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

Journal of the Brazilian Chemical Society

Emília M. G. Santos²  Cristina M. C. M. Couto²  Alberto N. Araújo²  M. Conceição B. S. M. Montenegro²  Boaventura F. Reis¹ 

[1] ,Faculty of Pharmacy Department of Physical Chemistry Porto,Portugal

关键词: gibberellic acid;    ion selective tubular electrode;    SIA;    metalloporphyrins;    agricultural growth promoters;   

DOI  :  10.1590/S0103-50532004000500015

来源: SciELO

【 摘 要 】

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 5×10-4 mol L-1 and 8×10-3 mol L-1, a slope of -64.5 ± 1.6 mV/dec and lower potentiometric selectivity coefficients (log Kpot) 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.

【 授权许可】

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