fulltext24 - Sensitive Terbium Probes for Luminescent...

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Sensitive Terbium Probes for Luminescent Determination of both Alkaline Phosphatase and Codeine Phosphate A XEL D UERKOP , a D ARYA A LEKSANDROVA , b Y ULIYA S CRIPINETS , b A LLA Y EGOROVA , a , b AND E KATERYNA V ITYUKOVA b a Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, Regensburg, Germany b A.V. Bogatsky Physico-chemical Institute of the National Academy of Sciences of Ukraine, Odessa, Ukraine New terbium complexes of 2-oxo-4-hydroxy-quinoline-3-carboxylic acid derivatives are reported for determination of alkaline phosphatase (aPase) and codeine phosphate (CP). Complexa- tion with terbium occurs by way of the oxygen atoms of the 4-hydroxyl group and the car- bonyl group of the 3-carboxy function, respectively. The complexes are highly luminescent and do not require luminescence enhancers. The excitation maxima of the terbium chelates are at 320 nm. The assay is based on the quenching of the hypersensitive 545-nm luminescence of the terbium complexes with the ligands 4-hydroxy-1-methyl-2-oxo-1,2-dihydro-quinoline- 3-carboxylic acid (5-ethyl-[1,3,4]thiadiazol-2-yl)-amide (L 1 ) and 1-ethyl-4-hydroxy-2-oxo-1,2- dihydro-quinoline-3-carboxylic acid (4-triFuoromethyl-phenyl)-amide (L 2 ) by phosphate ions. The assays require equimolar (1.0 μ M) concentrations of Tb 3 + and of the ligand at pH 8.0 (Tris– HCl buffer). The luminescence quenching is proportional to the concentration of aPase and CP within the range of 0.1–70 mU mL 1 and 0.3–20 μ gmL 1 , respectively. The detection limits were 0.05 mU mL 1 = 40.0 pmol L 1 of aPase and 0.120 μ 1 of CP. Key words: luminescence; terbium (III); assay; alkaline phosphatase; codeine phosphate Introduction Lanthanide-sensitized luminescence is widely used for bioassays. Lanthanide complexes with organic lig- ands are used for the determination and quantiFca- tion of drugs, such as hormonal, nonsteroidal anti- in±ammatory, or antiseptic preparations 1 , 2 ;andfo r determination of tetracycline 3 and catecholamines 4 in dosed forms and in various biological ±uids. The long-lived luminescence of lanthanide chelates is also used for the determination of enzyme activ- ities alkaline phosphatase (aPase) 5 and peroxidase. 6 A one-step method was described for the ±uoromet- ric determination of the activity of the enzyme cata- lase, based on the Fnding that H 2 O 2 bound to the europium (III)–tetracycline complex is consumed by catalase. 7 Several other methods for determination of Address for correspondence: Axel D¨urkop, Ph.D., Institute of Analyt- ical Chemistry, Chemo- and Biosensors, University of Regensburg, Uni- versit¨atsstrasse 31, 93040 Regensburg, Germany. Voice: + 0049 941 943 4063; fax: + 0049 941 943 4064. [email protected] aPase have been described, including spectrophotome- try, 8 ±uorometry, 9 ±ow injection analysis with chemilu- minescence detection, 10 amperometry, 11 , 12 and cyclic voltammetry.
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This note was uploaded on 07/11/2010 for the course SPECTOGRAP 545 taught by Professor Gdf during the Spring '10 term at AIB College of Business.

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fulltext24 - Sensitive Terbium Probes for Luminescent...

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