Determination of low concentrations of dibenzyl sulfoxide in aqueous solutions

1979 ◽  
Vol 44 (6) ◽  
pp. 1908-1917 ◽  
Author(s):  
František Vláčil ◽  
Huynh Dang Khanh
Keyword(s):  
Standard Deviation ◽  
Hydrochloric Acid ◽  
Low Flow ◽  
Optimum Conditions ◽  
Hydrochloric Acid Medium ◽  
Low Concentrations ◽  
Limit Of Determination ◽  
Relative Standard ◽  
Basic Anion

A spectrophotometric method was developed for the determination of low concentrations of sulfoxide in water, relying on the formation of a leuco-compound from the reaction of L-tryptophan with p-dimethylaminobenzaldehyde and its oxidation by sulfoxide in hydrochloric acid medium. The optimum conditions for the determination were found by using the simplex method. The calibration curve, measured at 620 nm, is linear up to the sulfoxide concentration 7.5 . 10-5 mol l-1 (i.e. 17.3 ppm), the limit of determination is 0.1 ppm, the reproducibility, expressed as the relative standard deviation (for n = 6) is 3-4%. Oxidants interfere with the determination. Nitrates can be removed by means of a strongly basic anion exchanger in the chloride form. Mixture water-acetone (6 + 1) passing with a low flow rate should be applied to the elution of the partly sorbed sulfoxide.

scholarly journals Spectrophotometric Determination of Citalopram Hydrobromide in Pharmaceuticals

2019 ◽  
Vol 54 (2) ◽  
Author(s):  
Badiadka Narayana ◽  
Kunnummel Veena
Keyword(s):  
Standard Deviation ◽  
Hydrochloric Acid ◽  
Spectrophotometric Determination ◽  
Dosage Forms ◽  
Complexing Agent ◽  
Fixed Amount ◽  
Thiocyanate Complex ◽  
Hydrochloric Acid Medium ◽  
Relative Standard

Simple, rapid and sensitive methods are described for the spectrophotometric determination of citalopram hydrobromide (CIT) in pharmaceuticals. The method A is based on the oxidation of citalopram by a known excess of bromate-bromide mixture in hydrochloric acid medium, reduction of the residual oxidant by a fixed amount of iron(II) and the formation of iron(III)-thiocyanate-complex which is measured at 480 nm. In the method B, 1,10-phenanthroline is used as a complexing agent and the formation of iron(II)-1,10-phenanthroline, which is measured at 510 nm. The system obeys Beer’s law in the concentration range of 1.0-7.0 μg mL-1 of CIT for method A and 0.6-6.2 μg mL-1 of CIT for method B. No interference observed from common pharmaceutical adjuvants. Both methods are equally precise as shown by the relative standard deviation values less than 2%. The apparent molar absorptivities and Sandell’s sensitivity for method A and B are found to be 2.10x104 L mol-1 cm-1, 0.019 μg cm-2 , 7.30x104 L mol-1 cm-1 and 5.5x10-3 μg cm-2, respectively. The methods have been successfully applied to the determination of citalopram hydrobromide in pure and dosage forms.

scholarly journals Aqueous Two-Phase Systems: A New Approach for the Determination of Brilliant Blue FCF in Water and Food Samples

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Sabah Shiri ◽  
Tahere Khezeli ◽  
Shahram Lotfi ◽  
Sina Shiri
Keyword(s):  
Polyethylene Glycol ◽  
Standard Deviation ◽  
Food Samples ◽  
Brilliant Blue ◽  
Phase System ◽  
Optimum Conditions ◽  
Two Phase ◽  
Brilliant Blue Fcf ◽  
Relative Standard

