污水中短长链全氟羧酸检测方法的开发

Method Development for Analysis of Short-and Long-chain Perfluorocarboxylates in Sewage

开发了弱阴离子交换柱固相萃取＋高效液相色谱-负电喷雾-串联质联法[WAX-SPE＋HPLC-ESI（-）-MS/MS]检测污水中碳链长度在2-14内的全氟羧酸（PFCAs）.采用弱阴离子交换（WAX）柱进行固相萃取时,将污水水样用甲酸酸化至pH=3.0,并使用2%甲酸溶液作净化溶剂、1%氢氧化铵甲醇溶液作洗脱溶剂,则可使短长链PFCAs（C2-C14）均具有较高的回收率,并克服了反相固相萃取柱对短链PFCAs（C2-C5）回收率低的缺点.为了验证方法的有效性,对上海市市政污水处理厂A和B的进水进行检测,结果表明各种PFCAs的回收率分别在56%-121%和54%-120%的范围内,相对标准偏差（RSD）分别小于11%和14%,方法检出限和定量限分别在0.2-1.0 ng/L和1.0-5.0 ng/L的范围内,这充分证明了该方法的可靠性.此外,在处理厂A和B内含量最高的PFCAs均为全氟辛酸（分别为743 ng/L和837 ng/L）,其次为三氟乙酸（分别为139 ng/L和489 ng/L）.

A method using weak anion exchange cartridge for solid phase extraction before high performance liquid chromatography-negative electronspray ionization-tandem mass spectrometry [WAX-SPE ＋ HPLC-ESI（-）-MS/MS] detection has been developed to measure C2-C14 perfluorocarboxylates （PFCAs） in sewages. When the weak anion exchange （WAX） cartridges were used for solid phase extraction （SPE）, the better recoveries of short- and long-chain PFCAs （C2-C 14） were achieved as the sewage samples were acidified to pH = 3.0 by formic acid, 2% formic acid was used for washing solvent and 1% ammonium hydroxide in methanol was used for elution solvent. The WAX cartridges used for SPE overcame the disadvantages of reverse phase solid phase extraction cartridges, i.e. the recoveries of short-chain PFCAs （C2-C5） were very low. The validity of this method was demonstrated by determination of short- and long-chain PFCAs （C2-C14） in influent of municipal wastewater treatment plant A and B in Shanghai, China. The results indicate that the recoveries of all PFCAs in influent of plant A and B are 56%-121% and 54%-120%, respectively; the recovery relative standard deviations （RSD） of plant A and B are 〈 11% and 〈 14%, respectively; and the method detection limits （MDL） and method quantitation limits （MQL） are 0. 2-1.0 ng/L and 1.0-5.0 ng/L, respectively. In addition, the perfluorooctanoate （743 ng/L and 837 ng/L, respectively） and trifluoroacetic acid （139 ng/L and 489 ng/L, respectively） are the most and the second most PFCAs found in both plant A and B.