CDL99 versus Cameca minimum detection limit

[Heather Lowers]

I have a user doing magnetite analyses who came across a paper, Dupuis & Beaudoin Miner Deposita (2011) 46:319-335, that reports detection limits for V, Cr, Mn at ~50 ppm and Ni, Cu, Zn at 180-470 ppm.  V, Cr, Mn were collected on LLIF and Ni, Cu, and Zn were collected on LIF all at 15kV, 100nA, and 20 seconds on peak.   The reported detection limits in the paper are lower than the CDL99 detection limits reported in PFE and we are counting over 100 seconds for each element at 15kv and 100nA.

As a JEOL user wondering

1. Is the Cmin from Cameca software more like a 60ci detection limit?  They provide the formula in the paper (Ancey et al. 1978) and I do not know what the F refers to?  They say it is a "computed correction factor".  Is this to get the standard used back to the pure element intensity? Also not sure I understand what the lambda(alpha,beta) statistical parameter is.

2. Can some one provide a comparison of actual count rates on a LiF versus an LLiF?

[Probeman]

I have a user doing magnetite analyses who came across a paper, Dupuis & Beaudoin Miner Deposita (2011) 46:319-335, that reports detection limits for V, Cr, Mn at ~50 ppm and Ni, Cu, Zn at 180-470 ppm.  V, Cr, Mn were collected on LLIF and Ni, Cu, and Zn were collected on LIF all at 15kV, 100nA, and 20 seconds on peak.   The reported detection limits in the paper are lower than the CDL99 detection limits reported in PFE and we are counting over 100 seconds for each element at 15kv and 100nA.

As a JEOL user wondering

1. Is the Cmin from Cameca software more like a 60ci detection limit?  They provide the formula in the paper (Ancey et al. 1978) and I do not know what the F refers to?  They say it is a "computed correction factor".  Is this to get the standard used back to the pure element intensity? Also not sure I understand what the lambda(alpha,beta) statistical parameter is.

2. Can some one provide a comparison of actual count rates on a LiF versus an LLiF?

Hi Heather,
I can't tell you what Cameca is using for detection limits calculations, but Mike Jercinovic or Julien Allaz are sure to know.

I will tell you that I'm having Edgar Chavez out *real soon now* according to Cameca to align the crystals on our spectrometers as we have replaced a few crystal flip motors and those spectrometers are now a bit away from their nominal positions.  So, I'll run a crystal intensity test now, and then again after the crystals are re-aligned.

The real issue with crystal alignment is of course the proper actual takeoff angle for major element analysis.  On those spectrometers that are a bit off from ideal alignment, we are seeing some slightly different k-ratios compared to our venerable SX50, so we know we need to do this alignment anyway.

I should also mention that of course P/B is the most important parameter for detection sensitivity and I'll report those values along with the absolute intensities tomorrow. I'm running Mn ka and Ti Ka on both spectrometers overnight.

That was fun hanging with you and Mike before M&M- let's do it again.
john

[UofO EPMA Lab]

I have a user doing magnetite analyses who came across a paper, Dupuis & Beaudoin Miner Deposita (2011) 46:319-335, that reports detection limits for V, Cr, Mn at ~50 ppm and Ni, Cu, Zn at 180-470 ppm.  V, Cr, Mn were collected on LLIF and Ni, Cu, and Zn were collected on LIF all at 15kV, 100nA, and 20 seconds on peak.   The reported detection limits in the paper are lower than the CDL99 detection limits reported in PFE and we are counting over 100 seconds for each element at 15kv and 100nA.

As a JEOL user wondering

1. Is the Cmin from Cameca software more like a 60ci detection limit?  They provide the formula in the paper (Ancey et al. 1978) and I do not know what the F refers to?  They say it is a "computed correction factor".  Is this to get the standard used back to the pure element intensity? Also not sure I understand what the lambda(alpha,beta) statistical parameter is.