A novel, simple, and more sensitive spectrophotometric procedure has been developed for the determination of brilliant blue FCF in water and food samples by an aqueous two-phase system (ATPS). In this method, adequate amount of polyethylene glycol/ sodium carbonate (PEG-4000/Na2CO3) was added to aqueous solution for formation of a homogeneous solution. To the mixture solution, suitable amount ofNa2CO3was added, the mixture solution was shaken until the salt was dissolved, and then it was separated into two clear phases easily and rapidly. The target analyte in the water sample was extracted into the polyethylene glycol phase. After extraction, measuring the absorbance at 634 nm was done. The effects of different parameters such as polyethylene glycol (type and concentration), pH, salt (type and amount), centrifuge time, and temperature on the ATPS of dye was investigated and optimum conditions were established. Linear calibration curves were obtained in the range of 0.25–750 ng/mL for brilliant blue FCF under optimum conditions. Detection limit based on three times the standard deviation of the blank (3Sb) was 0.12 ng/mL. The relative standard deviation (RSD) for 400 ng/mL was 3.14%. The method was successfully applied to the determination of brilliant blue FCF in spiked samples with satisfactory results. The relative recovery was between 96.0 and 102.2%.

Cloud Point Extraction-Fluorimetric Combined Methodology for the Determination of Magnolol

2013 ◽  
Vol 699 ◽  
pp. 34-39
Author(s):  
Li Liu ◽  
Xia Shi Zhu
Keyword(s):  
Standard Deviation ◽  
Detection Limit ◽  
Cloud Point ◽  
Relative Standard Deviation ◽  
Cloud Point Extraction ◽  
Calibration Graph ◽  
Optimum Conditions ◽  
Relative Standard ◽  
Triton X

A new Triton X-114 cloud point extraction combined with fluorometry method for analysis of magnolol in drug samples was developed. Under the optimum conditions, the calibration graph was linear in the range of 2.0-150.0ng/mL of magnolol in the initial solution with r = 0.9998. Detection limit (DL) was 0.03ng/mL (S/N=3) and the relative standard deviation (RSD) for 20.0ng/mL of magnolol was 2.79%(n=11). The method was successfully applied for the determination of magnolol in drug samples with satisfactory results.

Photometric determination of aluminium and zinc with salicylaldehyde semicarbazone

1984 ◽  
Vol 49 (6) ◽  
pp. 1468-1473 ◽  
Author(s):  
Záviš Holzbecher ◽  
Dagmar Lipská
Keyword(s):  
Ethyl Acetate ◽  
Fluorescence Spectra ◽  
Photometric Determination ◽  
Optimum Conditions ◽  
Fluorometric Determination ◽  
Limit Of Determination ◽  
Relative Standard ◽  
Tenfold Excess ◽  
Masking Agents

The effect of some tensides on the absorption, excitation, and fluorescence spectra of Al and Zn complexes of salicylaldehyde semicarbazone in aqueous-alcoholic solutions and on their extractability into ethyl acetate has been studied. The shape of the absorption spectra is unaffected by the presence of the tensides while the time of the complex formation is shorter. The complexes are extractable into ethyl acetate in the presence of the anionactive tenside tested, sodium lauryl sulphate. The optimum conditions for the spectrophotometric and fluorometric determination of Al and Zn have been established. The limit of determination is 2 ng ml-1 (pH 3.8-4.8) for Al and 50 ng ml-1 (pH 8.4-8.6) for Zn. Using thiosulphate or fluoride as masking agents, Zn can be determined in a concentration of 2 μg ml-1 in the presence of the same quantity of Al or Cu, or in the presence of a tenfold excess of Fe, with a relative standard deviation of 1.5%.

Iodometric determination of 2-mercaptobenzthiazole by coulometric titration

1982 ◽  
Vol 47 (2) ◽  
pp. 588-593 ◽  
Author(s):  
Zdeněk Kučera ◽  
Milan Karlík ◽  
Jiří Krofta
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Coulometric Titration ◽  
Optimum Conditions ◽  
End Point ◽  
Relative Standard ◽  
Standard Deviations

The optimum conditions were found for the determination of 2-mercaptobenzthiazole (MBT) by coulometric titration with the generated iodine using biamperometric indication of the titration end point. Use is made of the oxidation to the disulphide (n = 1) and to benzothiazole-2-sulphinate (n = 4) in the regions pH 4.5-8.5 and 10-12, respectively. Eight repeated titrations to the disulphide gave the relative standard deviations 0.27% and 1.23% in the determination of 1 675 and 33.5 μg MBT, respectively, seven repeated titrations of 419 μg MBT to benzothiazole-2-sulphinate afforded results with the relative standard deviation 0.34%.

