Efficient Extraction of Cr(VI) from Real Samples Using Graphene Oxide-Mesoporous Silica Nanosheets in Packed Syringe Microextraction

Efficient techniques for extracting and preconcentrating Cr (VI) from water samples are increasingly important because of its harmful impact on both human health and the environment. In this study, a new adsorbent was developed, consisting of graphene oxide-mesoporous silica nanosheets functionalized with an ion-imprinted polymer (GO@mSiO ₂ @Cr(VI)-IIP). The effectiveness of this adsorbent for extracting Cr (VI) was assessed using the microextraction in a packed syringe (MEPS) technique. The adsorbent was characterized using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TGA). The adsorption capacity of the synthesized material was optimized by assessing the impact of sample pH, adsorbent quantity, sample volume, elution volume, and number of extraction cycles. The results of this study demonstrated that the optimal conditions for Cr (VI) extraction were a sample pH of 2, five cycles of sample loading, 3 mg of the adsorbent material, a sample volume of 900 µL, and an elution volume of 300 µL. The method demonstrated exceptional sensitivity, as evidenced by a calculated limit of detection (LOD) of 4.88 ng/mL and limit of quantification (LOQ) of 20.16 ng/mL. The technique demonstrated impressive repeatability, as evidenced by a relative standard deviation (RSD) of 1.7%. The GO@mSiO ₂ @Cr(VI)-IIP adsorbent had a maximum adsorption capacity of 0.416 µg/mg. Moreover, the method demonstrated notable selectivity for Cr(VI) compared to other interfering ions. The preconcentration factor was determined to be 2.97, highlighting the effectiveness of the method in concentrating Cr(VI) ions. This technique was successfully utilized to extract and analyze the speciation of Cr(VI) in real water samples, with recovery rates exceeding 97% for the majority of samples. The proposed method offers a straightforward, rapid, and cost-effective approach for the preconcentration and analysis of Cr(VI) in environmental specimens.