2. Can some one provide a comparison of actual count rates on a LiF versus an LLiF?

This topic really should be in the JEOL vs. Cameca board, but everyone seems to be afraid to post there?  Why is that?  But let's start with the raw x-ray intensities question that Heather had. Using 30 nA at 15 keV on pure Ti we obtain the following off-peak corrected x-ray intensities (unnormalized to beam current and time):

Stat       ti ka Off   ti ka Off  ti ka Off   ti ka Off  ti ka Off      Beam   
SPEC:              1           2          3           4          5
CRYST:           PET        LPET       LLIF         PET        LIF
Average:   1080002.0   3182417.0   647360.5   1080289.0   173223.0     29.938   
Std Dev:      1699.8      5715.5     1913.8      2336.3      267.5       .002   
OneSigma:     1039.2      1783.9      804.6      1039.4      416.2   
Std Err:       601.0      2020.7      676.6       826.0       94.6   
%Rel SD:         .16         .18        .30         .22        .15   
Minimum:   1078156.0   3174160.0   644277.7   1077681.0   172806.2       .000   
Maximum:   1082722.0   3189773.0   650443.8   1083945.0   173613.9       .000   


Here's the same for Mn Ka on pure Mn, also off-peak corrected and unnormalized:

Stat       mn ka Off   mn ka Off  mn ka Off   mn ka Off  mn ka Off      Beam
SPEC:              1           2          3           4          5
CRYST:           PET        LPET       LLIF         PET        LIF
Average:    728725.3   2467205.0  1223708.0    770316.3   348176.7     29.937   
Std Dev:      4603.4     13266.5     5079.8      5227.6     5771.8       .001   
OneSigma:      853.7      1570.7     1106.2       877.7      590.1   
Std Err:      1627.6      4690.4     1796.0      1848.2     2040.6   
%Rel SD:         .63         .54        .42         .68       1.66   
Minimum:    718696.6   2447567.0   1214469.0   761617.0   344666.8       .000   
Maximum:    732618.3   2494132.0   1231553.0   776949.8   362068.8       .000   

And remember, two of these spectrometers are quite out of alignment and so I will post this test again after the service alignment.  OK, so what about sensitivity? 

First here is the Ti data as measured on pure Mn metal, 15 keV and 100 nA, using 20 sec on-peak and 10 sec (x2) for the off-peaks:

St  522 Set  10 Titanium metal
TakeOff = 40.0  KiloVolt = 15.0  Beam Current = 100.  Beam Size =    0
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =     1000, Magnification (imaging) =    100)
Image Shift (X,Y):                                          .00,   .00

From Tony Tomsia, LBL
1/16" wire, 99.995%
Number of Data Lines:   8             Number of 'Good' Data Lines:   8
First/Last Date-Time: 08/12/2015 09:18:42 AM to 08/12/2015 09:27:36 AM
WARNING- Using Exponential Off-Peak correction for mn ka
WARNING- Using Exponential Off-Peak correction for mn ka
WARNING- Using Exponential Off-Peak correction for mn ka

Average Total Oxygen:         .000     Average Total Weight%:   99.995
Average Calculated Oxygen:    .000     Average Atomic Number:   21.930
Average Excess Oxygen:        .000     Average Atomic Weight:   47.427
Average ZAF Iteration:        1.75     Average Quant Iterate:     2.00
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.

St  522 Set  10 Titanium metal, Results in Elemental Weight Percents
 
ELEM:       Mn      Mn      Mn      Mn      Mn      Ti       O
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    SPEC    SPEC
BGDS:      EXP     EXP     LIN     EXP     LIN
TIME:    20.00   20.00   20.00   20.00   20.00     ---     ---
BEAM:    99.85   99.85   99.85   99.85   99.85     ---     ---

ELEM:       Mn      Mn      Mn      Mn      Mn      Ti       O   SUM 
XRAY:     (ka)    (ka)    (ka)    (ka)    (ka)      ()      ()
CRYST:     PET    LPET    LLIF     PET     LIF
   585   -.009    .003    .003   -.007   -.013  99.500    .500  99.978
   586   -.017    .028   -.012    .013   -.026  99.500    .500  99.986
   587   -.016    .023   -.005   -.023    .001  99.500    .500  99.979
   588   -.017    .025    .008    .000   -.007  99.500    .500 100.008
   589    .010    .014   -.001   -.024    .003  99.500    .500 100.001
   590   -.024    .005    .003    .003   -.014  99.500    .500  99.973
   591   -.003    .015    .004   -.002   -.002  99.500    .500 100.013
   592    .002    .017    .004   -.006    .012  99.500    .500 100.028

