纳米TiO_2微柱分离富集-分光光度法测定环境样品中的微量硒

以处理过的纳米TiO2为微柱吸附材料,采用流动注射技术进行微量硒的分离富集,考察了纳米TiO2微柱对Se(Ⅳ)的吸附性能,探讨了溶液的pH值、试样流速、试样体积、洗脱液浓度和用量以及干扰离子等因素的影响。实验结果表明,pH在1～6范围内,试样流速为0.5mL/min,纳米TiO2对Se(Ⅳ)具有良好的吸附性能,吸附率可达98.3%,动态饱和吸附容量为7.92mg/g;选用1mL0.1mol/LNaOH溶液可将吸附的Se(Ⅳ)完全洗脱,富集倍数为40。本法的检出限(3σ)为0.13mg/L,相对标准偏差为1.56%。将本法应用于国家标准样品GBW07280的分析,测定值与参考值一致。     

纳米TiO2微柱分离富集测定环境样品中的微量碲

以处理过的纳米TiO2为微柱吸附材料,采用流动注射技术进行微量碲的分离富集,探讨了溶液的pH值、试样流速、试样体积、洗脱液浓度和用量以及干扰离子等因素的影响。 实验结果表明,pH值在8～9.5范围内,纳米TiO2对Te(Ⅳ)具有良好的吸附性能,吸附率接近99%,动态饱和吸附容量为37.02 mg/g;选用2 mL 0.5 mol/L NaOH溶液可将吸附的Te(Ⅳ)完全洗脱,富集倍数为30。 本法的检出限(3σ)为0.013 mg/L,相对标准偏差为RSD=1.99%。 将本法应用于水样的分析,碲的回收率在98%~103%之间,结果令人满意。     

纳米二氧化钛富集-分光光度法测定水体中痕量5-磺基水杨酸

采用纳米TiO2化学吸附法富集水样中痕量5-磺基水杨酸。5-磺基水杨酸含有酚羟基(OH)和羧基(COOH)可与TiO2表面上的羟基(OH)发生酯化反应,形成稳定的六元环结构。纳米TiO2对5-磺基水杨酸的吸附量≤18.47mg/g,在pH2.5、吸附时间20min、吸附剂用量1.80g/L的条件下,纳米TiO2对试样中5-磺基水杨酸的吸附率达到99.0%,以5mL2mol/L NaOH为洗脱液,洗脱率达99.8%,对试样中5-磺基水杨酸的富集倍数达50倍,检出限(3σ,n=11)为26.7μg/L。本法操作简便,直接用于九龙江和海水中痕量5-磺基水杨酸的测定,结果准确,回收率达到95.5%～98.5%。     

桑色素修饰的纳米TiO_2分离富集铬和铝

建立了在表面活性剂十二烷基硫酸钠(SLS)的活化作用下,桑色素修饰的纳米TiO2分离富集,电感耦合等离子体原子发射光谱(ICP-AES)测定Cr3+和A l3+的新方法。考察了溶液pH、洗脱条件和干扰离子等因素对分析物分离富集的影响。结果表明,在pH 3.0时,Cr3+和A l3+可被桑色素修饰的纳米TiO2定量富集,吸附的金属离子可用1.5 mL 0.50 mol/L HC l溶液完全洗脱。在优化的实验条件下,纳米TiO2-桑色素对Cr3+和A l3+的吸附容量分别为9.69 mg/g和12.76 mg/g。本法对Cr3+和A l3+的检出限(3σ)分别为:0.21和0.49 ng/mL,相对标准偏差(RSD)分别为2.2%和1.6%(n=11,C=50 ng/mL)。本法应用于藏药和扇贝标准样品(GBW 10024)中Cr3+和A l3+的测定,测定值与标准值基本吻合,分析结果满意。     

