Optimization of slurry nebulization inductively-coupled plasma atomic emission spectrometry for the analysis of ZrO2-powder

The optimization and use of ICP-AES with slurry nebulization for the direct analysis of ZrO₂-powder is described. The powder samples are dispersed in water, acidified to pH 2 and the slurry is fed into a Babington nebulizer. The effects of grain size, pH of the suspending medium and standing time on the stability of the slurry are discussed. For the optimization of the ICP operating conditions, a simplex technique is applied and for this purpose three types of objective functions were examined. Identical behaviour of slurries and solutions with the same matrix concentrations in the ICP-AES is achieved for powders with particle sizes lower than 10 m; in the latter case calibration can be performed by standard addition with aqueous solutions. The detection limits for Al, B, Ca, Cu, Fe, Mg, Mn, Na, Ti, V. Y are 0.03 g/g to 10 g/g and the standard deviation is generally lower than 10%. Six commercially available ZrO₂ powders are analyzed by slurry nebulization ICP-AES and the results were found to agree well with those obtained by ICP-AES after chemical decomposition of the samples.On leave from Department of Analytical Chemistry, Technical University, PL-00-664 Warsaw, Poland     

Determination of cadmium in polyethylene by analytical atomic spectrometry with gas-phase sample introduction technique

Cadmium in polyethylene was determined by both inductively coupled plasma atomic emission spectrometry (ICP-AES) and atomic absorption spectrometry (AAS) with continuous-flow gas-phase sample introduction in a reaction medium of ascorbic acid. In the presence of mixture of cobalt and thiourea in the ascorbic acid solution, the sensitivities by both ICP-AES and AAS for cadmium were greatly enhanced. The gaseous cadmium species was phase-separated in a gas–liquid separator and directed via a stream of argon carrier gas to an inductively coupled plasma and an electrically heated quartz tube atomizer (QTA) for atomic spectrometry. Under the optimized experimental conditions, the best attainable detection limits at Cd I 228.802 nm line were 1.3 and 0.017 ng/ml with linear dynamic ranges of 10–500 ng/ml and 0.1–1 ng/ml in concentrations by ICP-AES and QTA-AAS, respectively. The instrumental precisions expressed as the relative standard deviation (R.S.D.) from ten replicate measurements of 50 and 1 ng/ml cadmium by ICP-AES and QTA-AAS were 5.6% and 3.2%, respectively. With the use of ICP-AES and QTA-AAS with gas-phase sample introduction method, six- and 200-fold improvements in detection limits for cadmium were obtained in comparison with their conventional solution nebulization methods, respectively. After the effects of several diverse elements on the determination of cadmium by ICP-AES and QTA-AAS with the present gas-phase sample introduction systems were examined, these methods were applied to the determination of low concentrations of cadmium in polyethylene. The results obtained by the present method were in good agreement with the certified values.     

Determination of platinum metals and gold by optical emission spectrometry with a radiofrequency inductively-coupled argon plasma source

Optimum operating conditions in a 2-kW inductively-coupled argon plasma source for the detection of the elements platinum, palladium, rhodium, ruthenium, iridium, osmium and gold have been established. Detection limits obtained for aqueous solutions introduced into the plasma by pneumatic nebulization range from 1.5 ppb (Rh) to 34 ppb (Ir). No interelement effects caused by chemical interference have been observed between the elements investigated or from a number of base metals; several spectral interferences were observed with the spectrometer employed. The effect of the presence of mineral acids on the nebulization of sample solutions is reported.     

Use of a capacitively coupled microwave plasma (CMP) with Ar, N2 and air as working gases for atomic spectrometric elemental determinations in aqueous solutions and oils

A comparative study was performed of 600 W capacitively coupled microwave plasmas (CMP) with different plasma gases (Ar, N₂ and air) and aerosol generation with the aid of a Légère pneumatic nebulizer. Detection limits with the different working gases are in the order of 15–4000 ng/mL for Fe, Cr, Zn, Mg and Ca in aqueous solutions. The influence of organic solutions on the stability of the plasma is discussed. The determination of Co, Cr, Fe, Mg and Ni in different oil samples by OES is described, using an air-CMP and pneumatic nebulization after dilution of the oils by 20% with cyclohexane. The detection limits for these elements are in the 100–400 ng/g range. Results obtained for a waste motor oil for the elements mentioned in the concentration range of 4–50 μg/g were found to be in good agreement with those obtained by ICP-OES after digestion of the oils at high pressure in PTFE vessels. Received: 10 March 1997 / Revised: 23 May 1997 / Accepted: 30 May 1997     

Possibilities of inductively coupled plasma atomic emission spectrometry with electrothermal vaporization in the analysis of high-purity reagents

Possibilities of electrothermal sample vaporization in inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) in the analysis of high-purity reagents were studied on an example high-purity waters, acid solutions, and trace impurity concentrates. The analytical and background signals in the injection of solutions into inductively coupled plasma (ICP) by pneumatic nebulization and electrothermal vaporization were compared and the of limits of detection in the analysis of high-purity reagents with impurity preconcentration by evaporation were estimated and compared.     

