薄膜梯度扩散-硫氰酸钾分光光度法富集测量水中痕量Mo(VI)

建立了薄膜梯度扩散(DGT)-硫氰酸钾(PT)分光光度法(DGT-PT法)富集测量水中痕量Mo(VI)的分析方法。先以聚季铵盐(PQAS)溶液为结合相的DGT技术(PQAS DGT)原位分离富集水中Mo(VI),再以PT分光光度法测定DGT结合相中Mo(VI)的含量,最后依据DGT方程计算水中Mo(VI)的浓度。DGT-PT法测得配制水中Mo(VI)的回收率为96.3%~101.3%,相对标准偏差(RSD)为1.3%~4.0%;测得工业废水中Mo(VI)的浓度为27.13~121.79μg/L,加标回收率为96.0%~101.6%。当采样时间为48h,PQAS DGT对水中Mo(VI)富集近18倍,可显著降低分析方法的检测限,实现水中痕量Mo(VI)的定量检测。     

薄膜梯度扩散-分光光度法富集测量水中痕量Cr(VI)

建立了薄膜梯度扩散(DGT)-二苯碳酰二肼(DPC)分光光度法富集测量水中痕量Cr(VI)的分析方法。先以聚季铵盐(PQAS)溶液为结合相的DGT技术(PQAS DGT)原位分离富集水中Cr(VI),再以DPC分光光度法测定DGT结合相中Cr(VI)的含量,最后依据DGT方程计算水中Cr(VI)的浓度。DGT-DPC法测得配制水中Cr(VI)的回收率为95.1%~101.3%,相对标准偏差为1.60%~3.58%;测得工业废水中Cr(VI)的浓度为18.54~137.61μg/L,加标回收率为94.3%~101.8%。当采样时间为48h,PQAS DGT对水中Cr(VI)富集近10倍,可显著降低分析方法的检测限,实现水中痕量Cr(VI)的定量检测。     

薄膜梯度扩散-分光光度法富集测量水中痕量Cr(Ⅵ)

建立了薄膜梯度扩散(DGT)-二苯碳酰二肼(DPC)分光光度法富集测量水中痕量Cr(Ⅵ)的分析方法.先以聚季铵盐(PQAS)溶液为结合相的DGT技术(PQAS DGT)原位分离富集水中Cr(Ⅵ),再以DPC分光光度法测定DGT结合相中Cr(Ⅵ)的含量,最后依据DGT方程计算水中Cr(Ⅵ)的浓度.DGT-DPC法测得配制水中Cr(Ⅵ)的回收率为95.1％～101.3％,相对标准偏差为1.60％～3.58％;测得工业废水中Cr(Ⅵ)的浓度为18.54 ～ 137.61μg/L,加标回收率为94.3％～101.8％.当采样时间为48h,PQAS DGT对水中Cr(Ⅵ)富集近10倍,可显著降低分析方法的检测限,实现水中痕量Cr(Ⅵ)的定量检测.     

薄膜梯度扩散-原子吸收光谱法富集测量水中痕量镉

建立了薄膜梯度扩散-原子吸收光谱(DGT-AAS)法富集测量水中痕量镉的分析方法。先以海藻酸钠(SA)溶液为结合相的DGT技术(SA DGT)原位分离富集水中Cd~(2+),再以AAS法测定DGT结合相中镉的含量,最后依据DGT方程计算水中Cd~(2+)浓度。DGT-AAS法测得配制水中Cd~(2+)的回收率为95.6%~102.7%,相对标准偏差(RSD)为1.5%~3.1%;测得河水和人工湖水中加标Cd~(2+)的DGT有效态分数分别为22.46%和15.19%。当采样时间为48h,SA DGT对水中Cd~(2+)的富集倍数为20倍,可显著降低分析方法的检测限,实现水中痕量Cd~(2+)的定量检测。     

阴离子纤维微柱-紫外分光光度法快速富集检测水中痕量Cr(Ⅵ)

