A Rapid Sample Preparation Method for the Determination of Cadmium and Lead in Spinach and Artichoke Leaves Using Ozone

A novel method for sample preparation using an ozone-based process was optimized for the determination of Cd and Pb using electrothermal atomic absorption spectrometry (ET-AAS). Advanced oxidation processes, which involve the in situ generation of highly potent chemical oxidants, are a promising technology to accelerate the oxidation at room temperature and the degradation of organic matter. A certified reference material of spinach leaves was used to evaluate the methodology. The sample was treated with diluted nitric acid, then a glass device was immersed in the solution and ozone was passed through for 10 minutes. The experimental conditions were optimized by means of a multivariate experiment. Figures of merit were: detection limits (3s): 0.002 mg kg-1 (Cd), 0.01 mg kg-1 (Pb), relative standard deviation lower than 10 % for both elements (n=5), the mean recovery was 97.6 % (Cd) and 98.3 % (Pb) compared with the certified value (n=5). The method was also applied for monitoring these elements in artichoke leaves and the results were in good agreement with those obtained with microwave digestion procedure. This procedure is simple, fast and showed to be adequate for the monitoring of these inorganic contaminants in spinach leaves and artichoke leaves.