Optimization and experimental designs methodology in atomic absorption spectrometry: Rapid determination of copper traces in butter

Traces of copper in emulsified fats are determined directly by atomic absor ption spectroscopy with electrothermic atomization (AAS-EA) after dispersio n of the sample in a BTA/water/THF (48/12/40) mixture and without previous acidic digestion. The two significant factors of the thermic program: char- ashing ramp (factor X-1 = 40 s) and atomization temperature (factor X-2 = 2 450 degrees C) were optimized by means of a centered composite plane. A fai r agreement is obtained between calibration in a "reconstituted butter" mat rix (anhydrous butter oil and water) and calibration in simple medium. The detection limit is about 3 ppb and the sensibility expressed in characteris tic mass is about 7 pg/0.0044 U.A. The thermic program is well-suitable for the analysis of butter when increasing the char-ashing temperature to 900 degrees C. The calibration is carried out in a butter matrix with a detecti on limit of 7 ppb and sensibility of 17 pg/0.0044 U.A.