Highly sensitive and simultaneous electrochemical determination of lead and cadmium ions by poly(thionine)/MWCNTs-modified glassy carbon electrode in the presence of bismuth ions

Journal of Applied Electrochemistry - A novel low-cost method for simultaneous measurement of Cd2+ and Pb2+ is proposed. In this method, the surface of the glassy carbon electrode (GCE) was...     

多壁碳纳米管修饰电极测定水样中痕量镉

通过多壁碳纳米管修饰玻碳电极,建立了水样中痕量镉的线性扫描阳极溶出伏安分析法。优化了支持电解质及pH、修饰剂用量、富集电位及时间等测定条件,在pH 4.0的NaAc-HAc缓冲液中,-1.10 V富集5 min后,溶出峰电流与Cd2 浓度在2.0×10-8~5.0×10-5mol/L的范围内呈良好的线性关系,检测限为8.0×10-9mol/L。该法用于实际水样中痕量镉的测定,平均回收率在98.7%~105.0%之间,结果满意。     

光度法测定水中微量镉

在 pH为 9的硼砂 -盐酸缓冲溶液中 ,DSPCF与镉生成蓝色络合物 ,最大吸收波长为 6 10nm ,测得表观摩尔吸光系数为 5 .76× 10 4L/ (mol·cm )。镉量在 0 1.6mg/L内符合比耳定律。采用甲基膦酸二甲庚脂 -HBr体系萃取色层分离微量镉 ,以提高方法的选择性 ,该法用于测定水中微量镉 ,获得了满意的结果     

水中痕量镉的高灵敏检测方法研究

研究了在Cd(Ⅱ)离子印迹聚合物分离富集后,用火焰原子吸收分光光度法测定水中痕量镉的方法.首先采用悬浮聚合技术,以甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,合成了Cd(Ⅱ)离子印迹聚合物.采用静态和动态方法对其吸附水溶液中Cd(Ⅱ)的影响因素进行了系统研究.结果表明,Cd(Ⅱ)离子印迹聚合物对水溶液的Cd(Ⅱ)具有很好的选择识别性能,而且具有快速的吸附动力学性质,吸附在20 min内即达到平衡.常见的金属离子不干扰测定,相对标准偏差为4.88%,检出限(3σ)为0.76μg/L.将该方法用于实际水样的测定,结果令人满意.     

水样中痕量铜的富集和测定的研究

铜离子与1-(2-吡啶偶氮)-2-萘酚(PAN)反应,生成疏水性的络合物,在助溶剂乙醇的作用下,被萃取到三氯甲烷相中,用分光光度法测定三氯甲烷相中的Cu2+-PAN,建立了析相富集-分光光度法测定水样中痕量铜的分析方法。对影响络合反应和相分离的各种条件进行了优化。在选择的实验条件下,铜的质量浓度在0.50～15μg/mL范围内与吸光度呈线性关系,相关系数为0.999 57,方法的检出限为0.089μg/mL,对铜浓度为5.0μg/mL的样品溶液进行7次平行测定,相对标准偏差为1.67%。该方法用于水样中铜的测定,回收率在95.6%～101.5%之间。     

改良离子选择电极法测定水样中氟化物

利用带有统计功能的计算器处理离子选择电极法测定数据,可以直接得到水样中氟化物浓度。结果表明,该方法不需要建立标准曲线,相关系数r=0.999 5,检出限0.1 mg/L,相对标准偏差为1.3%,平均回收率98%。     

Novel coated graphite electrode for the selective determination of Gd(III) in rocks and waste water samples

A novel gadolinium selective coated graphite electrode based on 2,6-bis-[1-{N-cyanopropyl,N-(2-methylpridyl)}aminoethyl]pyridine [P] is described. The best performance was exhibited by the electrode having membrane composition P:NaTPB:PVC:NPOE as 8:4:30:58 (%, w/w). The electrode demonstrates excellent potentiometric characteristics towards gadolinium ion over several interfering ions. The electrode exhibited a Nernstian response to Gd³⁺ ion over a wide concentration range 2.8 × 10⁻⁷ to 5.0 × 10⁻² M with a detection limit (6.3 ± 0.1) × 10⁻⁸ M and slope 19.6 ± 0.1 mV decade⁻¹ of a_Gd³⁺. Furthermore, it showed a fast response time (12 s) and can be used for 2.5 months without significant divergence in its characteristics. Noticeably, the electrode can tolerate the concentration of different surfactants up to 1.0 × 10⁻⁴ M and can be used successfully in 30% (v/v) ethanol media and 10% (v/v) methanol and acetonitrile water mixture. The useful pH range of this sensor is 2.0 to 8.0. It is sufficiently selective and can be used for the determination of Gd³⁺ ions in waste water and rock samples. It also serves as a good indicator in the potentiometric titration of GdCl₃ with EDTA.     

