Song Yihuan, Ma Qingfang, Cheng Heyong, Liu Jinhua, Wang Yuanchao
College of Material Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou, 311121, China.
Key Laboratory of Organosilicon Chemistry and Material Technology, Hangzhou Normal University, Hangzhou, 311121, China.
Anal Chim Acta. 2021 May 1;1157:338388. doi: 10.1016/j.aca.2021.338388. Epub 2021 Mar 13.
Quantification of ultra-trace inorganic and organic species of lead and mercury in unpolluted environmental water is crucial to estimate the mobility, toxicity and bioavailability and interactions. Simultaneous pre-concentration of Pb and Hg species in pg L levels followed by multi-elemental speciation analysis makes great sense to a large set of unstable samples because of time advantages. Herein simultaneous enrichment and speciation analysis of ultra-trace lead and mercury in water was developed by online solid-phase extraction coupled with high performance liquid chromatography and inductively coupled plasma mass spectrometry (SPE-HPLC-ICP-MS) for this aim. Pb(II), trimethyl lead (TML), triethyl lead (TEL), Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) were baseline separated in 11 min under gradient elution using 5 mM l-cysteine (Cys) at pH 2.5 in the 0-1 and 4-15 min and 5 mM Cys + 0.5 mM tetrabutyl ammonium hydroxide solution at pH 2.5 in the 1-4 min. Lead and mercury species in 10 mL intact water samples were adsorbed on a 1 cm C enrichment column pre-conditioned with 10 mL of 1 mM 2-mercaptoethanol at 10 mL min, and then directly desorbed by the mobile phases. High enrichment factors (459 for Pb(II), 1248 for TML, 1627 for TEL, 2485 for Hg(II), 1984 for MeHg and 1866 for EtHg) were obtained with good relative standard deviations (<5%), leading to low LODs (0.001-0.011 ng L) and LOQs (0.004-0.036 ng L). Good accuracy of this method was validated by two certified reference materials of total lead in water (GBW08601) and total mercury in water (GBW08603) along with spiked recoveries (89-93%). The method was applied to analyze trace lead and mercury species in river, lake, tap and rain water, and purified and mineral water. Inorganic lead of 13-68 ng L and inorganic mercury of 21-49 ng L were measured in the nine water samples whereas TML, TEL and MeHg were not detected with 2-5 ng L EtHg presented only in one river water and tap water.
对未受污染环境水中痕量无机和有机形态的铅和汞进行定量分析，对于评估其迁移性、毒性、生物有效性及相互作用至关重要。由于时间优势，对皮克每升水平的铅和汞形态进行同时预富集，随后进行多元素形态分析，对于大量不稳定样品而言意义重大。为此，本文开发了一种在线固相萃取结合高效液相色谱和电感耦合等离子体质谱（SPE-HPLC-ICP-MS）的方法，用于水中超痕量铅和汞的同时富集与形态分析。在梯度洗脱条件下，使用5 mM l-半胱氨酸（Cys）在pH 2.5的溶液，于0至1分钟和4至15分钟时，以及在1至4分钟时使用5 mM Cys + 0.5 mM氢氧化四丁铵溶液在pH 2.5的条件下，Pb(II)、三甲基铅（TML）、三乙基铅（TEL）、Hg(II)、甲基汞（MeHg）和乙基汞（EtHg）在11分钟内实现基线分离。10 mL完整水样中的铅和汞形态在一根1 cm的C富集柱上吸附，该富集柱预先用10 mL 1 mM 2-巯基乙醇以10 mL每分钟的流速进行预处理，然后直接用流动相解吸。获得了较高的富集因子（Pb(II)为459、TML为1248、TEL为1627、Hg(II)为2485、MeHg为1984、EtHg为1866），相对标准偏差良好（<5%），从而实现了较低的检测限（0.001 - 0.011 ng/L）和定量限（0.004 - 0.036 ng/L）。通过两种水中总铅（GBW08601）和总汞（GBW08603）的有证标准物质以及加标回收率（89 - 93%）验证了该方法的良好准确性。该方法应用于分析河流、湖泊、自来水、雨水以及纯净水和矿泉水中的痕量铅和汞形态。在九个水样中测得无机铅含量为13 - 68 ng/L，无机汞含量为21 - 49 ng/L，而未检测到TML、TEL和MeHg，仅在一个河水样和自来水样中检测到2 - 5 ng/L的EtHg。
