Lead in micro-samples of whole blood by Rhenium-cup in-torch vaporization-inductively coupled plasma-atomic emission spectrometry (ITV-ICP-AES)

A method is described for screening of lead in diluted micro-samples of whole blood by a Re-cup, in-torch vaporization (ITV) sample introduction system for inductively coupled plasma-atomic emission spectrometry (ICP-AES). The method required minimum sample preparation. For example, blood was diluted with water and Triton X-100 in 0.5% HNO3 and, 5 microL were deposited on the Re-cup of the ITV sample introduction system. Samples were dried and charred in-situ prior to vaporization. Levels 1, 2, 3 and 4 (Pb concentration: 4.04, 10.3, 20.59 and 39.36 microg/dL) of NIST Standard Reference Material 955b 'lead in bovine blood' were used to test accuracy and precision. Accuracy was acceptable and precision was below 10% for levels 2-4 and 15% for level 1.     

A novel bottom-viewed inductively coupled plasma-atomic emission spectrometry

A novel optical configuration for inductively coupled plasma (ICP)-atomic emission spectrometry is presented. Plasma emission is measured axially via the bottom end of the ICP torch. Analytical performance, such as increase in signal-to-background ratio (SBR) over radially viewed ICP and linear dynamic range, is comparable to that of end-on axially viewed ICP reported in the literatures. Under typical ICP operating conditions (forward power=1.0–1.6 kW, central channel gas flow rate=0.8–1.4 l/min), SBR is generally five times or more that of radial-viewing mode (observation heights=3–20 mm) for atomic lines of elements of low to medium ionization potential (Na, K, Sr and Ba). The enhancement factor in SBR is two to four times for ionic lines (e.g. MgII) and atomic lines of elements of high ionization potential (Zn). The influence of ICP forward power and carrier gas flow rate on analyte emission intensity and SBR were also studied. Similar to radially viewed ICP, as forward power increases, the net emission intensity increases and SBR decreases. Using a constant flux of analyte aerosols, the net intensity decreases as the central channel gas flow rate increases. No trend of SBR vs. central channel gas flow rate, however, is found. The linear dynamic range starts and ends at analyte concentration 0.5–1 order of magnitude lower than the corresponding radial-viewing mode. As a result, the span of linear dynamic range is similar for all viewing modes. Matrix effects of K and Ca on atomic lines are different from those reported for end-on axially viewed ICPs, probably due to the difference in the plasma regions that were probed. The matrix effects on ionic lines, however, are similar in magnitude.     

Speciation of arsenic(III) and arsenic(V) by inductively coupled plasma-atomic emission spectrometry coupled with preconcentration system

A novel and simple flow-based method was developed for the simultaneous determination of As(III) and As(V) in freshwater samples. Two miniature columns with a solid phase anion exchange resin, placed on two 6-way valves were utilized for the solid-phase collection/concentration of arsenic(III) and arsenic(V), respectively. As(III) could be retained on the column after its oxidation to As(V) species with an oxidizing agent. The collected analytes were then sequentially eluted by 2 M nitric acid and introduced into ICP-AES. Potassium permanganate was examined as potential oxidizing agent for conversion of As(III) to As(V). The standard deviation of the analytical signals (peak height) for the replicate analysis (n = 5) of 0.5 μg l⁻¹ solution were 3 and 5% for As(III) and As(V), respectively. The limit of detection (3σ) for both As(III) and As(V) were 0.1 μg l⁻¹. The proposed system produced satisfactory results on the application to the direct analysis of inorganic arsenic species in freshwater samples.     

Lead determination in whole blood by laser ablation coupled with inductively coupled plasma mass spectrometry

This work describes a simple procedure for blood lead level determination. The proposed method requires little sample pretreatment and subsequent direct analysis of a dried blood spot on a filter membrane using laser ablation coupled with inductively coupled plasma mass spectrometry (LA-ICP-MS). In general, LA-ICP-MS studies are somewhat limited by the lack of matrix-matched standards for calibration purposes. Here we describe aqueous standard calibration and matrix-matched calibration methods. This method was validated by analysis of the reference materials. With the matrix-matched calibration method, the recovery ranged from 97.8% to 112.8%, while the aqueous standard calibration method ranged 90.4% to 122.4%. The lower detection limit was estimated as 0.1 ng mL⁻¹. The determination precision, expressed as the relative standard deviation (RSD), was not worse than 10% for all results. A sample throughput of approximately 5 min per sample made it possible to rapidly screen a large number of samples.     

Slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry for the direct determination of metal impurities in aluminium oxide ceramic powders

A new analytical procedure for the direct determination of metal impurities (Cr, Cu, Fe and V) in aluminium oxide ceramic powders by slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-AES) is reported. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization of impurity elements in aluminium oxide ceramic powders from the graphite tube. A vaporization stage with a long ramp time and a short hold time provided the possibility of temporal analyte-matrix separation. The experimental results indicated that a 10 microL 1% m/v slurry of aluminium oxide could be destroyed and vaporized completely with 600 micrograms PTFE under the selected conditions. Two aluminium oxide ceramic powder samples were used without any additional pretreatment. Analytical results obtained by using standard addition method with aqueous standard solution were checked by comparison of the results with pneumatic nebulization (PN)-ICP-AES based on the wet-chemical decomposition and analyte-matrix separation. The limits of detection (LODs) between 0.30 microgram g-1 (Fe) and 0.08 microgram g-1 (Cu) were achieved, and, the repeatability of measurements was mainly better than 10%.     

Slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry for the direct determination of metal impurities in aluminium oxide ceramic powders

A new analytical procedure for the direct determination of metal impurities (Cr, Cu, Fe and V) in aluminium oxide ceramic powders by slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-AES) is reported. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization of impurity elements in aluminium oxide ceramic powders from the graphite tube. A vaporization stage with a long ramp time and a short hold time provided the possibility of temporal analyte-matrix separation. The experimental results indicated that a 10 μL 1% m/v slurry of aluminium oxide could be destroyed and vaporized completely with 600 μg PTFE under the selected conditions. Two aluminium oxide ceramic powder samples were used without any additional pretreatment. Analytical results obtained by using standard addition method with aqueous standard solution were checked by comparison of the results with pneumatic nebulization (PN)-ICP-AES based on the wet-chemical decomposition and analyte-matrix separation. The limits of detection (LODs) between 0.30 μg g^–1 (Fe ) and 0.08 μg g^–1 (Cu) were achieved, and, the repeatability of measurements was mainly better than 10%. Received: 28 August 2000 / Revised: 1 November 2000 / Accepted: 12 November 2000     

Erbium determination in preforms of optical fibres by inductively coupled plasma-atomic emission spectrometry

Erbium which is used in the composition of heavy metal fluoride optical fibres was determined in preforms of these materials by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The new analytical procedure developed comprises: solid sample dissolution, via an alkaline fusion with sodium carbonate, and acid leaching with dilute hydrochloric acid, and measurements of emission intensities of 337.276 nm. This method has a detection limit of 31 ng/ml and a reproducibility of 0.90% r.s.d.     

Determination of arsenic in homeopathic drugs by bromide volatilization-inductively coupled plasma-atomic emission spectrometry

Arsenic in homeopathic drugs was determined by coupling a volatile generation with inductively coupled plasma-atomic emission spectrometry. The method is based on the chemical vaporization of arsenic(III) with bromide ions in sulfuric acid media using a batch procedure and subsequent introduction of the gaseous analyte into the plasma torch. The main and interactive effects of the experimental variables affecting this method were evaluated by a 2-level full factorial design. In optimized conditions by Simplex, the method shows an absolute detection limit (3 s) of 0.28 microg for the injection of 230 microL sample. The precision (% relative standard deviation) of the determination was 4.2% at a level of 50 microg/mL As(III) (n = 5). The interference effect of various ions on the arsenic signal was evaluated.     

电感耦合等离子体原子发射光谱法测定自来水中的8种元素

采用电感耦合等离子体原子发射光谱法(ICP-AES)测定了化学实验室自来水中铝、钾、锶、钡、锰、钴、钼、硒8种元素的含量;对仪器的工作条件进行了优化,确定了各元素的分析波长和检出限.结果表明,所述方法可以方便地用于测定化学实验室自来水样品中的8种元素,相对标准偏差为0.08%～6.90%.     

Determination of impurities in highly pure platinum by inductively coupled plasma-atomic emission spectrometry

In this work, a cyclone spray chamber system is used in conjunction with an inductively coupled plasma-atomic emission spectrometer instead of the conventional Scott-type chamber system to reduce the lower limit of detection achieved by the instrument, and an internal standard element (Y) is introduced to eliminate the effects caused by the drift in the plasma background level. An ICP-AES method for the determination of 13 impurity elements in a highly pure platinum sample has been developed. In this method, it is not necessary either to add a platinum matrix to the calibration standard or to separate and concentrate the elements to be determined in the samples. The effect of the platinum matrix on the elements to be analyzed is corrected for by a background equivalent concentration subtraction method. The determination ranges of the method are as follows: 0.00010-0.0050% for Mg, Mn, Cu, Ag, Fe and Zn; 0.00030-0.015% for Au, Ir, Ni and Pb; 0.00050-0.025% for Rh and Al; and 0.00080-0.040% for Pd. The method is simple, rapid and accurate, and can be applied to the analysis of 99.9–99.995% pure platinum.     

