Determination of Cr and Mn in moisturizing creams by graphite furnace atomic absorption spectrometry through direct introduction of the samples in the form of emulsions

Abstract

This paper reports the development of a novel method for the determination of Cr and Mn in moisturizing creams by graphite furnace atomic absorption spectrometry (GF AAS) through direct introduction of the samples in the form of emulsion. The method was optimized by evaluating the influence of several variables such as the sonication time, concentration of acid and mass of sample employed in the procedure and emulsion stability. The curves of pyrolysis and atomization were constructed for both analytes in order to evaluate their thermal behavior in the presence of the matrix and to investigate the possible use of different chemical modifiers. The optimized conditions of both Cr and Mn were achieved when 1000mg of the samples was mixed with 0.5molL−1 HCl solution sufficient to complete 5mL. Then, the mixture was sonicated for 20min, using an ultrasonic probe. The emulsions prepared in this way remained stable for 60min, at least. The developed method was successfully applied in the determination of Cr and Mn in five samples of commercially available moisturizing creams. Recovery tests were performed, yielding recovery percentages in the range of 93%–108% and 87%–104% for Mn and Cr, respectively.