Usefulness of ionic liquids as mobile phase modifiers in HPLC-CV-AFS for mercury speciation analysis in food

ALEXANDER CASTRO-GRIJALBA; PAMELA Y. QUINTAS; EMILIANO F. FIORENTINI; RODOLFO G. WUILLOUD

JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY

ROYAL SOC CHEMISTRY

Año: 2018

0267-9477

Different ionic liquids (ILs) were studied in this work as mobile phase modifiers for the separation and determination of Hg2+, methylmercury (CH3Hg+) and ethylmercury (C2H5Hg+) species by reversed-phase high-performance liquid chromatography coupled to UV-cold vapor atomic fluorescence spectrometry(RP-HPLC-UV-CV-AFS). Several parameters influencing the chromatographic eparation of Hg species, such as pH, sodium chloride concentration, organic solvent concentration, as well as chemical structure and concentration of ILs were evaluated. After a careful optimization, the separation of Hg species wasachieved within 12 min using a C18 column and a gradient developed by mixing methanol and a solution composed of 0.4% (v/v) 1-octyl-3-methylimidazolium chloride [C8mim]Cl, 100 mmol L-1 NaCl and 20 mmol L-1 buffer citric acid/citrate at pH 2.0. In addition, a multivariate methodology was applied to optimize the parameters involved in UV-CV-AFS detection of Hg species. The proposed method allowed the separation of inorganic and organic Hg species in a single chromatographic run. The limits of detection obtained for Hg species were in the range of 0.05?0.11 mg L-1. The usefulness of the proposed method was demonstrated by performing Hg speciation analysis in highly complex samples,such as seafood, yeast and garlic, obtaining accurate and precise results in all cases.