[Peak-width quantitation for flow-injection microwave plasma torch-atomic emission spectrometry].
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Abstract:
A peak-width quantitation method for flow-injection microwave plasma torch atomic emission spectrometry was proposed. Sensitivity and linearity of the peak-width quantitation were investigated under different emission intensities. Recoveries of Zn2+, Cu2+ and Ag+ existing in various matrix were determined by using the peak-width quantitation, and were compared with the results obtained by the peak-height method. The results indicated that the peak-width quantitation can efficiently remove matrix interference in the FI-MPT-AES system, and expand its linear determination range. The peak-width quantitation (recovery: 92%-107%) surpasses conventional peak-height method (recovery: 61.3%-122%). Optimized determination conditions were as follows: the sampling volume was 350 mL, the flow rate of the carrier was 1.5 mL x min(-1), the power of microwave was 110 W, the flow rates of the carrier gas and working gas (argon) were 1.4 and 0.4 L x min(-1), respectively.Keywords:
Matrix (chemical analysis)
Torch
Atomic emission spectroscopy
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Two-dimensional gas
Flame ionization detector
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The method for determination of phosphorus in steel by multi-component spectral fitting(MSF)-inductively coupled plasma atomic emission spectrometry (ICP-AES) was introduced.In this paper,the MSF method was used to correct spectral interference and the spectral line with the wavelength of 213.617 nm was selected as the analysis line for phosphorus.Samples were dissolved in nitric acid (1+5) and concentrated hydrochloric acid,and then without any separation were determined by ICP.The influence of instrument working parameters on the results were discussed.The optimal instrumental conditions were determined as following:13 mm of observation height,0.7 L/min of nebulizer gas flow rate and 1 300 W of RF power.The method has a wide linear rang of 0.05～100 mg/L with the linear correlation coefficient of 0.999 8.The detection limit was 0.041 1 mg/L with relative standard deviations of 1.8% and the recovery was in the range of 96.1%～100.8%.The method is accurate and simple with satisfactory precision and accuracy,and is suitable for the determination of phosphorus in steel.
Hydrochloric acid
Nitric acid
Accuracy and precision
Atomic emission spectroscopy
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A 22 mm torch has been developed and characterized for use in inductively coupled plasma atomic emission spectrometry. A stability curve (radio-frequency power vs. outer-gas flow rate) was constructed for the modified torch which indicates that the larger torch can be operated at flow rates and powers similar to those for an 18 mm torch. Four operating parameters were optimized by means of a simplex algorithm. Several criteria for optimization were used, including net signal intensity for Ca(II); signal-to-background noise (S/N B ) for Ca(II), Mg(II), and Fe(II); and the Mg(II)/Mg(I) line-intensity ratio. The results from these simplex optimizations are compared. Mg(II)/Mg(I) was used as the final criterion for optimization for both the 22 mm and the conventional 18 mm torches. Two-dimensional spatial images of the larger plasma were compared with those of a conventional plasma (18 mm) for a variety of plasma emission features. Detection limits were determined in two ways for a suite of analytes under conditions optimized for the Mg(II)/Mg(I) ratio. The 18 mm torch affords the better limits of detection by an averaged factor of 1.5 because its smaller volume gives a lower background level. Finally, nitrogen molecular-ion emission maps were collected from both the 22 mm and a conventional 18 mm plasma as an indicator of the degree of air entrainment in the plasma. Several spatial regions of the plasma have been evaluated on the basis of the local intensity of N 2 + emission for their applicability for use in atomic emission and atomic mass spectrometry. The 22 mm torch shows a larger region in and around the central channel of low or zero N 2 + emission and so may be better suited for sampling into a mass spectrometer.
Torch
Plasma torch
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Cold vapor cavity ringdown spectroscopy has been successfully applied to the detection of elemental mercury. Using an absorption cell 0.18 m in length, detection limits of 0.027 and 0.12 ng were obtained using peak area and peak height measurements, respectively. For the peak area measurement, this corresponds to a gas phase concentration of less than 25 ng m−3. For comparison, using a similar absorption cell, standard AAS yielded a Hg detection limit (peak height) of 9 ng, (gas phase concentration of ≡ 8.3 μg m−3).
