A simple and fast procedure for the determination of Al, Cu, Fe and Mn in biodiesel using high-resolution continuum source electrothermal atomic absorption spectrometry

A procedure for the determination of Al, Cu, Fe and Mn in biodiesel samples by high resolution continuum source electrothermal atomic absorption spectrometry is proposed. Sample preparation consists in simply diluting the biodiesel samples with ethanol at room temperature. For Al determination, a Zr-treated graphite tube was used as permanent modifier; for the other analytes no modifier was required. Calibration was carried out against aqueous standards, except for Al, for which calibration solutions were prepared using ethanol. Accuracy was verified by means of recovery tests and comparison with the results obtained using a different analytical procedure. The precision, expressed as the relative standard deviation, was typically better than 7%. Detection limits at ng g-1 levels for all analytes were obtained. The concentration of the analytes in biodiesel samples was generally very low, around a few tens of ng g-1, except for two samples for which the Fe concentrations were in the μg g-1 level. The proposed method has proved to be simple, precise and accurate.