AVER:    -.009    .016    .000   -.006   -.006  99.500    .500  99.995
SDEV:     .011    .009    .006    .013    .012    .000    .000    .020
SERR:     .004    .003    .002    .004    .004    .000    .000
%RSD:  -121.02   55.32 1368.48 -211.97 -197.92     .00     .00

PUBL:     n.a.    n.a.    n.a.    n.a.    n.a.  99.500    .500 100.000
%VAR:      ---     ---     ---     ---     ---     .00     .00
DIFF:      ---     ---     ---     ---     ---    .000    .000
STDS:      525     525     525     525     525     ---     ---

STKF:   1.0000  1.0000  1.0000  1.0000  1.0000     ---     ---
STCT:  12213.6 41110.6 20423.5 12758.2  5795.9     ---     ---

UNKF:   -.0001   .0001   .0000  -.0001  -.0001     ---     ---
UNCT:     -1.0     5.9      .1     -.7     -.3     ---     ---
UNBG:     56.8   142.0    30.8    52.2    10.4     ---     ---

ZCOR:   1.1211  1.1211  1.1211  1.1211  1.1211     ---     ---
KRAW:   -.0001   .0001   .0000  -.0001  -.0001     ---     ---
PKBG:      .98    1.04    1.00     .99     .97     ---     ---

Detection limit at 99 % Confidence in Elemental Weight Percent (Single Line):

ELEM:       Mn      Mn      Mn      Mn      Mn
   585    .025    .012    .011    .023    .023
   586    .026    .012    .011    .023    .024
   587    .025    .012    .011    .024    .023
   588    .026    .012    .011    .023    .023
   589    .025    .012    .011    .024    .022
   590    .026    .012    .011    .023    .023
   591    .025    .012    .011    .023    .023
   592    .025    .012    .011    .024    .023

AVER:     .025    .012    .011    .023    .023
SDEV:     .000    .000    .000    .000    .001
SERR:     .000    .000    .000    .000    .000

Detection Limit (t-test) in Elemental Weight Percent (Average of Sample):

ELEM:       Mn      Mn      Mn      Mn      Mn
  60ci    .003    .003    .001    .003    .003
  80ci    .005    .004    .002    .005    .005
  90ci    .006    .005    .003    .007    .006
  95ci    .008    .007    .003    .009    .008
  99ci    .012    .010    .005    .013    .012

So the single point 3 sigma (99% CI) range from 110 to 250 PPM and for the average of 8 points we get a 99% CI t-test of 50 to 130 PPM for Mn Ka in Ti metal.


For Ti Ka in Mn metal, we get the following:

St  525 Set   6 Manganese metal
TakeOff = 40.0  KiloVolt = 15.0  Beam Current = 100.  Beam Size =    0
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =     1000, Magnification (imaging) =    100)
Image Shift (X,Y):                                          .00,   .00

From Aesar, Batch #S96590, 99.99%
Mg 50 ppm, Ti 30 ppm, Cr 3 ppm, Fe 1 ppm
Al, Ca, Cu, Ni, Si < 1 ppm
Number of Data Lines:   8             Number of 'Good' Data Lines:   8
First/Last Date-Time: 08/12/2015 09:29:19 AM to 08/12/2015 09:38:11 AM
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Exponential Off-Peak correction for ti ka

Average Total Oxygen:         .000     Average Total Weight%:   99.993
Average Calculated Oxygen:    .000     Average Atomic Number:   25.000
Average Excess Oxygen:        .000     Average Atomic Weight:   54.939
Average ZAF Iteration:        1.50     Average Quant Iterate:     2.00
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.

St  525 Set   6 Manganese metal, Results in Elemental Weight Percents
 
ELEM:       Ti      Ti      Ti      Ti      Ti      Mn
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    SPEC
BGDS:      EXP     EXP     LIN     EXP     LIN
TIME:    20.00   20.00   20.00   20.00   20.00     ---
BEAM:    99.82   99.82   99.82   99.82   99.82     ---