Spctrophotometric Determination of Trace Ruthenium by its Catalytic Effect on Oxidation of 3,5-DiBr-PADAP with KIO4

2012 ◽  
Vol 554-556 ◽  
pp. 1999-2005
Author(s):  
Zhi Rong Zhou ◽  
Qun Wang ◽  
Shu Yuan Zhang
Keyword(s):  
Activation Energy ◽  
Standard Deviation ◽  
Detection Limit ◽  
Catalytic Reaction ◽  
Oxidation Reaction ◽  
Catalytic Effect ◽  
Optimum Conditions ◽  
Potassium Periodate ◽  
Relative Standard

A spectrophotometric method for the determination of ruthenium (III) is described, based on its catalytic effect on the oxidation reaction of 2-[(3,5-dibromo-2-pyridy)azo]-5-diethylaminophenol (3,5-diBr-PADAP) with potassium periodate in 0.008 mol/L sodium hydroxide medium and in the presence of OP emulsifier (p-iso-octyl phenoxy polyethoxy ethanol) at 100 °C. The above reaction is followed spectrophotometrically by measuring the decrease in the absorbance at 530 nm for the catalytic reaction of 3,5-diBr-PADAP. The calibration curve for the recommended method was linear in the concentration range over 0.04 µg/L–1.0 µg/L and the detection limit of the method for Ru (III) is 0.012 µg/L. The influence of the factors such as acidity, concentration of reactants, reaction time, temperature and co-existing ions on the reaction is discussed. The optimum conditions of reaction are established and some kinetic parameters are determined. The apparent activation energy of catalytic reaction is 100.48 kJ/mol. The relative standard deviation for the determination of ruthenium (III) at the concentration of 0.02 µg/25mL is calculated to be 2.30 % (n=11). In combination with distilled separation, the method has been successfully applied for the determination of trace ruthenium (III) in some ores and metallurgy products with the relative standard deviations (RSD) over 1.8 %–2.9 % and the recovery over 98.1 %–103.1 %.

Determination of Trace Chromium (VI) in Tanning Wastewater by Flow Injection Spectrophotometry

2010 ◽  
Vol 113-116 ◽  
pp. 1732-1734
Author(s):  
Xin Zhao ◽  
Zhi Hui Sui ◽  
Jing Bin Zhang
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Flow Injection ◽  
Spectrophotometric Method ◽  
H2so4 Solution ◽  
Optimum Conditions ◽  
Chromium Vi ◽  
Relative Standard ◽  
Simple Flow

In 1.0 mol/L H2SO4 solution, a rapid and simple flow—injection spectrophotometric method has been developed for Cr(Ⅵ) determination, based on the violet—red Cr(Ⅵ)—diphenylcarbazide chelates formed by reactions. The results show, under optimum conditions, the maximum absorption of the complex is at 540 nm and the detection limits of the method is 0.0136mg/L for Cr(Ⅵ) and Beer’s law is obeyed for Cr(Ⅵ) in the range of 0.03—1.60mg/L. The determination frequency is l00 times/h. The relative standard deviation of eleven replicates is less than 4.0%. The method has been applied to the determination of trace Cr(Ⅵ) in tanning wastewater with satisfactory results.