A novel magnetic ion imprinted polymer for selective adsorption of trace amounts of lead(II) ions in environment samples

In this work a novel ion imprinted polymer (IIP) based on 4-(vinylamino)pyridine-2,6-dicarboxylicacid (VPyDC), was coated on Fe₃O₄ nano-particles. The application of this magnetic sorbent was investigated for preconcentration and determination of trace Pb(II) ions by flame atomic absorption spectrometry. Effects of various parameters such as sample pH, adsorption/desorption time and eluent were investigated during this study. The relative standard deviation and limit of detection of the method were found to be 1.8% and 0.9 ng mL⁻¹, respectively. The accuracy of this method was confirmed using various standard reference materials, then it was used for Pb(II) determination in environmental samples.     

用3,5-diBr-PADAT催化光度法测定水样中亚硝酸根

在磷酸介质中,根据亚硝酸根催化溴酸钾氧化5-(3,5-二溴-2-吡啶偶氮)-2,4-二氨基甲苯(3,5-diBr-PADAT)的退色反应,建立了催化光度法测定微量亚硝酸根的新方法.亚硝酸根催化3,5-diBr-PADAT退色反应前后在434 nm 吸收峰产生的吸光度差,与亚硝酸根的浓度呈线性关系,方法的检出限为4.56×10-7mol/L,线性范围1.0×10-7～1.25×10-5mol/L.用于湖水等水样的测定,结果令人满意.     

Separation and preconcentration system for lead and cadmium determination in natural samples using 2-aminoacetylthiophenol modified polyurethane foam

A new modified polyurethane foam using 2-aminoacetylthiophenol (AATP) was employed for selective separation, preconcentration and determination of Cd and Pb ions in different samples by flame atomic absorption spectrometry (FAAS). This new modified foam was used as an effective sorbent for the solid-phase extraction (SPE) of Cd and Pb ions from aqueous solutions from natural samples. Experimental conditions for effective separation of trace levels of the analyte ions were optimized with respect to different experimental parameters in batch process. The preconcentration factors are 167 and 250 for Pb and Cd respectively. The relative standard deviation (R.S.D.) under optimum conditions is < 10% (n = 5). The accuracy of the method was estimated by using a reference material BDH Cat no: 456422W real samples that were spiked with the analyte ions. The extraction isotherm of both Cd and Pb ions was obtained. This study indicated that the novel foam presents a high affinity for Cd and Pb due to the presence of good extractive sites (S, N and O) which are introduced to the foam material. The bonding of the studied metal ions by the foam is useful for the removal of metal contamination from real samples.     

苹果中微量铅的荧光光度法测定

建立了利用荧光法测定苹果中微量铅的新方法。该方法的线性范围0.03～2.00mg/mL,检出限为9.1×10-3mg/mL,用于鲜苹果样品中微量铅的测定,加标回收率96.22%～100.04%。     

聚L-丝氨酸/碳纳米管复合导电薄膜的制备及在多巴胺的电化学测定中的应用

研究了玻碳电极涂有碳纳米管后,基于功能化的带负电荷碳纳米管的羧基和氨基酸的—NH2质子化之间的静电吸附作用,制备聚L-丝氨酸/碳纳米管(PL-Ser/MWNTs)修饰电极的方法,并讨论了多巴胺(DA)在修饰电极上的电化学行为。试验发现多巴胺浓度在1.0×10-6~2.0×10-4mol/L范围内与其脉冲电流信号成线性关系,检出限2.0×10-7mol/L。修饰电极具有较好的稳定性能,应用于针剂中多巴胺含量的测定,结果满意。     

Utilization of sodium montmorillonite clay-modified electrode for the determination of isoproturon and carbendazim in soil and water samples

Redox behavior of two pesticides namely isoproturon and carbendazim were investigated electrochemically using sodium montmorillonite clay-modified glassy carbon electrode in the presence and absence of a surfactant, cetyl trimethyl ammonium bromide. A solution of 0.1 M H₂SO₄ in both 50% aqueous alcohol (pH 1.0) was found to be a suitable medium for electroanalysis. Isoproturon exhibited one well-defined oxidation peak around 1.17 V along with one more oxidation and reduction peaks. Carbendazim showed only one well-defined anodic peak around 1.5 V. The main electron transfer was irreversible and the mass transfer was by diffusion for both cases. Controlled potential coulometric studies revealed 2e⁻ and 1e⁻ transfer for isoproturon and carbendazim, respectively. The surfactant had only little effect on the electrochemical properties of isoproturon and pronounced effect with carbendazim. Electroanalytical procedure for the determination of these pesticides was developed using differential pulse stripping voltammogram under their maximum current experimental conditions. Calibration plot was made for both pesticides. The determination limit and standard deviations were arrived at. The applicability of the method was also verified in a soil sample and water analyte.     