ELEM:       Ti      Ti      Ti      Ti      Ti      Mn   SUM 
XRAY:     (ka)    (ka)    (ka)    (ka)    (ka)      ()
CRYST:     PET    LPET    LLIF     PET     LIF
   593    .000   -.004   -.003    .004   -.010 100.000  99.986
   594    .001   -.004    .000   -.004   -.012 100.000  99.981
   595    .003   -.002   -.002    .002    .015 100.000 100.016
   596    .004   -.010   -.002   -.002   -.007 100.000  99.984
   597    .003   -.012   -.004   -.003    .014 100.000  99.999
   598    .000   -.008   -.003    .010    .000 100.000 100.000
   599    .010   -.009    .005    .009   -.007 100.000 100.007
   600    .000   -.006    .004   -.008   -.016 100.000  99.974

AVER:     .003   -.007    .000    .001   -.003 100.000  99.993
SDEV:     .003    .003    .003    .006    .012    .000    .014
SERR:     .001    .001    .001    .002    .004    .000
%RSD:   126.72  -50.25 -743.39  691.28 -421.05     .00

PUBL:     n.a.    n.a.    n.a.    n.a.    n.a. 100.000 100.000
%VAR:      ---     ---     ---     ---     ---     .00
DIFF:      ---     ---     ---     ---     ---    .000
STDS:      522     522     522     522     522     ---

STKF:    .9940   .9940   .9940   .9940   .9940     ---
STCT:  18085.6 53149.1 10845.1 17974.5  2894.4     ---

UNKF:    .0000  -.0001   .0000   .0000   .0000     ---
UNCT:       .6    -3.8     -.1      .2     -.1     ---
UNBG:     45.9   115.6    13.5    40.5     4.0     ---

ZCOR:    .8454   .9899   .8454   .8249   .8661     ---
KRAW:    .0000  -.0001   .0000   .0000   .0000     ---
PKBG:     1.01     .97    1.00    1.01     .98     ---

Detection limit at 99 % Confidence in Elemental Weight Percent (Single Line):

ELEM:       Ti      Ti      Ti      Ti      Ti
   593    .014    .007    .012    .011    .025
   594    .011    .007    .010    .011    .025
   595    .011    .007    .010    .011    .021
   596    .011    .007    .010    .011    .020
   597    .011    .007    .010    .011    .020
   598    .011    .007    .010    .011    .021
   599    .011    .007    .010    .011    .021
   600    .011    .007    .010    .011    .021

AVER:     .012    .007    .010    .011    .022
SDEV:     .001    .000    .001    .000    .002
SERR:     .000    .000    .000    .000    .001

Detection Limit (t-test) in Elemental Weight Percent (Average of Sample):

ELEM:       Ti      Ti      Ti      Ti      Ti
  60ci    .002    .001    .002    .002    .006
  80ci    .002    .001    .003    .004    .009
  90ci    .003    .002    .004    .005    .012
  95ci    .004    .002    .005    .006    .015
  99ci    .006    .003    .008    .009    .023

So we get 70 to 120 PPM for single measurements (99% CI) and for the average of 8 points we get a t-test sensitivity of 30 to 230 PPM depending on the crystal.  So yes, the large LIF and large PET do pay off for trace element sensitivity.

JEOL people: please post your results for the same conditions.
john

I just realized that for a real comparison with the paper heather mentioned I should run these on a magnetite standard, so I will do that next!  <face palm>

[John Donovan]

1. Is the Cmin from Cameca software more like a 60ci detection limit?  They provide the formula in the paper (Ancey et al. 1978) and I do not know what the F refers to?  They say it is a "computed correction factor".  Is this to get the standard used back to the pure element intensity? Also not sure I understand what the lambda(alpha,beta) statistical parameter is.

Hi Heather,
I have the magnetite sensitivity data and will post that tomorrow. I found I had to use "same side" off-peaks for Mn on the PET crystals due to the tail of the Fe line.  Of course if one wants the best sensitivity, one should use MAN background corrections!   

As far as detection limit calculation formulas, the one I use is from Love-Scott (this is documented in the PFE User Manual), and it also includes a correction for the matrix effects in the detection limit calculation.

I haven't had a chance to read the Ancey paper, but I'll bet Mike and/or Julien know it. 
john

[John Donovan]

I have a user doing magnetite analyses who came across a paper, Dupuis & Beaudoin Miner Deposita (2011) 46:319-335, that reports detection limits for V, Cr, Mn at ~50 ppm and Ni, Cu, Zn at 180-470 ppm.  V, Cr, Mn were collected on LLIF and Ni, Cu, and Zn were collected on LIF all at 15kV, 100nA, and 20 seconds on peak.   The reported detection limits in the paper are lower than the CDL99 detection limits reported in PFE and we are counting over 100 seconds for each element at 15kv and 100nA.

