ABSTRACT
A method for the determination of 15 kinds of nitroaromatics in aqueous samples was developed by dispersive liquid-liquid microextraction and gas chromatography with electron capture detection. A high-density extractant applied in electron capture detector was screened out. The chromatographic conditions, types and dosages of extractants, types and dosages of dispersants, extraction time and the extraction temperature were optimized. The results showed that DB-35 capillary column had the best separation performance for the 15 kinds of nitroaromatics. The nitroaromatics could be separated within 22 min using programmed temperature control as follows: holding at an initial temperature of 80℃ and then heating to 180℃ at a ramping rate of 5℃ / min. For the extraction of 15 kinds of nitroaromatics from 5 mL of aqueous sample, the extraction equilibrium could be reached within 30 s with a high extraction recovery of over 90%when using 100 μL of chlorobenzene as extracting solvent and 400 μL of methanol as disperser solvent. In addition, the enrichment factor could approach a high value of 45. 0 - 48. 8. The sediment collected by centrifugation was injected and analyzed by gas chromatography with electron capture detector. The limits of quantification of the developed method were 0. 03 - 0. 15 μg / L ( S / N = 10). The linear range was from 0. 20 μg / L to 50. 0 μg / L, while the correlation coefficients (R2 ) were more than 0. 998. At the spiked level of 0. 200 μg / L, the relative standard deviations of this method were 3. 3% -8. 9% , the relative recoveries ranged from 86. 0% to 103. 5% . At higher spiked level, the relative standard deviations were less than 5% , and the relative recoveries ranged from 94. 5% to 101. 5% .