Absorptiometric determination of micro- and submicroamounts of iron using an extractive method with pyridine-2-acetaldehyde salicyloylhydrazone

The formation and extraction into chloroform of iron complex with PASH (λ_max = 640 nm) was studied. Beer's law is obeyed between 2.7 and 16.0 μg · ml⁻¹ of iron, in organic phase (10 ml). The method can be applied to volume ratios V_aq.:V_org. from 1:1 to 20:1. The minimum concentration determinable in aqueous phase is 135 ng ml⁻¹ of iron. The interferences of 73 species were evaluated and eliminated when it was possible. The extraction method of the green complex was applied for the spectrophotometric determination of iron(II) in several standard, geochemical, and bromatological samples. A procedure based on the standard addition method was applied satisfactorily to the determination of as little as 25 ng of iron(II) per milliliter.     

Analytical applications of picolinealdehyde salicyloylhydrazone: II. Extraction and spectrophotometric determination of vanadium(V)

Picolinealdehyde salicyloylhydrazone reacts with vanadium(V) to produce a yellow 1:1 complex (λ_max = 400 nm, ? = 2.17 × 10⁴ liters · mol^?1 cm^?1) in aqueous ethanolic solution. The yellow complex can be extracted into chlorobenzene (λ_max = 425 nm, ? = 2.16 × 10⁴ liters · mol^?1 cm^?1) and used for the spectrophotometric determination of trace amounts of vanadium. Interferences have been investigated. The method has been applied to the determination of vanadium in steel and in lead concentrates.     

Extraction of lead(II) with cyanex 302 and its spectrophotometric determination with PAR

A method is developed for the extraction of lead(II) from an aqueous solution of pH 2.1-8.3 with cyanex 302 [bis(2,4,4-trimethylpentyl monothiophosphinic acid)] in toluene as an extractant. Lead(II) was stripped with 0.1 mol dm(-3) nitric acid and determined spectrophotometrically with PAR. The method is most sensitive and permits the separation of lead(II) from binary mixtures containing commonly associated metal ions. The method is applicable for the separation and determination of lead in alloys and environmental samples.     

Extraction—spectrophotometric determination of manganese(II) with xanthates

Manganese(II) (0.04–2 μmol) is extracted into chloroform from an aqueous phase at pH 6.5–9.0, containing a large excess of (n-butyl) xanthate and measured spectrophotometrically at 457 nm. The apparent molar absorptivity is 5.5 × 10³ dm³ mol^-1 cm^-1. The extractability of the manganese complexes decreases in the order n-butyl = benzyl- ? n-propyl- ? ethyl- ? methyl-xanthate. Interfering ions can be removed by a preliminary extraction with ethylxanthate. Ni, Co, Zn, Cd, Pb, Hg(II), Fe(III), As(III), Ce(III), Se(IV), V(V), Mo(VI), and the alkali and alkaline earth metals do not interfere.     

Extraction and spectrophotometric determination of cobalt(II) with isonitroso-5-methyl-2-hexanone

A simple and selective method is proposed for the extraction of cobalt(II) for its spectrophotometric determination using (HIMH) as an extractant. Cobalt(II) forms a yellow coloured complex with HIMH which can be extracted into chloroform. The calibration curve is rectilinear in the concentration range 0.1–5.0 μg ml⁻¹ of cobalt(II). The extracted species shows an absorption maximum at 400 nm with molar absorptivity of 1.135×10⁴ l mol⁻¹ cm⁻¹. The method has been applied for the determination of cobalt in synthetic mixtures, pharmaceutical, biological and high speed steel samples.     

Solvent extraction and spectrophotometric determination of uranium(VI) with pyridine-2-carboxaldehyde 2-hydroxybenzoylhydrazone

Pyridine-2-carboxaldehyde 2-hydroxybenzoylhydrazone (PAHB) is proposed as an extractant for the separation and spectrophotometric determination of uranium(VI). The optimum extraction conditions have been evaluated by studying various parameters such as pH, diluents, equilibration time and reagent concentration. PAHB forms yellow colored complex with uranium(VI) in the pH range of 3.5-4.6 which can be extracted by isobutyl methyl ketone. The extracted complex exhibits an absorption maximum at 375 nm. Beer's law was obeyed in the concentration range 1.0-5.6 ppm of uranium(VI). The nature of the extracted species (1:2) was determined by log D-log c plot. The proposed method permits selective separation of uranium(VI) from its binary mixtures. The method is also applied for the estimation of uranium in multicomponent mixtures and monazite sand.     

