Routine analysis of ultra pure water by ICP-MS in the low- and sub-ng/L level

The chemical analysis with inductively coupled plasma-mass spectrometry (ICP-MS) can help to examine the purity of ultra pure water (UPW) down to 10 part per trillion (ng/L) and lower. For a proper determination of a high number of samples per week the analysis must be divided into two parts: the routine analysis and the reference water analysis. The routine analysis is done by direct measurement of the ultra pure water samples. Applying a standard addition method under particular clean conditions, the reference water analysis leads to the definition of the accurate zero. A quick evaluation scheme is also presented for the reference water analysis. The method is tested for its fitness for application by examining LOD (for relevant element < 2 ng/L), reproducibility and linearity of calibration. The ICP-MS was optimized according to the methodology of G. Taguchi to improve reproducibility and LOD. Received: 16 June 1999 / Revised: 2 August 1999 / Accepted: 6 August 1999     

纯铜、纯镍中磷的ICP-MS法测定

试验了31 P的ICP MS法的测定条件 ,建立了纯铜、纯镍中微量磷的测定方法。采用基体匹配消除基体影响 ,方法检出限为 0 .5 4ng/mL ,测定下限为质量分数 5 .4× 1 0 - 4 % ,回收率为 93.5 %～ 1 0 2 %。对于w(P) <1× 1 0 - 3%和w(P)≥1× 1 0 - 3%的试样 ,其RSD(n =5 )分别为 1 5 %和 6.1 %。本法与光度法分析结果一致 ,较光度法快速、简便     

Determination of uranium and thorium at the sub-ng/g-level in high-purity aluminium by radiochemical neutron activation analysis

Summary A radiochemical neutron activation analysis technique for the determination of uranium und thorium in highpurity aluminium via the indicator radionuclides ²³⁹Np and ²³³Pa, respectively, has been developed. The separation procedure is based on the removal of ²⁴Na on hydrated antimony pentoxide followed by ion-exchange on Dowex-1X8 from HCl/HF and HCl medium. The eluate fraction being of interest for the determination of uranium and thorium contains > 99% of ²³⁹Np and ²³³Pa and, in addition, 11±2% of hafnium and 29±5% of zirconium, and non-detectable fractions of other radionuclides. For a 3-day irradiation of a 100 mg sample at a thermal neutron flux of 10¹⁴cm^–2s^–1 and a decay time of 5 days, the attainable detection limit for both elements is 0.05 ng/g. The method was applied to the analysis of different high-purity aluminium samples, and the results are compared with those obtained in other laboratories.

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Bestimmung von Uran und Thorium in hochreinem Aluminium im sub-ng/g-Bereich durch radiochemische Neutronenaktivierungsanalyse

     

高纯二氧化锗中痕量杂质的ICP-MS法测定

建立了高纯二氧化锗中痕量杂质Mg、Al、Ni、Cu、Zn、In、Pb的ICP-MS测定方法。选择了仪器最佳工作条件,研究了锗基体对被测元素的干扰,方法回收率为94％～114％,RSD为11．1％～57％。     

Determination of sodium and chlorine in pure water by neutron activation analysis

Neutron activation analysis was applied to determine sodium and chlorine in high purity water samples. After irradiation of the sample,³⁸Cl was purified from⁸²Br and other nuclides by carbon tetrachloride extraction and silver chloride precipitation, and²⁴Na was separated from other alkali elements and other nuclides by adsorption of²⁴Na on HAP. The activities of both elements were measured by conventional G.M. counter. The contamination of the elements from container walls during neutron irradiation and the interference with³⁸Ar(n, p)³⁸Cl reaction on argon dissolved in water were also examined. Water samples containing 3 ppb of chlorine could not be determined accurately, owing to the above mentioned interfering reaction.     

Depth profiling of ultra trace metal impurities in polytetrafluoroethylene wares by surface scraping and acid-vapor extraction followed by ICP-MS analysis.

