Thermo-responsive polymer coated fiber-in-tube capillary microextraction and its application to on-line determination of Co, Ni and Cd by inductively coupled plasma mass spectrometry (ICP-MS)

The poly(N-isopropylacrylamide) (PNIPA) gel is a widely studied thermo-responsive material that exhibits discontinuous change in volume when the external temperature is increased. In this paper, PNIPA gel was prepared and applied as a novel polymer coating for fiber-in-tube capillary microextraction of trace Co, Ni and Cd followed by on-line ICP-MS detection. The PNIPA coating was synthesized by using ethylene triethoxysilane (ETEOS) as the cross-linking agent under acidic conditions. This siloxane incorporated PNIPA gel achieves a dramatically rapid response rate when the external temperature is changed. The micro-structure of PNIPA coating was examined by scanning electron micrograph (SEM). Various experimental parameters including pH, temperature, sample flow rate and volume, elution solution and interfering ions affecting the extraction of the target analytes have been carefully investigated and optimized. Under the optimized conditions, the limits of detection were 0.45, 4.6 and 6.9 ng L⁻¹ for Co, Ni and Cd, respectively. With a sampling frequency of 13 h⁻¹, the relative standard deviations (RSDs) for Co, Ni and Cd were 4.8, 5.1 and 6.4% (C = 1 μg L⁻¹, n = 7), respectively. The proposed method had been successfully applied to the determination of Co, Ni and Cd in human urine. To validate the proposed method, certified reference materials of NIES No. 10-b rice flour and GBW07601 (GSH-1) human hair were analyzed and the determined values were in a good agreement with the certified values. The PNIPA coated fiber-in-tube capillary can be reused for more than 150 times without decreasing the extraction efficiency.     

电感耦合等离子体质谱法测定血液和精液中的硼

采用HNO3-H2O2和氨水-甘露醇两种方法处理样品,电感耦合等离子体质谱法（ICP-MS）测定血液和精液中的硼。Be作内标补偿基体效应,并用标准加入法验证了方法的可靠性,标准加入法与外标法测定结果相吻合。在测定B的同时,还可进行Cr、Cu、Cd、Ba、Sr、Mn、Co、Tl、Li、Pb、Zn、Sc、Ti、V、As等多元素测定。两种样品处理方法的测定值呈显著正相关（r=0.99919）。方法检出限为0．11ng／mL（氨水-甘露醇法）,0.06ng／mL（HNO3-H2O2）。已用于测定某硼矿区血液和精液样品中的硼。     

The use of carbon nanofibers microcolumn preconcentration for inductively coupled plasma mass spectrometry determination of Mn,Co and Ni

Based on carbon nanofibers (CNFs) as a solid phase extraction adsorbent, a microcolumn preconcentration method coupled to inductively coupled plasma mass spectrometry (ICP–MS) was developed for the determination of trace elements (Mn, Co and Ni). The effect of various experimental parameters such as pH, sample flow rate and volume, elution solution and interfering ions on the retention of the studied ions have been investigated systematically. During all the steps of the experimental process, Mn, Co and Ni could be quantitatively sorbed on the microcolumn containing CNFs in the range of pH 6.0–9.0, and then eluted completely with 0.5 mol ml^− 1 HNO₃. A preconcentration factor of 150-fold was obtained. The detection limits for Mn, Co and Ni were 40, 0.4 and 8.0 pg ml^− 1, respectively, with relative standard deviations less than 6.0%. In order to validate the proposed method, two certified reference materials of human hair (GBW 07601) and mussel (GBW 08571), and water sample were analyzed with satisfactory results. The recoveries were between 95.0 and 114%.     

An off-line automated preconcentration system with ethylenediaminetriacetate chelating resin for the determination of trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry

A novel automated off-line preconcentration system for trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in seawater was developed by improving a commercially available solid-phase extraction system SPE-100 (Hiranuma Sangyo). The utilized chelating resin was NOBIAS Chelate-PA1 (Hitachi High-Technologies) with ethylenediaminetriacetic acid and iminodiacetic acid functional groups. Parts of the 8-way valve made of alumina and zirconia in the original SPE-100 system were replaced with parts made of polychlorotrifluoroethylene in order to reduce contamination of trace metals. The eluent pass was altered for the back flush elution of trace metals. We optimized the cleaning procedures for the chelating resin column and flow lines of the preconcentration system, and developed a preconcentration procedure, which required less labor and led to a superior performance compared to manual preconcentration (Sohrin et al. [5]). The nine trace metals were simultaneously and quantitatively preconcentrated from ∼120 g of seawater, eluted with ∼15 g of 1 M HNO₃, and determined by HR-ICP-MS using the calibration curve method. The single-step preconcentration removed more than 99.998% of Na, K, Mg, Ca, and Sr from seawater. The procedural blanks and detection limits were lower than the lowest concentrations in seawater for Mn, Ni, Cu, and Pb, while they were as low as the lowest concentrations in seawater for Al, Fe, Co, Zn, and Cd. The accuracy and precision of this method were confirmed by the analysis of reference seawater samples (CASS-5, NASS-5, GEOTRACES GS, and GD) and seawater samples for vertical distribution in the western North Pacific Ocean.     

