An amino-functionalised mesoporous silica (KIT-6) as a sorbent for dispersive and ultrasonication-assisted micro solid phase extraction of hippuric acid and methylhippuric acid, two biomarkers for toluene and xylene exposure

The authors described a new application of amino-functionalised KIT-6 for dispersive ultrasonication-assisted micro solid phase extraction of hippuric acid (HA) and methyl hippuric acid (MHA) from human urine and water samples. In the first step, an amino-functionalised mesoporous silica of type KIT-6 was synthesised. It was characterised by field emission scanning electron microscopy, Fourier transform infrared spectrometry, nitrogen adsorption-desorption analysis, thermogravimetry and X-ray diffraction. Following sorption and desorption with 1.0 mL methanol/NH4OH (1%; v/v), HA and MHA were quantified by HPLC with UV detection. Various important parameters were optimised by Box-Behnken design. Under optimised conditions, the limit of detections (LOD) were calculated by a signal-to-noise ratio of 3, which were 0.5 ?g L-1 and 0.2 ?g L-1 for HA and MHA, respectively, and the calibration plot is linear in the 1-1000 ?g L-1 concentration range. Only small matrix effects were found. The method was successfully implemented for the sensitive determination of HA and MHA in (spiked) human urine samples. Graphical abstract Schematic of a sorbent for dispersive micro solid phase extraction coupled with ultrasonic power. It consists of amino functionalised KIT-6 and was used for the simultaneous preconcentration and determination of low levels of hippuric and methyl hippuric acid in urine and water samples.

Authors: Behbahani M, Bagheri S, Omidi F, Amini MM. ; Full Source: Microchimica Acta. 2018 Oct 11;185(11):505. doi: 10.1007/s00604-018-3038-5.