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Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed for preconcentration and determination of tramadol, ((±)-cis-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol-HCl), in aqueous and biological samples (urine, blood). DLLME is a simple, rapid and efficient method for determination of drugs in aqueous samples. Efficient factors on the DLLME process has defined and optimized for extraction of tramadol including type of extraction and disperser solvents and their volumes, pH of donor phase, time of extraction and ionic strength of donor phase. Based on the results of this study, under optimal conditions and by using 2-nitro phenol as internal standard, tramadol was determined by GC-MS, and the figures of merit of this work were evaluated. The enrichment factor, relative recovery and limit of detection were obtained 420, 99.2% and 0.08 μg L-1, respectively. The linear range was between 0.26 and 220.00 μg L-1 (R² = 0.9970). The relative standard deviation for 50.00 μg L-1 of tramadol in aqueous samples by using 2-nitro phenol as IS was 3.6% (n = 7). Finally, the performance of DLLME was evaluated for analysis of tramadol in urine and blood. [ABSTRACT FROM AUTHOR]

Abstract: Polyoxometalates (POM) supported on zirconia, H3PW12O40/ZrO2, were prepared by incorporating polyphosphotungstate into a zirconia matrix via sol–gel technique that involving the hydrolysis of zirconium (IV) n-butoxide, Zr (n-OBu)4, as the ZrO2 source. This insoluble and readily separable catalyst was characterized by using XRD, FT-IR, SEM, and UV diffuse reflectance spectroscopy (UV-DRS), indicating that the polyphosphotungstate was chemically attached to the zirconia supports, and primary Keggin structure remained intact. The photocatalytic and sonocatalytic activity of the supported polyphosphotungstate was tested via degradation of different dyes in aqueous solutions. The POM–ZrO2 nanocomposite showed higher photocatalytic and sonocatalytic activity than pure polyoxometalate or pure ZrO2. [Copyright &y& Elsevier]

The authors have modified a carbon paste electrode with Al2O3-supported palladium nanoparticles (PdNP@Al2O3) to obtain a sensor for simultaneous voltammetric determination of melatonin (MT), dopamine (DA) and acetaminophen (AC). The PdNP@Al2O3 was characterized by scanning electron microscopy and energy-dispersive X-ray spectra. The sensor can detect DA, AC, MT and their mixtures by giving distinct signals at working voltages of typically 236, 480 and 650 mV (vs. Ag/AgCl), respectively. Differential pulse voltammetric peak currents of DA, AC and MT increase linearly in the 50 nmol L−1 - 1.45 mmol L−1, 40 nmol L−1 -1.4 mmol L−1, and 6.0 nmol L−1 - 1.4 mmol L−1 concentration ranges. The limits of detection are 36.5 nmol L−1 for DA, 36.5 nmol L−1 for AC, and 21.6 nmol L−1 for MT. The sensor was successfully used to detect the analytes in (spiked) human serum and drug samples. [ABSTRACT FROM AUTHOR]