通过两步接枝法制备了一种季铵型离子交换纤维PP-g-DMAEMA-Br,将其用作纤维管内固相微萃取方法中的吸附剂,并结合紫外-可见分光光度法富集检测水溶液中痕量的Cr(Ⅵ),开发了一套预富集检测水中痕量Cr(Ⅵ)的新工艺。研究了样品流速,p H值对纤维微柱吸附水中痕量Cr(Ⅵ)的影响,以及洗脱剂类型、浓度、体积、洗脱剂流速对Cr(Ⅵ)洗脱回收率的影响。在最佳条件下,该方法对于Cr(Ⅵ)最低检测限为0.2μg/L,富集因子为100,富集效率为98.06~101.26%,时间为15min左右。该方法简单快速,灵敏度高,重复性好,可以和便携式仪器连用,适用于在线检测、尤其是偏远地区的实际样品测定。     

催化分光加入标准法测定废水中痕量汞的研究

研究催化分光光度法测定水中痕量汞(Ⅱ)的各种干扰因素及消除方法.建立用于测定多组分共存水样中痕量汞(Ⅱ)的催化分光光度加入标准法.以催化分光光度加入标准法测定废水中痕量汞(Ⅱ),其线性范围为3.0×10-3~8.0×10-2mg/L,加标回收率97.79%~102.78%,相对标准偏差(RSD)为0.116%,测定结果与原子吸收光谱法相同.     

阳离子交换树脂分离-分光光度法测定水中痕量铜

采用静态法研究了HD-8阳离子交换树脂对铜的吸附速率、吸附温度和吸附量等性能。试验结果表明:在0.1～0.5mol·L~(-1)盐酸溶液介质中铜的吸附率在95%以上,用3mol·L~(-1)盐酸溶液3mL可将吸附于柱上的铜(Ⅱ)完全洗脱下来。在优化的试验条件下,该HD-8阳离子交换树脂微柱对铜的富集限为2μg/200mL,富集倍数为67倍。在此基础上提出了一种阳离子交换树脂分离分光光度法测定水样中痕量铜的方法。该方法用于测定鄱阳湖水中痕量铜,测得平均回收率为101.5%之间,相对标准偏差(n=5)为1.82%。     

活性炭柱吸附富集-分光光度法测定饮用水中痕量钼(Ⅵ)

提出了一种预富集水中痕量钼(VI)的新方法,研究了影响Mo α 安息香肟螯合物定量吸附于活性炭柱上的参数,找出了最佳吸附解吸时的条件。该方法避免了用活性炭作为吸附材料的常规方法中,活性炭只能使用一次的间歇式操作,以及用浓硝酸解吸这种费时污染大的解吸方法,同时用NaOH解吸时,大部分金属离子以氢氧化物沉淀的形式留在活性炭上,减少了干扰。该法已用于测定水中痕量钼(Ⅵ),加标回收率达到94.6%～101.4%,RSD3.6%～8.6%。     

支撑液膜在线萃取富集流动注射分光光度法测定水中的痕量铅

研究了以双硫腙为流动载体,煤油为膜溶剂的支撑液膜萃取体系,建立了支撑液膜在线萃取富集流动注射分光光度法测定水中痕量铅(Ⅱ)的新方法。优化了支撑液膜萃取富集条件,优化结果为:试样pH=6,反萃液柠檬酸浓度为0.5 mol/L,载体双硫腙浓度为0.03%,膜孔径为0.3μm,富集时间为30 m in。在此条件下,方法的检出限为0.2μg/L;线性范围为0.5~100μg/L。应用于自来水、河水和工业污水中铅(Ⅱ)的检测,结果满意。     

阴离子交换树脂分离富集水中痕量镉

先用草酸处理水样中的镉离子,生成的[Cd(C2O4)2]2-络阴离子通过强碱性阴离子交换树脂分离富集,最后用火焰原子吸收分光光度法测定了水样中的痕量镉。该法简便,选择性好,富集倍数高,应用于实际水样的检测,回收率为98%~102%,结果令人满意。     

介孔二氧化硅纳米球对水中Mo(VI)的吸附研究

本研究制备了介孔二氧化硅纳米球(MSN),并用之吸附脱除水中的Mo(VI)。应用扫描电镜、介孔分析仪、红外光谱等对MSN进行了表征。考察了pH、吸附时间、MSN投加量和温度对水中Mo(VI)脱除率的影响,并在单因素试验基础上通过正交试验法确定了Mo(VI)的最佳脱除条件：pH=3,MSN投加量为 8.5g/L,吸附时间为36h。在优化吸附试验条件下MSN对加标水中Mo(VI)的脱除率为93.6% ~ 97.3%。     