Hi Heather,
Here is the data for Ti ka and Mn ka on magnetite (my #395 Port Henry, NY). The single point sensitivity seems to be very slightly better than the metal data which makes sense as the average atomic number of magnetite is a little lower than Mn or Ti metal and the average sensitivity seems to be slightly worse, which probably means the natural magnetite sample isn't as homogeneous as the metals:

St  395 Set   5 Magnetite U.C. #3380
TakeOff = 40.0  KiloVolt = 15.0  Beam Current = 100.  Beam Size =    0
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =     1000, Magnification (imaging) =    100)
Image Shift (X,Y):                                          .00,   .00

Port Henry, NY
FeO=30.93% (ISE Carmichael)
Fe2O3=68.85%, FeO=30.92% (as FeO=92.73% + 6.90% O)
(Total FeO=92.73%, by EPMA, JJD)
Number of Data Lines:   8             Number of 'Good' Data Lines:   8
First/Last Date-Time: 08/12/2015 04:45:26 PM to 08/12/2015 04:54:20 PM
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Exponential Off-Peak correction for ti ka
WARNING- Using Exponential Off-Peak correction for ti ka

Average Total Oxygen:         .000     Average Total Weight%:  100.336
Average Calculated Oxygen:    .000     Average Atomic Number:   20.971
Average Excess Oxygen:        .000     Average Atomic Weight:   32.979
Average ZAF Iteration:        2.00     Average Quant Iterate:     2.00
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.

St  395 Set   5 Magnetite U.C. #3380, Results in Elemental Weight Percents
 
ELEM:       Ti      Ti      Ti      Ti      Ti      Fe      Mn      Al      Si      Mg       O
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    SPEC    SPEC    SPEC    SPEC    SPEC    SPEC
BGDS:      EXP     EXP     LIN     EXP     LIN
TIME:    20.00   20.00   20.00   20.00   20.00     ---     ---     ---     ---     ---     ---
BEAM:    99.92   99.92   99.92   99.92   99.92     ---     ---     ---     ---     ---     ---

ELEM:       Ti      Ti      Ti      Ti      Ti      Fe      Mn      Al      Si      Mg       O   SUM 
XRAY:     (ka)    (ka)    (ka)    (ka)    (ka)      ()      ()      ()      ()      ()      ()
SPEC:        1       2       3       4       5
CRYST:     PET    LPET    LLIF     PET     LIF
   258    .028    .030    .030    .034    .036  72.080    .054    .201    .000    .072  27.803 100.368
   259    .026    .019    .021    .023    .037  72.080    .054    .201    .000    .072  27.803 100.336
   260    .030    .028    .025    .031    .024  72.080    .054    .201    .000    .072  27.803 100.348
   261    .029    .013    .022    .021    .031  72.080    .054    .201    .000    .072  27.803 100.326
   262    .027    .019    .024    .024    .026  72.080    .054    .201    .000    .072  27.803 100.330
   263    .028    .025    .041    .028    .008  72.080    .054    .201    .000    .072  27.803 100.339
   264    .033    .023    .025    .017    .018  72.080    .054    .201    .000    .072  27.803 100.327
   265    .021    .013    .022    .017    .033  72.080    .054    .201    .000    .072  27.803 100.316

AVER:     .028    .021    .026    .024    .027  72.080    .054    .201    .000    .072  27.803 100.336
SDEV:     .003    .006    .007    .006    .010    .000    .000    .000    .000    .000    .000    .016
SERR:     .001    .002    .002    .002    .004    .000    .000    .000    .000    .000    .000
%RSD:    12.27   29.32   25.17   24.85   37.29     .00     .00     .00     .00     .00     .00

PUBL:     .012    .012    .012    .012    .012  72.080    .054    .201    .000    .072  27.803 100.222
%VAR:   131.58   78.04  118.76  102.42  121.89     .00     .00     .00     .00     .00     .00
DIFF:     .016    .009    .014    .012    .015    .000    .000    .000    .000    .000    .000
STDS:      522     522     522     522     522     ---     ---     ---     ---     ---     ---

