Cr₂TiC₂T_<i>x</i> MXene as an adsorbent material in ultrasonic-assisted d-μ-solid phase extraction for trace detection of heavy metals

MXenes are a large family of two-dimensional transition metal carbides, nitrides, and carbonitrides. While MXenes have great potential for applications in analytical chemistry, most of the studies in this field are focused on Ti₃C₂T_<i>x</i>, the most popular MXene material. For example, several studies employed Ti₃C₂T_<i>x</i> as an adsorbent for the trace detection of toxic analytes, but there is limited knowledge on the utility of other MXene materials for this application. In this work, we investigated the potential of Cr₂TiC₂T_<i>x</i>, one of the least studied MXenes, for application as an adsorbent material in ultrasonic-assisted dispersive micro solid-phase extraction (d-μ-SPE) method for the detection of heavy metals at trace levels in food and soil samples. We synthesized large monolayer flakes of Cr₂TiC₂T_<i>x</i> and characterized it by a variety of microscopic and spectroscopic techniques. Cr₂TiC₂T_<i>x</i> MXene showed remarkable performance in the d-μ-SPE method with the detection limits of 0.09 and 1.9 ng mL^-1, and dynamic ranges of 0.3-90 μg L^-1 and 6-120 μg L^-1 for cadmium (Cd²⁺) and lead (Pb²⁺) ions, respectively. The great performance of Cr₂TiC₂T_<i>x</i> MXene as an adsorbent for the trace detection of heavy metals highlights the importance of investigating other MXenes beyond Ti₃C₂T_<i>x</i> for analytical applications.