Slurry nebulization ICP-AES spectrometry method for the determination of tin in organotin(IV) complexes

This paper proposes a quick, novel method for tin determination in organotin chemicals by slurry nebulization inductively coupled plasma atomic emission (ICP-AES) spectrometry. The method was tested by the measurement of five organotin carboxylate complexes of known composition for obtaining simple stoichiometric data. The slurries were prepared by first dissolving the organotins in an adequate solvent (methanol, pyridine or acetone) well miscible with water and then adding this solution drop-by-drop to a 0.005% TX-100 tenzide solution while maintaining intensive mixing. Dynamic laser light scattering experiments showed that the average equivalent particle size in the resulting slurry was ≈0.3 μm for all samples and solvents. Under suitable ICP-AES measuring conditions, the signal recoveries were found to be between 101.8 and 106.6%, which allowed direct nebulization and calibration against aqueous solutions. Typically, 70 μg l⁻¹ detection limit and 1–5% relative S.D. on five replicates can be achieved by the described method.     

Liquid Chromatographic Determination of Glutamine in Cerebrospinal Fluid Using 2-Hydroxynaphthaldehyde Derivatizing Reagent

Summary An analytical procedure has been developed for the selective determination of glutamine from cerebrospinal fluid (CSF) using 2-hydroxynaphthaldehyde derivatizing reagent. Arginine and tyramine could also be determined simultaneously. Separation was on a Phenomenex C-18, (150 × 4.6 mm i.d.) column with methanol: water (63:38 v/v) mobile phase at 1mL min^–1 and UV detection at 330nm. Detection limits for glutamine, arginine, and tyramine were 2.8 ng, 17.4 ng and 3.45 ng injection^–1 (5 L), respectively. A large number of amines and amino acids eluted did not affect the determination of glutamine. The analysis of CSF of four patients suffering from hydrocephalus for glutamine indicated concentrations within range 37.4–11.24 g mL^–1 with coefficient of variation 3.0–6.2%.     

Determination of 6-amino-2,2-dimethyl-1,3-dioxepan-5-ol by postcolumn derivatization witho-phthalaldehyde/2-mercapto-ethanol after ion-pair chromatography

Summary A high-performance liquid chromatographic method is discribed for the determination of 6-amino-2,2-dimethyl-1,3-dioxepan-5-ol using Spherisorb ODS II stationary phase and mobile phase 30:70 (v/v) methanol: aqueous 1-octane sulfonic acid. Detection was fluorimetric following postcolumn derivatization with o-phthaladehyde/2-mercaptoethanol. The procedure was applied to the analysis of aqueous solutions and microcrystalline suspensions in liquid paraffin, prepared for investigation of the toxicological profile. The method was validated for selectivity, linearity of detector response, repeatability, limit of detection and quantitation. The HPLC method was selective. The instrumental limit of detection was 0.5 ng per injection (0.05 g mL^–1). The method detection limits were 0.5 g mL^–1 aqueous solution and 5 g mL^–1 liquid paraffin suspension, the quantitation limit 0.05 mg mL^–1 aqueous solution and 1.0 mg mL^–1 liquid paraffin. Linearity was within 0.94–47.1 g mL^–1. Intra-assay accuracy accounted for 99–100% in the range 0.05–226 mg mL^–1 aqueous solution, intra-assay precision for 2% (C.V.). For microcrystalline liquid paraffin suspensions with 1 and 250 mg mL^–1 99 and 109% was found for intra-assay accuracy. Intra-assay precision was 5% (C.V.). Reliable results over a wide concentration range can be obtained. The procedure is considered valid for determination of the analyte in aqueous solution or microcrystalline paraffin oil suspensions.     