Extraction and spectrophotometric determination of trace amounts of tin(II) with diphenylglyoxal bis(2-hydroxybenzoylhydrazone)

Diphenylglyoxal bis(2-hydroxybenzoylhydrazone) has been used as a sensitive reagent for the spectrophotometric determination of tin. This reagent forms an orange-yellow complex with stannous ion at pH 3.5–7.0 (λ_max = 455 nm, ? = 2.25 × 10⁴ liter mol^?1/cm^?1 while no reaction is observed with quadrivalent tin. The colored complex extracted into isobutyl methyl ketone has been used for the spectrophotometric determination of trace amounts of tin(II). The molar absorption in the organic solvent is 3.54 × 10⁴ liter mol^?1 cm^?1 and the compound shows its maximum absorbance at 455 nm. The interferences of foreign ions have been determined.     

Extraction and spectrophotometric determination of copper(II) with 1,1,1-trifluoro-3-(2-thenoyl)acetone

Copper(II)-trifluorothenoylacetone complex in chloroform does not undergo decomposition when scrubbed with sodium hydroxide solution. This allows the complete removal of the residual reagent, and a highly sensitive method for the extraction and spectrophotometric determination of copper(II) results.     

Extraction and spectrophotometric determination of cobalt(ii) with 2-thenoyltrifluoroacetone

The rapid extraction and simultaneous spectrophotometric determination of mg amounts of cobalt(II) by means of 2-thenoyltrifluoroacetone is described. The yellow cobalt(II)-TTA chelate solution in acetone-benzene obeys Beer's law at 430 mμ over the range 12 to 51 μg of cobalt(II) per ml. At pH 5.1–6.8 a single extraction with 0.15 M TTA in acetone is satisfactory. The system is stable for 96 h. Silver, zirconium, strontium, thorium, zinc, lead(II) and mercury(II) do not interfere.     

Extraction and spectrophotometric determination of trace amount of Pd(II) with 2,2'-dithiodianiline

A method for the extraction-spectrophotometric determination of palladium with 2,2′-dithiodianilline (DTDA) is described. DTDA–Pd(II) complex is extracted from an aqueous solution with pH 3 into isobutyl methyl ketone (IBMK) layer. The absorbance is measured at 397 nm and the molar absorptivity found to be 1.47×10⁶ l mol⁻¹ cm⁻¹. The complex system conforms to Beer's law over the range 0.3–220 ng ml⁻¹ palladium (II). The effect of pH (1–6), NaClO₄ concentration, DTDA concentration and shaking time were studied. The ratio of the metal ion to ligand molecules in the complex and its stability constant were found to be 1:1 and 1.45×10⁶, respectively. The tolerance limit for many cations and anions have been determined. Finally the method has been applied successfully to the determination of palladium in synthetic mixtures, alloy and catalyst samples.     

Extraction and spectrophotometric determination of cobalt(II) with thiobenzoylacetone and simultaneous determination of cobalt and nickel

Thiobenzoylacetone in benzene is used for the extraction and spectrophotometric determination of cobalt at pH 8.4-9.1. The orange-yellow complex is measured at 460 nm. The system conforms to Beer's law over the range 0.20-4.58 microg ml of extract. The colour of the complex is stable for at least 144 hr. Cobalt(II) is quantitatively extracted and determined in the presence of 200:1 (w w ratios) of various ions. The method is made selective by using common sequestering agents such as thiourea or fluoride or by selective extraction with mesityl oxide, tributylphosphate and acetylacetone. It is possible to determine cobalt in the presence of nickel by simultaneous spectrophotometry. The method is rapid, simple, selective and sensitive.     

