Discrimination of line overlap interference and analysis line selection in ICP spectrometer analysis
ICP spectrometer has become one of the most conventional analytical instruments. There are more and more people using ICP emission spectrometer for elemental analysis, and its application field is also wider and wider. Therefore, people engaged in ICP emission spectrum analysis continue to follow. increase. The spectrum of the ICP spectrometer is very much. Many friends don't know which line to use in the analysis. Let's briefly talk about it here. Various Linings PVC Coated Gloves Anti-Slip Rubber Dots Glove,Various Linings Pvc Coated Gloves,Custom Slip Resistant Gloves,Orange Winter Coated Gloves JINAN SHANDE SECURITY TECHNOLOGY CO., LTD , https://www.sdsxlb.com
The same is true for ICP spectrometer analysis, especially for spectral interference caused by line overlap. Because the spectrum of the emission spectrum is very large, for a simple structure element, the number of lines is at least two digits, and for those elements with complex structures, the number of lines is 5 digits. the above.
This is not difficult to understand, because gaseous free atoms can be excited after gaining energy, and each atom has many excited states. If the energy obtained by a gaseous free atom exceeds its ionization energy, it will also ionize. If the energy continues to be obtained after ionization, it will also be excited to transition to the excited state of the ion, so the atom of each element includes its ion. There will be many, many levels of energy.
Because there are so many spectral lines in the atomic emission spectrum, when the dispersive power and resolution of the spectroscopic system of the ICP emission spectrometer are insufficient, some spectral lines with small wavelength differences will partially or completely overlap. Spectral interference. To date, there is no spectroscopy instrument that can separate all atomic lines. This is why we have to deal with spectral interference when performing atomic emission spectroscopy. It is also a good thing that the spectral line is a bad thing, because it provides us with more choices while easily forming interference, and provides us with a very rich atomic structure information, which is why the qualitative analysis of the emission spectrum is accurate and reliable. important reason.
Fortunately, in the past emission spectroscopy instruments, there is a multi-channel instrument that uses a photomultiplier tube to detect the line intensity of the emission spectrum. Because it can perform multi-element simultaneous measurement, usually only one fixed wavelength is provided for each element. The spectral line, inevitably to solve the spectral interference caused by spectral line overlap, so in the past there have been many people specializing in this research, so many good and effective correction methods have been established, among which Now one of the more widely used direct reading instrument software is the interference coefficient method, and the other is the spectral line analysis method.
Knowing how the line overlap interference is corrected, the next question is how to judge and identify the interference. Today's full-spectrum direct-reading instruments use solid-state imaging detectors to record and measure the intensity of the line's emission. They generally have the function of presenting line profiles. We can directly observe the line of analysis through this function, even though They are all peak-shaped, but they may appear in various shapes depending on the elements or the lines. They may be symmetrical and asymmetrical, wide and thick, slim, and handsome. We can use this feature to see the wing overlap very intuitively.
For fully overlapping or nearly completely overlapping lines, the situation may be more complicated, because in general, the instrument software will provide more than one analysis line for each element, which can be selected for analysis and determination. For several spectral lines, if all the spectral lines can produce consistent results, it means that the analysis results are accurate and reliable, and there is no influence of the spectral line interference lines. Otherwise, if the results are obviously high, it is likely that there is complete overlap or near completeness. Overlapping interference lines. If we separate the matrix and subtract the blank, the spectral line that was previously significantly higher is no longer high, then it is generally possible to further determine that it has completely overlapping or nearly completely overlapping spectral line interference.
1. Try to select a spectrum with no interference or interference. The size of the interference can be judged by the self-emission intensity of the analysis line and the interference line and the relative content in the sample.
For the selection of the analysis line is appropriate, the final depends on the quality of the analysis. If the analysis result is accurate, there is no doubt that the analysis line is selected. Otherwise, it will be analyzed according to the specific situation, because it also involves the sample. The pre-treatment and water and reagent blanks also involve matrix matching of standard and analytical samples, as well as questions about whether the content of the measured elements in the sample solution is within the detection range of ICP emission spectroscopy.
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