茶叶和蔬菜中铅的同位素稀释电感耦合等离子体质谱的测定

采用同位素稀释电感耦合等离子体质谱(ID-ICP-MS)法测定了铅的含量,通过对茶叶标准物质(GBW-07605)中铅的测定,考察了方法的准确度和精密度,比较了同位素稀释法与普通外标定量法的测定结果。在5mLHNO3～0.5mLHF～1mLH2O2的消解体系中,ID-ICP-MS法测量茶叶中铅的回收率可达97.7%,相对标准偏差(RSD)小于1.2%。实验对市售的12种茶叶和10种蔬菜中Pb进行测定,铅含量符合相应国家标准的样品分别占总样品数的83%和90%。该法适合于植物样品中微量铅的测定。     

Method validation for determination of arsenic, cadmium, chromium and lead in milk by means of dynamic reaction cell inductively coupled plasma mass spectrometry

With Regulation No. 1881/2006 the European Union fixed a maximum level for lead in milk. Consequently, there is the need to determine very low concentration of elements that may be present in milk in trace and ultratrace levels.Quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) combined with dynamic reaction cell (DRC) has been widely employed in order to reach very low concentration, requested for this product. Furthermore, the DRC technology can help in removing polyatomic and argon-based interferences.In the present study, a method for the determination of arsenic, cadmium, chromium and lead in bovine milk was validated according to the EU common standards by means of DRC-ICP-MS. The main parameters evaluated in the validation were: recovery, repeatability and within-laboratory reproducibility, detection and quantification limits, linearity range and measurement uncertainty. Additionally, stability studies of the analyte in solution and ruggedness studies were carried out.The results obtained for limit of detection (LoD) and limit of quantification (LoQ) in μg kg⁻¹ were respectively: As, 3.1 and 9.5; Cd, 0.08 and 0.24; Cr, 0.229 and 0.693; Pb, 0.5 and 1.5. While for the recovery: As, 91%; Cd 96%; Cr 99%; Pb, 95%. As for the repeatability: As, 7%; Cd, 3%; Cr, 6%; Pb, 4%.     

Simultaneous determination of suspended particulate trace metals (Co, Ni, Cu, Zn, Cd and Pb) in seawater with small volume filtration assisted by microwave digestion and flow injection inductively coupled plasma mass spectrometer

A new technique for the determination of suspended particulate trace metals (P-metals >0.2 μm), such as Co, Ni, Cu, Zn, Cd and Pb, in open ocean seawater has been developed by using microwave digestion coupled with flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS). Suspended particulate matter (SPM) was collected from 500 mL of seawater on a Nuclepore filter (0.2 μm) using a closed filtration system. Both the SPM and filter were completely dissolved by microwave digestion. Reagents for the digestion were evaporated using a clean evaporation system, and the metals were redissolved in 0.8 M HNO₃. The solution was diluted with buffer solution to give pH 5.0 and the metals were determined by FI-ICP-MS using a chelating adsorbent of 8-hydroxyquinoline immobilized on fluorinated metal alkoxide glass (MAF-8HQ). The procedure blanks with a filter were found to be 0.048 ± 0.008, 10.3 ± 0.3, 0.27 ± 0.05, 3.3 ± 1.8, 0.02 ± 0.03 and 0.85 ± 0.09 ng L⁻¹ for Co, Ni, Cu, Zn, Cd and Pb, respectively (n = 14). Detection limits defined as 3 times the standard deviation of the blanks were 0.023, 0.90, 0.14, 5.3, 0.078 and 0.28 ng L⁻¹ for Co, Ni, Cu, Zn, Cd and Pb, respectively. Accuracy was evaluated using certified reference materials of chlorella (NES CRM No. 3) and marine sediment (HISS-1). The method was applied to the determination of vertical distributions for P-Co, Ni, Cu, Zn, Cd and Pb in the Western North Pacific.     