Mercury
Elemental mercury
Vapor phase
Parts-per notation
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Two-dimensional gas
Isothermal process
Two-Dimensional Chromatography
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Significant advancement has been achieved in single-particle analysis with the new conical ICP torch in terms of sensitivity, precision, and throughput. Monodisperse desolvated particles of eight elements (Na, Al, Ag, Sr, Ca, Mg, Fe, and Be) were injected into the conical torch, and signal peak characteristics, precision, and kinetics of atomization and ionization were investigated with optical spectrometry. A particle introduction system was designed to ensure a smooth and uninterrupted delivery of desolvated particles to the plasma. The important finding is that, compared with the conventional Fassel torch, the conical torch offers a 1.5–8 times higher peak intensity, a 2–4 times higher peak area, a 2 times shorter peak width, and higher precision (i.e., a 1.5 times lower RSD for peak intensity and a 1.8 times lower RSD for peak width on average). Also, mass detection limits were found to be similar or up to 8 times lower (i.e., 2 times lower diameter detection limit) for the conical torch. The results indicate that these features are due to a much higher electron density, excitation temperature, and robustness which, together with an improved particle trajectory, lead to rapid vaporization/atomization/ionization of particles with minimized atom/ion cloud diffusion. Finally, the torch was demonstrated to be capable of analyzing single particles at a rate of at least 2000 particles per second with high sensitivity and precision. On the basis of these results, the conical torch is expected to bring about new possibilities in ICP-based single-particle analysis.
Torch
Plasma torch
Particle (ecology)
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Experimental variables in continuous flow hydride generation inductively coupled plasma-optical emission spectrometry (CF-HG-ICP-OES) were optimized for determination of bismuth. Concentrations of NaBH4, HCl, and NaOH, flow rates of NaBH4, sample solution, waste and carrier argon, radio frequency power, lengths of reaction, and stripping coils were optimized to obtain lower detection limits. Under optimum conditions, the detection limit was calculated as 0.16 ng mL−1, and the calibration plot was linear between 1.0–50.0 ng mL−1. An improvement in detection limit of 5.75 times by CF-HG-ICP-OES was reached vs. ICP-OES. Relative standard deviation (RSD) for ten replicate measurements of 10.0 ng mL−1 Bi was calculated as 3.9%. Effect of possible interferic ions on Bi signal was evaluated. Accuracy of method was verified by using a standard reference material, SRM 1643e. Results found for Bi were in satisfactory agreement with certified values. The proposed method was then employed to determine trace concentration of Bi in milk samples. Bi amounts in samples were found in the range from lower than the quantitation limit to 14.5 ng mL−1, whereas Bi concentrations were lower than the detection limit in three samples.
Bismuth
Certified reference materials
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Micro computer
Dilution
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An introduction system for liquid micro-samples in inductively coupled plasma atomic-emission spectroscopy is described that allows the injection of 5–500-µl volumes into a rapidly flowing carrier reagent stream leading to the nebuliser. The effect on analyte signal was studied as a function of flow-rate, injection volume and sample concentration. It is shown that the carrier flow-rate determines the response time, sensitivity, precision and sample carry-over in the nebuliser. By the use of relatively rapid flow-rates of up to 7.5 ml min–1, fast injection of 10-µl samples is achieved at an injection rate of 240 h–1 with a relative standard deviation of 1.5% for a single-element analogue readout. Digital readout is used for multi-element determinations with similar or better precision. Detection limits of the order of 0.1 mg l–1 are obtained for 10-µl injections, limited by the volume injected, with a proportionate decrease in detection limit for increasing volumes.
Atomic emission spectroscopy
Flow injection analysis
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The most significant advance in atomic absorption spectroscopy in recent years has been the development of flameless devices for the generation of atomic vapor. These devices have been widely discussed. The sample is completely evaporated in less than 1 sec, which requires the use of a fast response recorder. The parameter most widely used for measuring signals in flameless atomic absorption spectroscopy is peak height, where peak height is proportional to concentration of atomic vapor produced by the tube or filament atomizer. An alternative method for measuring the absorbance signal is to measure the integrated absorbance, i.e., the area under the peak. One way to measure the area under the peak is to cut and weigh the recorder chart tracings. Improved precision and increases in linear ranges have been reported using peak area. Recently, Sturgeon et al. examined the results of preliminary investigation of the potential of an electronic integration method vs the peak height method of measuring signals generated by Varian's carbon rod atomizer (CRA 63) and Perkin-Elmer's hollow graphite atomizer (HGA-2100). Using a programmable calculator, Bancroft et al. showed that the peak area method gives better results than the peak height method.
Absorbance
Monochromator
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