Response surface methodology for optimization of cyanamide analysis by in situ derivatization and dispersive liquid-liquid microextraction

Cyanamide is widely used for agricultural purposes; therefore, its residues can be found in water. A new method was developed for its quantification using in situ derivatization with 2,6‐dimethyl‐4‐quinolinecarboxylic acid N‐hydroxysuccinimide ester followed by dispersive liquid–liquid microextraction (DLLME) and high‐performance liquid chromatography/fluorescence analysis. Multivariate chemometric techniques were successfully used to obtain the optimum conditions for direct derivatization and DLLME extraction. Derivatization parameters and DLLME extraction conditions were optimized by a two‐step design, 2k factorial design for screening, and central composite design for optimization. Best derivatization conditions were addition of 600 μL of derivatizing reagent, a temperature of 4 ºC, and pH 8.5, whereas for optimum extraction 800 μL of solvent, 30% NaCl conc. w/v, and pH 3.8 were chosen. The analytical performance of the method for routine analysis was evaluated. Excellent linearity was achieved from 10 to 200 µg L−1 with a correlation factor of 0.9996. Precision ranged from 3.5% to 5.5% for intraday assays and 8.5% to 8.6% for interday assays. The mean recoveries performed on water from different origins (ground, river, sea, tap, and mineral) at three levels of concentration (20, 75, and 200 µg L−1) ranged from 90.2% to 110.2%. Copyright © 2014 John Wiley & Sons, Ltd. Analysis of cyanamide in water samples was performed by applying in situ derivatization followed by dispersive liquid‐liquid microextraction (DLLME) extraction and high‐performance liquid chromatography/fluorescence analyses. Multivariate chemometric techniques were used to the screening of relevant derivatization and DLLME extraction variables and to establish optimum conditions with a minimal number of assays to obtain maximum cyanamide response. The proposed method was validated and applied to the analyses of groundwater, river, sea, tap, and mineral water, not finding detected levels of cyanamide in these samples.