ICP-MS测定土壤中铅同位素比值及地域差异性比较

建立用HNO_3-H_2O_2-HF体系微波消解前处理样品,利用电感耦合等离子体质谱测定土壤中铅同住素比值的方法,探讨并优化了影响测试结果的两种干扰因素.该方法中~(207)Pb/~(206)Pb和~(208)Pb/~(206)Pb的短期测量稳定性RSD分别达到0.12%和0.13%,长期测量的偏差分别在0.002和0.01以内,样品测量的最佳范围是10～40μg/L.采用标样-样品交叉法测定了湖南、湖北、云南、贵州、河南、福建、辽宁7个省的48个地区土壤中的铅同位素比值,结合聚类分析和主成分分析比较了各省土壤中同位素分布的差异,初步探讨了利用~(207)Pb/~(206)Pb和~(208)Pb/~(206)Pb比较烟叶产区的可能性.     

Determination of Cu, Mn, Ni and Sn in gasoline by electrothermal vaporization inductively coupled plasma mass spectrometry, and emulsion sample introduction

Trace metals in fuels, except in the case of additives, are usually undesirable and normally they occur in very low concentrations in gasoline, requiring sensitive techniques for their determination. Coupling of electrothermal vaporization with inductively coupled plasma mass spectrometry minimizes the problems related to the introduction of organic solvents into the plasma. Furthermore, sample preparation as oil-in-water emulsions reduces problems related to gasoline analysis. In this work, a method for determination of Cu, Mn, Ni and Sn in gasoline is proposed. Samples were prepared by forming a 10-fold diluted emulsion with a surfactant (Triton X-100), after treatment with concentrated HNO₃. The sample emulsion was pre-concentrated in the graphite tube by repeated pipetting and drying. External calibration was used with aqueous standards in a purified gasoline emulsion. Six samples from different gas stations were analyzed, and the analyte concentrations were found to be in the μg l⁻¹ range or below. The limits of detection were 0.22, 0.02, 0.38 and 0.03 μg l⁻¹ for Cu, Mn, Ni and Sn, respectively. The accuracy of the method was estimated using a recovery test.     

Synthesis of salicylaldehyde-modified mesoporous silica and its application as a new sorbent for separation, preconcentration and determination of uranium by inductively coupled plasma atomic emission spectrometry

A new functionalized mesoporous silica (MCM-41) using salicylaldehyde was utilized for the separation, preconcentration and determination of uranium in natural water by inductively coupled plasma atomic emission spectrometry (ICP-AES).Experimental conditions for effective adsorption of trace levels of U(VI) were optimized. The preconcentration factor was 100 (1.0 mL of elution for a 100 mL sample volume). The analytical curve was linear in the range 2-1000 μg L⁻¹ and the detection limit was 0.5 ng mL⁻¹. The relative standard deviation (R.S.D.) under optimum conditions was 2.5% (n = 10). Common coexisting ions did not interfere with the separation and determination of uranium at pH 5. The sorbent exhibited excellent stability and its sorption capacity under optimum conditions has been found to be 10 mg of uranium per gram of sorbent. The method was applied for the recovery and determination of uranium in different water samples.     

Isolation, preconcentration and determination of rhamnolipids in aqueous samples by dispersive liquid-liquid microextraction and liquid chromatography with tandem mass spectrometry

An analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS-MS) was developed for the determination of rhamnolipids. A dispersive liquid-liquid microextraction (DLLME) procedure was used to isolate and concentrate target compounds from aqueous samples collected from surface water, sewage treatment plant effluent and cultivation of microbial culture. Development of the DLLME procedure included optimization of several important parameters such as kind and volume of extracting and dispersing solvents as well as sample pH. Under optimized conditions a two-step extraction with sonication was used. Chloroform was applied as the extracting and acetone as the dispersing solvent. The recoveries of the analytes were 70-87%. Matrix effects investigated for the analytes revealed existence of ionization enhancement for both mono- and dirhamnolipids.     

