The first analytical method for the determination of 13 phosphoric acid mono- and diesters from aqueous samples is presented. The method consists of solid-phase extraction (SPE) and ion-pair liquid chromatographic separation with tri-n-butylamine coupled to electrospray ionization tandem mass spectrometry in the negative ion mode. Due to a lack of pure standards, only 3 of the 13 esters could be quantified. SPE recoveries ranged from 71 to 112% for di-n-butyl phosphate, diphenyl phosphate, and di-(2-ethylhexyl) phosphate (DEHP) with limits of quantification from 7 to 14 ng/L for 100-mL samples. At analyte concentrations ≥1 μg/L, aqueous samples can be analyzed by direct injection without extraction. In municipal wastewater, six diesters and one monoester were unambiguously identified by comparison with synthesized reference material. DEHP showed highest concentrations of 60 and 5 μg/L in raw and treated wastewater, respectively. The detection of monoethylhexyl phosphate was confirmed by LC−Q-TOF-MS analysis, and it was found at a concentration level comparable to DEHP. Laboratory degradation tests show that phosphoric acid diesters can be formed as intermediates in the microbial degradation of trialkyl phosphates that are being used as flame retardants and plasticizers.
本文介绍了用于测定
水样中13种
磷酸单酯和双酯的首次分析方法。该方法包括固相萃取(
SPE)和离子对
液相色谱分离,配合
三丁胺与电喷雾电离串联质谱(负离子模式)。由于缺乏纯标准品,仅能定量其中的3种酯。
SPE回收率对于二
丁基磷酸酯、
二苯基磷酸酯和二(2-乙基己基)
磷酸酯(DEHP)分别为71至112%,定量限为100毫升样品中的7至14纳克/升。当分析物浓度≥1微克/升时,
水样可直接注入分析而不需萃取。通过与合成参考物质的比对,在市政污
水中明确鉴定出了6种双酯和1种单酯。DEHP在原污
水和处理后的污
水中最高浓度分别为60和5微克/升。通过LC−Q-TOF-MS分析确认了单乙基己基
磷酸酯的存在,其浓度
水平与DEHP相当。实验室降解试验表明,
磷酸双酯可作为三烷基
磷酸盐微
生物降解过程中的中间产物,这些三烷基
磷酸盐被用作阻燃剂和
增塑剂。