Chromatography combined with mass spectrometry is the most commonly used detection technology, and it offers the advantages of high sensitivity and high selectivity. However, the contents of bisphenols (BPs) in water samples are at the ng/L level. Even if the BPs contents are determined by mass spectrometry, the samples must be pretreated and enriched. A quick, easy, inexpensive, effective, rugged, and safe technique (QuEChERS) can offer advantages such as cost effectiveness and time efficiency. The application of QuEChERS is currently extended to the analysis of contaminants in food and water samples. In this work, QuEChERS coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was proposed for the determination of eight BPs in surface water. Method optimization was carried out in terms of process efficiency (PE), which included the matrix effect (ME) and extraction recovery (RE). First, the water samples were extracted with 10 mL ethyl acetate and cleaned with 50 mg primary secondary amine (PSA) and 50 mg graphitized carbon black (GCB). Then, the organic layer was collected and evaporated to dryness under nitrogen flow (40 ℃). Finally, the extracts were redissolved in 0.5 mL of a methanol-water (1∶1, v/v) mixture and subjected to UPLC-MS/MS analysis. Chromatographic separation was accomplished on a Waters ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) with gradient elution. Methanol and 0.1 mmol/L ammonium bicarbonate aqueous solution were used as the mobile phases. The eight BPs were analyzed by MS/MS with negative electrospray ionization (ESI-) and in the multiple reaction monitoring (MRM) mode. The matrix matching external standard method was used for quantitative determination. The eight compounds could be analyzed within 8 min. Under the optimized conditions, the calibration curves showed good linearities for the eight BPs, and the coefficients of determination (R2) were greater than 0.9990. The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) were in the ranges of 0.1-2.3 ng/L and 0.3-6.1 ng/L, respectively. The average recoveries of the eight BPs in river water samples were 78.8%-116.6%, and the corresponding relative standard deviations (RSDs) were 1.8%-9.0% (n=6). This method was applied to the analysis of BPs pollution in Guangyuan section of Jialing river and its tributaries, and widespread pollution was confirmed. The detection rate of BPA was 100% with a content of 6.15-90.03 ng/L, and the detection rate of BPS was 91%, with the contents being in the range not detected (nd) to 4.63 ng/L. The method established in this study allowed for the rapid enrichment and purification of the eight BPs in water. With its advantages of simplicity, rapidness, high sensitivity, and low cost, the method can be used for the rapid determination of trace BPs in surface water such as lake water and river water.
建立了同时测定地表水中8种双酚类物质(BPs)的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法。方法基于QuEChERS处理技术,选用乙酸乙酯为提取剂,从基质效应(ME)和萃取回收率(RE)两方面对过程效率(PE)进行优化,确定了50 mg N-丙基乙二胺(PSA)和50 mg石墨化炭黑(GCB)混合吸附剂为净化剂。8种BPs使用Waters ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm, 1.7 μm)进行分离,以甲醇和0.1 mmol/L碳酸氢铵水溶液为流动相进行梯度洗脱,在电喷雾电离(ESI)源、负离子扫描及多反应监测(MRM)模式下进行质谱监测,基质匹配外标法定量。结果表明,8种BPs在8 min内完成色谱分离分析,在各自线性范围内线性关系良好,决定系数(R2)均大于0.9990,检出限(LOD)和定量限(LOQ)分别为0.1~2.3 ng/L和0.3~6.1 ng/L;以河水为样品基质,在不同添加水平下,8种BPs的平均加标回收率为78.8%~116.6%,相对标准偏差(RSD)为1.8%~9.0%。将该方法用于分析嘉陵江广元段及其支流中BPs的污染状况,结果显示,双酚A(BPA)检出率100%,含量为6.15 ~ 90.03 ng/L;双酚S(BPS)检出率91%,含量为未检出(nd)~4.63 ng/L。研究建立的方法实现了BPs在水中的快速富集与净化,具有简便、快速、灵敏度高和成本低廉等优势,可用于湖泊、河流等地表水中痕量BPs的快速检测。该方法的建立为我国地表水中BPs检测标准的制订和水质安全监控提供了参考。
Keywords: QuEChERS; bisphenols (BPs); surface water; ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).