固相膜萃取-膜上超声衍生法测定水中酸性有机物

Determination of Acidic Organic Compounds in Water by Solid Phase Membrane Extraction-Membrane Ultrasonic Assisted Extraction Method

建立了固相膜萃取-超声衍生-负化学源质谱测定水中芳香酸和酚酸的方法。取水样500 mL,用H3PO4(1∶1,V/V)调至pH≈3,使水样以约200 mL/min流速经过聚苯乙烯-二乙烯苯(SDB-XC)萃取膜。将除去水分后的膜片移入衍生瓶中,加入丙酮溶剂2 mL、10%五氟苄基溴溶液200μL和10%K2CO3溶液30μL,利用超声技术对膜片上的酸性有机物进行洗脱和衍生。超声水浴温度为60℃、时间为30 min、功率为60%。以HP-5MS(30 m×0.25 mm×0.25μm)为分析柱,采用负化学源质谱在11 min内完成衍生物的检测。结果表明,方法在2.5~200μg/L线性范围内各组分线性关系良好,相关系数r2>0.99,检出限低于1.0μg/L。不同基质、不同浓度的加标回收率在70%~110%之间;相对标准偏差在3.3%~10.7%之间。

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 approximately 3 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 2 mL acetone, 200 ~L pentafluorobenzylbromide （ 10% ） and 30 t^L K2CO3 （ 10% ）. The acidic organic compounds were eluted and derivatized under ultrasonic technology for 30 rain at temperature 60 ~C and power 60%. Then the derivatization products were separated in a HP-SMS （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 1.0μg/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%.