Determination of chromium, iron and selenium in foodstuffs of animal origin by collision cell technology, inductively coupled plasma mass spectrometry (ICP-MS), after closed vessel microwave digestion

The determination of chromium (⁵²Cr), iron (⁵⁶Fe) and selenium (⁸⁰Se) isotopes in foodstuffs of animal origin has been performed by collision cell technology (CCT) mode using an inductively coupled plasma mass spectrometry (ICP-MS) as detector after closed vessel microwave digestion. To significantly decrease the argon-based interferences at mass to charge ratios (m/z): 52 (⁴⁰Ar¹²C), 56 (⁴⁰Ar¹⁶O) and 80 (⁴⁰Ar⁴⁰Ar), the gas-flow rates of a helium and hydrogen mixture used in the hexapole collision cell were optimised to 1.5 ml min⁻¹ H₂ and 0.5 ml min⁻¹ He and the quadrupole bias was adjusted daily between −2 and −15 mV. Limits of quantification (LOQ) of 0.025, 0.086 and 0.041 mg kg⁻¹ for Cr, Fe and Se, respectively, in 6% HNO₃ were estimated under optimized CCT conditions. These LOQ were improved by a factor of approximately 10 for each element compared to standard mode.Precision under repeatability, intermediate precision reproducibility and trueness have been tested on nine different certified reference materials in foodstuffs of animal origin and on an external proficiency testing scheme. The results obtained for chromium, iron and selenium were in all cases in good agreement with the certified values and trueness was improved, compared to those obtained in standard mode.     

Simultaneous extraction and preconcentration of uranium and thorium in aqueous samples by new modified mesoporous silica prior to inductively coupled plasma optical emission spectrometry determination

A new synthesized modified mesoporous silica (MCM-41) using 5-nitro-2-furaldehyde (fural) was applied as an effective sorbent for the solid phase extraction of uranium(VI) and thorium(IV) ions from aqueous solution for the measurement by inductively coupled plasma optical emission spectrometry (ICP OES). The influences of some analytical parameters on the quantitative recoveries of the analyte ions were investigated in batch method. Under optimal conditions, the analyte ions were sorbed by the sorbent at pH 5.5 and then eluted with 1.0 mL of 1.0 mol L⁻¹ HNO₃. The preconcentration factor was 100 for a 100 mL sample volume. The limits of detection (LOD) obtained for uranium(VI) and thorium(IV) were 0.3 μg L⁻¹. The maximum sorption capacity of the modified MCM-41 was found to be 47 and 49 mg g⁻¹ for uranium(VI) and thorium(IV), respectively. The sorbent exhibited good stability, reusability, high adsorption capacity and fast rate of equilibrium for sorption/desorption of uranium and thorium ions. The applicability of the synthesized sorbent was examined using CRM and real water samples.     

Dual‐column capillary microextraction (CME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV‐ICP‐MS) for the speciation of arsenic in human hair extracts

In this work, dual‐column capillary microextraction (CME) system consisting of N‐(2‐aminoethyl)‐3‐aminopropyltrimethoxysilane (AAPTS)‐silica coated capillary (C1) and 3‐mercaptopropyl trimethoxysilane (MPTS)‐silica coated capillary (C2) was developed for sequential separation/preconcentration of arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)] in the extracts of human hair followed by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV‐ICP‐MS) detection with iridium as permanent modifier. Various experimental parameters affecting the dual‐column microextraction of different As species had been investigated in detail. It was found that at pH 9, As(V) and MMA could be quantitatively retained by C1 and only As(III) could be quantitatively retained by C2. With the aid of valve switching, As(V)/MMA(V) retained on C1 and As(III) retained on C2 could be sequentially desorbed by 10 µl of 0.01 mol l^?1 HNO₃ [for As(V)], 0.1 mol l^?1 HNO₃ [for MMA(V)] and 0.2 mol l^?1 HNO₃‐3% thiourea (m/v) [for As(III)], respectively, the eluents were immediately introduced into the Ir‐coated graphite tubes for further ETV‐ICP‐MS detection. With two‐step ETV pyrolysis program, Cl^? in the sample matrix could be in situ removed, and the total As in the human hair extracts or digested solution could be interference‐free, determined by ETV‐ICP‐MS. DMA(V) in the human hair extracts was obtained by subtraction of total As in the human hair extracts from other three As species. Under the optimized conditions, the detection limits (3 σ) of the method were 3.9 pg ml^?1 for As(III), 2.7 pg ml^?1 for As(V), 2.6 pg ml^?1 for MMA(V) and 124 pg ml^?1 for total As with the relative standard deviations less than 7.0% (C = 0.1 ng ml^?1, n = 7), and the enrichment factor was 286, 262 and 260 for As(III), As(V) and MMA(V), respectively. The developed method was successfully applied for the speciation of arsenic in the extracts of human hair. Copyright © 2009 John Wiley & Sons, Ltd.     

