The aluminon method was also essentially that used by Kerven et al.
The concentration of Al in each solution was measured with the aluminon method.
For both the PCV and aluminon methods the experiments were repeated at the 30 s reaction time.
The values of Al measured with the PCV and aluminon methods were compared with values of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] predicted from stability constant data.
Results for the determination of Al with the aluminon method as a function of reaction time are given in Fig.
Concentrations of Al from the 500 [micro]m Al solutions in the presence of various concentrations of organic acids, as measured with the aluminon method at several reaction times, are shown in Fig.
A similar pattern of results was obtained when the concentration of Al from the 100 [micro]M Al-organic acid solutions was determined with the aluminon method (Fig.
The extent of complexation predicted from stability constants was less than that apparent from measurement of `labile' Al by the aluminon method for the citrate and tartrate systems when the organic anion:Al ratio was 1:2 at both Al concentrations.
The aluminon method enabled measurement of much higher concentrations of Al, although the calibration line had significant curvature over the whole concentration range (Fig.
The reaction between aluminon and Al was significantly slower than was found for PCV, with only 60% reacting after 30 s and the fraction reacted continuing to increase to a significant extent up to 60 min.
4 for 500 [micro]M Al measured with the aluminon method are strikingly different.
The extent of complexation measured with the aluminon method at both 500 [micro]M and 100 [micro]M follows the general trends predicted from stability constants (Figs 4, 5).