Spectrophotometric and derivative spectrophotometric determination of copper (II) with dithizone in aqueous phase

A Spectrophotometric and derivative Spectrophotometric study of Cu-dithizonate complex in aqueous phase in the presence of Triton X-100, a neutral surfactant, is reported. The system obeys Beer's law between 1.0 × 10^–6–9.0 × 10^–6 mol/l of Cu²⁺; detection limit is 12 ng/ml. The molar absorption coefficient, specific absorptivity and Sandell's sensitivity of the complex are 3.06 × 10⁴ 1 mol^–1 cm^–1, 0.4825 ml g^–1 cm^–1 and 2.1 × 10^–3 g cm^–2, respectively. The conditional stability constant of the 1 2 complex, calculated considering simultaneously existing equilibria, has been found to be 1.73 × 10¹¹ I² mol² (I = 0.07, pH 1.4, temperature = 10 °C). Absorption studies in the derivative mode have been carried out to determine the absorption maximum of the complex and to overcome interference due to the presence of certain metal ions. The method has been validated by determination of copper in beers, wines, human hair, goat liver and fly ash samples.     

Derivative spectrophotometric determination of copper(II) in non-ionic micellar medium

A photometric method for trace analysis of Cu(II) with 1-(2-pyridylazo)-2-naphthol (PAN) in presence of a neutral surfactant, Triton X-100, has been reported in normal and derivative modes. The molar absorption coefficient () and Sandell's sensitivity (S) of PAN-Cu(II) complex at 555 nm is 5.21 x 10(4) l mol(-1) cm(-1) and 1.22 ng cm(-2) respectively. The detection limit of Cu(II) is 4.0 ng ml(-1) and Beer's law is obeyed in the range 0.08-4.00 mug ml(-1) of the analyte. Copper content of a number of commercially available alcoholic beverages, biological and standard alloy samples is reported. The results obtained are in excellent agreement with those obtained using AAS.     

Enhancing the sensitivity of spectrophotometric determination of formic acid with mercury(II) acetate

A precise spectrophotometric method was developed for determination of formic acid. The method surpasses in sensitivity the method based on proper UV absorption of formic acid.     

对磺酸基苯亚甲基若丹宁固相萃取光度法测定水中的汞

研究了对磺酸基苯基亚甲基若丹宁(SBDR)与汞的显色反应,在pH4.0的HAc NaAc缓冲介质中,吐温 80存在下,SBDR与汞反应生成2∶1稳定络合物,该络合物可被WatersPorapak Sep Park C18固相萃取小柱萃取,用乙醇洗脱后在乙醇介质中λmax=520nm,可用分光光度法测定,体系ε=1.16×105L/mol·cm。汞含量在0μg/mL～1.5μg/mL内符合比尔定律,方法可用于水样中汞含量的测定。     

Triangular silver nanoplates as a spectrophotometric reagent for the determination of mercury(II)

The applicability of triangular silver nanoplates (TNPs) as a spectrophotometric reagent for the determination of mercury(II) in an aqueous solution was estimated. The method is based on the oxidation of TNPs with a mean edge length of 52 nm and thickness of 4 nm by mercury(II) ions, which is accompanied by a decrease in the surface plasmon resonance of nanoparticles. The effect of reaction time, pH of solution, and TNP concentration on the sensitivity of mercury(II) determination was studied. The limit of mercury(II) detection under the selected conditions was 0.022 μg/mL.     

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.     

Development of sequential injection spectrophotometric method for determination of mercury (II) using pyrogallol red

A sequential injection analysis (SIA) spectrophotometric method for the determination of trace amount of mercury (II) with pyrogallol red (PGR) was described. The method was based on the measurement of absorbance of the mercury (II)–PGR complex, yielding a light yellow-coloured product at pH 9.0 with absorption maximum at 370 nm. The SIA parameters affecting the signal response were optimised in order to obtain the better sensitivity and minimum reagent consumption. The linear range for determination of mercury (II) was over the range of 0.1–2.0 mg L^?1. The limit of detection and limit of quantification, calculated following IUPAC were 0.06 and 0.10 mg L^?1, respectively. The repeatability was 1.25% (n = 10) for 0.5 mg L^?1 of mercury (II). The proposed method was successfully applied to determine the mercury (II) in commercial cosmetics, local Thai traditional medicines and water samples with a sampling rate of 40 h^?1. Results obtained were in justifiable agreement with those obtained by the official ICP-MS method at the 95% confidence level.     

Spectrophotometric determination of microamounts of mercury(II) and sulfide ions in aqueous solution

Ammonium (2′,3′-dihydroxy pyridyl-4′-azo)benzene-4-arsonate (DHP-4A) provides a simple, rapid, and sensitive spectrophotometric microdetermination of mercury(II) in aqueous solution. The magenta colored 1:2 metal to ligand complex formed has a molecular extinction coefficient 6.25 × 10⁴ liters mol^?1 cm^?1 at the maximum absorption of 535 nm in highly alkaline medium. Beer's law is obeyed up to 3.8 ppm and Sandell's sensitivity (for an absorbance of 0.001) is 0.0032 μg of mercury(II)/cm². The mercury(II) complexed with DHP-4A has also been used in microdetermination of sulfide ions using ligand exchange reaction. The optimum concentration range of sulfide ions which can reproducibly be determined is 0.16-5.05 μg/10 ml and sensitivity of sulfide ions determination (for an absorbance 0.001) is 7.3 × 10^?4 μg/cm².     