STKF:    .9940   .9940   .9940   .9940   .9940     ---     ---     ---     ---     ---     ---
STCT:  17926.3 53364.1 10692.8 17550.8  2881.0     ---     ---     ---     ---     ---     ---

UNKF:    .0003   .0002   .0003   .0003   .0003     ---     ---     ---     ---     ---     ---
UNCT:      5.3    12.0     3.0     4.5      .8     ---     ---     ---     ---     ---     ---
UNBG:     36.8    91.1    10.7    32.5     3.1     ---     ---     ---     ---     ---     ---

ZCOR:    .9539   .9539   .9539   .9539   .9539     ---     ---     ---     ---     ---     ---
KRAW:    .0003   .0002   .0003   .0003   .0003     ---     ---     ---     ---     ---     ---
PKBG:     1.14    1.13    1.28    1.14    1.27     ---     ---     ---     ---     ---     ---

Detection limit at 99 % Confidence in Elemental Weight Percent (Single Line):

ELEM:       Ti      Ti      Ti      Ti      Ti
   258    .012    .006    .011    .011    .021
   259    .012    .006    .011    .011    .020
   260    .012    .006    .011    .011    .022
   261    .012    .006    .011    .011    .021
   262    .012    .006    .011    .011    .020
   263    .012    .006    .010    .011    .023
   264    .012    .006    .011    .011    .021
   265    .012    .006    .011    .011    .022

AVER:     .012    .006    .011    .011    .021
SDEV:     .000    .000    .000    .000    .001
SERR:     .000    .000    .000    .000    .000

Detection Limit (t-test) in Elemental Weight Percent (Average of Sample):

ELEM:       Ti      Ti      Ti      Ti      Ti
  60ci    .003    .003    .003    .003    .004
  80ci    .004    .004    .004    .004    .006
  90ci    .006    .006    .006    .006    .008
  95ci    .007    .007    .007    .007    .009
  99ci    .011    .011    .010    .011    .014


So 60 to 210 PPM for single points and 100 to 140 PPM (99%CI t-test for the average for Ti Ka. For Mn:

St  395 Set   6 Magnetite U.C. #3380
TakeOff = 40.0  KiloVolt = 15.0  Beam Current = 100.  Beam Size =    0
(Magnification (analytical) =  20000),        Beam Mode = Analog  Spot
(Magnification (default) =     1000, Magnification (imaging) =    100)
Image Shift (X,Y):                                          .00,   .00

Port Henry, NY
FeO=30.93% (ISE Carmichael)
Fe2O3=68.85%, FeO=30.92% (as FeO=92.73% + 6.90% O)
(Total FeO=92.73%, by EPMA, JJD)
Number of Data Lines:   8             Number of 'Good' Data Lines:   8
First/Last Date-Time: 08/12/2015 04:55:43 PM to 08/12/2015 05:04:45 PM

Average Total Oxygen:         .000     Average Total Weight%:  100.359
Average Calculated Oxygen:    .000     Average Atomic Number:   20.975
Average Excess Oxygen:        .000     Average Atomic Weight:   32.986
Average ZAF Iteration:        2.00     Average Quant Iterate:     2.00
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.

St  395 Set   6 Magnetite U.C. #3380, Results in Elemental Weight Percents
 
ELEM:       Mn      Mn      Mn      Mn      Mn      Fe      Al      Si      Ti      Mg       O
TYPE:     ANAL    ANAL    ANAL    ANAL    ANAL    SPEC    SPEC    SPEC    SPEC    SPEC    SPEC
BGDS:      LIN     LIN     LIN     LIN     LIN
TIME:    20.00   20.00   20.00   20.00   20.00     ---     ---     ---     ---     ---     ---
BEAM:    99.93   99.93   99.93   99.93   99.93     ---     ---     ---     ---     ---     ---

