Determination of Acidic Organic Compounds in Water by Solid Phase Membrane Extraction-Membrane Ultrasonic Assisted Extraction Method
A method was established based on that the aromatic acids and phenolic acids in water were extracted by solid phase membrane,derivatized under ultrasonic technology, and detected by negative chemical ionization mass spectrometry. A 500-mL water sample that its pH value was adjusted to approximately3 by phosphoric acid( 1 ∶ 1,V / V) was controlled to pass the polystyrene-divinylbenzene( SDB-XC)membrane at 200 mL / min. After the membrane was drained,it was placed in a derivatization bottle,with 2mL acetone,200 μL pentafluorobenzylbromide( 10%) and 30 μL K2CO3( 10%). The acidic organic compounds were eluted and derivatized under ultrasonic technology for 30 min at temperature 60 ℃ and power60%. Then the derivatization products were separated in a HP-5MS( 30 m × 0. 25 mm × 0. 25 μm)column,and detected by negative chemical ionization mass spectrometry within 11 min. The result showed good linear relationship in the range of 2. 5-200 μg / L with correlation coefficients higher than 0. 99. The detection limits were less than 1. 0 μg / L. The spiked recoveries of different matrices and different concentrations varied from 70% to 110% with relative standard deviations between 3. 3% and 10. 7%.