纳米二氧化钛对水中Sn(Ⅱ)、Sn(Ⅳ)和二丁基锡吸附性能的研究

采用流动注射-氢化物发生-原子吸收光谱法研究纳米TiO2对Sn(Ⅱ)、Sn(Ⅳ)和二丁基锡(DBT)的吸附作用,探讨在不同pH值、吸附时间、试样浓度和试样体积下,不同用量的纳米TiO2的吸附效果以及试样的洗脱条件和效率。结果表明,Sn(Ⅱ)和Sn(Ⅳ)的浓度≤6.0μg/mL、体积≤500 mL、pH=3.0;DBT的浓度≤0.2μg/mL、体积≤50 mLp、H=4.0,30 mg纳米TiO2对Sn(Ⅱ)、Sn(Ⅳ)和DBT的吸附率≥90.0%。在25℃条件下,纳米TiO2对Sn(Ⅱ)、Sn(Ⅳ)和DBT的饱和吸附容量分别为23.6μg/mg、13.7μg/mg和0.628μg/mg,适用于无机锡和二丁基锡污染的吸附去除及对水中无机及丁基锡的定量富集。用4 mol/L HCl对吸附的Sn(Ⅱ)、Sn(Ⅳ)和DBT进行洗脱,洗脱率达到98%以上,可做为样品分析的前处理方法。     

纳米二氧化钛分离/富集-石墨原子吸收光谱法测定环境样品中痕量镉

以石墨炉原子吸收(GFAAS)为检测手段,研究了纳米二氧化钛(TiO2,锐钛型)对金属Cd(Ⅱ)的吸附性能,考察了吸附和解吸的主要影响因素.结果表明,在较宽的pH范围内,纳米TiO2对Cd(Ⅱ)具有良好的吸附性能,3.0 mol/L HCl能将所吸附的Cd(Ⅱ)完全洗脱.在优化的实验条件下,具有吸附容量大、吸附速度快的特点.本法的检出限(3σ)为10.6 ng/L;相对标准偏差(RSD)为1.5%,(n=7,C=2.0 μg/L),富集50倍.本法测定标准样品的测定值与参考值吻合.用于土壤类样品中Cd(Ⅱ)的测定,结果令人满意.     

纳米TiO2分离富集Mo(Ⅵ)和Re(Ⅶ)

本文研究了纳米TiO2吸附剂对Mo(VI)、Re(VII)的吸附行为,考察了溶液的pH值、吸附时间、温度等因素对吸附的影响。结果表明：纳米TiO2对Mo(VI)的吸附在pH 1～8条件下,吸附率超过99%,2 mL 0.05mol/L NaOH溶液可将吸附的Mo(VI)离子完全洗脱,解吸率能达到97%。在pH 1～10范围内,纳米TiO2不吸附Re(VII), 从而达到Mo(VI)、Re(VII)分离。在2℃～50℃温度范围内,Mo(VI)的吸附过程符合Langmiur等温式,纳米TiO2对Mo(VI)的最大吸附容量从11.51mg g-1增加到14.19 mg g-1;纳米TiO2分离钼后,溶液剩余的铼,用活性炭吸附,在pH1～10范围内, Re(VII)的吸附率可达99%,用浓氨水进行洗脱,洗脱率可达96%;吸附过程可用准二级反应动力学模型描述,是以化学吸附为控制步骤的吸附过程;吸附等温线与Freundlich模型有较好的拟合。     

纳米二氧化钛分离富集石墨炉原子吸收光谱法测定水样中痕量铅

提出了纳米TiO2分离富集,GFAAS测定水样中痕量铅的新方法。详细考察了纳米TiO2对铅的吸附行为,结果表明：在pH4．0时,Pb^2 可被纳米TiO2定量富集,吸附于纳米TiO2上的Pb^2 可用0．1mol／L的硝酸完全解脱。本法对Pb^2 的检出限为52ng／L,相对标准偏差为4．7％(n=10,C=0．02mg／L)。本法已用于实际水样中铅的测定,结果满意。     

