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A method for the determination of Ti and V using inductively coupled plasma atomic emission spectrometry (ICP OES) in Ziegler-Natta polymerization catalysts is proposed. The concentrations of both Ti and V are efficiently determined after catalyst acid digestion with a mixture of HNO3 + HCl + HF and heating (160 degrees C for 6 h) or with 10% (v/v) H2SO4 and heating (160 degrees C for 6 h) or with 10% (v/v) H2SO4 and sonication (during 2 min). The V and Ti detection limits are 0.002% and 0.08%, respectively, using 0.20 g of catalyst sample in 50 ml. The method is validated by a comparison with the Rutherford backscattering spectrometry (RBS) technique. In this case, catalyst samples are only pressed as pellets before analyte determination. Despite the fact that both the V and Ti concentrations cannot be determined individually by means of RBS, because the atomic numbers of Ti and V are very close, the sum of the V and Ti contents is in accordance with that attained by means of ICP OES. According to scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) it is observed that the Ti distribution on the catalyst grain is not homogenous.
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PMID:Determination of titanium and vanadium in Ziegler-Natta catalysts by inductively coupled plasma atomic emission spectrometry. 1677 85

A new sorbent, maleic acid grafted polytetrafluoroethylene fiber (MA-PTFE), was prepared and evaluated for on-line solid-phase extraction coupled with inductively coupled plasma mass spectrometry (ICP-MS) for fast, selective, and sensitive determination of (ultra)trace rare earth elements (REEs) in environmental samples. The REEs in aqueous samples at pH = 3.0 were selectively extracted onto a microcolumn packed with the MA-PTFE fiber, and the adsorbed REEs were subsequently eluted on-line with 0.9 mol l(-1) HNO3 for ICP-MS determination. The new sorbent extraction system allows effective preconcentration and separation of the REEs from the major matrix constituents of alkali and alkali earth elements, particularly their separation from barium that produces considerable isobaric interferences of 134Ba16O1H+, 135Ba16O+, 136Ba16O1H+, and 137Ba16O+ on 151Eu+ and 153Eu+. With the use of a sample loading flow rate of 7.4 ml min(-1) for 120 s preconcentration, enhancement factors of 69-97 and detection limits (3s) of 1-20 pg l(-1) were achieved at a sample throughput of 22 samples h(-1). The precision (RSD) for 16 replicate determinations of 50 ng l(-1) of REEs was 0.5-1.1%. The developed method was successfully applied to the determination of (ultra)trace REEs in sediment, soil, and seawater samples.
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PMID:Flow injection on-line solid phase extraction coupled with inductively coupled plasma mass spectrometry for determination of (ultra)trace rare earth elements in environmental materials using maleic acid grafted polytetrafluoroethylene fibers as sorbent. 1681 61

Direct determination of tellurium in geological samples by inductively coupled plasma mass spectrometry (ICP-MS) is often complicated by its low abundance, poor analytical sensitivity, and the presence of xenon interferences. Therefore, a simplified and rapid method for direct determination of nanogram levels of tellurium in geological samples using ICP-MS by reduction of interferences and improvement of sensitivity was developed. It is impossible to resolve 126Te and 128Te from isotope interferences of Xe even by currently available high-resolution magnetic mass spectrometry due to the extremely small mass difference (0.001-0.002 amu). However, the addition of 4% ethanol was found to suppress the interferences of Xe by a factor of 6 and increases the sensitivity of Te determination in ICP-MS by a factor of 3 relative to the values obtained in conventional 3% (v/v) HNO3 solution at the corresponding optimum operating conditions, respectively. The detection limits of 126Te and 128Te were reduced by a factor of 7.2 and 8.8, respectively, and the limit of quantitation (LOQ) for 126Te in the presence of 4% ethanol was 1.5 ng g(-1) (the LOQ is expressed as the concentration in the solid samples, thereby taking into account the dilution factor of 1000). The agreement between the determined Te concentration values (r = 0.998) in various geological samples (n = 140) by using isotopes of 126Te and 128Te indicates negligible contributions of polyatomic interferences produced by the addition of ethanol at these m/z. The proposed method was successfully applied to the direct determination of nanogram levels of Te in a series of international geological reference materials.
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PMID:Direct determination of tellurium in geological samples by inductively coupled plasma mass spectrometry using ethanol as a matrix modifier. 1685 66

The two oxidation states of thallium, Tl(I) and Tl(III), were quantified by IC-ICP-MS using complexation of Tl3+ with DTPA (penta-carboxymethyl-diethylenetriamine) and separation on a cation exchange column according to a modification of the method devised by Coetzee et al. In order to avoid successively lowered separation efficiency and loss of resolution during a run, a gradient elution was made using HCl instead of HNO3. With an ultrasonic nebuliser instead of a V-groove nebuliser the limit of detection for Tl(I) and Tl(III) could be lowered from 25 ng/L and 3.0 ng/L to 9.0 ng/L and 0.7 ng/L, respectively, which is adequate for many fresh water systems. The stability of Tl(III) in acidic solutions was found to be concentration dependent, with an initially high reduction rate of Tl(III). Exposure of the sample to light further increased the reduction rate. Addition of DTPA (0.01 mM) and acid (HNO3, 1%) to a sample with 1 mug/L Tl(III) stabilised the Tl(III) content for at least 48 h. Analysis of field samples showed that only acidification is inadequate to maintain the original distribution of Tl(I) and Tl(III). Internal calibration (standard addition) and correction of the analytical signal (205Tl) with a non-ionic internal standard (11B) yielded almost quantitative recoveries of both Tl(I) and Tl(III). A scheme for field sample preparation is proposed, including sampling, storage and pre-analysis treatment.
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PMID:Separation and quantification of Tl(I) and Tl(III) in fresh water samples. 1685 92