Direct determination of metals in milligram masses and microlitre volumes by direct-current argon-plasma emission spectrometry with sample introduction by electrothermal vaporization

The development of an electrothermal vaporization and direct-current argon-plasma emission spectrometric system which allowed the determination of metals in microlitre volumes and milligram masses is described. For the five metals investigated, the concentration detection limits were comparable to those for conventional pneumatic nebulization of solutions, and the mass detection limits were superior. The use of an ashing stage was found to reduce enhancement by sodium in the determination of copper and manganese by the plasma method. The system was shown to give accurate results for complex biological, nutritional, water and geological samples.     

Multivariate optimization and simultaneous determination of hydride and non-hydride-forming elements in samples of a wide pH range using dual-mode sample introduction with plasma techniques: application on leachates from cement mortar material

Analytical methods have been developed for the simultaneous determination of hydride-forming (As, Sb) and non-hydride-forming (Cr, Mo, V) elements in aqueous samples of a wide pH range (pH 3–13). The methods used dual-mode (DM) sample introduction with ICP-AES and ICP-MS instruments. The effect of selected experimental variables, i.e., sample pH and concentrations of HNO₃, thiourea, and NaBH₄, were studied in a multivariate way using face-centered central composite design (FC-CCD). Compromised optimum values of the experimental parameters were identified using a response optimizer. The statistically found optimum values were verified experimentally. The methods provided improved sensitivities for the hydride-forming elements compared with the respective conventional nebulization (Neb) systems by factors of 67 (As) and 64 (Sb) for ICP-AES and 36 (As) and 54 (Sb) for ICP-MS. Slight sensitivity improvements were also observed for the non-hydride-forming elements. The limits of detection (LOD) of As and Sb were lowered, respectively, to 0.8 and 0.9 μg L⁻¹ with the DM-ICP-AES system and to 0.01 and 0.02 μg L⁻¹ with the DM-ICP-MS system. The short-term stabilities of both methods were between 2.1 and 5.4%. The methods were applied for the analysis of leachates of a cement mortar material prepared in the pH range 3–13. The elemental concentration of the leachates determined by the two DM methods were statistically compared with the values obtained from Neb-ICP-MS analysis; the values showed good agreement at the 95% confidence level. Quantitative spike recoveries were obtained for the analytes from most of the leachates using both DM methods. Figure Schematic of the dual-mode sample introduction system used in combination with ICP-AES and ICP-MS for the simultaneous determination of hydride and non-hydride-forming elements     

Use of a multi-tube Nafion® membrane dryer for desolvation with thermospray sample introduction to inductively coupled plasma-atomic emission spectrometry

A multi-tube Nafion^® membrane dryer used as a part of a desolvation system in conjunction with thermospray nebulization was optimized and characterized with inductively coupled plasma-atomic emission spectrometry (ICP-AES). Either argon or nitrogen could be used as the sweep gas, and optimum conditions were found to be at low temperature and low sweep gas flow rate. Analyte sensitivity was not significantly affected by placing the membrane between the plasma and the nebulizer, although about 20% of the analyte entering the dryer is lost within the dryer. A dual role of the membrane dryer was demonstrated. As a secondary step within the desolvation system, it enabled a high desolvation efficiency of 99.94% for aerosols from 1% (v/v) nitric acid. Plasma solvent load could be reduced to 0.9 mg min⁻¹ with a tap water cooled condenser combined with the membrane dryer, compared to 21 mg min⁻¹ with the normal chilled condenser desolvation system. Meanwhile, the membrane was also found to act as a pulse dampener, eliminating the plasma pulsation in the central channel caused by thermospray nebulization and thus improving the analytical performance of the system. The average relative standard deviations (RSD) with the optimized membrane/thermospray system were 0.83% and 0.60% for the background and analyte signals, respectively, which were reduced by a factor of 1.9 and 2.7 for the background and analyte signals, respectively, compared to thermospray without the membrane desolvation, and were essentially identical to those obtained with pneumatic nebulization sample introduction. The improvements in detection limits with the membrane/thermospray system were 1.2–3.0 times with an average factor of 1.8 compared to thermospray without the membrane dryer, and 18–68 times with an average factor of 39 compared to the standard pneumatic nebulization sample introduction system without a desolvation unit. The detection limits for Mn, Mg, Cr and Cd with the present thermospray/membrane system were comparable to those reported for pneumatic nebulization ICP mass spectrometry.     

