Spectrofluorimetric determination of 5-fluorouracil by fluorescence quenching of 9-anthracenecarboxylic acid.
Photo-induced intermolecular electron transfer (PET) interaction between excited singlet (S(1)) state of 9-anthracene carboxylic acid (9-ANCA) and DNA bases of pyrimidines as uracil and 5-fluorouracil (5-FU) has been studied in water and ethanol solutions using steady-state fluorescence spectroscopy. The intensity of all emission bands of 9-ANCA was quenched in presence of uracil and 5-FU by electron transfer reaction without formation of an exciplex. It was found that uracil and 5-fluorouracil acts as effective electron donors and simultaneously quench the fluorescence of electron-accepting sensitizer 9-ANCA. The quenching by diffusion-controlled rate coincides well with the dynamic Stern-Volmer correlation. The bimolecular quenching rate constant (k(q)(ss)) and electron transfer rate constant (k(et)) observed are seen to be much higher for 5-fluorouracil than those for uracil. The thermodynamic parameters estimated by using the Rehm-Weller equation were used to propose a suitable mechanism for PET occurring between uracils and 9-ANCA. The proposed method was used to determine 5-fluorouracil from pharmaceutical samples with satisfactory results. The technique is more selective, sensitive and relatively free from coexisting substances.
Khot
M S
MS
Chh. Sambhaji Raje Sainik School, Jamge, (Khed) Ratnagiri, Maharashtra, India.
Bhattar
S L
SL
Kolekar
G B
GB
Patil
S R
SR
D000873:Anthracenes / Q000737:chemistry*; D004583:Electrons; D005453:Fluorescence; D005472:Fluorouracil / Q000032:analysis*; D007700:Kinetics; D004364:Pharmaceutical Preparations / Q000032:analysis; D012996:Solutions; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D000873:Anthracenes; D004364:Pharmaceutical Preparations; D012996:Solutions; C010030:9-anthroic acid; D005472:Fluorouracil