ELEM:       Mn      Mn      Mn      Mn      Mn      Fe      Al      Si      Ti      Mg       O   SUM 
XRAY:     (ka)    (ka)    (ka)    (ka)    (ka)      ()      ()      ()      ()      ()      ()
SPEC:        1       2       3       4       5
CRYST:     PET    LPET    LLIF     PET     LIF
   266    .063    .038    .039    .036    .022  72.080    .201    .000    .012    .072  27.803 100.365
   267   -.015    .065    .036    .043    .033  72.080    .201    .000    .012    .072  27.803 100.329
   268    .037    .043    .052    .041    .040  72.080    .201    .000    .012    .072  27.803 100.381
   269    .053    .056    .033    .030    .031  72.080    .201    .000    .012    .072  27.803 100.371
   270    .059    .026    .033    .028    .034  72.080    .201    .000    .012    .072  27.803 100.347
   271    .056    .047    .041    .029    .047  72.080    .201    .000    .012    .072  27.803 100.387
   272    .027    .065    .043    .024    .049  72.080    .201    .000    .012    .072  27.803 100.376
   273    .060    .046    .029   -.007    .022  72.080    .201    .000    .012    .072  27.803 100.317

AVER:     .042    .048    .038    .028    .035  72.080    .201    .000    .012    .072  27.803 100.359
SDEV:     .026    .013    .007    .016    .010    .000    .000    .000    .000    .000    .000    .025
SERR:     .009    .005    .003    .005    .004    .000    .000    .000    .000    .000    .000
%RSD:    62.14   28.00   18.87   55.54   29.43     .00     .00     .00     .00     .00     .00

PUBL:     .054    .054    .054    .054    .054  72.080    .201    .000    .012    .072  27.803 100.222
%VAR:   -21.54  -11.10  -29.26  -48.22  -35.79     .00     .00     .00     .00     .00     .00
DIFF:    -.012   -.006   -.016   -.026   -.019    .000    .000    .000    .000    .000    .000
STDS:      525     525     525     525     525     ---     ---     ---     ---     ---     ---

STKF:   1.0000  1.0000  1.0000  1.0000  1.0000     ---     ---     ---     ---     ---     ---
STCT:  12209.5 40042.6 20258.0 12912.1  5745.4     ---     ---     ---     ---     ---     ---

UNKF:    .0004   .0005   .0004   .0003   .0003     ---     ---     ---     ---     ---     ---
UNCT:      4.9    18.3     7.4     3.4     1.9     ---     ---     ---     ---     ---     ---
UNBG:     55.1   142.4    32.2    48.8     9.9     ---     ---     ---     ---     ---     ---

ZCOR:   1.0502  1.0502  1.0502  1.0502  1.0502     ---     ---     ---     ---     ---     ---
KRAW:    .0004   .0005   .0004   .0003   .0003     ---     ---     ---     ---     ---     ---
PKBG:     1.09    1.13    1.23    1.07    1.19     ---     ---     ---     ---     ---     ---

Detection limit at 99 % Confidence in Elemental Weight Percent (Single Line):

ELEM:       Mn      Mn      Mn      Mn      Mn
   266    .023    .012    .011    .021    .021
   267    .025    .011    .011    .021    .021
   268    .024    .012    .011    .021    .021
   269    .023    .011    .011    .021    .021
   270    .023    .012    .011    .021    .021
   271    .023    .012    .011    .021    .021
   272    .024    .011    .011    .021    .021
   273    .023    .012    .011    .022    .022

AVER:     .023    .012    .011    .021    .021
SDEV:     .001    .000    .000    .000    .000
SERR:     .000    .000    .000    .000    .000

Detection Limit (t-test) in Elemental Weight Percent (Average of Sample):

ELEM:       Mn      Mn      Mn      Mn      Mn
  60ci    .004    .003    .003    .002    .003
  80ci    .006    .004    .005    .003    .005
  90ci    .008    .005    .006    .004    .007
  95ci    .010    .007    .008    .006    .009
  99ci    .015    .010    .012    .008    .013


So 110 to 230 PPM (99%CI) for single points and 80 to 150 PPM sensitivity for the average of 8 points sensitivity (99%CI t-test).

But to answer your question, yes, the large area crystals (LLIF and LLPET) really do a good job.  I should also mention that we've been discussing precision, but for the MAN measurement I will perform next, accuracy will be the main concern as the precision of MAN trace measurement is much better than off-peaks. See here for more on this:

http://probesoftware.com/smf/index.php?topic=307.msg3190#msg3190

So, what I'd really like to have is a synthetic Fe3O4 standard for use as a blank calibration for traces in magnetite.  But anyway, it will be worth comparing what we get from MAN with the above off-peak analysis for accuracy.

