ATOMIC ABSORPTION MEASUREMENTS OF Al IN PLANT DIGESTS AND NEUTRAL SALT EXTRACTS OF SOILS

Abstract

Atomic absorption spectrophotometric measurements of Al in plant digests and neutral salt extracts of soils were studied. Using a new lamp (Westinghouse design) and 5 × scale expansion, 1.0 ± 0.08 ppm Al was measured. Lanthanum (2000 ppm) suppressed enhancements from Na, K, Sr, Fe and a mixture of a large number of constituents. The measurements in plant digests were independent of dilution, gave complete recovery of added Al and showed excellent agreement with the 8-quinolinolate colorimetric values. Similarly, there was complete recovery from soil extracts, but the measurements by atomic absorption were larger than by 8-quinolinolate or Aluminon. It was concluded that the new lamp provides adequate sensitivity, stability and freedom from interferences so that atomic absorption can be used for routine measurements of Al in plant digests and neutral salt extracts of soils.