Spectrophotometric determination of trace cadmium in vegetables with 3,5-bis(4-phenylazophenylaminodiazo)benzoic acid

A new highly sensitive and selective chromogenic reagent, 3,5-bis(4-phenylazophenylaminodiazo)benzoic acid (BPPABA) has been synthesized and applied to the determination of trace cadmium(II) in vegetables. The method is based on the color reaction between BPPABA and cadmium (II). In the presence of Triton X-100, cadmium(II) reacts with BPPABA in Na₂B₄O₇-NaOH buffer solution (pH 10.5), forming red complex with maximum absorption at 530 nm. Under the optimal conditions, Beer’s law is obeyed within 0–12 μg of cadmium within 25 mL of solution, and the apparent molar absorptive coefficient of the complex is 2.8 × 10⁵ L/mol cm. The detection limit and the relative standard deviation were found to be 0.92 μg/L and 1.0%, respectively. Interference of foreign ions was also investigated. Most of the metal ions are tolerated in considerable amounts except for Hg(II), Cu(II) and Ni(II). To eliminate the interference of foreign ions, metal ion imprinted polymer technique was utilized.     

二甲氧基羟基苯基荧光酮光度法测药物中的钼

钼是维持人体健康的重要微量元素之一,主要作用是防止龋齿,促进铁的新陈代谢,保持男子的性能力,预防贫血,尤其具有抗癌防癌等生物学效应。钼缺乏与很多疾病有关,尤其是动脉粥样硬化的致病因素。为了保持人体健康,就要保证微量元素钼的正常摄入量。世界卫生组织估     

Spectrophotometric and fluorometric determination of traces of molybdenum in soils and plants

The reaction of the molybdenum oxypentathiocyanate ion with the dyestuff Rhodamine B (RhB) produces the ternary complex. MoO(SCN)(5)(RhB)(2) The formation of this complex is accompanied by a colour change and by extinction of the fluorescence of RhB. A spectrophotometric and fluorometric method for the determination of Mo has been developed from these observations. The method is free from interferences and has detection limits of 0.1 mug and 0.05 mug of Mo for absorption and fluorescence measurements, respectively. The spectrophotometric method is applicable to the determination of Mo in soils and the fluorometric method is suited to the determination of Mo in plants.     

Spectrophotometric determination of molybdenum with lobeline

Lobeline hydrochloride has been tested as a reagent for molybdenum(V). Molybdenum(VI) is reduced with hydrazine sulfate in hydrochloric acid solution to Mo(V) only and complexed with thiocyanate and lobeline which is extracted with chloroform. In the paper experimental conditions for the formation of the ion pair of lobeline with molybdenum thiocyanate are described and the composition of this complex is given.     

Spectrophotometric determination of molybdenum with phenylfluorone

Spectrophotometric studies on the reaction between molybdenum as molybdate (MoO₄^2?) and phenylfluorone are presented. The reaction conditions are optimized to develop an intense color (molar absorptivity is 3.8 × 10³) selective and sensitive for the Spectrophotometric determination of molybdenum. The absorbance is measured at 560 nm, at a pH of 1.5–3. The colored complex is stable for up to 24 hr, Beer's law is obeyed, over the concentration range of 1 to 4 μg/25 ml. The relative standard deviation is 2% and the sensitivity of the method is 1.60 × 10^?4 mg/ml.     

Spectrophotometric molybdenum determination with thiolactic acid

A quick, selective method for molybdenum(VI) is based on the formation of a yellow thiolactic acid complex. The complex is formed at pH 1.0-1.6, and the absorbance is measured at 365 nm.     

Spectrophotometric determination of molybdenum with 7,8-dihydroxy-4-methylcoumarin and cetyltrimethylammonium bromide

The 1:2 complexes formed between molybdenum and 7,8-dihydroxy-4-methylcoumarin in the presence and absence of cetyltrimethylammonium bromide (CTAB) have been studied. The binary complex formed at pH 5.6-6.0 in the absence of CTAB exhibits an absortion maximum at 360 nm with a molar absorptivity of 5.1 x 10(4) 1.mole(-1).cm(-1). The complex formed at pH 4.8-6.0 in the presence of CTAB has a molar absorptivity of 1.32 x 10(5) 1.mole(-1).cm (-1) at 400 nm, the wavelength of maximum absorption. Optimum conditions for complex formation were investigated and a rapid, sensitive and relatively selective method for the determination of up to approximately 70% of Mo in diverse alloys and steels is described. Small amounts of zirconium and tungsten interfere.     

