Selective and sensitive method for the determination of metoprolol in human plasma using liquid chromatography coupled with tandem mass spectrometry.

A high-performance liquid chromatography-tandem mass spectrometric method was developed and validated for the determination of metoprolol in human plasma. The analyte and internal standard, nevirapine, were extracted from plasma matrix by liquid-liquid extraction with ethyl acetate. Chromatographic separation was achieved on a C-18 analytical column with an isocratic mobile phase of 15:85 (V/V) 10 mmol L-1 ammonium acetate (pH 5.0)/acetonitrile. The atmospheric pressure chemical ionization technique was used for sample ionization in positive ion mode and enhanced selectivity was achieved by tandem mass spectrometric analysis via two multiple reaction monitoring (MRM) transitions, 268.2 → 116.2 for metoprolol and 267.1 → 226.2 for nevirapine, respectively. The assay was validated for human plasma over a concentration range of 1-200 ng mL-1 with the precision and accuracy ranging from 0.9 to 8.8% and 89.9 to 105.8%, respectively.

Removal of mercury from aqueous solutions using activated carbon prepared from agricultural by-product/waste.

Removal of mercury from aqueous solutions using activated carbon prepared from Ceiba pentandra hulls, Phaseolus aureus hulls and Cicer arietinum waste was investigated. The influence of various parameters such as effect of pH, contact time, initial metal ion concentration and adsorbent dose for the removal of mercury was studied using a batch process. The experiments demonstrated that the adsorption process corresponds to the pseudo-second-order-kinetic models and the equilibrium adsorption data fit the Freundlich isotherm model well. The prepared adsorbents ACCPH, ACPAH and ACCAW had removal capacities of 25.88 mg/g, 23.66 mg/g and 22.88 mg/g, respectively, at an initial Hg(II) concentration of 40 mg/L. The order of Hg(II) removal capacities of these three adsorbents was ACCPH>ACPAH>ACCAW. The adsorption behavior of the activated carbon is explained on the basis of its chemical nature. The feasibility of regeneration of spent activated carbon adsorbents for recovery of Hg(II) and reuse of the adsorbent was determined using HCl solution.