Multivariate Optimization of Ultrasound-Assisted Extraction Procedure for the Determination of Ca, Fe, K, Mg, Mn, P, and Zn in Pepper Samples by ICP OES

In the present study, a simple and fast procedure using ultrasound-assisted extraction was developed for the determination of Ca, Fe, K, Mg, Mn, P, and Zn in pepper samples by inductively coupled plasma optical emission spectrometry (ICP OES). For the optimization of variables, the procedure used was the factorial design (2 3 ) and the conditions evaluated and optimized were concentration of nitric acid (1 mol L −1 ), sonication time (5 min), and sonication temperature (40 °C). A certified reference material (CRM) of tomato leaves (NIST 1573a) was used to evaluate the accuracy of the developed procedure by ultrasound-assisted extraction. The obtained concentration values were concordant with the certified values based on Student t test at 95% of confidence level. Therefore, the optimized conditions were applied to determine the analytes in five pepper samples, and the concentration values ranged between 1639 and 4861 mg kg −1 (Ca), 51 and 196 mg kg −1 (Fe), 558 and 13,050 mg kg −1 (K), 553 and 1662 mg kg −1 (Mg), 7 and 46 mg kg −1 (Mn), 2306 and 3793 mg Kg −1 (P), and 8–21 mg kg −1 (Zn).