Development and characterization of bottom-viewed inductively coupled plasma-atomic emission spectrometry

In bottom-viewed inductively coupled plasma-atomic emission spectrometry (BV-ICP-AES), emission from the central channel of the plasma is measured axially from the bottom of the plasma. A straight quartz tube was used as a hollow light pipe (HLP) to collect plasma emission in this study. The HLP also serves as an injector for aerosols transport and injection into the ICP. The optical characteristics of HLPs with the original reflective surface and roughened outer surface are reported. The roughened HLP is effective in rejecting light beams that are not in line with the HLP. The transmission efficiency of the HLP, however, is high (> 70%) for light beams from a source that has the same dimension as the entrance of the HLP and is flush with the HLP. The HLP is effective in rejecting background emission from the core of the plasma that encircles the plasma central channel and yet efficient in light collection from the central channel of the plasma.     

The application of chemical modification in electrothermal vaporization-inductively coupled plasma atomic emission spectrometry

In this paper, several fluoride chemical modifiers have been tested for electrothermal vaporization-inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) determination of different volatile elements, such as refractory element Ti, medium volatile element Ni and easy volatile element Pb. Reagents tested include polytetrafluoroethylene (PTFE), NH(4)F, NaF and CuF(2).2H(2)O. The best overall results are obtained using 6% PTFE added to sample. Under the compromise operating conditions, the detection limits of analytes are in the range of 0.8-59 ng ml(-1) and the calibration curves are linear for over three orders of magnitude. The direct determination of Ti, Ni and Pb in GBW 08505 tea leaves reference sample is shown as an example of PTFE chemical modification.     

Qualities related to spectra acquisition in inductively coupled plasma-atomic emission spectrometry

As many elements emit line-rich spectra in ICP-AES, the role of the resolution of the dispersive system has been considered as crucial not only to minimize spectral interferences but also to improve signal-to-background ratios. Resolution is mainly based on the line width measured at half of the peak intensity. Because of the availability of modern gratings, the practical resolution is no longer limited by the diffraction patterns produced by the grating, but is mainly bandpass and optical aberration limited. High resolutions of 5 pm may be obtained in the UV, which has to be compared with the physical line widths in the range 1–6 pm. However, such a high resolution cannot be achieved in the visible region because it is no longer possible to use a high line number for conventional gratings and high diffraction orders for echelle gratings. Moreover, the resolution concept does not consider the line wings, which are of concern for background correction. It is then suggested a measurement of the line profile at 1% of the peak intensity and a comparison with that measured at 50%. Because of the current possibility to have acquisition of the entire, or at least large portions of the UV-visible spectra, wavelength reproducibility may become the most important parameter to facilitate data processing such as spectra addition and subtraction, filtering, deconvolution and line correlation.     

Evaluation of spray chambers for use in inductively coupled plasma-atomic emission spectrometry

A laboratory-built spray chamber featuring aerosol collection at the centre of the chamber by means of a funnel is described and compared with a commercially available, dual tube chamber. The influence of some chamber design parameters on the emission signal intensity and stability, the nebulizer efficiency and chamber clean-out time is studied.     

Prediction of spectral interference in inductively coupled plasma-atomic emission spectrometry by primary computer expert system

Spectra and spectral interferences in inductively coupled plasma-atomic emission spectrometry, ICP-AES, have been simulated and predicted by a primary expert system under contrasting conditions of local temperature equilibrium (LTE) and non-LTE. In this expert system a comprehensive computer model has been applied to provide expert knowledge on an non-LTE ICP discharge, analyte ionization and excitation, and spectral line shape. The system also includes several databases to supply the calculation with spectral and elemental parameters. Some typical examples are illustrated, with satisfactory outcomes. It is found that predictions under non-LTE conditions are much closer to the reality than those under LTE conditions.     

