Spectrophotometric determination of beryllium

Summary A spectrophotometric method for determination of beryllium ing quantities is described which is based on color reaction between beryllium and rufigallol having maximum absorption at 530 nm. Comparing various solvents, the suitable medium found is DMSO-H₂O (3 2). Interference of Al, Zr, Th, Hf and many other cations have been removed by solvent extraction of their oxinates with chloroform.

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Zusammenfassung Eine spektrophotometrische Bestimmungsmethode für Mikrogrammmengen Be wurde beschrieben, die auf der Farbreaktion mit Rufigallol mit einem Absorptionsmaximum bei 530 nm beruht. Als geeignetes Medium erwies sich Dimethylsulfoxid in Wasser (3 2). Störende Kationen wie Al, Zr, Th, Hf und viele andere werden in Form ihrer Oxinate mit Chloroform extrahiert.

     

Spectrophotometric determination of beryllium with calcichrome

A method is established for the spectrophotometric determination of small amounts of beryllium as a 1:1 complex with Calcichrome in slightly acidic solution. Beer's law is obeyed over the range 0.05-0.6 ppm Be in the final solution and the apparent molar absorptivity is 9.7 x 10(3) l.mole(-1). cm(-1) at 625 nm. Up to about 15 mug of beryllium in the final solution can be sensitively and selectively determined with a relative error of less than 2% in the presence of EDTA as masking agent.     

Spectrophotometric determination of beryllium with carminic acid

Summary A new reagent has been proposed for the determination of beryllium. The method is based on the reaction between beryllium and carminic acid, forming a Be-carminic acid complex at pH 4. The absorption is measured at 580 nm. The molar absorptivity is 2.25×10³ mol^–1 cm^–1. Beer's law is obeyed from 0.4 ppm to 1.6 ppm of beryllium. The effects of pH, reagent concentration and interferences from foreign ions have been studied. The method has been applied to the determination of beryllium in polluted water and blood samples.

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Spektralphotometrische Bestimmung von Beryllium mit CarminsÄure

     

Spectrophotometric determination of trace amounts of beryllium in silicate materials

Although photometric determination of beryllium is generally quite satisfactory in trace analysis, application to geochemical samples is restricted because of the numerous interfering ions. Introduction of an extraction procedure eliminates the interference of Al and Fe, which occur in high concentrations in most silicate rocks, and enables beryllium to be determined with Eriochrome Cyanine R. Use of the method for analysis of six international geochemical reference samples containing between 1 and 30 ppm beryllium has given satisfactory results (relative standard deviation from 1.6 to 7.8%).     

Spectrophotometric determination of formaldehyde in air

A spectrophotometric method for the determination of formaldehyde in air is described, based on the colour reaction of formaldehyde, p-aminoazobenzene and sulphur dioxide in hydrochloric acid medium. Beer's law is obeyed at 505 nm in the range 2-12 mug of formaldehyde per 25ml of final solution (0.08-0.48 ppm). Optimum conditions for colour development, and possible interferences, have been studied.     

Spectrophotometric determination of beryllium in bronzes with Chrome Azurol S

Summary Spectrophotometric Determination of Beryllium in Bronzes with Chrome Azttrol S Some remarks on the spectrophotometric determination of beryllium in bronzes using Chrome Azurol S (CAS) are given. The determination was performed at pH=6.5 and 10.0 using hexamethylene-tetramine and ammoniacal buffers, respectively. It was demonstrated that the determination of Be with CAS at pH=10.0 is slightly less sensitive, but it has two advantages which are important in obtaining reliable results. First, is the shorter time to reach the equilibrium between Be and CAS, and second, is lower pH sensitivity so that a better precision of the results at pH=10.0 overcompensate the slightly lower sensitivity at this pH in comparison with that at pH=6.5.     

Spectrophotometric determination of beryllium and zirconium using chromotrope-2C

Summary Disodium salt of o-carboxyphenylazo chromotropic acid (chromotrope 2C) has been used for the colorimetric determination of microamounts of beryllium and zirconium. The red-violet complexes show maximum absorption at 580 nm and the colour systems obey Beer's law from 0.025 to 0.375 ppm of beryllium and 2 to 12 ppm of zirconium. The optimum concentration ranges are from 0.125 to 0.375 ppm for beryllium and from 4 to 12 ppm for zirconium, where the percent relative errors per 1% absolute photometric error are, respectively, 3.014 and 3.22. The sensitivity of the reactions per cm² are 0.00067 g Be and 0.027 g Zr. The complexes, with the metal to reagent ratio of 11, have instability constants as 2.836 · 10^–6 for beryllium and 6.026 · 10^–6 for zirconium.     

Spectrophotometric determination of beryllium in water samples after micelle-mediated extraction preconcentration

A new micelle-mediated phase preconcentration method for preconcentration of ultra-trace quantities of beryllium as a prior step to its determination by spectrophotometry has been developed. Chrome Azurol S (CAS) and cetyltrimethylammonium bromide (CTAB) were used as chelating agent and cationic surfactant, respectively. The method evaluates and eliminates the blank bias error present in such procedures using mean centering of ratio spectra. This procedure gives more accurate results than the traditional approach using absorbance values against reagent blank. The optimal extraction and reaction conditions were studied and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration and improvement factors) were obtained. Linearity was obeyed in the range of 0.9-18.0 ng mL⁻¹ (1.00 × 10⁻⁷-2.00 × 10⁻⁶ mol L⁻¹) of beryllium. The detection limit of the method is 0.51 ng mL⁻¹ (5.66 × 10⁻⁸ mol L⁻¹) of beryllium. The interference effect of some anions and cations was also tested. The method was applied to the determination of beryllium in spring water samples.     

