Induction-coupled plasma spectral analyses

R. K. Winge, V A. Fassel, V. J. Peterson, and M. A. Floyd. Inductively Coupled Plasma Atomic Emission Spectroscopy An Atlas of Spectral Information. Elsevier, Amsrerdam, 1985. ICP-OES specrral scans near emission lines usefol for analysis. 

Segal, I., Kloner, A., and Brenner, I. B. (1994). Multielement analysis of archaeological bronze objects using inductively coupled plasma-atomic emission spectrometry -aspects of sample preparation and spectral-line selection. Journal of Analytical Atomic Spectrometry 9 737-744. 

In inductively coupled plasma-mass spectrometry, isobaric interference occurs between species with the same mass and charge. Interference can be eliminated if the mass spectral resolution is sufficiently great or by dissociating an interfering polyatomic species with a collision cell. When laser ablation is used to sample a solid, matrix-matched standards are often necessary for quantitative analysis. 

Inductively coupled plasma mass spectrometry has been used for the analysis of uranium. However, the technique suffers from spectral interferences and it has relatively poor detection limits. 

Marshall, J., and Franks, J. (1990) Multielement analysis and reduction of spectral interferences using electrothermal vaporization inductively coupled plasma-mass spectrometry. Atomic Spectroscopy 11, 177-186. 

Inductively Coupled Plasma-Mass Spectrometry ICP-MS has been accepted as a powerful technique for elemental and isotopic analysis [21D25]. It is characterized by a linear dynamic range of Eve to six orders of magnitude, rapid multielemental analysis, comparative freedom from spectral interferences, and LoDs in the range of 10D100 pg mL-1 for most elements. This makes it ideal for the multielemental analysis of food samples on a routine basis. 

Knowledge of the atomic spectra is also very important so as to be able to select interference-free analysis lines for a given element in a well-defined matrix at a certain concentration level. To do this, wavelength atlases or spectral cards for the different sources can be used, as they have been published for arcs and sparks, glow discharges and inductively coupled plasma atomic emission spectrometry (see earlier). In the case of ICP-OES, for example, an atlas with spectral scans around a large number of prominent analytical lines [329] is available, as well as tables with normalized intensities and critical concentrations for atomic emission spectrometers with different spectral bandwidths for a large number of these measured ICP line intensities, and also for intensities calculated from arc and spark tables [334]. The problem of the selection of interference-free lines in any case is much more complex than in AAS or AFS work. 

ICP-ESA Inductive coupled plasma - emission spectral analysis... 

Inductively coupled plasma (ICP) and direct current plasma (DCP) atomic emission spectrometry have become widely accepted techniques for simultaneous multielemental analysis. These techniques are highly sensitive and have a very wide dynamic range. A wealth of information is contained in the emission signal, including several atomic and ionic emission lines for each element in the sample. In even the simplest sample, there are thousands of observable spectral lines. To make full use of this enormous spectral information the analyst requires an instrument capable of observing a very wide spectral range simultaneously, preferably from 190 nM to 800 nM with a resolution of approximately 0.01 nM. 

Some of the problems In forensic analysis related to sample matrix and detection limits can be found In other analytical laboratories as well. Besides the enhancement and suppression effects on analyte signals described by Mr. Mldklff In the previous section. Dr. Watters and Ms. Wood of the National Bureau of Standards provide some specific Information regarding matrix effects on spectral background. Background level and spectral structure comprise the chief source of measured signal when blanks are being measured for detection limit estimation. Their example Is taken from Inductively coupled plasma (ICP) spectrometry. 

There are different spectrophotometric techniques for analysis of contaminants in biofuels. Simultaneous detection of the absorption spectrum and refractive index ratio with a spectrophotometer for monitoring contaminants in bioethanol has been carried out by Kontturi et al., 2011. Inductively Coupled Plasma Atomic Emission Spectrometry and optical emission spectral analysis with inductively coupled plasma (ICP-OES) have also been used to analyze biodiesel samples for trace metals (ASTM, 2007 ECS, 2006). An ICP-MS instrument fitted with an octopole reaction system (ORS) was used to directly measure the inorganic contents of several biofuel materials. Following sample prepwation by simple... 

European Committee for Standardization (ECS) (2006). Fat and oil derivatives -Fatty acid methyl ester (FAME) -Determination of Ca, K, Mg and Na content by optical emission spectral analysis with inductively coupled plasma (ICP-OES). EN 14538, 2006. 

Inductively coupled plasma (ICP) ionization has currently assumed a more prominent role in the field of elemental and isotopic analysis [1,2,14]. It is apphcable to solid-state as well as to solution-phase samples. A plasma is defined as a form of matter that contains a significant concentration of ions and electrons. The heart of this technique is a plasma torch, first developed as an efficient source for optical emission spectroscopy (OES) [15,16]. Multielement analysis with OES has, however, some serious shortcomings, such as complicated spectra, spectral interferences, high background levels, and inadequate detection of some rare-earth and heavy elements. The high ionization efficiency (>90%) of ICP for most elements is an attractive feature for its coupling to mass spectrometry. 

With respect to the analyte, it must be taken into account that the matrix is soluble and stable in the digestion method selected. The concentration of the analyte in the sample should also be considered, since lesser the concentration greater is the need to obtain low quantification limits. The limits of detection and elemental interferences of the matrix can depend on the matrix-analyte-acid combination. The analysis technique should take extreme care to avoid interferences in the final detection. Thus, when inductively coupled plasma mass spectrometry is employed, the use of H2SO4 and HCl can cause important spectral interferences that can completely annul the results. 

Van derVelde-Koerts,T, and De Boer,J. L. M. (1994). Minimization of spectral interferences in inductively coupled plasma mass spectrometry by simplex optimization and nitrogen addition to the aerosol carrier for multi-element environmental analysis.. Anal. At. Spectrom. 9(10), 1093. 

Vanhoe, H., Goossens, J., Moens, L., and Dams, R. (1994). Spectral interferences encountered in the analysis of biological materials by inductively coupled plasma mass spectrometry. J. Anal. At. Spectrom. 9(3), 177—186. 

Spectral methods (spark source mass spectrometry SSMS, secondary ion mass spectrometry SIMS, inductively coupled argon plasma for emission spectroscopy ICAP-ES) which avoid separation steps are increasingly applied for multi-element analysis. Hot extraction is used for 0, N, H determinations. Oxygen is also determined by activation analysis, nitrogen after adaptation of classical methods (micro-Kjeldahl). Combination and comparison of different, independent methods are desirable, but hampered by the often limited availability of samples of actinides. 

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