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Direct determination of ammonium and amines in high salinity water samples by ion chromatography using conductivity detection is impossible due to the presence of high potassium and sodium concentrations. This work describes a simple and fast method for the determination of ammonium, monomethylamine and monoethylamine in high salinity waters by ion chromatography. An ultrasound-assisted purge-and-trap extraction system was used to eliminate matrix interferences. This system was optimized using a full two-level factorial (2 3 ) design followed by a two-level factorial (2 2 ) design. In the first factorial design, the variables: extraction time, concentration of sodium hydroxide solution and analyte mass were tested. In the second factorial design, the mass of each analyte was maintained constant. Parameters of the analytical curves, prepared in different matrices: sulfuric solution and extracts from working standard solutions prepared in water and saline solution were compared. Limits of detection of 0.02, 0.03 and 0.03 mg L − 1 were found for ammonium, monomethylamine and monoethylamine, respectively. Saline waters from Brazilian oil industry, pre-treated to remove nitrogen compounds, were analyzed. Satisfactory recoveries (93–111%) of the analytes were obtained for all spiked samples. Precision was ≤ 10% ( n = 3). The proposed method is adequate for analyzing saline waters containing sodium to ammonium, monomethylamine and monoethylamine concentration ratios up to 56,000:1 and potassium to ammonium, monomethylamine and monoethylamine concentration ratios up to 24,000:1. [ABSTRACT FROM AUTHOR]

Cuphea glutinosa is a medicinal species abundant in South of Brazil, known because of its flavonoids, which have pharmacological properties as antioxidant, anti-hypertensive, diuretic, and antimicrobial. The present study aimed to optimize the extraction and validate an ultra-performance liquid chromatographic method coupled to a photodiode array detector (UPLC-PDA) method for the quantification of a chemical marker miquelianin in C. glutinosa leaves. The optimum conditions for the extraction of miquelianin from leaves of C. glutinosa were determined using a fractional factorial design (FFD) and a central composite design (CCD). An UPLC-PDA method was validated, following the ICH guidelines and RDC 166/2017 of ANVISA (Brazil). The extraction-optimization methodology was obtained with the following parameters: plant:solvent 1:60 (w/v), percentage solvent 38% ethanol, 60 min time, five extractions and particle size ≤ 180 μm. The validation parameters of the quantification method were satisfactory. The results revealed a method with excellent selectivity, linearity, precision (repeatability and intermediate precision were below 2.18 and 1.40%, respectively) and accuracy (mean recovery 90.6%). The average content of miquelianin was 1.03%. Briefly, the optimization of the extractive method in the leaves of C. glutinosa increased the concentration of miquelianin in the crude extract and the method was validated according to the current legislation. Image 1 • Ultrasound-assisted extraction optimization and validation from Cuphea glutinosa. • Ultrasound extraction optimization and validation for miquelianin quantification. • Optimization and validation for the quantification of miquelianin in Cuphea glutinosa. • Optimization and validation for the quantification of miquelianin. [ABSTRACT FROM AUTHOR]