Automated Measurement of Aqueous Aluminum by the Pyrocatechol Violet Method

In response to our need for a rapid method of analyzing numerous aluminum samples, we developed an automated procedure for measuring total monomeric aluminum in aqueous samples. Two separate designs for a continuous microflow analyzer are presented which enable detection over a combined range of 20 μg Al/l to 1000 μg Al/l. The best fit to the calibration curve for the high sensitivity manifold is not linear (r 2 = 0.998) as previously reported but third order (cubic, r 2 = 1.000). The choice of equations for curve fit for the low sensitivity range is less critical as first and third order equations provide comparable fit. Between-sample contamination is less that 3% and reproducibility is high; less than 1% variation for high (200 - 1000 μg Al/l) concentrations and less than 7% for lower (20 - 300 μg Al/l concentrations. Analysis of both water and soil extract samples for aluminum should be facilitated by use of this system.