Development of an ultrasonic slurry sampling method for the determination of Cu and Mn in antibiotic tablets by electrothermal atomic absorption spectrometry

A new method is described for simple, efficient and rapid determination of Cu and Mn in tablets of antibiotics (ciprofloxacin and cephalexin) by electrothermal atomic absorption spectrometry (ETAAS) using slurry sampling. In order to optimize the procedure, several variables that could affect the performance of the method were investigated. In the best conditions, the tablets could be analyzed by introducing into the graphite tube 20 μl of a slurry prepared with approximately 90–100 mg of the sample and 2 ml of a solution containing 5% m/v of Triton X-114 and 2.8 M of HNO3. Before the introduction, the slurries were sonicated for 15 min at 40% of amplitude (130 W maximum power) with an ultrasonic probe. The developed method was applied in the determination of Cu and Mn in four samples, and the results were compared with those obtained by focused microwave acid digestion with aqua regia (1:3 mixture of HNO3:HCl). There was no statistical difference between the obtained values at 95% confidence level when a paired Student t-test was applied.