Spectrophotometric determination of baygon and carbaryl in air

A spectrophotometric method for the determination of baygon and carbaryl in air is based on the coupling of their hydrolysation products with diazotised p-amino-acetophenone. The dyes formed are measured at 580 nm and 555 nm, respectively. Beer's law is obeyed in the range of 0.9–5.6 mg/m³ and 0.4–3.6 mg/m³.     

Spectrophotometric determination of nitrogen dioxide in air

Summary A sensitive spectrophotometric method for the determination of trace amounts of nitrogen dioxide, after fixing it as nitrite in alkaline sodium arsenite solution, is described. The reaction is based on the diazo-coupling of p-nitroaniline with chromotrophic acid in acetate medium (pH 6±0.5). The azo dye formed has its absorption maximum at 515 nm, with a molar absorptivity of 3.7×10⁴ l mol^–1 cm^–1. Beer's law is obeyed over the range 0–20 g of nitrite. The relative standard deviation is 2.5% for ten determinations of 10 g of nitrite. The effect of interfering gases and ions on the determination is discussed. The method has been applied to the determination of residual nitrogen dioxide in a laboratory fume cupboard and the results are compared with those obtained by the widely used sulphanilamide — NEDA method. Down to 0.5 g of nitrite can be determined.     

Spectrophotometric determination of hydrogen cyanide in air using phloroglucinol

Summary A spectrophotometric determination of hydrogen cyanide in air is described. Hydrogen cyanide from air is collected in dilute sodium hydroxide and then reacted with pyridine forming glutaconic aldehyde. The glutaconic aldehyde thus formed is subsequently coupled with aqueous phloroglucinol solution to form a polymethine red-violet dye having absorbance maxima at 540 nm. The colour system obeys Beer's law in the range of 0.45 to 3.6 mg/m³ of hydrogen cyanide (0.4 to 3.2 g/g). Collection efficiency of absorbing solution, molar absorptivity and Sandell's sensitivity have been evaluated. All other important analytical parameters have been studied and applied for the determination/detection of hydrogen cyanide in air samples and cigarette smoke.     

Spectrophotometric determination of beryllium with chromotropic acid azo dyes of the pyridine series

Summary Beryllium forms coloured complexes with azo dyes of the pyridine series e. g. 2-(pyridyl-2-azo)-chromotropic acid (A), 2-(pyridyl-3-azo)-chromotropic acid (B) and 2-(2-carboxy pyridyl-3-azo)-chromotropic acid (C). The latter two reagents react with aluminium also, but beryllium can be estimated in the presence of large excess of aluminium only with A.At pH 6.5, the colour systems formed show maximum absorptions at 580 nm with A and at 590 nm with B and C and obey Beer's law with optimum ranges of beryllium from 0.5 to 2.0 ppm with A, from 0.2 to 0.8 ppm with B and 0.3 to 2.0 ppm with C. The metal forms a 1:3 complex with A, a 12 complex with B and a 32 complex with C, with instability constants of the order of 10^–13, 10^–9 and 10^–17, respectively.

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Zusammenfassung Im Hinblick auf die spektrophotometrische Berylliumbestimmung wurden drei verschiedene Farbkomplexe untersucht, die Be mit Azofarbstoffen der Pyridinreihe bildet, nämlich mit 2-(Pyridyl-2-azo)-chromotropsäure (A), 2-(Pyridyl-3-azo)-chromotropsäure (B) und 2-(2-Carboxy-pyridyl-3-azo)-chromotropsäure (C). B und C reagieren auch mit Aluminium, jedoch kann Beryllium neben großen Mengen Al mit Reagens A bestimmt werden. Bei pH 6,5 liegen die Absorptionsmaxima bei 580 nm (A) bzw. 590 nm (B, C). Das Beersche Gesetz wird von 0,5 bis 2,0 ppm (A) bzw. 0,2–0,8 ppm (B) bzw. 0,3–2,0 ppm (C) befolgt. Die Zusammensetzung des Komplexes (Be: Reagens) beträgt 13, 12 bzw. 32; die Instabilitätskonstanten sind in der Größenordnung 10^–13, 10^–9 bzw. 10^–17 (für A, B, C).

     

Spectrophotometric study of the beryllium-thorin complex and its application to the determination of beryllium in alloys

A spectrophotornetric study of the beryllium complex with purified thorin shows the formation of a I : I complex at pH 12. The dissociation constant obtained after successive corrections for reagent absorbance is 1.38·10^-7. Beryllium in concentrations of 0.05% to 2.0% in copper base, zinc base, aluminiuin base and ferrous alloys can be determined by the formation of the thorin complex after its preliminary separation as accetylacetonate in presence of EDTA.