Effect of Surfactants and of Ultrasonic Mixing in the Determination of Calcium, Magnesium, Copper and Zinc in Whole Blood by Flow Injection Flame Atomic Absorption Spectrometry

Abstract

The behaviour of five non-ionic surfactants of different chain lengths was studied in relation to the improvement in sensitivity that their use affords as a sample pre-treatment procedure for the determination of calcium, magnesium, copper and zinc in real samples by flow injection flame atomic absorption spectrometry. The results show that the sensitivity changed with surfactant concentration, length of the hydrophobic chain and ultrasonic agitation time. Higher outputs were obtained with Triton X-100, which is the surfactant with the shortest chain length. In this case, the sensitivity of the atomic absorption signal increased 2.2, 2.2, 2.3 and 2.5-fold for aqueous solutions of calcium, magnesium, copper and zinc, respectively. The data also showed that ultrasonic agitation of the sample probe considerably improved the sensitivity, regardless of the element under evaluation. A relative precision between 0.6 and 3.3% was achieved with a smaller sample consumption than by the conventional atomic absorption method. The results obtained from the proposed sample pre-treatment procedure for the analysis of the elements under study were in good agreement with those obtained by microwave-assisted mineralization and flow injection AAS (for zinc and copper) and flame AAS (for calcium and magnesium).