A method is presented for the simultaneous determination of Cr(III) and Cr(VI) in yeast using species-specific double-spike isotope dilution (SSDSID) with anion-exchange liquid chromatography (LC) separation and sector field inductively coupled plasma mass spectrometric (SF-ICP-MS) detection. Total Cr is quantitated using ID SF-ICP-MS. Samples were digested on a hot plate at 95+/-2 degrees C for 6 h in an alkaline solution of 0.5 M NaOH and 0.28 M Na2CO3 for the determination of Cr(III) and Cr(VI), whereas microwave-assisted decomposition with HNO3 and H2O2 was used for the determination of total Cr. Concentrations of 2,014+/-16, 1,952+/-103 and 76+/-48 mg kg-1 (one standard deviation, n=4, 3, 3), respectively were obtained for total Cr, Cr(III) and Cr(VI) in the yeast sample. Significant oxidation of Cr(III) to Cr(VI) (24.2+/-7.6% Cr(III) oxidized, n=3) and reduction of Cr(VI) to Cr(III) (37.6+/-6.5% Cr(VI) reduced, n=3) occurred during alkaline extraction and subsequent chromatographic separation at pH 7. Despite this significant bidirectional redox transformation, quantitative recoveries for both Cr(III) and Cr(VI) were achieved using the SSDSID method. In addition, mass balance between total Cr and the sum of Cr(III) and Cr(VI) concentrations was achieved. Method detection limits of 0.3, 2 and 30 mg kg-1 were obtained for total Cr, Cr(VI) and Cr(III), respectively, based on a 0.2-g sub-sample.
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PMID:Application of double-spike isotope dilution for the accurate determination of Cr(III), Cr(VI) and total Cr in yeast. 1695 11

A procedure was developed for the determination of Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) after preconcentration on a morpholine dithiocarbamate (mor-DTC) supported by bagasse (Saccharam aphisinaram). The sorbed elements were subsequently eluted with 4,M HNO3 and the acid eluates were analysed by ICP-AES. The influence of various parameters such as pH, flow rate of sample, eluent concentration, volume of the sample and volume of eluent were investigated to enhance the sensitivity of the present method. A 20,mL disposable syringe served as preconcentration column. Under the optimal conditions Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in aqueous sample was concentrated about 100-fold. The sorption recoveries of elements were higher than 99.6%. The method is also applied for the analysis of natural and spiked water samples.
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PMID:Preconcentration technique for the determination of trace elements in natural water samples by ICP-AES. 1695 50

Niuhuang Jiedu tablets were digested with HNO3-H2O2 system by microwave digestion. The fourteen trace elements of As, Ca, Mg, Al, Mn, Sr, Ba, Se, Ni, Cd, Cu, Zn, Mo and Pb in the solution were determined by ICP-AES. The ICP-AES result proved to be reliable by adding standard recovery experiment to the process. By comparison with the result of chemical experiment, thr present method was accurate, quickly-accessible, and convenient. It was used for Niuhuang Jiedu tablets with result satisfactory.
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PMID:[Determination of trace elements in Niuhuang Jiedu tablets by microwave digestion and ICP-AES]. 1696 Dec 56

Determination of metal elements in buds of Syzygium aromaticum (L. )Merr. et Perry was studied by ICP-AES after HNO3-H2O2 digestion. The average recovery of the method for K, Mg, and trace elements such as Cu, Fe, Cr, Zn, Mn and Pb in the buds of Syzygium aromaticum (L.) Merr. et Perry was found to be 91.8% -112.2%, while RSD (n = 5) is 0.4% - 4.9% for the metal elements. The method was applied to the analysis of some practical samples, and the results obtained were satisfactory. There is rich Mn in the samples. It is of important significance to assess the value of the Chinese medicine by the determination of trace elements in Chinese medicine with ICP-AES.
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PMID:[Study on determination of metal elements in buds of Syzygium aromaticum (L.) Merr. et Perry by ICP-AES]. 1702 55

The method for the determination of copper and chromium in the cartridges of permanent pen oil base and ink by ICP-AES was reported. This mainly concerned the different methods for pretreatment of samples. The study indicated that the better method for the pretreatment of the cartridges of permanent pen and the ink containing resin is dry ashing at 550 degrees C followed by wet-decomposition with mixed acid (V(HNO3) : V(HClO4 = 3 : 1); the better method for the pretreatment of water soluble ink is hydrodigestion with mixed acid (V(HNO3 : V(HClO4 = 3 : 1). After suitable dilution with acid, copper and chromium were determinated by ICP-AES. It was shown that the method is reliable for the test of precision and accuracy. RSD and recovery were in the range of 5.9% - 7.9% and 90% - 104%, respectively.
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PMID:[Determination of copper and chromium in the cartridges of permanent marker pen and ink by ICP-AES]. 1702 56

The determination of elements in Euonymus alatus by ICP-AES was carried out in the present paper. The Euonymus alatus samples were digested by microwave digestion technique. The optimized conditions of microwave digestion procedure obtained by orthogonal array design were as follows: the volume ratio of HNO3-HCl is 2 : 1; the ratio of liquid/solid is 100 : 1; the sample particle size is 100-140 mesh. ICP-AES method was applied to the determination of ten trace elements in the sample, and was compared with AAS. The results showed that the method was rapid and simple with the relative standard deviations between 0.5%-6.2%, and the recovery between 85.5% and 105.6%.
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PMID:[Determination of elements in Euonymus alatus by microwave digestion-ICP-AES]. 1705 68


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