Facile and sensitive determination of urinary mandelic acid by combination of metal organic frameworks with microextraction by packed sorbents.

In this study, two hybrid metal organic frameworks including MOF-5@ Fe3O4-NH2 and MOF-5@ SBA-15 for the first time were synthetized and combined with microextraction by packed sorbent (MEPS) to extract of mandelic acid (MA) from urine samples. The synthetized sorbents were characterized using FE-SEM, XRD and FT-IR techniques. The important parameters in MEPS procedure including sample volume, extraction draw_discard cycles, elution solvent volume and desorption draw-eject cycles were optimized using response surface methodology (RSM) with central composite design (CCD). The results indicated that the volume of elution solvent was the most important parameter in the recovery of MA by MOF-MEPS procedure. The optimized MOF-MEPS method offered an acceptable efficiency for the recovery of MA from urine samples (MOF-5@Fe3O4-NH2 and MOF-5@SBA-15: 94.5% and 90.3%, respectively, RSD < 3.54%). The limit of detection (LOD) of MA calculated by MOF-MEPS procedure combined with high performance liquid chromatography for MOF-5@ Fe3O4-NH2 and MOF-5@ SBA-15 were calculated to be 0.10 and 0.13 μg mL-1, respectively. The linearity dynamic ranges (LDRs) determination of urinary MA by MOF-5@ Fe3O4-NH2 and MOF-5@ SBA-15 were 0.2-100 and 0.2-90 μg mL-1, respectively. The results of the present study implied that the proposed technique is a fast and sensitive procedure for extraction and determination of MA from urine samples.