Simultaneous speciation and preconcentration of ultra trace concentrations of mercury and selenium species in environmental and biological samples by hollow fiber liquid phase microextraction prior to high performance liquid chromatography coupled to indu

•Hollow-fiber membrane extraction is a powerful technique for chemical speciation.•Its precision is remarkable for overcoming one of the shortcomings of membrane techniques.•Sample carryover is absent due to the disposable nature of membranes.•The analytical method allows the simultaneous speciation of Hg and Se.•The procedure has been applied to real world samples with high reliability.

Nowadays, hollow fiber membrane extraction techniques are widely used due to the high enrichment factors obtained with many different types of analytes and samples. In this paper, we propose a new analytical method that allows the simultaneous extraction of methylmercury, inorganic mercury and Se4+ and determination by high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC–ICP-MS). The detection limits obtained are very low (110–230 ng/L) with relative standard deviations below 15% for all the analytes and averaged recoveries in fortified samples in the range of 71–99%. The precision of the analytical method is very good which overcomes one of the most important shortcomings of membrane extraction techniques. Several variables were studied to get optimal extraction conditions for the analytes. This method has been validated with real world samples such as water (tap, river and estuarine) and human blood plasma.