▎ 摘　　要

In this work, a novel analytical approach for determining methyl(cyclopentadienyl)-tricarbonyl (MMT) by total reflection X-ray fluorescence (TXRF) based on its trapping onto unmodified graphene membranes is described. Graphene membranes were synthesized by mild-thermal reduction of graphene oxide following drop-casting onto a glass substrate. High flexible and easy-to-handle graphene membranes with 10 mm diameter were obtained. In order to use the as-prepared membranes as extraction phases for headspace thin-solid film microextraction of MMT, they were fitted to quartz reflectors and placed onto the top of the glass vial containing the sample. Reflectors containing graphene membranes were directly used as sample carriers for TXRF analysis. Different parameters involved in the microextraction step were optimized in order to obtain the best performance. Detection and quantification limits were 18 and 60 ng L-1 MMT, respectively. An enrichment factor of 265 was obtained. The method was successfully applied for the specific detection of MMT in different water samples and a certified reference material e.g., NWTM-27.2 fortified lake water. A recovery study was carried out on spiked water samples showing recoveries in the range 98-104% with a relative standard deviation of 4% (N = 5). In addition, speciation of manganese, i.e. MMT and Mn(II),in water samples can be accomplished since only volatile MMT is transferred to the headspace and retained onto graphene membranes. (C) 2016 Elsevier B.V. All rights reserved.