Extraction and spectrophotometric determination of gallium with 4-(2-pyridylazo)resorcinol

A sensitive and selective spectrophotometric determination of gallium is described. It is based on extraction of gallium from 3 M hydrochloric acid solution as a chloro-complex into 1,2-dichlorobenzene and exchange of the chloro ligand with 4-(2-pyridylazo)resorcinol (PAR); the final association complex of Ga—PAR with tetraphenylarsonium ions is measured in the organic phase. The absorption maximum occurs at 510 nm and the effective molar absorptivity is (8.2 ±0.3) ·1O⁴ l mol^-1cm^-1. Beer's law is obeyed over the range 0.2–2 p.p.m. of gallium. Few ions interfere.     

Extraction and spectrophotometric determination of thallium(III) with thiothenoyltrifluoroacetone

A procedure is described for the extractive photometric determination of thallium(III) with thiothenoyltrifluoroacetone in carbon tetrachloride. Thallium(III) is extracted quantitatively at pH 4-5 and the bright yellow extract obeys Beer's law over the Tl(III) concentration range 2.5-17.5 mug/ml, at 440 nm. Thallium(III) can be determined in the presence of a large number of cations and anions.     

Extraction and spectrophotometric determination of vanadium(V) with ferron

Various metal complexes of 7-iodo-8-hydroxyquinoline-5-sulphonic acid (ferron) were found to be selectively extracted into immiscible alcohols. Vanadium(V) is almost completely extracted into n-butanol in a single extraction from solutions which are 0.05 M in sulphuric acid. A sensitive and selective spectrophotometric method can be based on this extraction. Beer's law is obeyed up to 15.3 μg of vanadium per ml; the sensitivity of the color reaction is 0.011 μg of vanadium per cm² at 430 mμ. The interference of iron(III) can be eliminated by adding excess pyrophosphate. The extracted species appears to contain vanadium, ferron and n-butanol in the ratio 1:2:4.     

Extraction spectrophotometric determination of mercury(II) using thiacrown ethers and Bromocresol Green

A reasonably sensitive and highly selective spectrophotometric method for the determination of mercury(II) is proposed. The method is based on the extraction of the ion-associate formed by a mercury(II) thiacrown ether cationic complex with Bromocresol Green as the anionic counter-ion using chloroform as the extracting solvent. The effect of thiacrown ethers of different cavity sizes, namely 1,4,7,10,13-pentathiacyclopentadecane (PTP) and 1,4,7,10,13,16-hexathiacyclooctadecane (HTO), the thiacrown ether concentration, the extracting solvent, the bromocresol green concentration and the aqueous phase pH on the extraction were investigated. Measurement of the absorbance at the lambda(max) (420 nm) of the extracted ion-associate reveals that Beer's law is obeyed over 0.5-12.0 ppm mercury(II) for both ligands. Slight interference from copper(II) and cadmium(II) is exhibited by the PTP ligand, while HTO is negligibly affected by these metal ions. Strong interference from silver(I) is evident for both ligands while alkali, alkaline earth and other transition metals tested posed negligible interference. Analysis of mercury in synthetic complex mixtures was satisfactory.     

Extraction and spectrophotometric determination of trace amounts of niobium with diphenylglioxal-bis-(2-hydroxybenzoylhydrazone)

A method is described for the direct spectrophotometric determination of microamounts of niobium based on its extraction into chloroform with dephenylglyoxal-bis-(2-hydroxy benzoyl) hydrazone (BSHB). This reagent builds up a chelate with Nb(V) in very acidic media, its chloroform solution being pink to reddish depending on niobium concentration (λ_max = 495 nm). Optimum conditions for chelate extraction and niobium determination have been established. The precision of procedure proposed, expressed in terms of relative standard deviation, is ±1.0%.It is shown that the method is sensitive, the molar absorptivity being 1.95 ± 0.02 × 10⁴ liter · mol⁻¹ · cm⁻¹ in the organic phase, and the interferences study demonstrates a high selectivity against common cations and the majority of those accompanying niobium in its natural sources and special alloys.