Spectrophotometric determination of molybdenum with 8-mercaptoquinoline

8-Mercaptoquinoline was found to be sensitive for the colorimetric determination of molybdenum. A procedure is outlined in which the complex formed, Mo(C₉H₆NS)₂, is extracted into chloroform and the extinction measured at 425 mμ. The effects and removal of interfering ions are discussed.     

2,4-二氯苯基荧光酮体系分光光度法测定微量铋

研究了在十六烷基三甲基溴化铵(CTMAB)存在下,铋与2,4 二氯苯基荧光酮的显色反应条件,该体系最大吸收峰位于570nm,表观摩尔吸光系数为ε=1.48×105L·mol-1·cm-1。在0～0 68μg/mL范围内符合比尔定律。本法可用于胃药和合金中微量铋的分析。     

Spectrophotometric determination of molybdenum in rocks with thiocyanate

A rapid procedure for the determination of microgram amounts of molybdenum in rocks is described. After acid decomposition, molybdenum is extracted from a hydrochloric acid solution into xylene with tributyl phosphate. After back-extraction with water, molybdenum is extracted as the α-benzoinoximate into chloroform, stripped into hydrochloric acid extracted as the thiocyanate into amyl alcohol, and determined spectrophotometrically. The molybdenum thiocyanate color produced is stable, sensitive, and reproducible. Results of analyses of several of the U.S. Geological Survey standard rocks are given.     

Spectrophotometric determination of silver with 4-(3,5-dibromo-2-pyridylazo)-N,N-diethylaniline in the presence of sodium dodecylsulfate

The bidentate ligands, 4-(3,5-DiBr-PAEA) and 4-(3,5-DiBr-PAESA) react with silver(I) ion to form the Agl2 chelate in the presence of anionic or nonionic surfactant. The molar absorptivity at 600 nm is 80 000 l mol^?1 cm^?1 in 0.1% sodium dodecylsulfate solution. Optimum conditions for the spectrophotometric determination of silver in the range 0.1–1.0 mg l^?1 with 3,5-diBr-PAEA are reported. A flow-injection procedure is also presented.     

Spectrophotometric and volumetric molybdenum determination with 2,2'-biquinoxalyl

Volumetric and spectrophotometric methods for molybdenum determination based on reaction with 2,2'-biquinoxalyl (2,2'-BQx) in concentrated hydrochloric acid media have been developed. Absorption spectra of the 1,1'-dihydro 2,2'-biquinoxalylene complex shows the most intensive absorption band at 685 nm with molar absorptivity = 3.3 x 10(4) 1. mole(-1). cm(-1). The compound is characterized by good durability to high temperatures and concentrated acid media. The mentioned indicator gives distinct colour changes at the titration end-point. The spectrophotometric method for molybdenum determination is based on the use of the difference in absorbance between the oxidized and reduced forms of 2,2'-BQx. The indicator is reduced with Sn(II) and then part of it is reoxided as a result of addition of Mo(VI). The difference in absorbance between the blank determination and molybdenum sample increases linearily in the concentration range 0.2-2.0 mug Mo/cm(3). 2,2'-Biquinoxalyl was used as an indicator in the volumetric method for the determination of molybdenum concentrations in steel alloy. The interfering ions FE(III) and Cr(III) are easily eliminated as the precipitate of hydroxides. The mineral acids, hydrochloric sulphuric and perchloric acids, have been tested as reaction media.     

Spectrophotometric determination of molybdenum and tungsten in niobium with dithiol

A new procedure for the determination of molybdenum and tungsten in niobium has been developed. The method involves the formation of the intensely colored complex of molybdenum with toluene-3,4-dithiol in an aqueous medium and its extraction into carbon tetrachloride followed by the reduction of tungsten and the formation and extraction of its complex. The recommended reagent is stable for at least 90 days. Both the molybdenum and the tungsten dithiol complexes are formed quantitatively within 5 min. Interlaboratory evaluation of the method reveals within-laboratory and between-laboratory relative standard deviations of about 1.5% and 2.9% respectively.     