This paper describes the development of the depth profiling method of ultra trace metal impurities in polytetrafluoroethylene (PTFE) wares based on contamination-free sampling followed by acid-vapor extraction and its application to evaluate the washing method for PTFE wares. A contamination-free sampling process was achieved by scraping the surface of PTFE wares with the cleft face of a silicon wafer followed by exposing the PTFE scraped to highly pure acid-vapor. The concentration of metal impurities in extractants was determined by ICP-MS equipped with an electrothermal vaporizer (ETV-ICP-MS). The blank values of Al, Cr, Fe, Ni and Cu by the depth profiling method were 0.006, 0.004, 0.005, 0.002 and 0.003 ng, respectively. By analyzing the depth profile of beakers, the distributions of ultra trace (ng g(-1) level) metal impurities were clarified. An examination of the washing methods by the depth profiling method also clarified that exposing to acid-vapor was more effective than the acid-dipping method for the elimination of metal impurities.     

Determination of sub-ng ml levels of mercury in water by electrolytic deposition and electrothermal atomic-absorption spectrophotometry

The determination of trace mercury in water samples by electrolytic deposition and electrothermal atomic-absorption spectrophotometry is described. Traces of mercury in water are preconcentrated by electrolytic reduction and deposition on a platinum wire cathode, which is then put into a graphite cup for direct atomization and measurement. The method is sensitive and simple, with a detection limit of 0.04 ng/ml. Almost all the metal ions commonly found in water samples can be tolerated, because of the selective deposition at controlled potential.     

Determination of uranium in tap water by ICP-MS

A fast and accurate procedure has been developed for the determination of uranium at microg L(-1) level in tap and mineral water. The method is based on the direct introduction of samples, without any chemical pre-treatment, into an inductively coupled plasma mass spectrometer (ICP-MS). Uranium was determined at the mass number 238 using Rh as internal standard. The method provides a limit of detection of 2 ng L(-1) and a good repeatability with relative standard deviation values (RSD) about 3% for five independent analyses of samples containing 73 microg L(-1) of uranium. Recovery percentage values found for the determination of uranium in spiked natural samples varied between 91% and 106%. Results obtained are comparable with those found by radiochemical methods for natural samples and of the same order for the certified content of a reference material, thus indicating the accuracy of the ICP-MS procedure without the need of using isotope dilution. A series of mineral and tap waters from different parts of Spain and Morocco were analysed.     

Sensitive determination of paraquat and diquat at the sub-ng ml-1 level by continuous amperometric flow methods.

Two methodologies are described for the determination of paraquat and diquat. The first is based on the pre-treatment of an electrode with a surfactant solution, which improves the electrochemical determination of the herbicides. Linear calibration graphs were obtained in the ranges 10-80 and 10-100 ng ml-1 for paraquat and diquat, respectively. The limits of detection were 6.32 for paraquat and 4.80 ng ml-1 for diquat. The method was applied to the determination of the herbicides in synthetic water samples. The second methodology is based on the preconcentration of paraquat and diquat in a minicolumn packed with a cation-exchange material. The determination ranges and detection limits depend on the sample volume used (5-50 ml). Thus, 50 ml of sample provides limits of detection of 0.016 and 0.020 ng ml-1 for paraquat and diquat, respectively. The applicability of the method was demonstrated with the determination of the herbicides in both synthetic and real water samples.     

Acid/base catalysis by pure water: the aldol reaction

[reaction: see text] The mechanism of aldol reactions in pure water has been studied with density functional calculations (B3LYP/6-311++G(3d,3p)//B3LYP/6-31G(d)). The reaction is a three-step process that involves: (1) water autoionization generates catalytic hydroxide and hydronium ions, (2) hydroxide and hydronium ions rapidly convert donor aldehyde or ketone into enol, and (3) C-C bond formation and proton transfer occur to give the aldol product. This study provides a general basis for understanding acid/base catalysis by pure water.     

MEKC combined with SPE and sample stacking for multiple analysis of pesticides in water samples at the ng/L level

In this work, a new multiresidue analytical method based on MEKC with UV detection combined with SPE as off-line preconcentration strategy, and reversed-electrode polarity stacking mode (REPSM) as on-line stacking procedure, has been developed for the monitoring of 12 pesticides (carbendazim, pirimicarb, metalaxyl, pyrimethanil, procymidone, nuarimol, azoxystrobin, tebufenozide, fenarimol, benalaxyl, penconazole, and tetradifon) that are currently being used in the Canary Islands (Spain). The optimized MEKC buffer, consisting of 100 mM sodium tetraborate and 30 mM SDS at pH 8.5 with 6% v/v 1-propanol, provided baseline resolution of the 12 pesticides in less than 20 min. The developed method was applied to the analysis of mineral, stagnant, and tap water samples. The proposed SPE-REPSM-MEKC-UV method showed high extraction efficiencies with detection limits (LODs) at the low ng/L level providing LOD values down to 64 ng/L for these real samples.     