Stability of selenium and its speciation analysis in water using automatic system separation and HR-ICP-MS measurement

A simple and convenient method has been developed for the pre-concentration and separation of inorganic selenium species from environmental water samples using anion exchange chromatographic column combined with high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) measurement. ⁷⁵Se(IV) and ⁷⁵Se(VI) were prepared and used as tracers during the experiments. The volatility of selenium during solution evaporation was investigated to establish a reliable water samples pretreatment procedure. The parameters which affect the uptake of Se(IV) and Se(VI) on Dowex1 × 8 resin was optimized and the procedure for Se(IV) and Se(VI) separation was proposed. Both Se(IV) and Se(VI) are retained on the column in natural or alkaline solution with high distribution coefficient. The successive gradient elution of pre-concentrated species of selenium with HNO₃ solution allows to differentiate between them. Se(IV) and Se(VI) finally were eluted with 0.05 mol/L HNO₃ and 5.0 mol/L HNO₃, respectively. The proposed method has been successfully verified using the certified reference materials (CRMs) of real water samples, and spiked recoveries for real samples were 98%-104% with 5% relative standard deviations (RSDs). The developed procedure is proved to be reliable and can be used for the rapid determination of selenium species in environmental water samples.     

Speciation of copper and zinc in natural freshwater: comparison of voltammetric measurements, diffusive gradients in thin films (DGT) and chemical equilibrium models

In situ measurements of copper and zinc using diffusive gradients in thin films (DGT) in two distinct natural water systems were compared to metal speciation assessed by competitive ligand exchange (CLE) and voltammetric measurements. In a dynamic river system, where dissolved metal concentrations vary significantly over short-time periods, DGT technique provided averaged values of the metal concentrations over time. In microcosms, at different total dissolved concentrations of copper and zinc, DGT technique measured a similar fraction as measurements of labile metal performed by voltammetry. The proportion of DGT and voltammetric-labile zinc to dissolved zinc was 61±4% and, respectively, 76±9%. DGT technique was measuring 81±8% of exchangeable copper (by exchange with catechol). These two fractions were similarly influenced by the addition of NTA. In the absence of NTA, copper measured by DGT represented 34±4% of dissolved copper whereas in the presence of NTA, this proportion raised to 57±2%. These measurements were compared to calculations performed with speciation programs using several models for the complexation by humic and fulvic substances, namely Model VI (WHAM), NICA-Donnan and SHM. The predicted speciation by these three models was similar. The prediction of free zinc ion and labile zinc concentrations were in agreement with experimental data. Calculated concentrations of free copper ion were overestimated because these models are not considering strong specific copper-binding ligands probably present in natural water.     

Speciation measurements of uranium in alkaline waters using diffusive gradients in thin films technique

This work investigated the application of diffusive gradients in thin films technique (DGT) to uranium speciation measurements in natural water. Two binding phases were examined, a commercially available affinity membrane, Whatman DE 81 (DE 81), with amino binding functional groups and the conventionally used Chelex 100 beads imbedded polyacrylamide hydrogel (Chelex) with iminodiacetate functional groups. The DGT devices assembled with the binding phases of DE 81 (DE 81 DGT) and Chelex gel (Chelex DGT) were tested both in synthetic river water solutions and in local river water. DE 81 DGT and Chelex DGT measured 80% and 75% of the total uranium in synthetic river water solution, respectively, and measured 73% and 60% of the total uranium in St. Lawrence River, Canada, respectively. The binding properties of the DE 81 membrane and Chelex gel for uranium, and the diffusion of uranyl complexes in the polyacrylamide gel (PAM) were also studied.     

