Please suggest me options to solve this issue while analysing metals in AA20F AAS - GTA 110
Hello, unfortunately, interferences from a variety of places are inevitable and will influence the absorbing species and the radiation reaching the detector. While it does not mean that the resulting spectrum is not the spectrum of the sample, it will result in a loss in spectral detail, such as broadening of peaks and peaks in places other than where the sample absorbs. This could influence quantitative and qualitative work. Spectral deviations from background interferences can be significant at times and slight at others, but with the proper application of background correction techniques, these deviations can be minimized while enhancing the signal from the analyte.
One technique that should be done for every analysis is to obtain the signal of a blank; a substance prepared in the same manner as the analyte, except it contains no analyte. You can calibrate the instrument you are using to be set to a signal of zero for the signal of the blank. You can also subtract the signal produced by the blank from all the signals obtained throughout the analysis, generating “corrected” values. The corrected values can then be used for further data manipulation such as generating calibration curves to solve for unknown concentrations (shown below). Instrumental settings can also be manipulated to counter matrix effects. Adjusting fuel-to-oxidant ratios in flames, or using a different oxidant, can reduce certain matrix interferences. If incomplete combustion is causing organic substances within the matrix to produce a signal, increasing the temperature of the flame can ensure complete combustion, reducing or eliminating the effects of organics.
Another way to think about Background correction is taking the fluctuation (Δ) of a blank reading and the fluctuation of a signal reading (Δ) then average the Δ between these variances to cancel out the noise. To increase the clarity of both the blank and the signal, the analyte should be run through the instrument multiple times to get more readings. More readings, means more values to average out and will result in a clearer absorption spectra.
The correspondence with the company technician has identified this Issue as two fold problem. One is the developing equilibrium optical beam in the source radiation from the hollow cathode lamp and the background radiation from the Deutrium lamp.both the lights should n equally balanced and produce a monoctonous round pinkish moon like image when projected on a white background.
Secondly due to the ageing of the deutrium lamp the radiation fluctuates during a single batch of analysis and created nuisance in the absorbance peak.
In addition there is another Provo noticed that the background radiation was greater sample radiation andfollows beer Lambert law with increasing concentration. This gives a speculation whether the detector or the software wrongly identiies each radiation interchanging their source.
Need more expert advice in this.
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