Rapid ultrasound-assisted dispersive solid-phase extraction of nonsteroidal anti-inflammatory drugs in urine using oleic acid functionalized magnetic graphene oxide.

We describe an ultrasound-assisted magnetic dispersive solid-phase extraction based on oleic acid functionalized magnetic graphene oxide followed by high-performance liquid chromatography with ultraviolet detection. The method was applied for the simultaneous determination of ibuprofen, diclofenac, naproxen, and mefenamic acid in urine. The application of sonication led to the good dispersion of the sorbent, and consequently, significant shortened the extraction time.

Simultaneous spectrophotometric determination of crystal violet and malachite green in water samples using partial least squares regression and central composite design after preconcentration by dispersive solid-phase extraction.

In this paper, a simple, fast, and inexpensive method is introduced for the simultaneous spectrophotometric determination of crystal violet (CV) and malachite green (MG) contents in aquatic samples using partial least squares regression (PLS) as a multivariate calibration technique after preconcentration by graphene oxide (GO). The method was based on the sorption and desorption of analytes onto GO and direct determination by ultraviolet-visible spectrophotometric techniques. GO was synthesized according to Hummers method.