Preconcentration and determination of chlordiazepoxide and diazepam drugs using dispersive nanomaterial-ultrasound assisted microextraction method followed by high performance liquid chromatography.

Benzodiazepines (BDs) are used widely in clinical practice, due to their multiple pharmacological functions. In this study a dispersive nanomaterial-ultrasound assisted- microextraction (DNUM) method followed by high performance liquid chromatography (HPLC) was used for the preconcentration and determination of chlordiazepoxide and diazepam drugs from urine and plasma samples. Various parameters such as amount of adsorbent (mg: ZnS-AC), pH and ionic strength of sample solution, vortex and ultrasonic time (min), and desorption volume (mL) were investigated by fractional factorial design (FFD) and central composite design (CCD). Regression models and desirability functions (DF) were applied to find the best experimental conditions for providing the maximum extraction recovery (ER). Under the optimal conditions a linear calibration curve were obtained in the range of 0.005-10µgmL(-1) and 0.006-10µgmL(-1) for chlordiazepoxide and diazepam, respectively. To demonstrate the analytical performance, figures of merits of the proposed method in urine and plasma spiked with chlordiazepoxide and diazepam were investigated. The limits of detection of chlordiazepoxide and diazepam in urine and plasma were ranged from 0.0012 to 0.0015µgmL(-1), respectively.

Structure-property correlation in EEMAO fabricated TiO2-Al2O3 nanocomposite coatings.

We grew TiO2-Al2O3 nanocomposite coatings on titanium substrates by electrophoretic enhanced microarc oxidation (EEMAO) technique under several voltages and established a correlation between microstructure, surface hardness, and corrosion resistance of the coatings in sulfuric acid and sodium chloride solutions. Structural analysis revealed that the coatings contained anatase, rutile, alumina, and tialite phases. Formation kinetics of tialite phase was studied. It was found that increasing the voltage gives rise to a coarser morphology, i.e., larger pore size, and incorporation of more alumina nanoparticles into the layers. It is shown that surface hardness of the titanium substrates increased by a factor of 4 following EEMAO treatment. Corrosion resistance of titanium was enhanced significantly. Resistance against pitting corrosion was improved as well. We proposed a formation mechanism for the TiO2-Al2O3 composite coatings at different voltages based on the chemical and electrochemical foundations.

An innovative technique to simply fabricate ZrO2-HA-TiO2 nanostructured layers.

For the first time, ZrO2-HA-TiO2 layers were synthesized through EPD-Enhanced MAO (EEMAO) technique in only one step where no supplementary treatment was required. SEM, XRD, EDX, and XPS techniques were employed to propose a correlation between the growth parameters and the physical and chemical properties of the layers. The layers revealed a porous structure where applying higher voltages and/or utilizing higher concentrated electrolytes resulted in formation of wider pores and increasing the zirconium concentration in the layers; meanwhile, prolonging the growth time had the same effects. The layers mainly consisted of anatase, hydroxyapatite, monoclinic ZrO2, and tetragonal ZrO2 phases. Increasing the voltage, electrolyte concentration, and time, hydroxyapatite as well as tetragonal ZrO2 was decomposed to α-TCP, monoclinic ZrO2, and ZrO. The nanosized zirconia particles (d = 20-60 nm) were further accumulated on the vicinity of the layers when thicker electrolytes were utilized or higher voltages were applied. Emphasizing on the chemical and electrochemical foundations, a probable formation mechanism was finally put forward.