Study on the Kinetic Spectrophotometric Determination of Selenium (IV) on Oxidation of Neutral Red with Potassium Periodate and its Application

2012 ◽  
Vol 610-613 ◽  
pp. 446-451
Author(s):  
Zhi Rong Zhou ◽  
Li Zhen Zhang
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Limit Of Detection ◽  
Fixed Time ◽  
Neutral Red ◽  
Optimum Conditions ◽  
Hair Samples ◽  
Relative Standard ◽  
Kinetic Spectrophotometric

Based on the oxidation of neutral red by KIO4 in 3.2×10-4 mol/L sulfuric acid solution, a simple kinetic spectrophotometric method was developed for the determination of trace amounts of Se(IV).The reaction was monitored spectrophotometrically by measuring the decrease in the absorbance of neutral red at 530 nm with a fixed-time method. The decrease in the absorbance of neutral red is proportional to the concentration of Se(IV) in the range 0.0–8.0 µg/L with a fixed time of 4–6 min from the initiation of the reaction. The limit of detection is 0.36 µg/L Se(IV). The influence of the factors such as acidity, concentration of reactants, reaction time, temperature and co-existing ions on the reaction is discussed. The optimum conditions of reaction are established and some kinetic parameters are determined. The apparent activation energy of catalytic reaction is 81.60 kJ/mol. The relative standard deviation for the determination of 0.1 and 0.2 µg/mL Se(IV) was 2.1 and 1.9 %, respectively. The method has been successfully applied to the determination of Se (IV) in tea and human hair samples with the relative standard deviation of 0.33 %–1.5 % and the recovery of 97.5 %–103.5 %.

scholarly journals THE OPTIMATION SIMULTANEUOS DETERMINATION OF LEAD(II) AND CADMIUM(II) BY ADSORPTIVE STRIPPING VOLTAMMETRY (ADSV)

2012 ◽  
Vol 5 (2) ◽  
pp. 100
Author(s):  
Deswati ◽  
Hamzar Suyani ◽  
Umiati Loekman ◽  
Nilam Sari
Keyword(s):  
Standard Deviation ◽  
Optimum Condition ◽  
Sea Water ◽  
Direct Determination ◽  
Stripping Voltammetry ◽  
Optimum Conditions ◽  
Accumulation Time ◽  
Accumulation Potential ◽  
Relative Standard

A selective and sensitive adsorptive stripping voltammetric (AdSV) method for simultaneous determination of lead(II) and cadmium(II) were proposed. The aim of this study was to get the optimum condition for simultaneuos determination of lead(II) and cadmium(II). The parameters were studied such as: variation of accumulation potential, accumulation time, pH, and variation ofcalcon concentration. In this case, the optimum conditions were reached at accumulation potential –0.7 V, accumulation time 80 s, concentration of 0.12 mM calcon, and pH 7.0. At the optimumconditions the relative standard deviation were 2.90% and 1.46% for Pb(II) and Cd(II) respectively for eight replicates (n = 8) measurements. The method was applied for the direct determination of Pb(II) and Cd(II) in sea water around Bungus, Padang City. Concentration Pb(II) and Cd(II) insample were 9.918 μg/L – 27.320 μg/L for Pb(II) and 7.997 μg/L - 32.521 μg/L for Cd(II), with recovery of 99.48%, and 103.28 for Pb(II), and Cd(II) respectively.

scholarly journals Catalytic Spectrophotometric Method for Determination of Formaldehyde Based on its Catalytic Effect on the ReactionBetween Bromate and Safranin

2010 ◽  
Vol 7 (s1) ◽  
pp. S481-S487
Author(s):  
Mohsen Keyvanfard
Keyword(s):  
Sulfuric Acid ◽  
Standard Deviation ◽  
Catalytic Effect ◽  
Limit Of Detection ◽  
Kinetic Method ◽  
Fixed Time ◽  
Optimum Conditions ◽  
Relative Standard ◽  
Replicate Measurements

The reaction monitored spectrophotometrically by measuring the decrease in absorbance of the reaction mixture at 533 nm. The fixed-time method was used for the first 60s. For initiation of the reaction, under the optimum conditions, in the concentration range of 0.02-1.5 μg mL–1formaldehyde can be determined with a limit of detection 9.5 ng mL–1. The relative standard deviation of five replicate measurements is 2.3% for 0.5 μg mL–1of formaldehyde. The method was used for the determination of formaldehyde in water samples with satisfactory results. A new simple and fast catalytic kinetic method for the determination of trace amount of formaldehyde is described. The method is based on the catalytic effect of formaldehyde on the oxidation of safranin by bromate in the present of sulfuric acid.

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