共查询到20条相似文献,搜索用时 31 毫秒
1.
Y. K. Agrawal G. D. Mehd 《International journal of environmental analytical chemistry》2013,93(3-4):183-188
Abstract The eight newly synthesized chlorosubstituted hydroxamic acids are described for the extraction and spectrophotometric determination of vanadium. The sensitive and selective reagent, N-m-Chlorophenylpalmito hydroxamic acid, (m-CPPHA), which gives violet coloured vanadium complex was extracted with chloroform from 6M HCl. The violet coloured complex thus obtained has a maximum absorbance at 520 nm and molar absorptivity 4.9 ± 1031mol?1cm?1. The Beer's law obeyed in the region 0.50-12.0ppm. Effects of acidity, reagent concentration, diverse ions have also been investigated. A comparison has been made with atomic absorption spectrophotometric method. Vanadium has been determined in the environment, e.g. plant, soil, rock, etc. 相似文献
2.
《Analytical letters》2012,45(12):2245-2261
Abstract A microdetermination method at μg 1?1 levels for vanadium by solid-phase spectrophotometry has been developed. 5-Bromosalicylhydroxamic acid was used as chromogenic reagent to form a 1:2 violet complex which is easily sorbed and concentrated on a dextran-type anion-exchange resin. The resin-phase absorbances at 560 and 850 nm were measured directly. Vanadium can be determined in the 5 - 60 μg 1?1 range with a RSD of 4.3%. The method is applied to the determination of vanadium in pet roleiim crudes and natural water, samples. 相似文献
3.
Promethazine hydrochloride forms a red colored species with vanadium(V) in 6.0–7.5 M phosphoric acid. A 16-fold molar excess of the reagent is necessary for full development of color intensity. Beer's law is valid over the concentration range of 0.1–7.0 ppm. The optimum concentration range as evaluated by Ringbom's method is 0.5–7.0 ppm. The sensitivity of the reaction is 0.005 μg cm?2 and the molar absorptivity is 9.60 × 103 liter mol?1 cm?1 at 517 nm. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions were reported. Vanadium in vanadium steel containing chromium, molybdenum, manganese, and nickel was determined. 相似文献
4.
《Analytical letters》2012,45(9):1027-1036
Abstract A highly sensitive, selective, and rapid method for the spectrophotometry determination of vanadium(V) at trace levels is described. The method is based on the selective extraction of vanadium(v) from strongly acidic (3–6 M hydrochloric acid) met ium with solution of N-0-methoxyphenyl-2- thenohydroxamic acid (0MTHA) in chloroform. The extract is then equilibrated with 3-(0-carboxyohenyl)-1-phenyltriazine-N-oxide(CPPTNO) at pH ? 1.5 and the resulting colour is measured at 445 nm. The colour system obeys Beer's law over the range 0–20 -μg/ml of vanadium; the molar absorptivityat the wavelength of maximum absorption (445 nm), and the Sandell sensitivity of the method are 1.1 × 1041. mole?1 cm?1 and 0.005 μg/ml respectively. 相似文献
5.
《Analytical letters》2012,45(20):2349-2357
Abstract A sensitive and selective method for the extraction and spectrophotometric determination of Zr(IV) with N-p-chlorophenyl-3,4-,5-trimethoxycinnamohydroxamic acid (PTCHA) has been developed. The binary complex of Zr(IV)-PTCHA is extracted from 2–6 M HCl into chloroform, having a maximum absorbance at 385 nm; molar absorptivity 2.1 × 104 1 mol?1 cm?1. A ternary complex with xylenol orange (Zr-PTCHA-XO) have been studied in chloroform-ethanol media, which absorbs at 540 nm; molar absorptivity 4.3 × 104 1 mol?1 cm?1. The present method is applied for the analysis of zirconium in standard samples. 相似文献
6.