Comparison of inductively coupled plasma spectrometry techniques for the direct determination of rare earth elements in digests from geological samples

Inductively coupled plasma quadrupole mass spectrometry (ICP-QMS), ICP sector field mass spectrometry (ICP-SFMS) and ICP atomic emission spectrometry (ICP-AES) were compared with regard to the direct determination of rare earth elements (REEs) in geological samples. In order to reduce the polyatomic interferences occurring in ICP-QMS, the use of a cooled spray chamber was optimized, obtaining a significant decrease of the oxide ions formation (about 50%) and a consequent mitigation of the interfering effects. Precision and accuracy of the method were demonstrated by the analyses of sediment and soil certified reference materials. ICP-SFMS working in high-resolution mode also provided accurate results, with similar precision to ICP-QMS (RSD%: 3-8%) and comparable or better limits of detection. Quantification limits of the procedures were 18-52 ng g⁻¹ and 10-780 ng g⁻¹ for sector field- and quadrupole-ICP-MS, respectively. Accurate and precise determination of most REEs was also achieved by ICP-AES using both pneumatic and ultrasonic nebulization, after a careful selection of the emission lines and compensation for non-spectral interferences by internal standardization. The three techniques were finally applied to glaciomarine sediment samples collected in Antarctica, providing comparable analytical data on REE abundance and depth pattern.     

Use of a capacitively coupled microwave plasma (CMP) with Ar, N2 and air as working gases for atomic spectrometric elemental determinations in aqueous solutions and oils

A comparative study was performed of 600 W capacitively coupled microwave plasmas (CMP) with different plasma gases (Ar, N₂ and air) and aerosol generation with the aid of a Légère pneumatic nebulizer. Detection limits with the different working gases are in the order of 15–4000 ng/mL for Fe, Cr, Zn, Mg and Ca in aqueous solutions. The influence of organic solutions on the stability of the plasma is discussed. The determination of Co, Cr, Fe, Mg and Ni in different oil samples by OES is described, using an air-CMP and pneumatic nebulization after dilution of the oils by 20% with cyclohexane. The detection limits for these elements are in the 100–400 ng/g range. Results obtained for a waste motor oil for the elements mentioned in the concentration range of 4–50 μg/g were found to be in good agreement with those obtained by ICP-OES after digestion of the oils at high pressure in PTFE vessels. Received: 10 March 1997 / Revised: 23 May 1997 / Accepted: 30 May 1997     

Analysis of glass by UV laser ablation inductively coupled plasma atomic emission spectrometry. Part 2. Analytical figures of merit

Two lasers working in the UV part of the spectrum have been used for the direct analysis of glass samples by laser ablation ICP-AES. An XeCl excimer laser (308 nm) and a Nd:YAG laser operating at the third harmonic (355 nm) and the fourth harmonic (266 nm) have been selected. The energy was 70 mJ and 5 mJ for the excimer laser and the Nd:YAG laser, respectively, with a 10 Hz repetition rate. Figures of merit such as repeatability, reproducibility, accuracy and limits of detection have been studied. Si was used as an internal standard to improve the repeatability, the reproducibility and the accuracy. Use of internal standardardization led to an RSD of less than 1% for most elements and to a linear calibration graph irrespective of the colour of the glass samples. Limits of detection in the solid were of the same magnitude as those obtained using sample dissolution and pneumatic nebulization. Results confirmed that the XeCl laser provided the best results of detection whereas the Nd:YAG laser, particularly at 266 nm, was less sensitive to glass colour.     

Three-filament and toroidal microwave induced plasmas as radiation sources for emission spectrometric analysis of solutions and gaseous samples—II: Analytical performance

The generation of two new types of the Ar-MIP and their analytical performance as radiation sources for atomic emission spectrometry in the extreme trace analysis of elements is described. A stable 3-filament Ar-MIP, and a toroidal Ar-MIP can be generated in a cylindrical TM₀₁₀ cavity with special mountings and adjustment devices for the discharge tube. The first was found to be suitable for the determination of volatile elements or compounds and the latter for the analysis of solutions subsequent to pneumatic nebulization. The influence of different plasma parameters, e.g. microwave power and argon gas flow was investigated. The detection limits for the elements Be, Ca, Cd, Co, Cr, Cu, Ga, Hg, Mg, Mn, Sr, Tl and Zn were found to be in the range of 1–50 ng ml^?1. As an example for the application of the toroidal MIP, analyses of natural water samples (drinking water, glacial ice and snow) were performed.     

