UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, NSW 2052, Australia.
Water Res. 2011 Nov 15;45(18):6249-58. doi: 10.1016/j.watres.2011.09.020. Epub 2011 Sep 17.
The enantiospecific fate of three common pharmaceuticals was monitored in a laboratory-scale membrane bioreactor (MBR). The MBR was operated with a hydraulic retention time of 24 h and a mixed liquor suspended solids concentration of 8.6-10 g/L. Standard solutions of ibuprofen, ketoprofen and naproxen were dosed into the synthetic feed of the MBR. Influent and permeate samples were then collected for enantiospecific analysis. The individual (R)- and (S)-enantiomers of the three pharmaceuticals were derivatised using a chiral derivatizing agent to form pairs of diastereomers, which could then be separated and analysed by gas chromatography-tandem mass spectrometry (GC-MS/MS). Accurate quantitation of individual enantiomers was undertaken by an isotope dilution process. By comparing the total concentration (as the sum of the two enantiomers) in the MBR influent and permeate, ibuprofen, ketoprofen and naproxen concentrations were observed to have been reduced as much as 99%, 43% and 68%, respectively. Furthermore, evidence of enantioselective biodegradation was observed for all three pharmaceuticals. (S)-Ibuprofen was shown to be preferentially degraded compared to (R)-ibuprofen with an average decrease in enantiomeric fraction (EF) from 0.52 to 0.39. In contrast, (R)-ketoprofen was preferentially degraded compared to (S)-ketoprofen with a relatively minor increase in EF from 0.52 to 0.63. The use of a relatively pure enantiomeric solution of (S)-naproxen resulted in a significant change in EF from 0.99 to 0.65. However, this experiment consistently revealed significantly increased concentrations of (R)-naproxen during MBR treatment. It is hypothesised that the source of this (R)-naproxen was the enantiomeric inversion of (S)-naproxen. Such enantiomeric inversion of chiral pharmaceuticals during wastewater treatment processes has not previously been reported.
三种常见药物的对映体选择性命运在实验室规模的膜生物反应器（MBR）中进行了监测。MBR 的水力停留时间为 24 小时，混合液悬浮固体浓度为 8.6-10 g/L。将布洛芬、酮洛芬和萘普生的标准溶液加入 MBR 的合成进料中。然后采集进水和渗透物样品进行对映体选择性分析。使用手性衍生试剂将三种药物的单个（R）-和（S）-对映异构体衍生化，形成一对非对映异构体，然后通过气相色谱-串联质谱（GC-MS/MS）进行分离和分析。通过同位素稀释过程对单个对映异构体进行准确定量。通过比较 MBR 进水和渗透物中总浓度（两个对映异构体之和），发现布洛芬、酮洛芬和萘普生的浓度分别降低了 99%、43%和 68%。此外，还观察到所有三种药物都存在对映选择性生物降解的证据。（S）-布洛芬比（R）-布洛芬更优先降解，对映体分数（EF）从 0.52 平均降低到 0.39。相比之下，（R）-酮洛芬比（S）-酮洛芬更优先降解，EF 相对较小地从 0.52 增加到 0.63。（S）-萘普生的相对纯净的对映体溶液的使用导致 EF 从 0.99 显著变化到 0.65。然而，该实验在 MBR 处理过程中始终显示出（R）-萘普生浓度显著增加。据推测，这种（R）-萘普生的来源是（S）-萘普生的对映体反转。手性药物在废水处理过程中的这种对映体反转以前没有报道过。
