophotometric method has been developed for the microdetermination of carbofuran in water. The method is based on the reaction of carbofuran phenol (2,3-dihydro-2,2-dimethyI-7-hydroxy benzofuran) with nitric acid to form a colored compound with an absorption maximum at 345 nm. The method is applicable to residues in the range 10-150 μg/5 mL solution.

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