Flow injection analysis with inductively coupled plasma-atomic emission spectroscopy: critical comparison of conventional pneumatic, ultrasonic and direct injection nebulization

The analytical figures of merit observed under flow injection analysis (FIA) conditions of a direct injection nebulizer (DIN) interfaced to an inductively coupled plasma-atomic emission spectroscopy (ICP-AES) facility were found to be comparable to or better than conventional pneumatic nebulization in terms of limits of detection, reproducibility and interelement effects. The DIN offered clog-free operation and part per billion limits of detection for 30μl sample injection volumes and carrier stream consumption rates in the range of 100–200μl min ⁻¹. The relative detection limits observed were generally comparable to those obtained for: (a) FIA introduction of 200μl or continuous sample introduction into a conventional cross flow nebulizer; and (b) FIA introduction of 500μl or continuous sample introduction into an ultrasonic nebulizer. Absolute and relative detection limits were comparable to or within the range of values reported for electrothermal vaporization-ICP-AES and comparable or superior to those reported for the graphite cup, direct insertion-ICP-AES. The reported absolute detection limits for the graphite-rod direct insertion approach ranged from comparable values to superior by a factor of 30. At the normal compromise observation height (20 mm), the interelement effects, to the extent they were observable, were comparable in magnitude for both the DIN and conventional cross-flow pneumatic nebulizer.     

A three-electrode direct current plasma as compared to an inductively coupled argon plasma

Summary A direct comparison of some analytical properties of a three-electrode direct current plasma and an inductively coupled argon plasma in the case of pneumatic nebulization of aqueous solutions was performed. The measurements were carried out under similar conditions using a 3.4-m spectrograph. The spectra to be compared were recorded on photographic plates in the spectral range from 250 nm to 430 nm. Strong molecular band systems of OH, NH, and N ₂ ⁺ were observed in the case of the direct current plasma. Detection limits for 27 spectral lines of 20 elements were determined for both sources yielding a slight advantage in favour of the inductively coupled plasma. The effect of sodium upon line and background intensities was investigated and found to be generally higher in the direct current plasma.

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Ein Drei-Elektroden-Gleichstromplasma im Vergleich zu einem induktiv gekoppelten Argonplasma

     

利用多功能LB-HG型雾化氢化物发生器与电感耦合等离子体原子发射光谱联用测定人发中砷、锑、汞、铅

采用多功能ＬＢ－ＨＧ型雾化氢化物发生器与ＩＣＰ－ＡＥＳ联用，测定砷、锑、铅。较传统的气动雾化法，检出限降低了１０～１００倍。标准人发样品的分析结果与推荐值相吻合。     

Determination of narciclasine in serum by reversed-phase high-performance liquid chromatography: comparison of amperometric, ultraviolet photometric and fluorescence detection

Narciclasine was determined in the blood of mice by reversed-phase high-performance liquid chromatography, using a C18 stationary phase and a mobile phase of methanol-0.025 M potassium dihydrogen phosphate (50:50, v/v) of pH 5.5. Amperometric detection at a carbon fibre array working electrode held at +1.8 V (Ag/AgCl) permitted determination down to concentrations of 10 and 15.4 ng ml-1 (at a signal-to-noise ratio of 2) in aqueous solution and in serum, respectively. Fluorescence detection (excitation and emission wavelengths of 360 and 480 nm, respectively) exhibited somewhat poorer sensitivities for aqueous and serum samples: the respective limits of detection were 25 and 32 ng ml-1 at a signal-to-noise ratio of 2. Both the amperometric and the fluorescence detection were free from interference from blood components, but the fluorescence measurement required a post-column pH adjustment. UV photometric detection at 254 nm exhibited detection limits of 15 and 65 ng ml-1 in aqueous samples and in serum, respectively, and suffered from interferences from blood components that strongly absorbed in the ultraviolet region. All three detection techniques exhibited good linearity and precision.     

Speciation analysis of iodine and bromine at picogram-per-gram levels in polar ice

Iodine and bromine species participate in key atmospheric reactions including the formation of cloud condensation nuclei and ozone depletion. We present a novel method coupling a high-performance liquid chromatography with ion chromatography and inductively coupled plasma mass spectrometry, which allows the determination of iodine (I) and bromine (Br) species (IO ₃ ^? , I^?, Br^?, BrO ₃ ^? ) at the picogram-per-gram levels presents in Antarctic ice. Chromatographic separation was achieved using an IONPAC® AS16 Analytical Column with NaOH as eluent. Detection limits for I and Br species were 5 to 9 pg g^?1 with an uncertainty of less than 2.5% for all considered species. Inorganic iodine and bromine species have been determined in Antarctic ice core samples, with concentrations close to the detection limits for iodine species, and approximately 150 pg g^?1 for Br^?. Although iodate (IO ₃ ^? ) is the most abundant iodine species in the atmosphere, only the much rarer iodide (I^?) species was present in Antarctic Holocene ice. Bromine was found to be present in Antarctic ice as Br^?.