Electrochemical determination of anticancer drug, flutamide in human plasma sample using a microfabricated sensor based on hyperbranchedpolyglycerol modified graphene oxide reinforced hollow fiber-pencil graphite electrode.

Flutamide (FLT) is a non-steroidal anti-androgen drug that has a specific anti-androgenic activity so that it is used in the treatment of prostate cancer. FLT may also be used to treat excess androgen levels in women. A sensitive electrochemical sensor based on hyperbranchedpolyglycerol functionalized- graphene oxide developed, using ionic liquid mediated hollow fiber-pencil graphite electrode (HF/HBP-GO/PGE) as a working electrode for determination of an anticancer drug, flutamide (FLT. In this design, a two centimeter piece of porous polypropylene hollow fiber membrane was impregnated with ionic liquid (1-Pentyl-3-methylimidazoliumbromide), and a graphite rod modified with hyperbranchedpolyglycerol/graphene oxide (HBP-GO), was located inside the fiber lumen. The modified electrode exhibits sorption activity, high sensitivity, stability and applicability over a wide range of concentration of FLT. The morphology and the electrochemical properties of the modified electrode were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The effect of the amount of graphene oxide (GO), scan rate, pH, concentration of ionic liquid, extraction time and agitation rate on electrochemical behavior of flutamide molecules was investigated. The square wave voltammetric method showed a linear behavior over the drug concentration range 0.1-110 µM. The limit of detection (LOD) and the limit of quantification (LOQ) were found to be 0.029 µM and 0.099 µM, respectively. The proposed sensor was applied for determination of FLT in human plasma sample with satisfactory results.

Hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction for measurement of ibuprofen and naproxen in hair and waste water samples.

A new design of hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction (HBP/GO -HF-SLPME) coupled with high performance liquid chromatography used for extraction and determination of ibuprofen and naproxen in hair and waste water samples. The graphene oxide first synthesized from graphite powders by using modified Hummers approach. The surface of graphene oxide was modified using hyperbranched polyglycerol, through direct polycondensation with thionyl chloride. The ready nanocomposite later wetted by a few microliter of an organic solvent (1-octanol), and then applied to extract the target analytes in direct immersion sampling mode.After the extraction process, the analytes were desorbed with methanol, and then detected via high performance liquid chromatography (HPLC). The experimental setup is very simple and highly affordable. The main factors influencing extraction such as; feed pH, extraction time, aqueous feed volume, agitation speed, the amount of functionalized graphene oxide and the desorption conditions have been examined in detail. Under the optimized experimental conditions, linearity was observed in the range of 5-30,000ngmL(-1) for ibuprofen and 2-10,000ngmL(-1) for naproxen with correlation coefficients of 0.9968 and 0.9925, respectively. The limits of detection were 2.95ngmL(-1) for ibuprofen and 1.51ngmL(-1) for naproxen. The relative standard deviations (RSDs) were found to be less than 5% (n=5).

Synthesis and application of a novel solid-phase microextraction adsorbent: hollow fiber supported carbon nanotube reinforced sol-gel for determination of phenobarbital.

A novel solid-phase microextraction technique using a hollow fiber-supported sol-gel combined with multi-walled carbon nanotubes was employed in the determination of phenobarbital in wastewater. In this new technique, a silica-based, organic-inorganic polymer containing functionalized multi-walled carbon nanotubes (MWCNTs) was prepared with sol-gel technology via the reaction of tetraethylorthosilicate (TEOS) with an acidic catalyst (HCl). This sol was injected into a polypropylene hollow fiber segment for in situ gelation. This device operated in direct immersion sampling mode. The experimental setup is simple and affordable, and the device is disposable, so there is no risk of cross-contamination or carry-over. Parameters affecting extraction such as pH of the aqueous solution, ageing and extraction times, aqueous sample volume, agitation speed and carbon nanotube amount were optimized. Linearity was observed over a range of 0.50-5000 ng mL(-1), with an estimation coefficient (r(2)) higher than 0.982. The limit of detection (LOD) was 0.32 ng mL(-1) (n=5), and repeatability (RSD%=2.9) was from the average of three levels of analyte concentrations (1, 1000 and 4500 ng mL(-1)) with three replicates for each within a single day. Finally, a pre-concentration factor of 2100 was obtained for phenobarbital.