Determination of gibberellic acid by sequential injection analysis using a potentiometric detector based on Mn(III)-porphyrin with improved characteristics

• Type: Article in International Scientific Journal
• Date: 2004

Authors

Santos, EMG (Author) Other; Couto, CMCM (Author) Other; Araujo, AN (Author) FFUP; Conceicao, M (Author) FFUP; Montenegro, BSM (Author) Other; Reis, BF (Author) Other

Journal

Title: Journal of the Brazilian Chemical Society

Vol. 15

Pages: 701-707

ISSN: 0103-5053

Publisher: Sociedade Brasileira de Quimica

Indexing

ISI Web of Knowledge - 7 Citations

ISI Web of Science

Scopus - 9 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

CORDIS: Health sciences

Other information

Authenticus ID: P-000-8TR

DOI: 10.1590/s0103-50532004000500015

Resumo (PT): Descreve-se a determinação de ácido giberélico em promotores de crescimento usados na agricultura, por análise de injecção sequencial e detecção potentiométrica. Os detectores potentiométricos com características melhoradas usam uma membrana de PVC preparada com Mn(III)tetrafenilporfirina-Cl ([(Mn(TPP)Cl]). Formularam-se diferentes membranas comparandose aditivos iónicos com o objectivo de se seleccionar as unidades com as melhores características de declive, tempo de resposta, reprodutibilidade e selectividade. Para fins analíticos foi seleccionada uma membrana com 6% de [(Mn(TPP)Cl], 27% de PVC, 66% de dibutilftalato (DBP), como solvente mediador, e 1% de tetrafenilborato de sódio, como aditivo aniónico. Quando inserido num sistema SIA o eléctrodo tubular apresentava um intervalo de linearidade de 5×10-4 mol L-1 a 8×10-3 mol L-1, declive de –64,5 ± 1,6 mV/dec e melhores coeficientes de selectividade potenciométrica (log Kpot) do que os obtidos com eléctrodos convencionais. Na análise de amostras comercializadas em Portugal obtiveram-se desvios padrão de 0,01 e 0,4 (n= 4) e um ritmo de amostragem de 30 amostras/hora. <br> <br> Keywords: gibberellic acid, ion selective tubular electrode, SIA, metalloporphyrins, agricultural growth promoters <br> <a target="_blank" href="http://jbcs.sbq.org.br/jbcs/2004/vol15_n5/14-171-03.pdf"> Texto integral </a> <br> <br>

Abstract (EN): This work describes the determination of gibberellic acid in growth promoters formulations used in agriculture by sequential injection analysis and potentiometric detection. The potentiometric detectors with improved characteristics used a PVC membrane prepared with Mn(III) tetraphenylporphyrin-Cl as electroactive specie. Different membranes formulated with several ionic additives were compared in order to select the most suitable one concerning slope, response time, reproducibility and selectivity. A membrane containing 6 wt% of manganese tetraphenylporphyrin-Cl [(Mn(TPP)Cl], 27 wt% of PVC, 66 wt% of dibutylphthalate (DBP), as mediator solvent, and 1 wt% of sodium tetraphenylborate, as anionic additive, was chosen for analytical applications. When coupled to a SIA system the tubular electrode presented a linear range between 5 x 10(-4) mol L-1 and 8 x 10(-3) mol L-1, a slope of -64.5 +/- 1.6 mV/dec and lower potentiometric selectivity coefficients (log K-pot) than those obtained with the conventional electrodes. Standard deviation of 0.01 and 0.4 (n = 4) and a sampling rate of 30 samples/hour were obtained in the analysis of real samples.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7