Diffusion characteristics of agarose hydrogel used in diffusive gradients in thin films for measurements of cations and anions

The agarose hydrogel has been increasingly used as a diffusive layer in diffusive gradients in thin films (DGT) measurements. However its diffusive characteristics have not been examined in detail. In this study, the performance of agarose gel was tested in DGT measurements of eight cations (Fe(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), and Cd(II)) and eight anions (P(V), As(V), Cr(VI), Mo(VI), Sb(V), Se(VI), V(V), and W(VI)). It was found that the thickness of agarose, a key parameter in the calculation of DGT measured concentration, remained unchanged after hydration followed by storage under the following conditions: pH 2–11, ionic strength 0–1.0 M, temperature 4–40 °C, and with the storage time extending to 300 d. Enrichment of cations and repelling of anions were observed in the gel under the ionic strengths of < 2–3 mM and <1 mM (NaNO₃), respectively, which was attributed to the electrostatic interactions of these ions with the fixed negatively charged groups (mainly pyruvate) in the gel. The diffusion coefficients of cations and anions through the agarose gel (plus a PVDF filter membrane) were on average 1.10 ± 0.04 times of the reported diffusion coefficients through the agarose cross-linked polyacrylamide (APA) hydrogel, typically used in DGT technique. The working pH ranges for the agarose gel-assembled DGTs were 4–10 and 5–9 for anions and cations, respectively. The use of agarose gel, either individually or along with different filter membranes, affected the overall diffusion rates of cations and anions. The measured DGT concentrations of cations and anions in filtered natural freshwater and seawater were mostly in line with those measured directly. The results showed that the agarose gel can be used as one of the standard diffusive layers in DGT measurements for a wide range of inorganic and organic analytes.     

单扫示波极谱滴定钼

提出了直流示波极谱滴定高含量钼的新方法，在ｐＨ为４．５￣５．５的乙酸－乙酸铵缓冲溶液中，以Ｐｂ（Ⅱ）为滴定剂滴定钼酸根离子，用ＪＰ－１Ａ型示波极谱仪作检测器，根据滴定过程中铅波的出现来指示终点的到达。方法简便，快速，结果的准确度，精密度均符合容量分析的要求，适于各类高含量钼矿样中的测定。     

Use of Gemini surfactant in a one-step ellagic acid assay by resonance light scattering technique

Ellagic acid (EA) reacted with Gemini zwitterionic surfactant, phosphodiesters quaternary ammonium salt (PQAS), and formed fine particles which produced strong enhancement in intensity of resonance light scattering (RLS). The effects of several factors on the RLS signal, such as pH, ionic strength, PQAS concentration and so on, were optimized. The relationship between enhanced RLS intensity and EA concentration was constructed. A novel and rapid method for the determination of EA was built. The linear range of this method was 0.016-4.0 μg mL⁻¹ and the detection limit was 13.9 ng mL⁻¹. Under the optimum conditions, the proposed method was applied to determine EA in body fluids with the results of quantitative recoveries between 98.4-101.4% in human serum samples and 99.1-102% in human urine samples. This method characterized by low limit detection is very sensitive and the cost is low, and constitutes a fast one-step procedure which requires only measuring the RLS intensities. The mechanism of the reaction was also studied. This investigation could contribute to the research on the delivery and release of bioactive molecules by Gemini surfactants.     

Use of the diffusion gradient thin film method to measure trace metals in fresh waters at low ionic strength

The diffusion gradients in thin films (DGT) method was investigated and used to measure trace metal concentrations in river water. The principle of DGT is that trace metal ions diffuse through a thin polyacrylamide gel film (the diffusion gel layer) and are subsequently immobilised and concentrated on a layer of Chelex-100 resin embedded in another polyacrylamide gel film (the resin gel layer). These layers are mounted in a plastic holder, which exposes a fixed area of the diffusion gel layer to the water being monitored. Replacement of the normal agarose cross-linked diffusion gel with bisacrylamide cross-linked gel altered the ion uptake properties of DGT. The bisacrylamide cross-linked gel weakly, and with little selectivity, bound metal ions prior to their irreversible binding to Chelex-100. Trace metal ion uptake by these DGT devices was thus dependent on ionic strength and temperature, although the ionic strength effect is relatively small for most natural waters and negligible in sea water. The concentrations of Cd, Co, Cu, Ni, Pb, and Zn in the Water of Leith, an urban stream in Dunedin, New Zealand, were measured by DGT and the results compared with total dissolved concentrations of these metals measured in conventional (bottle) samples collected in parallel with the DGT monitoring. Greater than 90% of the total dissolved Cd and Zn; 20-40% of the total dissolved Co, Ni, and Pb; and 5% of the total dissolved Cu was available to the DGT method.