Use of in-situ surfactant-based solid phase extraction for determination of low concentrations of CrIII in infusions of medicinal plants

Abstract A new solid phase extraction procedure, known as in situ surfactant-based solid phase extraction, has been proposed to detect the presence of CrIII in infusions of medicinal plants. In this work, a small amount of cetyltrimethylammonium bromide was injected into a sample containing CrIII, which was complexed by 1-(2-pyridylazo)-2-naphthol. After shaking, a small volume of NaClO Was added to the solution as an ion-pairing agent. After preconcentration, the settled phase was dissolved in a specific volume of HCl and then analyzed by Flame Atomic Absorption Spectrometry. A Doehlert matrix was used to optimize the CrIII complex formation conditions, such as the chelating agent concentration (0.18 mmol L-1) and pH of 9.5 in the reaction medium. A 23 factorial design was used to screen the variables that influence the extraction of the complex. The concentration of ionic-pairing agent (0.26 mol L-1) and the vortex mixer agitation time (7.51 minutes) were significant and optimized using response surface methodology. The limit of detection, limit of quantification, and preconcentration factor were 1.66 μg L-1, 5.5 μg L-1 and 12, respectively. The linear range was 5.5-5000 μg L-1. The method proved accuracy by the comparison with certified reference material APS-1071 (p>0.05), and the optimized conditions were successfully applied for the determination of CrIII in samples of medicinal plant infusions. GRAPHICAL ABSTRACT