A novel, rapid and simple acid extraction for multielemental determination in chocolate bars

摘要

A novel and simple method based on acid extraction was developed for the determination of Ca, Na, K, P, Mg, Cu, Mn and Zn in chocolate bars by inductively coupled plasma techniques, ICP OES and ICP-MS. The parameters time, temperature and nitric acid concentration were studied in multivariate form using a certified chocolate material. In the optimized conditions 20 mL of 1.4 mol L-1 HNO3, a temperature of 100 degrees C and 6 min of extraction were selected. Certified chocolate reference material was analyzed and the results were in agreement with certified concentrations (recoveries between 98% and 107%). In addition, the results obtained by analyzing six different chocolate samples with different cocoa contents (ranging between 28% and 85%) by the proposed method were compared with those obtained by microwave-assisted acid digestion. Recoveries were in the range of 90-110%. The proposed acid extraction was successfully applied to sixteen chocolate samples and the results indicated that concentrations of K, Mg, P, Cu, Mn and Zn increase with the cocoa content and an opposite effect was observed for Na and Ca. The proposed method is a good alternative to conventional acid digestion procedure and can be applied to routine analysis of major and minor constituents in chocolate bars. (C) 2015 Elsevier B.V. All rights reserved.