Voltammetric determination of Al(III) with adsorptive preconcentration of the pyrocatechol violet complex

A method is described for the determination of aluminium in aqueous samples by linear scan voltammetry after adsorptive accumulation of the pyrocatechol violet (PCV) complex. A pH 6.5 triethanolamine/perchloric acid electrolyte is used for the determination with adsorption onto a mercury drop electrode at −0.50 V (vs a Ag/AgCl/satd KCl reference). Scanning cathodically after adsorption gave a current peak at −0.70 V for reduction of adsorbed PCV and a peak at −0.90 V for reduction of the adsorbed Al-PCV complex. The peaks were well resolved. Using 1.0 μM PCV and a 60 s adsorption period gave linear calibration curves for Al in the range 1 to 25 ng mL−1 Al. The detection limit was 0.1 ng mL−1 Al. For analysis, calibration by the method of standard additions is required. Most other metal species do not interfere, but vanadium (V(IV) and V(V)) forms a complex with PCV that is adsorbed and reduced at the same potential as Al–PCV. The interference may be eliminated by complexation of the V with citrate. Al and V present together may be determined by analysis in the absence of citrate (total: Al + V) and in the presence of citrate (Al); V is determined as the difference in the two values.The analysis of a range of samples with Al concentrations from 6 ng mL−1 to 3 μg mL−1 gave results which were in good agreement with those obtained by other methods. Key words: aluminium, pyrocatechol violet, adsorption, voltammetry, environmental.

Effects of aluminium on some biochemical characteristics of wheat (Triticum aestivum L.)

Aluminium at 10 ppm increased chl a in Aghrani, Gourab, Kanchan and Sourab; chl b and carotinoids in Fang-60, Kanchan and Sourab, though at 100 ppm inhibited chl a in all nine varieties, chl b in Akbar and Protiva and carotinoids in Aghrahani, Gourab, Kanchan, Protiva, and Sonalica. Proline content increased in the seedlings of all varieties and the root had relatively higher proline content than that of shoot. Stimulatory effect of Al3+ on proline content was higher in Kanchan. Proline content also increased in Akbar, Gourab and Sonalika. Al3+ stress induced increase in protein and reducing sugar contents was more in root than in the shoot. Hamatoxylin test of the root tips also revealed differential responses of the varieties to Al3+ stress. Key words: Aluminium stress; HYV wheat; Metabolites; Hematoxylin test; Efficiency ratio DOI: 10.3329/bjb.v39i1.5519Bangladesh J. Bot. 39(1): 9-14, 2010 (June)

Effects of aluminium (Al3+) on seed germination and seedling growth of wheat (Triticum aestivum L.)

Effects of different concentrations of aluminium (Al3+) on seed germination of high yielding varieties of wheat (Triticum aestivum L.) were investigated. Al3+ at 500 ppm had inhibitory effect on seed germination, seedling growth and its dry matter. Relatively higher root and shoot dry matter in Sonlika, Fang-60 and lower in Baw-923 and Protiva were found. Root growth of Fang-60 and shoot growth of all except Akbar, Gourab and Protiva were stimulated at low concentration (10 ppm). Root growth was more susceptible to Al3+ stress than that of shoot. Key words: Aluminium stress; Seedling growth; Tolerance index; Wheat; Triticum aestivum DOI: 10.3329/bjb.v38i1.5111 Bangladesh J. Bot. 38(1): 1-6, 2009 (June)