Guiyun Zhu

Simultaneous spectrofluorimetric determination of terbium, samarium and europium with hexafluoroacetylacetone-trioctylphosphine oxide and Triton X-100

Abstract In aqueous solution, the fluorescence intensity is a linear function of concentration in the ranges 1.0 × 10 −4 -1.0 × 1.0 −6 M Sm and 1.0 × 10 −6 -1.0 × 10 −8 M Tb and Eu. The optimum conditions are 1 × 10 −3 M hexafluoroacetylacetone, 1 × 10 −4 M trioctylphosphine oxide and 0.05% Triton X-100 at pH 3.0.

Fluorescence enhancement of the europium-yttrium-diphacinone-ammonia system

Abstract A study of the enhanced (ca. 100 ×) fluorescence intensity of the Eu 3+ -diphacinone-ammonia system by Y 3+ was made using a colloidal suspension. The excitation and emission wavelengths were 330 and 612 nm, respectively. The fluorescence intensity was a linear function of the concentration of europium in the range 6.0 × 10 −11 –8.0 × 10 −7 M. The detection limit was 8.0 × 10 −14 M. The standard addition method was used for the determination of europium in rare earth oxides, with satisfactory results.

Study on sensitised luminescence of rare earths by fluorescence enhancement of the europium-gadolinium-diphacinone-ammonia complex system and its application

A study of the enhancement effect on the fluorescence intensity of the Eu3+-diphacinone(DPN)-ammonia system by La3+, Gd3+ and Y3+, has been carried out in a colloid-type suspension. Gadolinium caused the largest enhancement of the fluorescence intensity. In the presence of this element the fluorescence of the Eu-DPN-NH3 system was enhanced by a factor of about 100 at a pH of between 8.5 and 9.5. Excitation and emission wavelengths were 330 and 612 nm, respectively. Fluorescence intensity was a linear function of the concentration of europium in the range 8.0 × 10–9–1.0 × 10–11M. The detection limit was 6.0 × 10–14M. The standard additions method was used for the determination of europium in rare earth oxides and gave satisfactory results.

Study of the fluorescence of the europium–thenoyltrifluoroacetone–cetyltrimethylammonium bromide–Triton X-100 system

The europium–thenoyltrifluoroacetone (TTA)–cetyltrimethylammonium bromide (CTAB)–Triton X-100 system at pH 5.5–7.5 was studied and used for the spectrofluorimetric determination of europium. The excitation and emission wavelengths were 370 and 612 nm, respectively. Fluorescence intensity was a linear function of the concentration of europium in the range 1.0 × 10–7–1.0 × 10–9 mol dm–3. The detection limit was 2.0 × 10–12 mol dm–3. The standard additions method was used for the determination of europium in synthetic rare earth oxides and gave satisfactory results. The molar ratio method was carried out spectrofluorimetrically for the determination of the stoichiometric composition of the fluorescent species. A ratio of 1 : 4 : 1 for the ternary Eu–TTA–CTAB complex was found.

Study of the fluorescence enhancement system europium-gadolinium-thenoyltrifluoroacetone-cetyltrimethylammonium bromide-Triton X-100 and its application

Abstract A fluorescence enhancement phenomenon on adding Gd3+ to the europium-thenoyltrifluoroacetone-cetytrimethylammonium bromide-Triton X-100 fluorescence system was observed and studied in detail. The fluorescence intensity of this system was 60 times greater than that of the system without gadolinium. The optimum conditions are a Gd3+ concentration of 2.0 × 10−5 M and pH 7.5–8.5; the fluorescence intensity is a linear function of the concentration of europium in the range 6.0 × 10−11 −1.0 × 10−7 M and the detection limit is 2.0 × 10−12 M europium. This system was used for the determination of trace amounts of europium in rare earth samples with satisfactory results.

