Slurry Sampling Electrothermal Atomic Absorption Research Articles

Determination of trace impurities in titanium dioxide by slurry sampling electrothermal atomic absorption spectrometry

A slurry sampling electrothermal atomic absorption spectrometry method for the determination of Al, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, Tl and Zn in powdered titanium dioxide is described. The behaviour of the titanium matrix in the atomizer and its interferences with the determination of Al, Fe, Co, Ni and Mn were studied. A tungsten carbide modified graphite tube was used to improve the signal shape and the repeatability for the determination of Fe. For all elements, except for Cd and Pb, quantification by a calibration curve established with aqueous standards was possible. No chemical modifier was used throughout in order to minimize contamination. For the contamination risk elements such as Ca, Fe, K, Mg, Na and Zn, the slurry sampling technique allows to achieve limits of detection (3 σ of the blank) 5–20 times lower than the solution technique, resulting for these elements in values of 1, 3, 0.5, 0.5, 0.9 and 2 ng g −1, respectively, and, generally being in the range of 0.2 ng g −1 (Cd) to 10 ng g −1 (Al and Tl). The results obtained by the slurry sampling technique are compared with those of other independent methods including four solution methods and neutron activation analysis.

Determination of Impurities in Boron Nitride Powder by Slurry Sampling Electrothermal Atomic Absorption Spectrometry

A slurry sampling ETAAS method for the determination of Al, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Si and Zn in powdered boron nitride is described. The main aspects in the development of the method included preparation of slurry samples, pyrolysis and atomization parameters, minimization of the matrix effect by chemical modification and calibration. The accuracy was checked by comparison of the results with those obtained by analysis of sample digests by AAS and ICP-AES. The LODs achieved were of the order of 2 (Cd) and 400 (Si) ng g -1 .

Determination of Cobalt, Nickel and Copper in Flowers, Leaves, Stem and Roots of Plants Using Ultrasonic Slurry Sampling Electrothermal Atomic Absorption Spectrometry

D. T. TAKUWA, G. SAWULA, G. WIBETOE and W. LUND, J. Anal. At. Spectrom., 1997, 12, 849 DOI: 10.1039/A701266G

Solution and slurry sampling electrothermal atomic absorption spectrometry for the analysis of high purity quartz

A slurry sampling electrothermal atomic absorption spectrometry (ETAAS) method for the determination of Al, Cr, Cu, Fe, K, Li, Mg, Mn and Na at trace and ultratrace level in high purity quartz samples has been developed. The influence of atomization temperature, internal gas flow during atomization and carbide modification of the graphite tube on the background absorption has been studied. Simple quantification via calibration curves, recorded with aqueous standards, is possible for all elements except Al. The performance and the accuracy of the slurry sampling technique are compared to those of the analysis of hydrofluoric acid digests. With both methods, the blanks could be substantially reduced by minimization of sample handling. Because of essentially higher applicable sample portions, the solution technique provides lower limits of detection for all elements excluding Al, Na and K. For the slurry sampling technique, the achievable limits of detection are in the range of 2 (Mg) to 500 (Fe) ng g −1 and for the solution technique, they are between 0.4 (Mg) and 500 (Al) ng g −1. Thus, both developed methods are well suited for ultratrace analysis of high purity quartz for microelectronic applications. The results obtained by these two ETAAS techniques are compared with those of independent methods including neutron activation analysis.

Slurry sampling electrothermal atomic absorption spectrometry for the analysis of graphite powders

A direct method for the determination of Al, Ca, Cr, Cu, Fe, K, Mg, Na, Ni, Pb, Si, Sn and Zn in graphite powder using slurry sampling electrothermal atomic absorption spectrometry is described. The influence of the refractory matrix on the atomisation behaviour of the analyte elements is examined. The method is optimised in respect of slurry preparation, pyrolysis and atomisation parameters. Except for Mg and Si, no chemical modification is necessary. The limits of detection are in the range 8–30 ng g −1 for Ca, Cr, Cu, K, Mg, Na and Zn, between 50 and 200 ng g −1 for Al, Fe, Ni, Pb and Sn, and for Si a detection limit of 800 ng g −1 is achieved. By comparison of the results with those obtained by instrumental neutron activation analysis and by various other methods used in a collaborative study, it is shown that the proposed method provides good accuracy.