Extraction and spectrophotometric determination of mercury(II) with Xylenol Orange in the presence of diphenylguanidine as a synergistic agent

The system Hg(II)/XO/DPG extracted into several alcohols and mixtures alcohol/chloroform (as depressing of the solubility of the alcohol in water) is studied. A ternary complex 1:1:1 Hg(II)/XO/DPG is observed when the mixture 1:1 ($\text{V}\text{V}$) iso-amyl alcohol/chloroform is considered. This complex shows a molar absorptivity 2.3 × 10⁴ liter mol^?1 cm^?1 at 590 nm, pH_ex 8.0, and T ? 18 °C. This complex allows to determine Hg(II) in the concentration range 0.25-5.8 ppm. According to the experimental results a reaction mechanism in which the alcohol and DPG take part in the coordination sphere of Hg(II) ion is suggested. The optimal extraction conditions of XO and its mercury complex are discussed, as well as the study of the interferences.     

Liquid-liquid extraction of cobalt(II) thiocyanate with hexamethyl phosphoramide: Direct spectrophotometric determination in the organic phase

Summary Use of HMPA in Co(II) thiocyanate colour system gives a simple, sensitive and selective method for the determination of Co(II). Maximum colour intensity is attained in the acidity range of 0.15–0.75M HCl and thiocyanate concentration of 0.5–1.0M. The colour is completely extractable into chloroform, when 2 to 4 ml HMPA is used. The colour system shows maximum absorption at 610 nm. The Beer's law range is 2 to 52g Co/ml with optimum concentration range of 6–48g Co/ml. The molar absorptivity and sensitivity are 1.24 x 10³ l·mole^–1·cm^–1 and 0.047g Co/cm² respectively. The method has been applied to the determination of cobalt in steel.

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Flüssig-flüssig-Extraktion von Kobalt(II)thiocyanat mit Hexamethylpbos-phoramid (HMPA) und spektrophotometrische Bestimmung in der organischen Phase

Zusammenfassung Auf der Grundlage der Farbreaktion von Kobalt(II)thiocyanat mit HMPA wurde eine einfache, empfindliche und selektive Methode zur Bestimmung von Co(II) entwickelt. Das Farbmaximum erhält man in 0,15–0,75M salzsaurer Lösung bei 0,5–1,0M Thiocyanat-Konzentration. Die Färbung ist mit Chloroform vollständig extrahierbar, wenn 2—4 ml HMPA verwendet werden. Die maximale Absorption liegt bei 610 nm. Der optimale Konzentrationsbereich liegt zwischen 6 und 48g Co/ml. Die molare Absorption beträgt 1,24 x l0³l·mole^–1·cm^–1, die Empfindlichkeit 0,047g Co/cm². Die Methode wurde zur Bestimmung von Kobalt in Stahl verwendet.

     

固相萃取光度法测定食品中的微量汞

研究了氯磺酚偶氮硫代若丹宁(HSCT)与汞的显色反应,在pH 3.6的HAc-NaAc缓冲介质中,Triton X-100存在下,HSCT与汞反应生成21稳定络合物,该络合物可被C18固相萃取小柱定量萃取,小柱上保留的络合物用四氢呋喃洗脱后用分光光度法测定,λmax=550 nm,体系ε=9.64×104 L/mol/cm.汞含量在0～1.0μg/mL内符合比尔定律,方法可用于食品中痕量汞含量的测定.     

Flow-injection fluorimetric determination of mercury(II) with calcein

A flow-injection spectrofluorimetric method for the determination of Hg(II) is described. The method is based on the complex that is formed between Hg(II) and calcein at pH 11-12. This reagent was not used before for determining Hg(II). The excitation wavelength is 324 nm and the emission wavelength is 522 nm. The calibration graph shows a linear range between 7.7 and 128 microg l(-1) (relative standard deviation 2.0%), the sampling rate was 90 h(-1). The effect of several interferents has been examined. Trace mercury in natural waters were determined satisfactorily using a modified manifold, which has an EDTA stream in order to minimize the calcium and magnesium interference.     

Spectrophotometric determination of mercury(II) with sodium sulfite

A photometric procedure is developed for determining mercury(II) in aqueous media. It is based on the reaction of mercury(II) with sodium sulfite giving a product with an absorption maximum at 230 nm. The optimum conditions are found. The procedure allowed 0.5 to 13.0 μg/mL of mercury(II) to be determined for 1 min. The effect of some metal cations is estimated.     

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.     

Determination of sulfite by reaction with mercury(I) chloride and spectrophotometric measurement of mercury(II) complexes

Sulfite ion was determined in the 0.4 to 12-ppm range by reaction with insoluble mercury(I) chloride to form the soluble Hg(SO₃)₂^staggered2? ion and elemental mercury. The uv absorption of the sulfite complex or an anion species, HgX₄^staggered2?, formed on adding an excess of KBr, KCl, KI, or KSCN is measured. The mercury(II) in solution can also be determined by lowering the pH, adding KCl, and forming the crystal violet adduct of the HgCl₃^staggered? ion. This adduct is extracted into benzene and the absorbance measured at 605 nm.     

Gravimetric and spectrophotometric determination of mercury with n-benzoyl-n-phenylhydroxylamine

N-Benzoyl-N-phenylhydroxylamine (BPHA) is suggested for the gravimetric determination of mercury(II) at pH 3.0–6.0; the precipitate, Hg(C₁₃H₁₀O₂N)₂, is dried at 105° and weighed. Separation from NH₄⁺, Pb, Bi, Sb, As, Cd, Sn, etc. is possible, but chloride, cyanide and (EDTA) interfere. Mercury(II) can also be extracted with a BPHA solution in chloroform: the extracted mercury complex is yellow and shows an absorbance maximum at 340 mμ. The optimum concentration range for determination is 15–52 μg Hg/ml, the molar extinction coefficient is 2693 ±10 and the sensitivity is 0.075 μg/cm². Interferences are similar to those found in the gravimetric method.