《Analytical letters》2012,45(9):1347-1361
Abstract A method is presented for the highly sensitive, selective, and rapid determination of vanadium (V) at sub-microgram levels in rocks, animal tissues, plant tissues and natural waters. The method is based on the selective extraction of vanadium (V) from strongly acidic (3-8 M hydrochloric acid) medium with solution of N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform. The reddish-violet extract (molar absorbance 8.6x103 1 mole?1 cm?1 at λ max 545 nm) is then equilibrated with 3-(o-carboxyphenyl)-1-phenyltriazine-N-oxide (CPPTNO) at pH = 1.5. The resulting ternary complex has enhanced colour (molar absorbance 1.4 × 104 1 mole?1 cm?1 at Λ max 450 nm). The ternary system obeys Beer's Law at 450 nm over the range 0-18 μ g/ml of vanadium. The extraction system achieves 20-fold enrichment of vanadium and enables the determination of the metal down to parts per billion (ng 1?1) levels. The method tolerates the presence of a large number of anions and cations which are normally present with vanadium in rocks, plant tissues, animal tissues and natural waters. The applicability of the method was tested by the analysis of vanadium in these matrices. MFHA was selected from nine hydroxamic acids as it provided maximum sensitivity and selectivity. 相似文献
7.
A method is described for the determination of vanadium and molybdenum in samples of tap and bottled mineral water. After acidification with citric acid the water sample is heated to about 80°C to remove CO2; sodium citrate and ascorbic acid are added and the resulting solution of pH 3 is passed through a column of the strongly basic anion-exchange resin Dowex 1-X8 (citrate form) on which both vanadium and molybdenum are adsorbed as anionic citrate complexes. Vanadium is eluted with 6 M hydrochloric acid; molybdenum is recovered with 2 M perchloric acid-1 M hydrochloric acid. Vanadium and molybdenum are determined in the eluates by atomic-absorption spectrometry. The samples analysed contained 0.1–0.9 μg l?1 vanadium and 0.2–13 μg l?1 molybdenum. 相似文献
8.
Anil K. Baveja V. K. Gupta 《International journal of environmental analytical chemistry》2013,93(3-4):299-306
Abstract Vanadium(V) reacts with N-m-Tolyl-p-methoxy benzohydroxamic acid to form 1:2 (metal to ligand) complex containing a basic V=O group and an acidic V-OH group, which forms addition compounds with thiocyanate to give a hyper and bathochromic effect in chloroform. On the basis of this bathochromic effect of thiocyanate a rapid, selective and sensitive method for the spectrophotometric determination of vanadium(V) has been developed. The blue coloured complex of vanadium(V) is extractable in chloroform having absorption maxima at 580nm and max 7100 ±50 1. mole?1 cm?1. The method is free from interferences of Mo(VI), W(VI), Zr(IV) and has been successfully applied for the analysis of steels and other complex materials. 相似文献
9.
《Analytical letters》2012,45(11-12):1177-1189
Abstract Five new substitued hydroxamic acids are used for extraction and spectrophotometric determination of vanadium(V) in trace amounts. the binary complex of vanadium (V) with H-p-ciloropheny 1-3,4,5-trimethoxycinnamohdroxamic acid (PTCHA) and the mixed ligand complex of vanadium (V) with N-p-cinlorpheny-p-chlorophenoxyisobutyrohydroxamic acid (PP3HA) and thiocyanete were studied. The molar absorbtivities of the bluish violet vanadium(V) hydroxamate and mixed ligand complexes are 6.9 × 103 and 1.1 × 104 cm3 mol?3 cm?1, respectively. The vanadium is also determined with AAs and the method is applied for its determination in steel. alloy, rock and environmental samples. 相似文献
10.
The reagent in 8-fold excess forms a violet species with vanadium(V) instantaneously in 1–3 M phosphoric acid. The absorption maximum is at 565 nm; the molar absorptivity is 1.65 × 104 l mol?1 cm?1. Beer's law is obeyed over the range 0.1–6.5 mg l?1 vanadium (V); the optimum range is 0.3–6.0 mg l?1; the Sandell sensitivity is 3.1 ng cm?2. The method is simple and selective. The method is applicable for the determination of vanadium in vanadium steels and minerals. 相似文献
11.
