Use Aggregated Intensities for Duplicate Quantitative Elements
If this option is checked and the samples contain duplicate elements (same element and x-ray line) for standards or unknown quantitative samples, then the program will sum the on and off peak intensities for the duplicated elements to the first instance of the duplicated element and set the duplicated element intensities to zero.
Normally this is utilized when extreme trace element analyses are required for very low concentration elements and there is a need for improving the statistics by aggregating the intensities from several spectrometers acquiring at the same time.
CAUTION: It is important realize that measuring the same element more than once is a non-physical situation so far as regards the matrix correction. Obviously if one measures a major element on multiple spectrometers the resulting excessively high totals will make it clear that this analytical situation cannot be handled properly in the matrix correction.
In the case where a major or even minor element is measured as a duplicate element the onus is on the user to ensure that the matrix correction is properly calculated either by using the Aggregate Intensity option or by using the Disable Quant feature in the Elements/Cations dialog to have the element appear only once in the matrix correction.
However, even in the case for duplicate trace elements, one must consider this effect also. Note for the unknown sample matrix, even though the change in the sample matrix correction is small, for the standard k-factor calculation a significant error can be introduced. Consider the following examples of measuring Ti on two spectrometers in a blank Quartz standard, where the Ti concentration is essentially zero.
In this calculation the program calculates the matrix correction for the quartz standard run as an unknown and the matrix correction of the sample is properly calculated as SiO2. However, the standard k-factor for Ti in TiO2 should be 0.5547 at 15 keV, but is calculated as 0.5707 because the matrix is assumed to be Ti2O2.
Note that the program warns the user of the accuracy problem for duplicate elements in this first example of Ti as a duplicate element.
Un 2 std 14 SiO2
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 200. Beam Size = 20
(Magnification (analytical) = 8000), Beam Mode = Analog Spot
(Magnification (default) = 600, Magnification (imaging) = 100)
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 02/26/2007 01:35:59 PM to 02/26/2007 03:03:33 PM
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Exponential Off-Peak correction for al ka
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Alternating On and Off Peak Acquisition
Average Total Oxygen: 53.256 Average Total Weight%: 100.000
Average Calculated Oxygen: 53.256 Average Atomic Number: 10.805
Average Excess Oxygen: .000 Average Atomic Weight: 20.029
Average ZAF Iteration: 1.00 Average Quant Iterate: 2.00
Oxygen Calculated by Cation Stoichiometry and Included in the Matrix Correction
Element Si is Calculated by Difference from 100%
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.
Results in Elemental Weight Percents
SPEC: Si O
TYPE: DIFF CALC
AVER: 46.740 53.256
SDEV: .004 .002
ELEM: Ti Fe Al Ti K
BGDS: EXP LIN EXP EXP LIN
TIME: 600.00 600.00 600.00 600.00 599.92
ELEM: Ti Fe Al Ti K SUM
XRAY: (ka) (ka) (ka) (ka) (ka)
110 .000 .002 .000 .000 .000 100.000
111 .000 .001 .000 .001 .000 100.000
112 .000 .002 .005 .000 .006 100.000
113 .000 .001 .000 .000 .000 100.000
114 .000 .001 .000 .001 .001 100.000
AVER: .000 .001 .001 .000 .002 100.000
SDEV: .000 .000 .002 .000 .003
SERR: .000 .000 .001 .000 .001
%RSD: 223.4 34.3 223.6 82.6 163.1
STDS: 22 395 374 22 374
STKF: .5707 .6779 .0701 .5707 .1132 < k-factor for TiO2 is wrong
STCT: 28957.5 14598.6 3841.1 10912.1 2424.3
UNKF: .0000 .0000 .0000 .0000 .0000
UNCT: -.2 .2 .3 .1 .3
UNBG: 56.2 20.6 32.9 19.7 11.5
ZCOR: 1.2024 1.2061 1.2286 1.2024 1.1696 < matrix correction is correct
KRAW: .0000 .0000 .0001 .0000 .0001
PKBG: 1.00 1.01 1.01 1.00 1.03
In the next example the aggregate intensity option (Analytical | Analysis Options menu) is turned on and the standard k-factor for the TiO2 standard is properly calculated because the x-ray counts from the two Ti channels are combined into a single channel.
Note that beam current and count time are averaged for the duplicate elements, since the calculation assumes that the aggregate intensity is simply increasing the geometric efficiency of the instrument. So two channels of Ti integrated at 600 seconds each is still displayed as at 600 seconds, but the total peak and off-peak counts are aggregated together to reflect the increased geometric efficiency.
