Simultaneous determination of the Lanthanides by tungsten coil atomic emission spectrometry

Abstract

The fourteen Lanthanides are determined by tungsten coil atomic emission spectrometry. Twentyfive microlitre sample aliquots are placed directly on the coil. A simple constant current power source carefully dries the sample prior to analysis. During this dry step, the voltage is monitored to prevent over heating. This allows for shorter atomization programs, while improving sensitivity and coil lifetime. During the 5 s high temperature atomization step, the emission signals for as many as seven Lanthanides are determined simultaneously in the same 55 nm spectral window. The analytical figures of merit for all 14 natural Lanthanides are reported and compared with nitrous oxide flame atomic emission spectrometry. Tungsten coil atomic emission concentration detection limits are in the range 0.8 (Yb) to 600 (Pr) mg l À1 , and are lower than those for the flame in most cases. The absolute detection limits are near or below the ng level: significantly lower than the flame detection limits due to the smaller sample volume required. A three-fold improvement in detection limit may be realized by combining the signals for multiple emission lines for a single element. The method is applied to the determination of seven Lanthanides in a soil sample acquired from the National Institute of Standards and Technology. After a simple acid extraction, the measured values agree with the reported values with 95% confidence in all cases but one, Yb. Finally, a conditioning program for new tungsten coils enhances reproducibility and maximizes the emission signal.

Tungsten coil atomic emission spectrometry combined with dispersive liquid–liquid microextraction: A synergistic association for chromium determination in water samples

“…Accordingly, devices based on tungsten coil as atomizer, such as atomic emission spectrometry (WCAES) is presented as an attractive option for use in detection of metals. Tungsten coil AES was proposed in 2005 by Rust et al [11] and several applications were developed [12][13][14][15]. However, the low temperature of the gas phase when using the tungsten coil atomizer [16] limits its application to elements with low excitation energies.…”

A Portable Tungsten Coil Atomic Emission Spectrometer for the Simultaneous Determination of Metals in Water and Soil Samples

“…1). 18 The W-coil filament was extracted from a 15 V, 150 W commercially available slide projector light bulb (Osram Xenophot 64633 HXL Pullach, Germany) and secured in a laboratory designed aluminum mount. The filament is coiled in ten turns and when viewing from the side, the turns are 3 mm high and together they occupy a width of 6 mm.…”

“…was 15 V, 200 W. The W-coil was heated using a previously reported atomization cycle which optimized the drying time and increased emission signal. 18 The radiation emitted by the coil during the high-temperature atomization step was collected by a 50-mm diameter focal length fused silica lens. A 1:1 image of the coil was formed by the lens on a light blocking aperture (4 mm diameter).…”

“…This indicated that the Ocean Optics USB4000 spectrometer was less sensitive compared with the benchtop spectrometer and chilled CCD detector described previously. [16][17][18] However, advantages associated with the portable spectrometer included its relatively large spectral window (200 nm compared to 50 nm reported previously), its low power requirement (provided by the laptop computer), and its operation at ambient temperature (requiring no circulating water). In addition, the Yb 555.6 nm line was observed with this system.…”

“…Limits of detection for most of the lanthanides were better than those reported for flame emission spectrometry. [17][18][19][20] In the current work, a small, portable CCD detector is used to improve the portability of the WCAES instrument. Fifteen elements are used to evaluate the system, and optimize method parameters such as sample volume, atomization power, and heating rate.…”