Metallofluorescent Indicator Research Articles

PH-dependent spectral behavior of substituted quinolones: potential fluorophore for metallofluorescent indicators

The 7-methoxy and 7-hydroxy derivatives of 2,3-dimethyl-4-quinolone have been characterized with respect to absorbance, steady-state fluorescence excitation and emission, and acid-base behavior in perchloric acid ( H 0 −5.68—pH 2.0) and aqueous buffers (pH 2.2–14.2); susceptibility to alkaline hydrolysis has been examined absorptiometrically. 7-Hydroxy-2,3-dimethyl-4-quinolone is resistant to attack by hydroxide ion. Aqueous solutions of it exhibit moderate to high fluorescence emission, which is dependent on solution acidity. It is recommended for incorporation into metallofluorescent indicators of the Calcein Blue type.

新たな金属蛍光試薬(3-Carboxy-2-naphthylamine-N, N-diacetic Acid)の合成とその応用

A new metallofluorescent reagent (3-carboxy-2-naphthylamine-N, N-diacetic acid (CNDA)) was synthesized. Its possible application was discussed. CNDA was stable in 1% NaHCO3 solution. The fluorescence intensity of CNDA increased by the addition of Al, La (III) and Zn at pH 3-5 and Ca and Mg at pH 10. The acid dissociation constants (pKa) of CNDA were determined by the potentiometric method. The dissociation constants of carboxylic protons of CNDA were 2.44 for pKa1 and 3.23 for pKa2, and the pKa3 of ammonium proton was 7.67. The stability constants of CNDA Ca, Mg and Zn chelate were determined potentiometrically in accordance with the Bjerrum's method at 25± 0.2°C. The stability constants of CNDA Al and La (III) chelate were determined by spectrophotometric method at 25±0.5°C. The constitution of the CNDA chelate with each metal ion was 1 : 1, and the logarithmic stability constants of Al, Ca, La (III), Mg and Zn chelate were 11.83, 5.16, 8.25, 3.24 and 8.26, respectively. The relative quantum yields of CNDA were 0.04-0.05 at pH 5.0 or bellow and 0.09-0.10 at pH 7.0 or more. The relative quantum yields of the fluorescence of CNDA chelate were 0.06 (pH 3.0), 0.09 (pH 4.0) and 0.11 (pH 4.5) for Al, 0.08 (pH 5.0) for La (III), 0.10 (pH 4.5) for Zn, 0.18 (pH 7.0) and 0.27 (pH 10) for Ca, and 0.14 (pH 7.0) for Mg. Since CNDA can react with hard acid, such as Al, La (III) and Ca, CNDA should be a useful reagent for fluorophotometry and a metallofluorescent indicator for chelatometric titration. Using CNDA as a metallofluorescent indicator, the fluorophotometric titration of fluoride in p-fluorobenzoic acid and dexamethasone with Al by the oxygen flask method was performed. In titration, the recoveries were 99.3% or more, and the standard deviation were within 0.23%.

Synthesis of a new metallofluorescent indicator (N-(2-naphthyl)ethylenediamine-N,N',N'-triacetic acid) and its application.

A new metallofluorescent indicator (N-(2-naphthyl)ethylenediamine-N, N', N'-triacetic acid, (NEDTA)) was synthesized. Its possible applications are discussed.NEDTA was synthesized in a high yield from 2-naphthol, and was stable in NaHCO3 alkaline solution. The acid dissociation constants of NEDTA determined by paper electrophoresis and potentiometry, were 2.2±0.1 (pKa1), 3.95±0.1 (pKa2), and 9.21±0.01 (pKa3). The fluorescence of NEDTA was quenched by various metal ions and NEDTA was proved to be useful as an indicator for fluorophotometric titration. Using NEDTA as a metallofluorescent indicator, 5 μmol of Cd, Cu(II), Fe(III), Hg(II), Pb(II) or Zn at pH 4 to 6 or 5 μmol of Cd, Cu(II), Hg(II), Ni(II) or Zn at pH 9 to 10 was titrated with ethylenediaminetetraacetic acid (EDTA), and back titration with Zn was performed for 5 μmol of Al, Ni(II) or Th(VI) at pH 4.6. In every titration, the coefficient of variation and the error were within 0.6%.

ChemInform Abstract: Synthesis of 2‐Naphthylamine‐N,N‐diacetic Acids and Their Application to Metallofluorescent Indicator.

AbstractAls Fluoreszenzindikatoren zur quantitativen Bestimmung von Metallen wie Kupfer, Cobalt und Nickel werden die 2‐Naphthylaminodiessigsäuren (Ia)‐(Ic) synthetisiert.

2-Naphthylamine-<I>N</I>, <I>N</I>-diacetic Acid誘導体の合成及び蛍光金属指示薬への応用

2-Naphthylamine-<I>N</I>, <I>N</I>-diacetic Acid誘導体の合成及び蛍光金属指示薬への応用

Studies of 7-hydroxybenzo-4-pyrones

Spectral data and rates of hydrolysis in 0.7 M potassium hydroxide are reported for a series of nine 7-hydroxybenzo-4-pyrones differing in substitution at positions 2 and 3. The results reveal that 2,3-dimethyl substitution produces a molecule, 7-hydroxy-2,3-dimethylchromone, sufficiently fluorescent and resistant to alkaline hydrolysis to warrant its use as the fluorescent moiety in a metallofluorescent indicator of the Calcein Blue type.