电感耦合等离子体原子发射光谱法测定铈矿中微量的砷、锑

采用过氧化钠熔融试样，用盐酸调节试液酸度，对电感耦合等离子体原子发射光谱（ICP－AES）法同时测定铈矿中微量砷和锑进行了研究，考察了铈基体及共存元素，试液酸度及介质等因素对砷和锑的光谱和非光谱影响。     

Speciation of magnesium in rat plasma using capillary electrophoresis-inductively coupled plasma-atomic emission spectrometry

A new method for speciation analysis of magnesium species and quantification of free magnesium concentrations in rat plasma was developed by on-line coupling of CE with inductively coupled plasma-atomic emission spectrometry (ICP-AES). Baseline separation of seven magnesium species was achieved by using a 120 cm (100 microm internal diameter) fused-silica capillary, a 20 kV separation voltage and a solution of 50 mmol/L NaAc-HAc (pH 5.5) as electrolyte buffer. CE-ICP-AES analysis of a rat plasma sample showed the presence of seven magnesium species, one of which was identified as free Mg2+ ion by spiking a Mg2+ standard; the migration time of the Mg2+ peak in the standard and the spiked sample matched with each other. One protein-bound magnesium species in rat plasma is associated with albumin, and the other three species are combined with globulin. The concentration of free magnesium in the plasma was 14.0 mg/L. The other six magnesium species were estimated to be 4-15 mg/L. RSDs of migration time and peak area for the magnesium species from ten replicates were less than 5%. The developed method was also applied to speciation analysis of magnesium species in spiked plasma samples. The recoveries of the free magnesium species in four samples ranged from 95.8 to 103.8%.     

Evaluation of vapor generation for the determination of nickel by inductively coupled plasma-atomic emission spectrometry

Volatile species of Ni were generated by merging acidified aqueous samples and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the inlet tube of the plasma torch. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for detection. The operating conditions (chemical and physical parameters) and the concentrations of different acids were evaluated for the efficient generation of Ni vapor. The detection limit (3 sigma(blank)) was 1.8 ng mL(-1). The precision (RSD) of the determination was 4.2% at a level of 500 ng mL(-1) and 7.3% for 20 ng mL(-1) (n=10). The efficiency of the generation process was estimated to be 51%. The possible interfering effect of transition metals (Cd, Co, Cu, Cr, Fe, Mn, Zn), hydride forming elements (As, Ge, Pb, Sb, Se, Sn, Te), and Hg on Ni signal was examined. This study has demonstrated that Ni vapor generation is markedly free of interferences.     

On-line preconcentration and simultaneous determination of heavy metal ions by inductively coupled plasma-atomic emission spectrometry

A flow injection analysis system for on-line preconcentration and simultaneous determination of Bi³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺ and Zn²⁺ in aqueous samples by inductively coupled plasma (ICP)-atomic emission spectrometry with a charge coupled detector is described. The preconcentration of analytes is accomplished by retention of their chelates with sodium diethyldithiocarbamate in aqueous solution on a solid phase containing octadecyl silica in a minicolumn. Methanol, as eluent, is introduced into the conventional nebulizer of the ICP instrument. The effects of different parameters, including preconcentration flow rate (equal to sample flow rate (SR)), eluent flow rate (ER), weight of solid phase (W) and eluent loop volume (EV), were optimized by the super-modified simplex method. The optimum conditions were evaluated to be SR 7.2 ml min⁻¹, ER 3.5 ml min⁻¹, W of 100 mg and EV of 0.8 ml. An enrichment factor of 312.5 for each analyte was obtained. The detection limits of the proposed method for Bi³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺ and Zn²⁺ were evaluated as 1.3, 1.0, 0.8, 0.3, 14.7, 0.5, 5.5 and 0.1 ng l⁻¹, respectively. The effect of several metal ions on percent recovery was also studied. The method was applied to the recovery of these heavy metals from real matrices and to the simultaneous determination of these cations in different water samples.     

Characterization of an aluminium(III)–citrate species by means of ion chromatography with inductively coupled plasma-atomic emission spectrometry detection

The aluminium(III)–citrate complex (NH₄)₄[Al₂(C₆H₄O₇)(C₆H₅O₇)₂]·4H₂O was characterized using anion exchange chromatography on-line coupled with the element specific ICP-AES detector. Time-dependent monitoring of individual species in aqueous solution at different temperatures gave information about the species stability and the decomposition pathway. The aluminium–citrate complex (NH₄)₄[Al₂(C₆H₄O₇)(C₆H₅O₇)₂]·4H₂O disintegrated via an unknown intermediary Al(III)–citrate species from which the thermodynamically stable complex [Al₃(C₆H₄O₇)₃(OH)(H₂O)]⁴⁻ was formed. The activation energy for the decomposition reaction and the pre-exponential factor were determinated to be E_a = 81.95 kJ mol⁻¹ and A = 3.62 × 10¹³ s⁻¹.