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Capillary zone electrophoresis determination of fluoride in seawater using transient isotachophoresis
- Fukushi, Keiichi, Fujita, Yuki, Nonogaki, Junpei, Tsujimoto, Jun-ichi, Hattori, Takanari, Inui, Hideyuki, Beškoski, VladimirP., Hotta, Hiroki, Hayashi, Mitsuru, Nakano, Takeshi
- Analytical and bioanalytical chemistry 2018 v.410 no.6 pp. 1825-1831
- capillary zone electrophoresis, cathodes, coastal water, detection limit, electric power, electrolytes, fluorides, methylcellulose, pH, salinity, seawater, spectrophotometers, statistical analysis, wavelengths, Japan
- We developed capillary zone electrophoresis (CZE) with indirect UV detection for the determination of fluoride (F⁻) in seawater using transient isotachophoresis (tITP) as an on-line concentration procedure. A method of correcting sample salinity effects was also proposed so that F⁻ concentrations were obtained using a calibration graph. The proposed method is simple: it requires no sample pretreatment aside from dilution. The following optimum conditions were established: background electrolyte (BGE), 5 mM 2,6-pyridinedicarboxylic acid (PDC) adjusted to pH 3.5 containing 0.03% m/v hydroxypropyl methylcellulose (HPMC); detection wavelength, 200 nm; vacuum (50 kPa) injection period of sample, 5 s (254 nL); and applied voltage, 23 kV with the sample inlet side as the cathode. The limit of detection (LOD, S/N = 3) and limit of quantification (LOQ, S/N = 10) for F⁻ reached 0.024 and 0.070 mg/L, respectively. The respective values of the relative standard deviation (RSD) of the peak area, peak height, and migration time for F⁻ were 2.5, 3.4, and 0.30%. The proposed method was applied for the determination of F⁻ in seawater samples collected from coastal waters of western Japan during August 26–28, 2014. Both results obtained using standard addition method and a calibration graph agreed with those obtained using a conventional spectrophotometric method.