Isocein-a new fluorescent reagent for calcium

A metallofluorescent indicator, isocein, has-been synthesized from 7-hydroxy-2-methylisoflavone, iminodiacetic acid and formaldehyde. It is readily obtained in pure form and in alkaline solutions is excited by light of 339 nm. It is recommended for use as a spectrofluorimetric reagent for calcium.

Metallofluorescent indicators as spray reagents for the in situ determination of organophosphorus pesticides on thin-layer chromatograms

Fluorescence-quenched solutions of palladium(II)-calcein and palladium(II)-calcein blue are shown to be sensitive spray reagents for the detection and in situ determination of organothiophosphorus insecticides on thin-layer chromatograms. The palladium is displaced from its non-fluorescent indicator complex by the pesticide producing fluorescent spots on the plate. Visual detection limits for 16 insecticides are given. As little as 10–50 ng of phosphorodithioate pesticides can be detected within l h after spraying and drying the plate, while the detection limits for phosphorothioates are somewhat higher ( ca. 50–100 ng). Quantitative measurements may be conveniently made 18–24 h after spraying and drying the plate. Plots of fluorescence (as peak area) versus quantity of pesticide are linear over a 10–15 fold range. The relative standard deviation of replicate spots of Guthion (50–400 ng) and Cygon (50–100 ng) is 4–9 % and less than 15 % for 10 ng of Cygon or 20 ng of Guthion. The method was applied to the analysis of lake water spiked with Cygon. The recovery of 2–20 μg l -1 of the pesticide was 87–113% with no clean-up other than t.l.c. required.

New studies on metallofluorescent indicators

Four new metallofluorescent indicators, analogous to calcein but prepared from glycine instead of iminodiacetic acid, have been synthesized and studied by thin-layer chromatography. In addition to fluorescein itself, three isomers of dichlorofluorescein were used in the syntheses. The product obtained with 2',7'-dichlorofluorescein, bis-4',5'-N,N-glycinemethylene-2',7'-dichlorofluorescein, is recommended as a fluorescent indicator for the titration of copper(II) with EDTA solutions.

Rapid complexometric determination of aluminium and total iron in silicate and other rock material

A method is proposed for the rapid determination of aluminium and total iron that involves no prior separation of interfering elements. The sum of iron, aluminium and titanium (as the peroxy complex) is determined by complexation with trans-1,2-diaminocyclohexane-NNN′N′-tetra-acetic acid and back-titration of the excess at a pH of 3·5 to 3·7 with a copper solution, with o-dianisidine-NNN′N′-tetra-acetic acid as a metallofluorescent indicator. The iron is determined in a separate aliquot in a similar manner, but with aluminium and titanium masked with fluoride. Manganese does not interfere. The titanium present is determined spectrophotometrically, thus enabling the aluminium present to be calculated. Satisfactory agreement is obtained with existing methods for a wide range of values of both elements in rock material.

Über peroxo-mischkomplexe von titan, niob und tantal—III: Die chelometrische titration von fünfwertigem niob

A chelatometric method for the titration of Nb v, using nitrilotriacetic acid is described. This forms a 1:1 complex with the peroxy-Nb v ion. NTA is added in excess, and the excess is backtitrated with Cu solution at pH 5·0–5·5 using the metallofluorescent indicator, Methylcalcein, under UV illumination. The reproducibility, for amounts of 4·56–23·68 mg of Nb is 0·07 mg of Nb. N-Hydroxyethylethylenediamine- N, N', N'-triacetic acid forms a similar 1:1 complex, and can be used instead of NTA, but with little advantage.

3,3'-Dihydroxybenzidine-n,n,n',n'-tetraacetic acid as a metallofluorescent indicator in edta titrations

3,3'-Dihydroxybenzidine-N,N,N',N'-tetraacetic acid has been prepared and examined as a metallofluorescent indicator in compleximetric titrations. Copper(II) and lead(II) are determined by titration with EDTA in the presence of the indicator, the blue fluorescence of which is restored at the end-point. Manganese, zinc, cobalt and cadmium can also be determined if a dyestuff such as Rhodamine B is present along with the indicator.

4,4'-Diaminostilbene-n,n,n',n'-tetraacetic acid and its 2,2'-disulphonic acid as metallo-fluorescent indicators

Highly sensitive metallofluoreacent indicators are formed by condensing 4,4'-diaminostilbene and 4,4'-diaminostilbene-2,2'-disulphonic acid with sodium chloroacetate. The resulting N,N,N',N'- tetraacetic acids in the form of their sodium salts are used as indicators in the titration of copper with EDTA down to 0.001 M concentration. A number of metal ions can be determined by a back-titration procedure in which an excess of EDTA is titrated with coppcr(II) in the presence of the indicators. The end-point is marked by the appearance (or disappearance in back-titration) of the blue fluorescence.

The screening of metallofluorescent indicators

The screening of metallofluorescent indicators

N :N :N' :N' -Tetracarboxymethyl derivatives of some benzidines as metallofluorescent indicators

Metallofluorescent indicators are formed by condensing 3:3'-disubstituted derivatives of benzidine with chloroacetate. These complexes can be used as indicators in titration of EDTA with, e.g., copper II. In consequence, a wide range of metal ions can be determined by back-titrating an excess of EDTA with copper II solution, using the disappearance of fluorescence of these complexans as indicators.