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Response surface methodology for optimization of cyanamide analysis by in situ derivatization and dispersive liquid–liquid microextraction
Author(s) -
Neves Junior Augusto C. V.,
Melo Armindo,
Pinho Carina,
Coneglian Regina C. C.,
Soares Antônio G.,
Ferreira Isabel M. P. L. V. O.
Publication year - 2014
Publication title -
journal of chemometrics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.47
H-Index - 92
eISSN - 1099-128X
pISSN - 0886-9383
DOI - 10.1002/cem.2639
Subject(s) - derivatization , chromatography , chemistry , extraction (chemistry) , central composite design , reagent , factorial experiment , response surface methodology , cyanamide , solvent , high performance liquid chromatography , organic chemistry , mathematics , statistics
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, 2 k 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.