A novel quantification strategy of transferrin and albumin in human serum by species-unspecific isotope dilution laser ablation inductively coupled plasma mass spectrometry (ICP-MS)

Species-specific (SS) isotope dilution analysis with gel electrophoresis (GE)-laser ablation (LA)-ICP-MS is a promising technique for the quantification of particular metal-binding proteins in biological samples. However, unavailable isotopically enriched spike and metal losses in GE separation are main limitations for SS-isotope dilution PAGE-LA-ICP-MS. In this study, we report for the first time the absolute quantification of transferrin (Tf) and albumin (Alb) in human serum by non-denaturing (native) GE combined with species-unspecific isotope dilution mass spectrometry (IDMS). In order to achieve a homogeneous distribution of both protein and isotope-enriched spike (simulated isotope equilibration), immersing the protein strips with ³⁴S spike solution after gel electrophoresis was demonstrated to be an effective way of spike addition. Furthermore, effects of immersion time and ³⁴S spike concentration were investigated to obtain optimal conditions of the post-electrophoresis isotope dilution method. The relative mass of spike and ablated sample (m_sp/m_sam) in IDMS equation was calculated by standard Tf and Alb proteins, which could be applied to the quantification of Tf and Alb in ERM-DA470k/IFCC for method confirmation. The results were in agreement with the certified value with good precision and small uncertainty (1.5–3%). In this method, species-specific spike protein is not necessary and the integrity of the heteroatom-protein could be maintained in sample preparation process. Moreover, the application of species-unspecific isotope dilution GE-LA-ICP-MS has the potential to offer reliable, direct and simultaneous quantification of proteins after conventional 1D and 2D gel electrophoretic separations.     

Examination of precipitation chemistry and improvements in precision using the Mg(OH)2 preconcentration inductively coupled plasma mass spectrometry (ICP-MS) method for high-throughput analysis of open-ocean Fe and Mn in seawater

The chemistry of magnesium precipitation preconcentration of Fe, Mn, and Co from seawater was investigated, and this analytical technique was adapted for use with the Element-2 inductively coupled plasma mass spectrometer (E2 ICP-MS). Experiments revealed that the scavenging efficiency of Mn using the precipitation protocol described here was ∼95% and similar to that previously observed with Fe. In contrast, the scavenging efficiency of Co was three-fold lower than that of Fe and Mn, resulting in poor recovery. An increase in sample size to 13 mL led to several desired effects: (1) an increase in the Fe and Mn signals allowing a final dilution of samples to 0.5 mL and the use of an autosampler, (2) an increase in precision to ∼1-2.5% R.S.D., and (3) an increase in signal relative to the blank. Experiments suggest metal concentration from seawater occurs during the formation of Mg(OH)₂ precipitate, whereas P was scavenged by adsorption onto the Mg(OH)₂ particles. Example vertical profiles are shown for dissolved Fe and Mn from the Equatorial Pacific.     

微波消解-电感耦合等离子体质谱法测量小麦粉中铅、镉、砷和铬

在我国局部都存在不同程度的铅、镉、砷和铬的土壤和水资源污染,土壤和水域中的有毒有害元素经食物链累积在人体,对人们的身体造成极大的危害,因此对食品中这些限量元素进行准确高效定量非常必要。本文建立了微波消解-电感耦合等离子体质谱(ICP-MS)法对小麦粉中的Pb、Cd、As和Cr进行测量,测量方法采用内标法,内标元素选择Rh、In和Bi。另外对微波消解前处理方法和ICP-MS使用参数进行了优化,测量方法简单高效。工作标准曲线呈良好的线性关系,相关系数均大于0.9999。该方法采用GBW(E)100493小麦粉标准物质和NIST 1567b Wheat Flour对本实验所采用的方法进行验证,结果显示测量值和标准值一致,表明本实验中小麦粉中Pb、Cd、As和Cr的测定方法是准确可靠的。     

Micro-column preconcentration/separation using thiacalix[4]arene tetracarboxylate derivative modified mesoporous TiO2 as packing materials on-line coupled to inductively coupled plasma optical emission spectrometry for the determination of trace heavy metals in environmental water samples

