This work presents the integration between phase‐separation by magnetic‐stirring salt‐induced high‐temperature liquid‐liquid extraction (PS‐MSSI‐HT‐LLE) and batch injection analysis with amperometric detection (BIA‐AD) as an alternative strategy for pre‐concentration of analytes before hydrodynamic electroanalysis. To demonstrate the performance of this analytical system, the emerging contaminant levofloxacin was quantified in tap, aquarium and lake water at low concentration level. In the optimized conditions, BIA‐AD enabled fast (160 h−1) and reproducible results (RSD<2 %) and the PS‐MSSI‐HT‐LLE allowed the detection of levofloxacin concentration levels not detected by direct electroanalysis (70 and 80 nmol L−1) corresponding to 100‐folds enrichment factors. The performance of proposed method was evaluated by addition‐recovery test and was obtained satisfactory recovery values (between 70 and 96 %). Moreover, PS‐MSSI‐HT‐LLE allows the pre‐concentration of many samples simultaneously, which is advantageous over pre‐concentration on working electrode surface (stripping methods).
Tadalafil (TDL) is the active ingredient of Cialis ® , one of the top selling drugs for the treatment of erectile dysfunction and very counterfeit worldwide. In this work, two amperometric methods are proposed for (1) determination and (2) screening of TDL in pharmaceutical products using a boron-doped diamond electrode assembled in a 3Dprinted Batch Injection Analysis cell. Cyclic voltammograms showed that TDL presented one irreversible oxidation and pH dependent process at about 1.0 V (vs Ag/AgCl) with maximum current in Britton-Robinson buffer pH 4.0. For the method 1, a constant potential of + 1.3 V was applied and, under optimized conditions, good linear range for TDL quantification (from 1.0 to 150.0 μmol L À 1), LOD of 1.0 μmol L À 1 (experimental), high repeatability (RSD = 1.9 %; n = 20) and good sample throughput (270 h À 1) were obtained. Method 1 was used for the determination of TDL in genuine and generic formulations, and the results were not statistically different from a comparative spectrophotometric method at a 95 % confidence level. In method 2, the multiple pulse amperometric detection (MPAD) was taken through the application of sequential potential pulses (+ 1.0, + 1.2 and + 1.5 V). The comparative profile of each sample was done after peak ratios from each amperogram (R 1 = i pa1.2V /i pa1.0V , R 2 = i pa1.5V /i pa1.2V , R 3 = i pa1.5V /i pa1.0V). This simple current normalization allowed the recognition of similar profiles between samples containing only TDL and differences between samples adulterated with other drugs (sildenafil, paracetamol, dipyrone, and caffeine). Finally, these methods are fast, use portable low-cost apparatus and unmodified electrodes. Such features are attractive for routine analysis in forensic and pharmaceutical sciences.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.