title: Sensitivity enhancement in the fluorometric determination of aliphatic amines using naphthalene-2,3-dicarboxaldehyde derivatization followed by vortex-assisted liquid-liquid microextraction.
abstract: A highly sensitive liquid chromatographic method was developed for the fluorometric determination of trace amounts of linear aliphatic primary amines. Prior to extraction, amines were derivatized with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide ion (CN) and extracted by vortex-assisted liquid-liquid microextraction (VALLME). The optimum conditions were as follows: derivatization reaction time for 5 min in 2.0 mL aqueous donor samples with 50 μM NDA/CN, and 10mM borate buffer at pH 9; vortex extraction time for 20s in the VALLME step with 50 μL of isooctane as the extractant phase; centrifugation for 1 min at 6000 rpm. Under the optimum conditions, the limits of detection (LOD) were between 0.01 and 0.04 nmol L(-1). The calibration curves showed good linearity in the range of 0.1-20 nmol L(-1). In comparison with previous work using o-phthalaldehyde/2-mercaptoethanol derivatization, the method has much more stable fluorescent derivatives, higher fluorescence intensities, and greater extraction efficiencies. The sensitivity enhancement factors (SEF) were between 2 and 70, which is in good agreement with the theoretical values calculated from partition coefficients in VALLME system.
authors.affiliation: Environmental Chemistry Laboratory, Department of Biomedical Engineering and Environmental Sciences, College of Nuclear Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Chin-Yi
authors.initials: CY
authors.lastname: Wang
authors.affiliation: Environmental Chemistry Laboratory, Department of Biomedical Engineering and Environmental Sciences, College of Nuclear Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Shu-Yin
authors.initials: SY
authors.lastname: Tung
authors.affiliation: Environmental Chemistry Laboratory, Department of Biomedical Engineering and Environmental Sciences, College of Nuclear Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Yu-Shiu
authors.initials: YS
authors.lastname: Lo
authors.affiliation: Department of Nutrition and Health Science, Fooyin University, 151 Chinhsueh Road, Ta-Liao, Kaohsiung 83102, Taiwan.
authors.forename: Hsien-Lu
authors.initials: HL
authors.lastname: Huang
authors.affiliation: School of Forestry and Resource Conservation, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Chun-Han
authors.initials: CH
authors.lastname: Ko
authors.affiliation: Environmental Chemistry Laboratory, Department of Biomedical Engineering and Environmental Sciences, College of Nuclear Science, National Tsing Hua University, Hsinchu 30013, Taiwan. Electronic address: chwu@mx.nthu.edu.tw.
authors.forename: Chien-Hou
authors.initials: CH
authors.lastname: Wu
keywords: Amine; Derivatization; Fluorometric determination; HPLC; Naphthalene-2,3-dicarboxaldehyde; Vortex-assisted liquid–liquid microextraction