纳米二氧化锆微柱分离电感耦合等离子-质谱分析水样中铬的形态

以纳米ZrO2为微柱填充材料,采用电感耦合等离子-质谱(ICP-MS)研究了Cr(Ⅵ)/Cr(Ⅲ)在纳米ZrO2微柱上的吸附性能。当pH值为8时,纳米ZrO2能完全吸附Cr(Ⅲ),而对Cr(Ⅵ)基本不吸附。对影响Cr(Ⅵ)和Cr(Ⅲ)分离的主要因素进行了详细研究,据此建立了纳米ZrO2微柱分离ICP-MS分析铬形态的新方法。方法对铬的检出限(3σ)为0.06ng/mL,定量测定下限(10σ)为0.37ng/mL,相对标准偏差为2.2%(n=9,c=100ng/mL)。本法选择性好、简便、快速,已用于不同水样中铬形态的测定,结果满意。     

双硫腙修饰纳米TiO2分离富集石墨炉原子吸收光谱法测定水样中痕量金属离子

建立了双硫腙修饰纳米TiO2分离富集-石墨炉原子吸收光谱法测定水样中痕量镉、铬和铅的新方法,优化了纳米TiO2-双硫腙对试样中这3种痕量物质的吸附和解吸条件。结果表明,在pH 5.0时,镉、铬和铅可被定量吸附,静态饱和吸附容量分别为13.3、5.5、21.8 mg/g。吸附的各种金属离子可用5 mL 0.1mol/L的硝酸完全洗脱。该方法对Cd2+、Cr3+和Pb2+的检出限(3σ,n=11)分别为0.18、0.51、1.92 ng/L,相对标准偏差分别为2.8%、2.3%和1.0%,加标回收率为96%～101%。该方法已成功应用于环境水样中镉、铬和铅的测定。     

离子印迹壳聚糖/凹土分离富集-火焰原子吸收光谱测定中药材中痕量Cd(Ⅱ)的研究

建立了离子印迹壳聚糖/凹凸棒石(IICA)分离富集-火焰原子吸收光谱(FAAS)测定中药材中痕量Cd(Ⅱ)的新方法。在动态吸附条件下,系统研究了溶液pH值、流速、洗脱条件和干扰离子对痕量Cd(Ⅱ)分离富集的影响。研究表明,在pH为4.5,上样流速为0.60mL/min条件下,Cd(Ⅱ)能被IICA定量富集;吸附的Cd(Ⅱ)可用1.0mol/L HCl-0.1mol/L甲基异丁酮的乙醇溶液,在流速为0.96mL/min条件下完全洗脱。优化条件下,IICA对Cd(Ⅱ)的动态吸附容量为56.45mg/g。线性范围为0.00097～1.28mg/L,r=0.9994,检出限(3σ,n=11)为0.97μg/L,相对标准偏差为1.32%(n=6,c=0.08mg/L),回收率在96.5%～106.4%之间。该方法操作简便,灵敏度和精密度高,可应用于实际中药材样品中痕量镉的测定。     

Separation and preconcentration of trace amounts of gold(III) ions using modified multiwalled carbon nanotube sorbent prior to flame atomic absorption spectrometry determination

Multiwalled carbon nanotubes are attractive as sorbents for SPE because they can be used for enrichment of organic compounds and metal ions at trace levels. In this study, multiwalled carbon nanotubes were oxidized with concentrated HNO3, and then the oxidized multiwalled carbon nanotubes were modified with 5-(4'-dimethylamino-benzyliden)-rhodanine. The modified multiwalled carbon nanotubes were used as a solid sorbent for separation and preconcentration of trace amounts of Au(III) ions. The sorption of Au(III) ions was quantitative in the pH range of 2.0-5.0, whereas quantitative desorption occurred instantaneously with 5.0 mL 2.0 M Na2S2O3. The eluted solution was aspirated directly into the flame for atomic absorption spectrometry. The proposed method resulted in an enrichment factor of 94. The RSD of the method was +/- 1.11% (n=10, 2.0 microg/mL) and the LOD was 0.15 ng/mL. The calibration curve for Au(III) was linear between 0.53 ng/mL and 36.0 microg/mL in the initial solution, with an R2 value of 0.9999. The sorbent capacity of the modified multiwalled carbon nanotubes was 7.3 mg Au(III)/g sorbent. The influences of the experimental parameters, including sample pH, sample flow rate, eluent volume and flow rate, sample volume, and interference of some ions on the recoveries of the Au ions, were investigated. The proposed method was applied for preconcentration and determination of Au in different samples.     

