Abstract
We established capillary zone electrophoresis (CZE) for the simultaneous determination of bromide (Br－), iodide (I－), nitrite (NO2－), and nitrate (NO3－) in salts. To accomplish the simultaneous determination, 10 mM cetyltrimethylammonium chloride (CTAC) was added to the background electrolyte (BGE). The interaction of these anions with CTAC was utilized to adjust the electrophoretic mobilities of the anions. The achieved limits of detection (LOD, signal-to-noise ratio (S/N) = 3) and limits of quantification (LOQ, S/N ＝ 10) were respectively 0.73 and 2.4 mg/L for Br－, 0.079 and 0.26 mg/L for I－, 0.049 and 0.16 mg/L for NO2－-N ( as N), and 0.039 and 0.13 mg/L for NO3－-N. The respective values of the relative standard deviation (RSD, n ＝ 4) of the peak area, peak height, and migration time were 5.2, 1.9, and 0.37 ％ for Br－ (10 mg/L), 3.5, 5.2, and 0.45 ％ for I－(1.0 mg/L), 0.98, 1.9, and 0.42 ％ for NO2－ (1.0 mg/L), and 2.3, 1.3, and 0.40 ％ for NO3－(1.0 mg/L). Linear calibration graphs were obtained for these analytes using both the peak area and peak height （correlation coefficients, 0.9976‒0.9999). The proposed method was used to find the analytes in salt samples including seaweed salts, sea salts, and rock salts. The salts used for this experiment contained 144‒1490 mg/kg of Br－, 3.85‒48.0 mg/kg of I－, and 1.46‒2.65 mg/kg of NO3－-N. NO2－ was not detected from any sample. The CZE results for the analytes agreed with those obtained using ion chromatography (IC). The recoveries were 89.4‒116 ％ when analyzing salt solutions with 0‒15.0 mg/L Br－, 0‒1.50 mg/L I－, NO2－, and NO3－.
