Indirect A.C. Oscillopolarographic Determination of Total Monomeric and Acid-Reactive Aluminum in Natural Waters by Using Pyrocatechol Violet

ABSTRACT

Indirect determination of total monomelic and acid-reactive aluminum in natural waters by a.c. oscillopolarography in the presence of pyrocatechol violet (PCV) is presented in this paper. In 0.5 mol 1⁻¹ NH₄Ac buffer solution (pH 6.4) containing l×lO⁻³ mol 1⁻¹ PCV, PCV yields two incisions on the a.c oscillogram at the potentials of - 0.80 and - 1.20 V, respectively. The incision depth declines when adding aluminum in the solution. The decreases of incision depth (Ep = -1.20 V) has a linear relationship with increasing Al concentrations (4×10⁻⁷ - 4×10⁻⁶ mol 1⁻). It is the basis for indirect quantitative analysis. The relative standard deviation is 8.3% for 1×10⁻⁶ mol 1⁻¹ Al (n = 10) and the detection limit is 2 × 10⁻⁷ mol 1^−1. The proposed method has been applied to determine total and acid-reactive Al in natural waters and the results are compared with Driscoll's 8-HQ-MIBK-GF/AAS and PCV colorimetric methods.

Keywords:

• A.c. oscillopolarography
• Total monomelic aluminum
• Acid-reactive aluminum
• Natural waters
• Pyrocatechol violet