Pseudo-Saturation in Qtegra

Issue

Prerequisite: This procedure assumes that a Torch Alignment and Autopeak adjust has already been performed while troubleshooting this issue.

Sometimes a peak will appear to be saturated in the subarray by the presence of missing pixel(s) even though the amount of the element in the solution being analyzed should not cause the wavelength pertaining to that a element to be saturated (see Figure 1). This is what is commonly referred to as pseudo-saturation. If this occurs, please perform the following steps to try and correct it.

 Figure 1: An apparent saturation of Na 589.592

Environment

 iCAP 6000, iCAP 7000

Resolution 

1)    Click on Intensities under Evaluation Results

Figure 2: Intensities

2)    Double-click on the result which contains a replicate which has saturated (the intensity value will be blue).

Figure 3: Intensities in blue

3)    Increase the center (‘C’) pixels to include the area under the peak (see Figure 4). Typically, this will involve increasing the center pixels by one on either side of the current grouping of center pixels. In the example in Figure 4, the center pixels have been increased from 3 to 5.

Note: occasionally you might have to increase the subarray width greater than the default of 12 and turn off a Left or Right background correction point.

Figure 4: Center pixels were increased from 3 to 5 to totally encompass the peak

4)   Click on  to save apply changes. to save apply changes.

5)    Aspirate a solution containing the element pertaining to the wavelength exhibiting pseudo-saturation and perform an Autopeak Adjust

Note: Do NOT perform an Autopeak Adjust on all wavelengths at the same time which are “saturating”. Instead, an Autopeak Adjust should be performed individually on each wavelength which is “saturating”.

6)    Using the same solution used to perform the autopeak adjust in step 5, run one repeat of an Unknown and then double click on the result in Intensities in order to view the Subarray

7)    Optimize the number of center pixels (see Figure 5)

Figure 5: Center pixels for Na 589.592 have been optimized.

8)    Click on   to save apply changes.

9)    Repeat steps 1-6 for any other wavelengths which are also exhibiting pseudo-saturation.

Analysis 

Missing pixels in subarray

Cause

Missing pixels in subarray