Determination of trace amounts of Pd(II) ions in water and road dust samples by flame atomic absorption spectrometry after preconcentration on modified organo nanoclay

This paper describes the application of organo nanoclay, an easily prepared and stable solid sorbent, to the preconcentration of trace amounts of palladium ions in aqueous solution. The organo nanoclay was prepared by adding tetradecyldimethylbenzylamonium chloride onto montmorillonite, which was then modified with 1-(2-pyridylazo)-2-naphthol. The modified nanoclay was used as a solid sorbent for separation and preconcentration of trace amounts of Pd(II) ions, and a simple, sensitive, and economical method was developed for determination of trace amounts of palladium by flame atomic absorption spectrometry. The sorption of Pd(II) ions was quantitative in the pH range of 1.5-5.0, whereas quantitative desorption occurred with 5.0 mL of a mixture containing 1.0 M thiourea and 1.0 M HCl. The RSD of the method was +/- 2.1% (n = 10; concn = 0.5 microg/mL), and the LOD (3sigma(bl); sigma = SD and bl = blank) was 0.1 ng/mL. The calibration curve was linear for concentrations of 0.5-8.0 microg/mL in the initial solution, and the preconcentration factor was 140. The maximum capacity of the sorbent was 2.4 mg Pd(II)/g modified organo nanoclay. The influences of the experimental parameters, including sample pH, eluant volume, eluant type, sample volume, and interfering ions, on the recoveries of the palladium ion were investigated. The proposed method was applied to the preconcentration and determination of palladium in different samples.     

Solid-phase extraction of antimony using chemically modified SiO2-PAN nanoparticles

A new analytical method using 1-(2-pyridylazo)-2-naphthol (PAN)-modified SiO2 nanoparticles as solid-phase extractant has been developed for the preconcentration of trace amounts of Sb(III) in different water samples. Conditions of the analysis such as preconcentration factor, effect of pH, sample volume, shaking time, elution conditions, and effects of interfering ions for the recovery of the analyte were investigated. The adsorption capacity of nanometer SiO2-PAN was found to be 186.25 micromol/g at optimum pH and the LOD (3sigma) was 0.60 microg/L. The extractant showed rapid kinetic sorption. The adsorption equilibrium of Sb(III) on nanometer SiO2-PAN was achieved in 10 min. Adsorbed Sb(III) was easily eluted with 4 mL 2 M hydrochloric acid. The maximum preconcentration factor was 62.20. The method was applied for the determination of trace amounts of Sb(III) in various water samples (tap, mineral water, and industrial effluents).     

Column preconcentration and electrothermal atomic absorption spectrometric determination of rhodium in some food and standard samples

In the present work, an electrothermal atomic absorption spectrometric method has been developed for the determination of ultra‐trace amounts of rhodium after adsorption of its 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol/tetraphenylborate ion associated complex at the surface of alumina. Several factors affecting the extraction efficiency such as the pH, type of eluent, sample and eluent flow rates, sorption capacity of alumina and sample volume were investigated and optimized. The relative standard deviation for eight measurements of 0.1 ng/mL of rhodium was ±6.3%. In this method, the detection limit was 0.003 ng/mL in the original solution. The sorption capacity of alumina and the linear range for Rh(III) were evaluated as 0.8 mg/g and 0.015–0.45 ng/mL in the original solution, respectively. The proposed method was successfully applied for the extraction and determination of rhodium content in some food and standard samples with high recovery values.     