Fluorescence enhancement of rare earths by yttrium and its application

Abstract A study of the enhancement effect on the fluorescence intensity of the Eu3+–-thenoyltrifluoroacetone (TTA)–-cetyltri–-methylammonium bromide (CTMAB) and the Dy3+ pyrocatechol–-3,5-disulphonic acid (Tiron) systems by Y3+has been carried out. In the presence of yttrium the fluorescence intensity of the systems was enhanced by a factor of about 100 and 15, respectively. The fluorescence intensity was a linear function of the concentration of europium or dysprosium in the range 1.0 × 10−10–-1.0 × 10−8mol dm−3 and 8.0 × 10−8–-9.0 × 10−6mol dm−3, respectively. The detection limit was 1.0 × 10−11mol dm−3 and 1.0 × 10−10mol dm−3, respectively. The standard addition method was used for the determination of europium or dysprosium in rare earth oxides and gave satisfactory results. The mechanism of enhanced fluorescence was proposed.

Study of sensitized luminescence of rare earths. Fluorescence enhancement of the europium—terbium (or lutetium)—β-diketone—synergistic agent complex system and its application

Abstract Study of the enhancement effect on the fluorescence intensities of the Eu3+-thenoyltrifluoroacetone(TTA)-cetyltrimethylammonium bromide (CMAB) system by Tb3+ and of the Eu3+-dibenzoylmethane(DBM)—diethylamine(DEA) system by Lu3+ has been carried out in a colloidal suspension. In the presence of terbium or lutetium the fluorescence intensities of the above systems were enhanced by a factor of about 100 at a pH from 5.5 to 8.0 and 9.5 to 11.5, respectively. The excitation wavelength was 372nm for the Eu-TTA-CTMAB system and 390nm for Eu-DBM-DEA system. The emission wavelength was 612 nm. Fluorescence intensity was a linear function of the concentration of europium in the range 1.0 × 10−12-1.0 × 10−8 mol dm−3 for the Eu-TTA-CTMAB system and 5.0 × 10−11-1.0 × 10−7 mol dm−3 for the Eu-DBM-DEA system, respectively. The detection limit was 1.0 × 10−13 mol dm−3 for the Eu-TTA-CTMAB system and 5.0 × 10−12 mol dm−3 for the Eu-DBM-DEA system. The standard addition method was used for the determination of europium in rare earth oxides and gave satisfactory results.

FLUORESCENCE OF LANTHANIDE/EDTA/NAOX TERNARY COMPLEXES AND THEIR APPLICATION

A ternary complex is formed when 7-(1′-naphthylamine-azo)-8-hydroxyquinoline-5-sulfonic acid (NAOX) occupied the two remaining coordination sites on a lanthanide ion complexed by a hexadentate aminopolycarboxylate ligand. The effects on the fluorescence intensity are studied. The NAOX/EDTA reagent system provides sensitive and selective determination of Lu3+ and Y3+, with the detection limits of 5.0×10−7 and 7.0×10−7 mol/l, respectively. In addition, the ternary complex can be used for determination of EDTA or other hexadentate aminopolycarboxylic acids.

Enhanced fluorimetric determination of europium with dibenzoylmethane and diphenylguanidine by terbium

Abstract A study of the enhanced fluorescence intensity of Eu-dibenzoylmethane(DBM)-diphenylguanidine(DPG) by terbium was made. The excitation and emission wavelengths were 390 and 612 nm, respectively. The fluorescence intensity was a linear function of the concentration of europium in the range 5.0×10−10 −6.0×10−8 M. The detection limit was 5.0×10−11 M. The standard addition method was used for the determination of europium in rare earth oxides.

Study of the fluorescent dysprosium/EDTA/Tiron/surfactant system

Abstract A dysprosium/EDTA/Tiron/surfactant system at pH 11–12 is used for the spectrofluorimetric determination of dysprosium. The fluorescence intensity is increased 22-fold on addition of cetyltrimethylammonium bromide. There is no interference from at least a 100-fold molar excess of other rare earth ions, except for terbium.