Determination of mercury in fluorescent lamp cullet by slurry sampling electrothermal atomic absorption spectrometry

A method for the determination of mercury in fluorescent lamp cullet by slurry sampling ETAAS is proposed. Palladium nitrate was applied as an effective matrix modifier. The furnace programme was optimized. The stability of slurries, mercury partitioning between solid and liquid phases for different media and the influence of palladium modifier were investigated. Using the optimized conditions, a detection limit (based on a 3σ criterion) for mercury of 24 ng g–1 was achieved. For 1.55 and 2.16 µg g–1 of mercury in the phosphor sample the RSDs (n= 9) were 8.3 and 8.7%, respectively. Calibration was performed using the standard additions method. The results obtained using this method suggest that the determination of mercury in fluorescent lamp cullet can be carried out effectively and rapidly.

Determination of silicon in boron nitride by slurry sampling electrothermal atomic absorption spectrometry

A method for the determination of silicon in boron nitride by electrothermal atomic absorption spectrometry using the slurry sampling technique has been developed. The procedure was optimized with respect to chemical modification, temperature programme and slurry concentration applicable. For the reduction of otherwise strong matrix interference, magnesium nitrate proved to be the best suited chemical modifier. Calibration was performed by both the standard addition method and the calibration curve using aqueous standards. The limit of detection of the optimized procedure is 3 μg g −1. In the determination of silicon contents of 20 μg g −1, standard deviations of 8.3 and 10.5% were obtained using the standard addition and the calibration curve method, respectively.

Electrothermal vaporization inductively coupled plasma atomic emission spectrometric technique using a tungsten coil furnace and slurry sampling

A simple and inexpensive electrothermal vaporization device consisting of a double-layer tungsten coil, of the type normally manufactured for halogen lamps, was used for the simultaneous determination of Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni and Ti in aqueous suspensions of silicon carbide powder by inductively coupled plasma atomic emission spectrometry (ICP-AES). Possible interferences were investigated and background correction are discussed. Excluding Al, the limits of detection achievable were at the sub-µg g–1 and µg g–1 level. The accuracy was checked by comparison of the results with those obtained by instrumental neutron activation analysis (INAA), slurry sampling electrothermal atomic absorption spectrometry and ICP-AES involving decomposition of the sample. The precision expressed as relative standard deviation was between 3.3%(for 210 µg g–1 of Ti) and 13.5%(for 8.9 µg g–1 of Ni).

An improved electrothermal atomic absorption spectroscopy method for the determination of lithium in molybdenum oxide using slurry sampling and a tungsten atomizer

A transversely heated tungsten-tube atomizer, WETA 82, was used for the direct determination of lithium in ultra-high purity molybdenum trioxide by slurry sampling electrothermal atomic absorption spectrometry. Optimized conditions with regard to sample preparation, temperature program, possible spectral interferences and depressive effects of sample matrix were presented. Analytical performance of the conventional graphite atomizer and the tungsten atomizer were compared. Using the WETA 82 atomizer, a detection limit for lithium of 2 ng g −1 can be achieved, which is one order of magnitude lower than that for conventional graphite atomizers.

Determination of trace elements in high-purity molybdenum trioxide by slurry sampling electrothermal atomic absorption spectrometry

A method for the direct determination of Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na and Ni in high-purity molybdenum trioxide by slurry sampling electrothermal atomic absorption spectrometry is described. As a result of the substantial blank reduction achieved by using ‘selected pots’ for the performance of the slurry sampling technique, in the case of elements with high overall concentrations such as Ca, K, Mg and Na, the detection limits can be improved by two orders of magnitude, as compared with the dissolution procedure, reaching 2, 1, 0.5 and 1 ng g–1 for Ca, K, Mg and Na, respectively. Control of the blank for both the solution and the slurry techniques, the background attenuation caused by the molybdenum matrix and sample homogeneity are discussed.

Determination of the high aluminium content in suspended matter samples collected in natural waters by slurry sampling–electrothermal atomic absorption spectrometry

The problems encountered during the determination of particulate Al, as the main matrix element, in very small samples by slurry sampling–electrothermal atomic absorption spectrometry are described. In view of the high Al concentrations, a reduction in sensitivity must be achieved. The combination of the use of an alternative Al analytical line and gas-flow facility and the interference from other main matrix elements allows the determination of Al levels of up to 10% m/m in the initial solid sample. Reliability of the entire procedure was confirmed by analyses performed on three standard reference sediments.