Separation and extraction of Co(II) using magnetic chitosan nanoparticles grafted with β-cyclodextrin and determination by FAAS

A novel and selective method for the fast determination of trace amounts of Co(II) ions in water samples has been developed. The procedure is based on the selective sorption of Co(II) ions using magnetic chitosan nanoparticles grafted with β-cyclodextrin at different pH followed by elution with organic eluents and determination by atomic absorption spectrometry The preconcentration factor was 100 (1 mL elution volume) for a 100 mL sample volume. The limit of detection of the proposed method is 1.0 ng mL^?1. The maximum sorption capacity of sorbent under optimum conditions has been found to be 5 mg of Co per gram of sorbent. The relative standard deviation under optimum conditions was 3.0% (n = 10). Accuracy and applicability of the method was estimated using test samples of natural and model water with different amounts of Co(II).     

Polyacrylic acid-modified alumina for solid-phase extraction and preconcentration of trace iron and chromium from plant samples

A new method is presented for simultaneous preconcentration of trace Fe(III) and Cr(III) by using polyacrylic acid-alumina as a sorbent. The separation/preconcentration conditions of analytes were investigated, including effect of pH, flow rate, elution conditions, sample volume, and interfering ions. At pH 4, the maximum sorption capacities of Fe3+ and Cr3+ were 8.0 and 13.0 mg/g, respectively, by the column method. The linearity was maintained in the concentration range of 0.175-6.0 x 10(3) ng/mL for iron and 0.175-8.0 x 10(3) ng/mL for chromium in the original solution. The RSD values under optimum conditions were +/- 1.73 and +/- 1.28% for 2.0 microg/mL Fe and Cr, respectively. The preconcentration factor was 400 for both of the elements, and detection limits were 0.025 and 0.023 ng/mL for Fe and Cr in the original solutions. The proposed method was successfully applied to the determination of trace amounts of Fe and Cr in plant samples.     

高碘酸钾氧化中性红褪色催化动力学光度法测定痕量硒(Ⅳ)

基于3.2×10-4mol/LH2SO4介质中,痕量硒(Ⅳ)催化KIO4氧化中性红的褪色反应,建立了测定痕量硒(Ⅳ)的动力学光度法。在固定加热时间段(6min)后,于530nm处测定中性红的吸光度降低值监控反应速率。方法检出限为0.36μg/L,校准曲线的质量浓度线性范围为0～8.0μg/L。实验了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响。研究了反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为81.60kJ/mol。11次重复测定0.1μg/25mL和0.2μg/25mLSe(Ⅳ)的相对标准偏差分别为2.1%和1.9%。方法用于食品和人发样品中痕量硒(Ⅳ)的测定,相对标准偏差为0.33%～3.8%,加标回收率为96.0%～103.0%。     

Separation and preconcentration of trace manganese from various samples with Amberlyst 36 column and determination by flame atomic absorption spectrometry

This work assesses the potential of a new adsorptive material, Amberlyst 36, for the separation and preconcentration of trace manganese(II) from various media. It is based on the sorption of manganese(II) ions onto a column filled with Amberlyst 36 cation exchange resin, followed by the elution with 5 mL of 3 mol/L nitric acid and determination by flame atomic absorption spectrometry (FAAS) without interference of the matrix. Different factors including pH of sample solution, sample volume, amount of resin, flow rate of sample solution, volume and concentration of eluent, and matrix effects for preconcentration were investigated. Good relative standard deviation (3%) and high recovery (>95%) at 100 μg/L and high enrichment factor (200) and low analytical detection limit (0.245 μg/L) were obtained. The adsorption equilibrium was described well by the Langmuir isotherm model with maximum adsorption capacity of 88 mg/g of manganese on the resin. The method was applied for the manganese determination by FAAS in tap water, commercial natural drinking water, commercial treated drinking water and commercial tea bag sample. The accuracy of the method is confirmed by analyzing the certified reference material (tea leaves GBW 07605). The results demonstrated good agreement with the certified values.