Experimental design approach for the extraction of methylmercury from certified reference materials using microwave energy

Methylmercury (MeHg) has been extracted from biological samples using Micro wave Assisted Extraction (MAE). In order to find the optimal experimental c onditions to extract samples a screening experimental design was used allow ing the establishment of the significant MAE operating variables affecting the total recovery of Methylmercury. A reference material (DORM-1) was used as sample in this screening study. Four variables were selected for evalua tion: temperature, extraction time, added 6M HCl amount and solvent (toluen e) volume. The statistical treatment of the obtained results indicated that HCl amount and temperature were the only variables that significantly affe ct methylmercury recoveries. Then to obtain the optimal conditions a respon se surface experimental design was applied and a reproducibility study was carried out in the optimum reached conditions showing a mean recovery of 10 0.2+/-2.0 % in the case of DORM-1. Other available reference materials were also applied to validate the microwave extraction procedure. (C) 1999 Else vier Science Ltd. All rights reserved.