ICP-OES ACTIVA-M - HORIBA Jobin Yvon - #2

The classical way of conducting the determination of an element in ICP-AES is to select a single line with adequate sensitivity and free from spectral interferen­ces. If the nature and the concentration of the matrix elements are not constant, there is a risk of unexpected spectral interferences, which can become significant, and the concentration deduced from the use of a single line may then be wrong, with no means of detecting the bias.

When the analyte peak is interfered, a positive bias will be generated, while the bias may be negative when the matrix influences the background correction.

The ideal approach is to conduct multi-line analysis, a far more efficient way of taking benefit from all the available information of the plasma. With the use of

multi-channel detection such as CCD detectors, the amount of spectral information has significantly increa­sed and it is then possible to have acquisition of the full UV-visible spectrum for each element, and to use multiple lines per element.

Multi-line analysis makes the detection of outliers pos­sible, thereby coping with unexpected spectral interfe­rences and, consequently, improving the reliability of the results.

S³-base (Single-element Spectra, Spectroscopic data) is essential to take full benefit of multi-line analysis. Such a base responds to the need of reliability in terms of wavelength compilation and line intensity, because currently available wavelength tables are not based upon ICP experiments, but on alternative radiation sources such as arc or spark.

As a consequence, ICP users must perform tedious ex­periments for line selection by overlapping spectra of the different elements expected in the sample, to find a sensitive line free from spectral interferences. When the multi-line concept is used, method development becomes even more complex.

Thanks to the specific instrumental configuration of ACTIVA-M, single-element, entire spectrum acquisi­tions were performed under standard ICP operating conditions.

This allowed the assignment of ICP lines and the cal­culation of spectroscopic data, which led to the crea­tion of a base with double access: a collection of single-element spectra and a data base containing wa­velengths, ionisation state, excitation energy, sensitivity (S), background level, limit of detection (LOD), maxi­mum concentration below detector saturation (C_max) and line width (FWHM).

More than 50 000 lines have been, then, assigned, with the corresponding spectroscopic data varying for example from 60 lines for Pb, 183 for Ca, ~3000 for Cr to ~5200 lines for Th.

1.6 x 10⁷ 1.4 x 10⁷ 1.2 x 10⁷ 1.0 x 10⁷ 8.0 x 10⁶ 6.0 x 10⁶ 4.0 x 10⁶ 2.0 x 10⁶ 0.0

Because method development and its validation may be a complex task, performing multi-line analysis implies :

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Wavelength (nm)

S³-base provides appropriate spectroscopic data information for multi-line selection with MASTER.

^ List of sensitive lines

Lines that can be used over ^ a given concentration range

^ Potential spectral interferences