Determination of uranium in pore water from coastal sediment by standard addition ICP-MS analysis

Mass spectrometry using ICP-MS was applied to determine the uranium content in pore water samples through the standard addition method. This method requires less than 0.2 ml of a water sample, without any chemical separation. The sample solution (50 mg) was diluted with ∼1% HNO₃ to make a total weight of 5.00 g, after the addition of uranium standard. The method introduced 1% of analytical precision for measured uranium in the samples. This rapid and simple technique allows multi-trace elemental quantification using mixed standards. The behavior of uranium in pore water and the variations of uranium content at different depths of pore water are discussed.     

镉基体分离及纯镉中杂质成分的ICP-MS法测定

研究了用阴离子交换树脂分离纯镉中铜、锌、铅、铁的条件，所得优化分离条件为：717型阴离子交换树脂柱，样品溶液为2mol/L HCl溶液；三段淋洗液依次为2mol/L HCl溶液、0．2mol/L HBr 0．25mol/L HNO3的混合酸溶液及3mol/L HNO3溶液。经ICP-MS测定证明，95％以上的镉得到分离，95％以上的铜、锌、铅、铁可以分离测定，有效地降低了ICP-MS测定纯镉中铜、锌、铅、铁时镉基体的干扰。     

Determination of gadolinium in river water by SPE preconcentration and ICP-MS

An analytical scheme was developed for the determination of Gd-diethylenetriaminepentaacetate (Gd-DTPA), Gd and the other rare earth elements (REE) in river water by inductively coupled plasma (quadrupole) mass spectrometry (ICP-Q-MS). The preconcentration step was essential, since the limits of detection of this multielemental analytical technique are higher than the trace concentrations of the interesting elements in river water.Solid phase extraction (SPE) with different commercially available complexing agents (Chelex 100, Toyopearl and ethylhexylphosphates) was employed for the preconcentration of REE. The investigations revealed that complex stability (varying in dependence of the pH value) has a strong influence on the degree of the enrichment of Gd-DTPA. Based on acidified water samples (pH<3) a procedure using ethylhexylphosphates was proposed for the preconcentration of Gd and REE from surface water samples. For this purpose C₁₈-cartridges loaded with ethylhexylphosphates were used, resulting in an enrichment factor of 40.     

Using ultrapure water in ion chromatography to run analyses at the ng/L level

Thanks to enhanced capabilities, ion chromatography (IC) occupies an increasing position in many types of applications. Achieving ideal performances for an extended life-time can only be reached, however, if the IC system is operated in optimum experimental conditions. Among the various parameters that need to be controlled, water is particularly important, because it is used throughout the analysis, from sample preparation to column rinsing, elution, and mobile phase preparation. More and more, devices are included in IC systems to generate the eluent in situ, and ultrapure water becomes the major reagent. Data of pre-concentration of high purity water show that detection limits at the ng/L level can be expected with water purified using the right combination of technologies.     

Trends in single-cell analysis by use of ICP-MS

The analysis of single cells is a growing research field in many disciplines such as toxicology, medical diagnosis, drug and cancer research or metallomics, and different methods based on microscopic, mass spectrometric, and spectroscopic techniques are under investigation. This review focuses on the most recent trends in which inductively coupled plasma mass spectrometry (ICP-MS) and ICP optical emission spectrometry (ICP-OES) are applied for single-cell analysis using metal atoms being intrinsically present in cells, taken up by cells (e.g., nanoparticles), or which are artificially bound to a cell. For the latter, especially element tagged antibodies are of high interest and are discussed in the review. The application of different sample introduction systems for liquid analysis (pneumatic nebulization, droplet generation) and elemental imaging by laser ablation ICP-MS (LA-ICP-MS) of single cells are highlighted. Because of the high complexity of biological systems and for a better understanding of processes and dynamics of biologically or medically relevant cells, the authors discuss the idea of “multimodal spectroscopies.”     

