simultaneous determination
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Fluorine and chlorine are important tracers for geochemical and environmental studies. In this study, a rapid alkaline digestion (NaOH) method for the simultaneous determination of fluorine and chlorine in marine and stream sediment reference samples using ion chromatography is developed. The proposed method suppresses the volatilization loss of fluorine and chlorine and decreases the matrix effects. The results are in good agreement with fluorine ~100%, chlorine ranging from 90 to 95% of the expected concentrations. The detection limits of this method were 0.05 μg/g for fluorine and 0.10 μg/g for chlorine. This method is simple, economical, precise and accurate, which shows great potential for the rapid simultaneous determination of fluorine and chlorine in large batches of geological and environmental samples commonly analyzed for environmental geochemistry studies.

There has been no assessment of the greenness of the described analytical techniques for the simultaneous determination (SMD) of caffeine and paracetamol. As a result, in comparison to the greener normal-phase high-performance thin-layer chromatography (HPTLC) technique, this research was conducted to develop a rapid, sensitive, and greener reversed-phase HPTLC approach for the SMD of caffeine and paracetamol in commercial formulations. The greenness of both techniques was calculated using the AGREE method. For the SMD of caffeine and paracetamol, the greener normal-phase and reversed-phase HPTLC methods were linear in the 50–500 ng/band and 25–800 ng/band ranges, respectively. For the SMD of caffeine and paracetamol, the greener reversed-phase HPTLC approach was more sensitive, accurate, precise, and robust than the greener normal-phase HPTLC technique. For the SMD of caffeine paracetamol in commercial PANEXT and SAFEXT tablets, the greener reversed-phase HPTLC technique was superior to the greener normal-phase HPTLC approach. The AGREE scores for the greener normal-phase and reversed-phase HPTLC approaches were estimated as 0.81 and 0.83, respectively, indicated excellent greenness profiles for both analytical approaches. The greener reversed-phase HPTLC approach is judged superior to the greener normal-phase HPTLC approach based on numerous validation parameters and pharmaceutical assays.

Abstract A sensitive, selective, and stable sensor for the simultaneous determination of Cd2+ and Pb2+ in aqueous solution has been developed based on the carbon dots (CDs) and Nafion-modified bismuth film glassy carbon electrode (GCE). High graphitized CDs prepared by the sulfuric acid-assisted hydrothermal synthesis were directly electrodeposited on the GCE surface by cyclic voltammetry. Compared with the conventional bismuth film electrodes, CDs greatly improved the electrochemical activity of the bismuth film electrode for the detection of Cd2+ and Pb2+. After decorating CDs, the surface impedance of the GCE was decreased from 10.9 kΩ to 4.84 kΩ. Meanwhile, the corresponding response currents of the Bi/GCE were increased over 7.4 and 2.4 times for Cd2+ and Pb2+ with a wide linear range of 0.05-0.50 mg/L, respectively. High sensitivity was obtained with the detection limits of 3.1 μg L-1 (Cd2+) and 2.3 μg L-1 (Pb2+). Moreover, good stability was obtained for the simultaneous determination of Cd2+ and Pb2+ in the practical underground water with the relative standard deviations less than 10%. The results indicated that the CDs-modified bismuth film electrode could potentially be applied to detect the heavy metal ion concentrations in practical environment.