《Analytical letters》2012,45(6):995-1003
Abstract The use of 1-chloro-2, 4-dinitrobenzene is described for spectrophotometric estimation of ascorbic acid. The procedure is based on the interaction of ascorbic acid with 1-chloro-2, 4-dinitrobenzene in alkaline medium. The product absorbs maximally at 380 nm and has the molar absorptivity 0.14 × 1041 mole?1cm?1. Beer's law is obeyed in the concentration range 0.12–0.6 mg/10ml of ascorbic acid. 相似文献
12.
《Analytical letters》2012,45(7):1181-1190
Abstract The spectral characteristics and analytical properties of 4, 4′-Biazobenzenediazoaminobenzene as a new chromogenic reagent have been described and the optimum conditions for reaction with eight metal ions are presented. In the presence of Triton X-100 and sodium tetraborate solution, the reagent can be used for the determination of Hg, Ni, Cd. The molar absorptivities are 1.8×105 l.mol?1. cm?1 at 515 nm for mercury, 2.0×105 l.mol?1. cm?1 at 540 nm for nickel, and 1.8×105 l.mol?1.cm?1 at 526 nm for cadmium. The recommended procedure has been used for the spectrophotometric determination of cadmium in waste water. 相似文献
13.
《Analytical letters》2012,45(11):2063-2075
Abstract A new, sensitive and selective method for separation, and extraction - spectrophotometric determination of V (V) with pyrogallol {Ar (OH)3} and hydroxyamidines (HOA) is described. The molar absorptivities of the colored species with six substituted HOA lie in the range of (0.52–1.5)x 106 L mole?1 cm?1 at λmax 430–440 nm. Of these, the simplest compound, N-hydroxy-N, N- diphenylbenz-amidine (HDPBA) gives the most sensitive color reaction and hence, it is used for detailed studies. No interference of almost all diverse ions tested is noticed. The method offers the determination of vanadium in different environmental samples. 相似文献
14.
《Analytical letters》2012,45(7):1219-1230
Abstract An indirect photometric method with a continuous-flow analysis is presented for the determination of trace amounts of vanadium(IV). It is based on the redox reaction of copper(II) with vanadium(1V) in the presence of neocuproine. In the presence of neocuproine, copper(I1) is reduced easily by vanadium(I V) to a copper(1)-neocuproine complex, which shows a n absorption maximum at 454 nm. By measuring t h e absorbance of the complex at this wavelength, vanadium(1V) in t h e range 2×10?6 - 8 × mol dm?5 mol dm?3 can be determined at a rate of 120 samples h?1. The fractional determination of vanadium(1V) and iron(I1) is also studied. 相似文献
15.
《Analytical letters》2012,45(7):1807-1817
Abstract A new selective and sensitive method for extraction of yellow Mo (VI)-caffeic acid complex with a liquid ion exchanger, Aliquat 336 from 4.0 pH, and spectrophotometric determination of molybdenum in trace amounts is described. the molar absorptivity of the complex is 1.1 × 105 1 mol?1 cm?1 at 340 nm and the colour system obeys Beer's law in the range 0.04–0.99 ppm of Mo(VI). the molybdenum is also determined with AAS and the method is applied for its determination in steel and environmental samples. 相似文献
16.
《Analytical letters》2012,45(12):2333-2343
Abstract A comparison has been made on the selectivity, accuracy and precision of spectrophotometric, conductometric and potentiometric methods for the determination of ascorbic acid in water which is based on the reduction of gold(III) ion by ascorbic acid. Gold(III) ion forms a complex with gelatin in alkaline medium which on reduction with ascorbic acid produces coloured gold sol. The sol shows an absorption maximum at 540 nm with molar absorptivity of 2.3×10?3litre mol?1 cm?1 and the Sandell's sensitivity of 7.6 × 10?2 μgcm?2. The relative standard deviation is 0.22% and the confidence limit (20 determinations, 95%) is 2.0 ± 0.009%. To examine the extent of sensitivity of the spectrophotometric method the proposed method is compared with the sensitivities of the conductometric and potentiometric methods. 相似文献
17.
