大气PM_(2.5)中4种无机离子的离子色谱测定法

Determination of four inorganic anions in atmospheric PM_(2.5) by ion chromatography

目的建立测定大气细颗粒物(PM_(2.5))中氯离子(Cl^-)、硝酸根离子(NO_3^-)、硫酸根离子(SO_4^(2-))、铵根离子(NH_4^+)的离子色谱法。方法取采集有大气PM_(2.5)的石英滤膜1/8,用陶瓷剪刀剪碎,置于10 ml的刻度离心管中,加入10.0 ml超纯水浸没滤膜,于超声水浴提取30 min后,以4 500 r/min离心5 min(离心力半径=6 cm),取出上清液过滤后进行离子色谱分析。阴离子采用20 mmol/L的KOH溶液作为淋洗液,用AS19阴离子交换柱进行分离,阳离子采用20 mmol/L甲基磺酸作为淋洗液,用CS12A阳离子交换柱进行分离。结果该方法在0.10~80 mg/L范围内线性关系良好(r>0.999 4),加标回收率在95.5%~103.0%,相对标准偏差(RSD)为1.26%~2.82%。结论本方法操作简便、灵敏度高、结果准确可靠、实用性强,适用于大气PM_(2.5)中4种水溶性无机离子的测定。

[Objective] To establish a method for measuring chloride ion（Cl-）,nitrate ion（NO3-）,sulfate ion（SO42-） and ammonium ion（NH4＋） in atmospheric PM2.5 by ion chromatography[Methods]1/8 of quartz membrane which was used to collect the atmospheric particles（PM2.5） was cut into pieces by ceramic scissors,put into 10 ml polypropylene plastic centrifuge tube,adding 10 ml pure water to the sampling qartz membrane for extraction 30 minutes by ultrasonic,and the extraction solutions were obtained by 4 500 r/min for five minutes（centrifugal force radius =6 cm）. The supernatant was filtered and analyzed by ion chromatography. The anions was tested with 20 mmol/L KOH as eluent,and separated by AS19 anions exchange column. The cation was tested with 20 mmol/L methanesulfonic acid as eluent,and separated by CS12 A anions exchange column.[Results]The method had good linearity in the range of 0.10-80 mg/L（r〉0.999 4）,the recovery was 95.5%-103.0%,and the relative standard deviation（RSD）was1.26%-2.82%.[Conclusion]The method is simple,sensitive,accurate and reliable,which is suitable for the determination of four water-solubility inorganic anions in atmospheric PM2.5.