Simultaneous determination of trace aluminum (III), copper (II) and cadmium (II) in water samples by square-wave adsorptive cathodic stripping voltammetry in the presence of oxine

A validated adsorptive cathodic stripping voltammetry method is described for simultaneous determination of Al(III), Cu(II) and Cd(II) in water samples. In acetate buffer (pH 5) containing 10 μM oxine, these metal ions were determined as oxine complexes following adsorptive accumulation onto the HMDE at −0.05 V versus Ag/AgCl/KCl_s. The best signal to noise ratio was obtained using a square wave of scan increment 10 mV, frequency 120 Hz, and pulse-amplitude 25 mV. Limits of detection as low as 0.020 μg L⁻¹ Al(III), 0.012 μg L⁻¹ Cu(II) and 0.028 μg L⁻¹ Cd(II) were achieved. Interference due to various cations (K(I), Na(I), Mg(II), Ca(II), Mn(II), Fe(III), Bi(III), Sb(III), Se(IV), Pb(II), Zn(II), Ni(II), Co(II)), anions (Cl⁻, NO³⁻, SO₄ ²⁻, PO₄ ³⁻) and ascorbic acid was minimal as the measured signals change by 4% at the maximum. The stripping voltammetry method was successfully applied for simultaneous determination of Al(III), Cu(II) and Cd(II) in tap and natural bottled water samples.     

镍离子对分光光度法测定水样中COD的影响

通过测定Cr3+、Cr2O72-和Ni2+ 的吸收曲线及标准水样的COD,研究了Ni2+对分光光度法测定COD的影响.结果表明,当水样中Ni2+质量浓度＜100 mg/L时,对测定结果无明显影响;若水样中Ni2+质量浓度＞100 mg/L时,应将水样稀释后再进行测定.     

吸附溶出伏安法同时测定电站锅炉用水中的痕量铜、铁

建立了吸附溶出伏安法同时测定痕量铜、铁的方法.以邻苯二酚为配合剂,哌嗪-1,4-双(2-乙烷磺酸)(PIPES)为缓冲溶液,在最优条件下,对铜离子的测量范围为0～35μg/L相关系数r=0.999 4;对铁离子的测量范围为0～30μg,L,相关系数r=0.998 0.两者的检测限分别为0.069、0.407μg/L.此法应用于电站锅炉用水中痕量铜、铁的测定,回收率分别为103.6%和104.7%.说明该法不仅灵敏度高、准确性好.而且操作简单、快速.     

Automatic simultaneous determination of copper and lead in biological samples by flow injection/stripping voltammetric analysis

An automatic-continuous method for the simultaneous determination of copper and lead based on flow injection analysis (FIA) and stripping voltammetry (SV) is proposed. The method affords the determination of the analytes at the ng/ml level (linear ranges 0.64 to 64.0 ng/ml and 2.1 to 62.2 ng/ml for copper and lead, respectively) with good precision (r.s.d. values smaller than 4%). The selectivity of SV allows the method to be applied to the determination of these analytes in bovine liver fresh samples and certified reference materials from the National Institute for Standards and Technology and the Community Bureau of Reference. The performance of the method was assessed by repeatability and validation statistical studies.     

Crosslinking assisted fabrication of ultrafine poly(vinyl alcohol)/functionalized graphene electrospun nanofibers for crystal violet adsorption

This article reports the fabrication of water‐stable electrospun mats made from water‐soluble poly(vinyl alcohol) and comprising ultrafine nanofibers for a high surface area to volume ratio as required for the adsorption of crystal violet. Acid‐catalyzed crosslinking is uniquely demonstrated as a facile strategy to improve water stability and, just as importantly, fine‐tune the nanofiber size of the electrospun mats. Amine‐functionalized graphene nanoplatelets are incorporated as an adsorption performance enhancer instead of the more widely reported graphene oxide. The functionalized graphene also facilitates fabrication of the composite electrospun mats by direct mixing of the water‐dispersible graphene with the aqueous polymer solution. The enhanced adsorption performance of the polymer nanocomposite mats is explained in detail at the molecular level, while the adsorption mechanism is supported by adsorption isotherm and related kinetic data. Moreover, the adsorbent mats can be removed from the water after use with the mat integrity still maintained. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46318.     

Organo-inorganic bentonite for simultaneous adsorption of Acid Orange 10 and lead ions

Partial substitution of the interlayer cations of a local bentonite (Bogovina) by hexadecyl trimethylammonium ions (HDTMA) was performed to prepare adsorbents able to simultaneously adsorb toxic metal cations and organic pollutants.Acid Orange10 adsorption increased with increasing HDTMA addition, while the adsorption of Pb²⁺ decreased with increasing organophilicity. The adsorption of the dye and Pb²⁺ and their mixture onto Na-rich bentonite and HDTMA-bentonites, regardless of adsorbents' organophilicity, obeyed the pseudo-second-order kinetics model.     

巯基棉富集一氢化物原子荧光光谱法测定天然水中痕量铅

提出在pH为5－6的HAC－NaAC介质条件下,用巯基棉富集天然水中铅,以0．05mol/L HCI溶液洗脱铅,采用HG－AFS法在K2Cr2O7-H2O2-K3Fe(CN)6存在的酸性体系中测铅,方法的检出限为0．11μg/L,RSD％为4．40％,加标回收率在98％－104％之间。