Determination of trace amounts of permanent gases in ultra pure hydrogen by gas chromatography

Summary A HP-5880A gas Chromatograph equipped with TCD and FID has been used to determine trace amounts of O₂+Ar, N₂, CO, CH₄ and CO₂ in pure and ultra pure hydrogen. Utilizing the preconcentration technique, the minimum detectability with a 10-liter sample is around 0.2 ppb (v/v) for O₂+Ar, 0.4 ppb (v/v) for N₂, 0.05 ppb (v/v) for CO, 0.2 ppb (v/v) for CH₄ and 0.3 ppb (v/v) for CO₂. Calculation of results in trace gas analysis is discussed and a calculation method is proposed for the concentration of impurities in the sample calculated from the difference of successive sampling volumes and peak areas.

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Spurenbestimmung von permanenten Gasen in hochreinem Wasserstoff mit Hilfe der Gas-Chromatographie

     

Rapid and interference free determination of ultra trace level of uranium in potable water originating from different geochemical environments by ICP-OES

Direct determination of uranium in the concentration range of 8 μg L⁻¹ to mg L⁻¹ in water samples originating from different geochemical environments has been done using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Uranium detection with 2–3% RSD (relative standard deviation) has been achieved in water samples by optimizing the plasma power, argon and sheath gas flow. These parameters were optimized for three different emission lines of uranium at 385.958, 409.014 and 424.167 nm. Interference arising due to the variation in concentration of bicarbonate, sodium chloride, calcium chloride, Fe and dissolved organic carbon (DOC) on the determination of uranium in water samples was also cheeked as these are the elements which vary as per the prevailing geochemical environment in groundwater samples. The concentration of NaHCO₃, CaCl₂ and NaCl in water was varied in the range 0.5–2.0%; whereas Fe ranged between 1 and 10 μg mL⁻¹ and DOC between 0.1–1%. No marked interference in quantitative determination of uranium was observed due to elevated level of NaHCO₃, CaCl₂ and NaCl and Fe and DOC in groundwater samples. Concentration of uranium was also determined by other techniques like adsorptive striping voltametry (AdSv); laser fluorimetry and alpha spectrometry. Results indicate distinct advantage for uranium determination by ICP-OES compare to other techniques.     

Evaluation of different calibration strategies for the analysis of pure copper and zinc samples using femtosecond laser ablation ICP-MS

Solution-doped metal powder pellets as well as aspirated liquids were used as calibration samples to analyze pure copper and zinc certified reference materials (CRMs) by femtosecond laser ablation ICP-MS. It was demonstrated that calibration by copper pellets resulted in relative deviations up to 20%, whereas fs-LA-ICP-MS among copper-based CRMs led to inaccuracies in the same range unless nominal mass fractions were chosen to be <3 mg/kg. Calibration by zinc pellets generally provided better accuracy. Depending on the analyte considered, deviations below 10% were obtained even for mass fractions close to the limit of quantification. Our data, therefore, indicate solution-doped metal powder pellets to be suitable as calibration samples for fs-LA-ICP-MS of metals. Furthermore, the utilization of liquid standards for calibration was found to result in stronger deviations of up to 50% for both copper and zinc samples which, in addition, turned out to be dependent on the plasma conditions.      

The determination of polycyclic aromatic hydrocarbons at the ng/L level in Ottawa tap water.

Samples of Ottawa drinking water, collected in January and February 1978 were analysed by Gas Chromatography/Mass Spectrometry (GC/MS) for fifty polycyclic aromatic hydrocarbons (PAH) and five oxygenated polycyclic aromatic hydrocarbons (O-PAH), following extraction of the organic species using Amberlite XAD-2 macroreticular resin. In the January sample, thirty PAHs, ranging in concentration from 0.05 to 14 ng/L with a mean value of 3.8 ng/L and a total weight of 114 ng/L and four O-PAHs, ranging in concentration from 0.10 to 1.8 ng/L with a mean value of 0.91 ng/L and a total weight of 3.7 ng/L, were detected. In the February sample, thirty-six PAHs, ranging in concentration from 0.05 to 8.1 ng/L with a mean value of 1.4 ng/L and a total weight of 50.4 ng/L and five O-PAHs, ranging in concentration from 0.20 to 2.4 ng/L with a mean value of 1.0 ng/L and a total weight of 5.2 ng/L, were detected. Twenty-eight PAHs and four O-pahs were common to the two samples. The use of Amberlite XAD-2 macroreticular resin to extract PAHs from drinking water is shown to be effective, although the recovery of individual PAHs from artificially loaded XAD-2 resin varied from 57 to 100%.