[Jeremy Wykes]

Ancey paper here:
http://probesoftware.com/smf/index.php?topic=143.msg1841#msg1841

[John Donovan]

The comparison of off-peak versus MAN background corrections for trace elements in magnetite has been moved to here:

http://probesoftware.com/smf/index.php?topic=571.0

This topic remains open for discussion of Cameca (and other) detection limits.
john

[Probeman]

So I remeasured the Ti and Mn ka intensities again at 15 keV and 30 nA, For comparison here are the intensities *before* aligning the crystals:

Stat       ti ka Off   ti ka Off  ti ka Off   ti ka Off  ti ka Off      Beam   
SPEC:              1           2          3           4          5
CRYST:           PET        LPET       LLIF         PET        LIF
Average:   1080002.0   3182417.0   647360.5   1080289.0   173223.0     29.938   
Std Dev:      1699.8      5715.5     1913.8      2336.3      267.5       .002   
OneSigma:     1039.2      1783.9      804.6      1039.4      416.2   
Std Err:       601.0      2020.7      676.6       826.0       94.6   
%Rel SD:         .16         .18        .30         .22        .15   
Minimum:   1078156.0   3174160.0   644277.7   1077681.0   172806.2       .000   
Maximum:   1082722.0   3189773.0   650443.8   1083945.0   173613.9       .000   

Here's the same for Mn Ka on pure Mn, also off-peak corrected and unnormalized:

Stat       mn ka Off   mn ka Off  mn ka Off   mn ka Off  mn ka Off      Beam
SPEC:              1           2          3           4          5
CRYST:           PET        LPET       LLIF         PET        LIF
Average:    728725.3   2467205.0  1223708.0    770316.3   348176.7     29.937   
Std Dev:      4603.4     13266.5     5079.8      5227.6     5771.8       .001   
OneSigma:      853.7      1570.7     1106.2       877.7      590.1   
Std Err:      1627.6      4690.4     1796.0      1848.2     2040.6   
%Rel SD:         .63         .54        .42         .68       1.66   
Minimum:    718696.6   2447567.0   1214469.0   761617.0   344666.8       .000   
Maximum:    732618.3   2494132.0   1231553.0   776949.8   362068.8       .000


And here are the same intensities measured *after* our crystal alignment, first for Ti Ka:

Stat       ti ka Off   ti ka Off  ti ka Off   ti ka Off  ti ka Off      Beam   
SPEC:              1           2          3           4          5
CRYST:           PET        LPET       LLIF         PET        LIF
Average:    356544.5   1115314.0   215384.2    330625.3    56606.0     29.974   
Std Dev:      1222.4      2248.7      701.0      1472.6      396.6       .001   
OneSigma:      597.1      1056.1      464.1       575.0      237.9   
Std Err:       432.2       795.0      247.8       520.6      140.2   
%Rel SD:         .34         .20        .33         .45        .70   
Minimum:    355043.6   1112523.0   214159.7    328113.5    56006.6       .000   
Maximum:    358299.3   1118479.0   216417.9    332523.6    57235.9       .000   

and now for Mn Ka:

Stat       mn ka Off   mn ka Off  mn ka Off   mn ka Off  mn ka Off      Beam
SPEC:              1           2          3           4          5
CRYST:           PET        LPET       LLIF         PET        LIF
Average:    724626.0   2491145.0   1222839.0   766949.9   349863.0     29.976   
Std Dev:      1084.1      4748.7      2051.1     2828.0      956.8       .001   
OneSigma:      851.2      1578.3      1105.8      875.8      591.5   
Std Err:       409.7      1794.8       775.3     1068.9      361.6   
%Rel SD:         .15         .19         .17        .37        .27   
Minimum:    722518.5   2484331.0   1218780.0   763815.9   348466.3       .000   
Maximum:    725566.3   2498223.0   1224832.0   772508.3   351151.3       .000   


Well first of all as you can see the Mn ka intrensities are about the same, but the Ti Ka intensities are only 1/2 to 1/3 of the previous intensities!  And here I thought that aligning the spectrometer crystals would help...

My engineer is on vacation but when he gets back I'll have a couple of questions for him (and Edgar)!

[Heather Lowers]

Ancey paper here:
http://probesoftware.com/smf/index.php?topic=143.msg1841#msg1841

Thanks for the paper Jeremy!  I've passed it on to interested parties.

h.