《Analytical letters》2012,45(10):2065-2073
ABSTRACT A simple and sensitive kinetic method for the determination of vanadium(V) based on its inhibitory effect on the reduction of thionine by ascorbic acid at pH=5 is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of thionine at 598 nm after a fixed time (10 min). The calibration graph is linear in the range of 10 ? 120 ng ml?1 of vanadium(V) and the detection limit is 6 ng ml?1. The relative standard deviation (RSD) for 80 ng ml?1 of V(V) was 0.96% (n=10). The method was successfully applied to the determination of vanadium in a certified reference sample. 相似文献
18.
《Analytical letters》2012,45(9):1131-1142
Abstract Colourless silver-gelatin complex is quantitatively reduced by ascorbic acid to yellow silver sol in water within the pH range 7.5–10.0 at room temperature. The determination of 1–10μg/ml of ascorbic acid is possible at 415 nm in the presence of glycine, alanine, fructose, sucrose, citric, tartaric, oxalic, malic, succinic acids and also in the presence of various reducing agents. The molar absorptivity of ascorbic acid at the δmax is found to be 21500 lit mol?1 cm?1 and the Sandell sensitivity of the sol is 8.18x10?3 μg ascorbic acid cm?2 for 0.001 absorbance. The relative standard deviation is ±0.22% and the confidence limit (20 determinations, 95%) being 8.806±0.0093%. 相似文献
19.
The spectrophotometric determination of vanadium(V) as a mixed thiocyanate-3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) complex and as a mixed thiocyanate-3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) complex is described. The extracted complexes in chloroform have a maximum absorbance at 450 and 650 nm. The optimal conditions for the extraction and spectrophotometric determination of vanadium(V) are determined. The solutions of the V-SCN-HX and V-SCN-HY complexes in chloroform obey Beer's law in the range 1–10 ppm of vanadium, and are stable for at least 24 hr. The molar absorptivity of the method is 6.8 × 103 liters mol?1 cm?1. The molar ratio V:SCN:HX (HY) of the extracted complex is 1:1:2. 相似文献
20.
《Analytical letters》2012,45(20):2521-2536
Abstract A selective and sensitive spectrophotometric and atomic absorption spectrophotometric method is developed for the determination of traces of mercury with N-phenylcinnamohydroxamic acid (PCHA) in the environment. Mercury is extracted into a chloroform solution of PCHA at pH 8.5-10.0 and determined by AAS. The mercury hydroxamate binary complex is yellow in colour having a maximum absorbance at 390 nm and molar absorptivity 4.3 × 103 1 mol?1 cm?1, sandell sensitivity 0.0466 μg/cm2. The ternary system using 1-(2-pyridylazo)-2-naphthol has molar absorptivity 8.82 × 103 1 mol?1 cm?1 at 550nm, sandell sensitivity 0.0228 μ/cm2. Beer's law is obeyed in the concentration range of 2.37-38.0 ppm and 0.80-19.5 ppm of mercury for binary and ternary system, respectively. The extraction of Hg-PCHA binary system is studied with a liquid cation exchanger, bis-(2-ethyl hexyl) phosphoric acid (HDEHP) and found to have better selectivity than Hg-PCHA-PAN system. The molar absorptivity of the Hg-PCHA-HDEHP system is 8.82 × 103 1 mol?1 cm?1 at 390 nm and Beer's law is obeyed in the concentration range of 0.47-20 ppm of mercury. The present method is applied to the determination of mercury in eye drops, aurvedic drugs and environmental samples. 相似文献