Un 2 std 14 SiO2
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 200. Beam Size = 20
(Magnification (analytical) = 8000), Beam Mode = Analog Spot
(Magnification (default) = 600, Magnification (imaging) = 100)
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 02/26/2007 01:35:59 PM to 02/26/2007 03:03:33 PM
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Exponential Off-Peak correction for al ka
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Alternating On and Off Peak Acquisition
WARNING- Using Aggregate Intensities for Duplicate Elements
Average Total Oxygen: 53.256 Average Total Weight%: 100.000
Average Calculated Oxygen: 53.256 Average Atomic Number: 10.805
Average Excess Oxygen: .000 Average Atomic Weight: 20.029
Average ZAF Iteration: 1.00 Average Quant Iterate: 2.00
Oxygen Calculated by Cation Stoichiometry and Included in the Matrix Correction
Element Si is Calculated by Difference from 100%
Results in Elemental Weight Percents
SPEC: Si O
TYPE: DIFF CALC
AVER: 46.740 53.256
SDEV: .004 .002
ELEM: Ti Fe Al Ti K
BGDS: EXP LIN EXP EXP LIN
TIME: 600.00 600.00 600.00 .00 599.92
ELEM: Ti Fe Al Ti K SUM
XRAY: (ka) (ka) (ka) (ka) (ka)
110 .000 .002 .000 .000 .000 100.000
111 .000 .001 .000 .000 .000 100.000
112 .000 .002 .005 .000 .006 100.000
113 .000 .001 .000 .000 .000 100.000
114 .000 .001 .000 .000 .001 100.000
AVER: .000 .001 .001 .000 .002 100.000
SDEV: .000 .000 .002 .000 .003
SERR: .000 .000 .001 .000 .001
%RSD: 213.9 34.3 223.6 .0 163.1
STDS: 22 395 374 22 374
STKF: .5547 .6779 .0701 .0000 .1132 < k-factor for TiO2 is correct
STCT: 39869.6 14598.6 3841.1 .0 2424.3
UNKF: .0000 .0000 .0000 .0000 .0000
UNCT: -.2 .2 .3 .0 .3
UNBG: 75.9 20.6 32.9 .0 11.5
ZCOR: 1.2024 1.2061 1.2286 1.0000 1.1696 < matrix correction is correct
KRAW: .0000 .0000 .0001 .0000 .0001
PKBG: 1.00 1.01 1.01 .00 1.03
In this last example the standard k-factor is properly calculated because the second Ti channel is disabled for quantification using the Disable Quant feature in the Elements/Cations dialog. Note that the first Ti channel could be disabled and the second Ti channel enabled to compare the two spectrometers. The duplicate element warning can be ignored in these cases.
Un 2 std 14 SiO2
TakeOff = 40.0 KiloVolt = 15.0 Beam Current = 200. Beam Size = 20
(Magnification (analytical) = 8000), Beam Mode = Analog Spot
(Magnification (default) = 600, Magnification (imaging) = 100)
Number of Data Lines: 5 Number of 'Good' Data Lines: 5
First/Last Date-Time: 02/26/2007 01:35:59 PM to 02/26/2007 03:03:33 PM
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Exponential Off-Peak correction for al ka
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Alternating On and Off Peak Acquisition
WARNING- Quantitation is Disabled For ti ka
Average Total Oxygen: 53.256 Average Total Weight%: 100.000
Average Calculated Oxygen: 53.256 Average Atomic Number: 10.805
Average Excess Oxygen: .000 Average Atomic Weight: 20.029
Average ZAF Iteration: 1.00 Average Quant Iterate: 2.00
Oxygen Calculated by Cation Stoichiometry and Included in the Matrix Correction
Element Si is Calculated by Difference from 100%
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.
Results in Elemental Weight Percents
SPEC: Si O
TYPE: DIFF CALC
AVER: 46.740 53.256
SDEV: .004 .002
ELEM: Ti Fe Al Ti K
BGDS: EXP LIN EXP EXP LIN
TIME: 600.00 600.00 600.00 600.00 599.92
ELEM: Ti-D Fe Al Ti K SUM
XRAY: (ka) (ka) (ka) (ka) (ka)
110 .000 .002 .000 .000 .000 100.000
111 .000 .001 .000 .001 .000 100.000
112 .000 .002 .005 .000 .006 100.000
113 .000 .001 .000 .000 .000 100.000
114 .000 .001 .000 .001 .001 100.000
AVER: .000 .001 .001 .000 .002 100.000
SDEV: .000 .000 .002 .000 .003
SERR: .000 .000 .001 .000 .001
%RSD: .0 34.3 223.6 82.6 163.1
STDS: 22 395 374 22 374
STKF: .0000 .6779 .0701 .5547 .1132 < k-factor for TiO2 is correct
STCT: 28957.5 14598.6 3841.1 10912.1 2424.3
UNKF: .0000 .0000 .0000 .0000 .0000
UNCT: .0 .2 .3 .1 .3
UNBG: .0 20.6 32.9 19.7 11.5
ZCOR: 1.0000 1.2061 1.2286 1.2024 1.1696 < matrix correction is correct
KRAW: .0000 .0000 .0001 .0000 .0001
PKBG: .00 1.01 1.01 1.00 1.03