A novel adsorbent of thiacalix[4]arene tetracarboxylate derivative modified mesoporous TiO₂ was prepared and was used as a packing material for flow injection (FI) micro-column (20 mm × 4.0 mm i.d.) separation/preconcentration on-line coupled to inductively coupled plasma optical emission spectrometry (ICP-OES) simultaneous determination of trace metals (V, Cu, Pb, Cr) in environmental water samples. The experimental conditions for modified mesoporous TiO₂ packed micro-column separation/preconcentration of the target metals were optimized and the interference of commonly coexisting ions was examined. The adsorption capacities of thiacalix[4]arene tetracarboxylate derivative modified mesoporous TiO₂ for V, Cu, Pb and Cr were found to be 14.0, 11.7, 17.7 and 14.5 mg g^− 1, respectively. The detection limits of the method were 0.09, 0.23, 0.50 and 0.15 µg L^− 1 for V, Cu, Pb and Cr, respectively, with a preconcentration factor of 20. The precision of this method were 1.7% (V), 3.9% (Cu), 4.6% (Pb) and 2.9% (Cr) (n = 7, C = 5 µg L^− 1), respectively. The developed method was applied to the determination of trace heavy metals in real samples and the recoveries for spiked samples were found to be in the range of 88.7-107.1%. For validation, a certified reference material of GSBZ50009-88 environmental water sample was analyzed and the determined values were in good agreement with the certified values.     

Cadmium (II) imprinted 3-mercaptopropyltrimethoxysilane coated stir bar for selective extraction of trace cadmium from environmental water samples followed by inductively coupled plasma mass spectrometry detection

Cd(II) imprinted 3-mercaptopropyltrimethoxysilane (MPTS)-silica coated stir bar was prepared by sol–gel technique combining with a double-imprinting concept for the first time and was employed for stir bar sorptive extraction (SBSE) of trace Cd(II) from water samples followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. A tetramethoxysilane (TMOS) coating was first in situ created on the glass bar surface. Afterward, a sol solution containing MPTS as the functional precursor, ethanol as the solvent and both Cd(II) and surfactant micelles (cetyltrimethylammonium bromide, CTAB) as the template was again coated on the TMOS bar. The structures of the stir bar coating were characterized by FT-IR spectroscopy. Round-bottom vial was used for the extraction of Cd(II) by SBSE to avoid abrasion of stir bar coatings. The factors affecting the extraction of Cd(II) by SBSE such as pH, stirring rate and time, sample/elution volume and interfering ions have been investigated in detail, and the optimized experimental parameters were obtained. Under the optimized conditions, the adsorption capacities of non-imprinted and imprinted coating stir bars were found to be 0.5 μg and 0.8 μg bar⁻¹. The detection limit (3σ) based on three times standard deviations of the method blanks by 7 replicates was 4.40 ng L⁻¹ and the relative standard deviation (RSD) was 3.38% (c = 1 μg L⁻¹, n = 7). The proposed method was successfully applied for the analysis of trace Cd(II) in rain water, East Lake and Yangtze River water. To validate the proposed method, certified reference material of GSBZ 50009-88 environmental water was analyzed and the determined value is in a good agreement with the certified value. The developed method is rapid, selective, sensitive and applicable for the analysis of trace Cd(II) in environmental water samples.     

Preconcentration and atomic spectrometric determination of rare earth elements (REEs) in natural water samples by inductively coupled plasma atomic emission spectrometry

The usage of a variety of sorbents has been shown as promising matrix removal/preconcentration strategies for the determination of rare earth elements (REEs) in various natural water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES). The sorption efficiency of various zeolites (clinoptilolite, mordenite, zeolite Y, zeolite Beta), ion-exchangers (Amberlite CG-120, Amberlite IR-120, Rexyn 101, Dowex 50W X18) and chelating resins (Muromac, Chelex 100, Amberlite IRC-718) towards REEs was investigated in terms of solution pH, shaking time and sorbent amount. The results have shown that most of the materials can take up REEs at a wide pH range. The experiments were continued with clinoptilolite, zeolite Y and Chelex 100 and it was demonstrated that all three materials displayed very fast kinetics for REE sorption (higher than 96% in 1 min). Desorption from the sorbents was realized with 2.0 M HNO₃ for clinoptilolite and 0.1 M HNO₃ for zeolite Y and Chelex 100. Only the lower concentration range (0.01-2.0 mg l⁻¹) of matrix-matched standards were used in quantitation although the calibration graphs were linear at least up to 10.0 mg l⁻¹ for all REEs studied. The limit of detection (3 s) without preconcentration was 0.1, 1.0, and 0.2 μg l⁻¹ for Eu, La, and Yb, respectively. The validity of the method with the selected sorbents was checked through spike recovery experiments.