Determination of mercury species in foodstuffs using LC-ICP-MS: the applicability and limitations of the method

Abstract

Reversed-phase liquid chromatography hyphenated with inductively coupled plasma mass spectrometry (LC-ICP-MS) was used for mercury speciation analysis in food samples. A short chromatographic column (Purospher^® RP-8e, 75 ´ 4 mm, 3 µm) and a mobile phase containing 0.02 mol/l CH₃COONH₄ + 0.2% (v/v) 2-mercaptoethanol (2-ME) + 1% (v/v) CH₃OH were applied. A repeated extraction of samples with hydrochloric acid/2-ME solution (1 mol/l HCl + 0.2% (v/v) 2-ME) was applied as the isolation step. The results were satisfactory for most food matrices (fish, shellfish, plant materials). Conversely, to analyse high-protein animal matrices, which contain mostly the inorganic form of mercury, a procedure including partial hydrolysis using hydrochloric acid should be used. For methylmercury and inorganic divalent mercury, the LOQ values of 0.3 and 2 ng/g, respectively, can be achieved if precautionary measures against contamination are fulfilled. The method was applied for the determination of methylmercury and inorganic divalent mercury in fish, vegetables, herbs and cereal products.