An electroanalytical method for the simultaneous determination of paracetamol (PAR), caffeine (CAF), and orphenadrine (ORPH) using the square‐wave voltammetry (SWV) and a cathodically pretreated boron‐doped diamond electrode was developed. The method exhibits linear responses to PAR, CAF, and ORPH in the concentration ranges 5.4×10−7–6.1×10−5 M, 7.8×10−7–3.5×10−5 M, and 7.8×10−7–3.5×10−5 M, respectively, with detection limits of 2.3×10−7 M, 9.6×10−8 M, and 8.4×10−8 M, respectively. The proposed method was successfully applied in the simultaneous determination of these analytes in pharmaceutical formulations.

We describe the analytical performance of a hybrid material composed of SiO 2 , Al 2 O 3 and TiO 2 . It was prepared by a sol-gel process and can act as an adsorbent in the continuous-flow enrichment of copper. A minicolumn was packed with the material, copper ions are adsorbed at pH 9.13, then eluted with 1.0 mol L −1 nitric acid, and determined by FAAS. The material was characterized by infrared spectroscopy, scanning electron and energy dispersive spectroscopy, energy dispersive X-ray fluorescence analysis, powder Xray diffraction, and specific surface area analysis. No significant interference was observed for most ions in up to copper/ interferent ratios of 1:100 and of 1:500 in case of Ca(II), Ba (II), and Mg(II). The breakthrough capacity is 1.4 mg g −1 under dynamic conditions. The limits of detection and of quantification are 0.50 and 1.4 μg L −1 , respectively, and the calibration plot is linear in the range from 5.0 to 245.0 μg L −1 (r00.999). The relative standard deviation is 3.20 (for n07 and at a Cu(II) concentration of 10 μg L −1 ). The method was applied to the determination of trace copper ions in water, vegetable and alcohol fuel samples.

Carbon black (CB) grafted with 3-mercaptopropyltrimethoxysilane (3-MPTMS) was used as solid phase extractor for Cd 2+ in a flow injection system coupled to flame atomic absorption spectrometry (FAAS). The influence of pH, buffer concentration, preconcentration flow rate and eluent concentration on preconcentration of Cd 2+ were investigated by means of chemometric tools. The characterization of the adsorbent chemically modified was performed by Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis, Raman spectroscopy and textural analysis. To perform the on-line preconcentration, 20.0 mL of a pH 7.0 Cd 2+ solution at a flow rate of 4.0 mL min −1 was loaded through 30.0 mg of modified CB and then eluted with 1.0 mol L −1 HCl toward the FAAS instrument. The limits of detection and quantification were found to be 0.20 and 0.66 µg L −1 , respectively. Addition and recovery tests carried out in real samples (mineral, tap and saline waters, and cigarette sample) and the analysis of certified reference material (TORT-2, lobster hepatopancreas reference) attested the applicability of proposed method.

In the present paper the assessment of a novel molecularly imprinted polymer, poly(methacrylic acid)/silica, for clean-up and selective extraction of cholesterol in milk samples is described. The relative selectivity coefficient (k) values for cholesterol/5-α-cholestane and cholesterol/7-dehydrocholesterol systems were found to be 5.08 and 6.08, respectively, thus attesting the selectivity of the MIP for cholesterol under competitive adsorption with structurally analogous steroid compounds. The milk analysis was initially based on saponification followed by liquid-liquid extraction with n-hexane. Then, the protocol of molecularly imprinted solid phase extraction (MISPE) was carried out by loading the milk hexanic extract through 200 mg of MIP or NIP (non-imprinted polymer) packed into SPE cartridges at a flow rate of 0.6 mL min(-1). The washing step was performed by using n-hexane followed by further elution with ethanol and HPLC-UV analysis at 208 nm. From the breakthrough curve the maximum adsorption capacity of the MIP towards cholesterol was found to be 29.51 mg g(-1). The precision of the MISPE protocol was assessed as intra- and inter-days yielding RSD (relative standard deviations) lower than 4.10%. Cleaner HPLC chromatograms were obtained for milk samples submitted to the MISPE protocol in comparison to the solid phase extraction using the NIP or modified octadecyl silica (C18). Recoveries varying from 96.6 up to 102.2% for milk samples spiked with cholesterol were achieved, thus ensuring the accuracy of the proposed method.