Spectrophotometric determination of microquantities of molybdenum

Summary A new spectrophotometric method for the determination of microquantities of molybdenum (VI) and rutin, respectively, has been described. In order to take all the advantages of this very sensitive method, the effect of some foreign ions on these determinations has been studied and a combined chromatographic-spectrophotometric procedure for the separation and the determination of microamounts of molybdenum (VI) in the presence of a large number of interfering ions has been developed.

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Spektrophotometrische Bestimmung von Mikromengen Molybdän

Zusammenfassung Eine neue spektralphotometrische Methode zur Bestimmung von Mikromengen von Molybdän(VI) bzw. von Rutin wurde beschrieben und der Einfluß einiger Fremdionen auf diese Bestimmung untersucht. Um die Anwendungsmöglichkeiten dieser Methode zu erweitern, wurde ein kombiniertes chromatographisch-spektrophotometrisches Verfahren zur Abtrennung und Bestimmung von Mikromengen Molybdän(VI) in Gegenwart einer größeren Zahl störender Ionen ausgearbeitet.

     

Spectrophotometric determination of silver with 2-(3,5-dibromo-2-pyridylazo)-5-diethyl-aminophenol in the presence of anionic surfactant

A sensitive and selective spectrophotometric method for silver has been established by reacting silver(I) with 2-(3,5-dibromo-2-pyridylazo)-5-diethylaminophenol (3,5-diBr-PADAP) in the presence of an anionic surfactant, sodium lauryl sulphate. The molar absorptivity is 7.7 x 10(4) l.mole(-1).cm(-1) at 570nm. The molar ratio of silver to 3,5-diBr-PADAP is 1:2. Beer's law is obeyed from 0.1 to 1 ppm of silver. With EDTA as masking agent, common ions do not interfere. The method has been applied to the determination of silver in waste water.     

Spectrophotometric determination of zinc with 2-(3,5-dibromo-2-pyridylazo)-5-diethylaminophenol in the presence of anionic surfactant

A sensitive spectrophotometric method for zinc has been established by reacting zinc with 2-(3,5-dibromo-2-pyridylazo)-5-diethylaminophenol (3,5-diBr-PADAP) in the presence of an anionic surfactant, sodium lauryl sulphate. The molar absorptivity is 1.3 x 10(5) l.mole(-1).cm(-1) at 570 nm. The molar ratio of zinc to 3,5-diBr-PADAP is 1:2. Beer's law is obeyed up to 0.7 ppm of zinc. With preseparation of zinc by extraction of its thiocyanate complex, the method has been applied to the determination of zinc in waste water.     

Spectrophotometric determination of zirconium with 5,7-dibromo-8-hydroxyquinoline in presence of thiocyanate

The characteristics of the ternary complex formed between zirconium(IV) and 5,7-dibromo-8-hydroxyquinoline in presence of thiocyanate have been studied with an analytical point of view. The resulting colored species is extractable into chloroform with absorption maximum at 416 nm, which leads to the determination of the trace amounts of the metal ion. The method obeys Beer’s law in the range 0.2–9.0 μg Zr/mL having molar absorbitivity and Sandell’s sensitivity values of 1.05 × 10⁴ L/mol cm and 0.0087 μg Zr/cm², respectively. The ratio of zirconium(IV), 5,7-dibromo-8-hydroxyquinoline and thiocyanate in the extracted species is found to be 1: 2: 2. A large number of foreign ions do not interfere in the proposed method. The applicability of the procedure is tested by carrying out satisfactorily the analysis of a wide variety of samples.     

Spectrophotometric determination of molybdenum(vi) with benzoylacetanilide

Abstract

The complex formed between molybdenum(VI) and benzoylacetanilide in the pH range 0.6 and 1.9 has been extracted into methyl isobutyl ketone and the absorbance has been measured at 410 mμ. Quantities of 0.15 to 2.10 mg of molybdenum have been determined with a standard deviation of 0.6%. The color is stable up to 2 hours. The presence of Co²⁺, Ni²⁺, Zn²⁺, Mn²⁺, Be²⁺, Al³⁺, Cr³⁺, Ce⁴⁺, Th⁴⁺ or UO²⁺ ₂ up to 100 μg causes no interference. Ordinarily, Fe³⁺ interferes with the determination, but when masked with 1 ml of 0.5% solution of ascorbic acid the tolerance limit is 10 mg. Thus, molybdenum can be determined in steel when present in amounts as low as 0.26%.