In this work a new method is presented for simultaneous colorimetric determination of morphine(MOR) and ibuprofen(IBU) based on the aggregation of citrate-capped gold nanoparticles (AuNPs). Citrate-capped gold nanoparticles were aggregated in the presence of morphine and ibuprofen. The difference in kinetics of AuNPs aggregation in the presence of morphine / ibuprofen was used for simultaneous analysis of morphine and ibuprofen. The formation and size of synthesized Au NPs and the aggregated forms were monitored by infra-Red (IR) spectroscopy and transmission electron microscopy (TEM) respectively.. By adding morphine or ibuprofen the absorbance was decreased at 520 nm and increased at 620 nm. The difference in kinetic profiles of aggregation was applied for simultaneous analysis of MOR and IBU using partial least square regression as an efficient multivariate calibration method. The number of PLS latent variables was optimized by leave-one-out cross-validation method using predicted residual error sum of square. The proposed model exhibited a high capability in simultaneous prediction of MOR and IBU concentrations in real samples. Our results showed linear ranges of 1.33–33.29 µg/mL (R2=0.9904) and 0.28–6.9 µg/mL (R2=0.9902) for MOR and IBU respectively with low detection limits of 0.15 and 0.03 µg/mL(S/N=5).
<p class="PaperAbstract">Cu<sub>x</sub>O-NiO nanocomposite film for the non-enzymatic determination of glucose was prepared by the novel modifying method. At first, anodized Cu electrode was kept in a mixture solution of CuSO<sub>4</sub>, NiSO<sub>4</sub> and H<sub>2</sub>SO<sub>4</sub> for 15 minutes. Then, a cathodization process with a step potential of -6 V in a mixture solution of CuSO<sub>4</sub> and NiSO<sub>4</sub> was initiated, generating formation of porous Cu-Ni film on the bare Cu electrode by electrodeposition assisted by the release of hydrogen bubbles acting as soft templates. Optimized conditions were determined by the experimental design software for electrodeposition process.<strong> </strong>Afterward, Cu-Ni modified electrode was scanned by cyclic voltammetry (CV) method in NaOH solution to convert Cu and Ni nanoparticles to the nano-scaled Cu<sub>x</sub>O-NiO film. The electrocatalytic behavior of the novel Cu<sub>x</sub>O-NiO film toward glucose oxidation was studied by CV and chronoamperometry (CHA) techniques. The calibration curve of glucose was found linear in a wide range of 0.04–5.76 mM, with a low limit of detection (LOD) of 7.3 µM (S/N = 3) and high sensitivity (1.38 mA mM<sup>-1</sup> cm<sup>-2</sup>). The sensor showed high selectivity against some usual interfering species and high stability (loss of only 6.3 % of its performance over one month). The prepared Cu<sub>x</sub>O-NiO nanofilm based sensor was successfully applied for monitoring glucose in human blood serum and urine samples.</p>
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