Graphene oxide grafted on cellulosic substrate for microextraction by packed sorbent of vitamins B2 and B7 followed by their determination by synchronous fluorescence spectrometry.

An innovative analytical method based on microextraction by packed sorbent (MEPS) was developed for determination of B-group vitamins in commercial energy drinks. A graphene oxide-modified cellulose (GO/Cell) sorbent was synthesized and characterized using field emission scanning electron microscopy (FESEM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD) analyses. Key parameters were optimized via central composite design. Method validation assessed linearity, limits of detection (LODs), limits of quantification (LOQs), precision, accuracy, and applicability to real samples. LODs were 1.6 and 1.7 ng mL-1 for vitamins B7 and B2, with corresponding LOQs of 5.3 and 5.5 ng mL-1, respectively. The method showed a linear dynamic range (LDR) of 5.5-600 ng mL-1, precision of 0.9 %-9.0 %, and relative recoveries of 92.8 %-104.0 %. The results demonstrated that the proposed MEPS-SFS approach offers high sensitivity, precision, and accuracy for vitamins analysis, making it suitable for routine quality control of energy drinks.