Southern Connecticut State University

                                Earth Science X-ray Analysis Laboratory

 

XRF Lab Procedures

 

The Earth Science X-ray Laboratory at Southern Connecticut State University produces chemical analyses of geological materials using Energy-Dispersive Polarization X-ray Fluorescence (EDPXRF) spectrometry.  The EDPXRF technique is a variation of secondary target, energy dispersive XRF.  The Spectro Analytical X-Lab 2000 XRF spectrometer used for the analyses incorporates a 400 watt Pd end-window x-ray tube that can be focused on various secondary targets to produce polarized or near monochromatic x-rays for optimal sample excitation.  The polarized x-ray beam produced by the instruments unique Cartesian geometry and Bragg crystal and Barkla scattering targets yields enhanced peak to background ratios compared to direct excitation or conventional secondary excitation EDXRF instruments.

 

 

Fused glass disks:

 

Fused glass disks are produced using  0.3000 grams of pre-ignited sample powder mixed with 2.4000 grams of a premixed anhydrous flux consisting of 35.3% lithium tetraborate and 64.7% lithium metaborate (eutectic composition).  The flux-sample mixture is fused in Pt- 5%Au crucibles using a muffle furnace set at 1030-1060°C.  Glass disks are hand cast with an aluminum plunger on a graphite platen.  Calibration parameters have been determined by the Alpha normalization method of deJongh.  Because of the large dilution of the original sample that occurs during production of the glass disks, trace element concentrations are better determined by the pressed powder pellet technique described below.

 

 

 

Al calibration Si calibration Ca calibraiton Fe calibration

 

 

   

Pressed powder pellets:

 

Pressed powder pellets are produced using 0.900 grams of a  binder material (N, N –Ethylenebisstearamide, Primier Lab Supply Pelletblend powder) and 4.000 grams of very finely ground sample powder. The mixture is blended in a glass vial and pressed at 15 tons in a 32mm stainless steel pellet-die.  The pellet-die surface is covered with a 6 mm mylar film to avoid metal contamination (Fe, Cr, Ni) from the die surface.   Elements heavier than Cr are calibrated using an extended Compton model based on the intensity of the Compton radiation scattered from the sample by the Mo secondary target.  Elements lighter than Cr are calibrated using a model based on a combination of fundamental parameter and extended Compton methods that has been developed by the instrument manufacturer (Turboquant).  Pressed powder pellet results for the lighter elements, in particular those < Si, are only considered qualitative because their accuracy suffers significantly from particle size and mineralogical affects associated with the pelletized powders.  The lighter elements (most major elements) are better analyzed quantitatively by fusion techniques described above.

 

 

Cr calibration Sr calibration Zr calibration Nb calibration
       
As calibration Ba calibration Ce calibration Pb calibration

 

Calibration Standards:

 

            Bureau of Analyzed Samples Ltd (BAS), United Kingdom  BCS-353, BCS-354, BCS-877-1

                        

            Canadian Certified Reference Materials Project (CCRMP), Canada  MRG-1, SY-3

                        

            Centre de Recherches Pétrographiques et Géochimiques (CRPG), France AC-E, Al-I, AN-G, BE-N, BX-N, DR-N, DT-N,

                                                          FK-N, GA, GH, GS-N, IF-G, MA-N, MDO-G, MICA-FE, MICA-MG, PM-S, UB-N, WS-E

 

            Czechoslovak Metrology Institute, Czechoslovakia ECO-12-1-04

                

            Institute of Geophysical and Geochemical Exploration (IGGE), China GSD-11, GSR-02, GSR-08

                   

            Institute of Mineral Raw Materials, Czechoslovakia SPS, MK

                   

            Geological Survey of Japan (GSJ), Japan  JA-2, JA-3, JB-1b, JB-2, JB-3, JCFA-1, JF-1, JF-2, JG-1a, JG-2, JG-3, JGb-1,

                                                                          JGb-2, JH-1, JLk-1, JMn-1, JP-1, JR-1, JR-2, JR-3, JSl-1, JSO-1, JSO-2, JSy-1

            

            National Institute of Standards and Technology (NIST), USA NBS-120c, NIST-696

              

            South Africa Bureau of Standards (SABS), South Africa SARM-05, SARM-08, SARM-13, SARM-16, SARM-19, SARM-20

            

            United States Geological Survey (USGS), USA  AGV-2, BCR-2, BHVO-2, BIR-1, DNC-1, DTS-2, G-2, GSP-2, MAG-1

                                                                                 QLO-1, RGM-1, SCO-1, SDC-1, STM-1, W-2

              

            Zentrales Geologisches Institut (ZGI), Germany  AN, GM, GnA

                       

 

 

 

Replicate analyses of rock standards Jb-1b, Jb-3, and sample 97-51-53 analyzed as fused glass disks.

 

 

Jb-1b

n=10 §

%1σ

Rec. Value

GSJ

 

Jb-3

n=10

%1σ

Rec. Value

GSJ

 

97-51-53

n=3

 §

%1σ

New Mexico Tech WDXRF

SiO2

52.26 0.3 0.6 52.19

 

51.00 0.16 0.3 50.77   55.95

0.21

  56.19

TiO2

1.24 0.01 0.8 1.29

 

1.40 0.01 0.7 1.43   1.97

0.02

  1.93

Al2O3

14.63 0.10 0.7 14.68

 

17.41 0.07 0.4 17.13   11.80

0.07

  11.73

Fe2O3

9.24 0.08 0.9 9.21

 

11.87 0.02 0.2 11.78   16.31

0.12

  16.39

MnO

0.148 0.001 0.7 0.150

 

0.181 0.002 1.1 0.176   0.196

0.002

  0.197

MgO

8.63 0.12 1.4 8.31

 

4.99 0.10 2.0 5.17   2.17

0.09

  2.26

CaO

9.69 0.06 0.6 9.80

 

9.78 0.04 0.4 9.75   6.82

0.04

  6.89

Na2O

2.72 0.23 8.5 2.69

 

2.64 0.18 6.8 2.72   2.59

0.13

  2.42

K2O

1.32 0.01 0.8 1.35

 

0.76 0.01 1.3 0.77   1.80

0.03

  1.75

P2O5

0.244 0.01 4.2 0.261

 

0.299 0.01 3.3 0.293   0.244

0.01

  0.258
                             

V

232 16 6.9 218

 

403 8.8   372   369

19

  420

Cr

430 8 1.9 448

 

52 4.4   58   <10

 

  18

Ni

157 8 5.1 151

 

27 6.0   36   18

1.3

  18

Cu

53 7 13 57

 

167 4.6   194   195

5.8

  228

Zn

77 3 3.9 82

 

103 4.0   100   139

2.9

  149

Rb

39 1.2 3.1 40

 

14 1.1   15   72

2.9

  67

Sr

467 9 1.9 448

 

414 2.9   403   133

4.1

  130

Y

21 2 9.5 25

 

24 1.9   27   58

3.5

  57

Zr

124 4 3.2 135

 

85 3.1   98   247

1.9

  232

Ba

571 46 8.1 572

 

237 8.7   245   455

11.6

  371

Pb

6.9 1.4 20 7

 

5.9 1.7   5.6   7.5

1.1

  11

 

§ Each analysis reflects preparation of a separate glass disk.

All analyses of same glass disk

 

 

 

Replicate analyses international rock standards JA-2 and G-2 analyzed as pressed powder pellets.

 

 

JA-2

1σ

n=6

%1σ

Rec. Value

GSJ

 

G-2

1σ

n=6

%1σ

Rec. Value

USGS

SiO2

57.27

0.18

0.31

56.42

 

70.63

0.12

0.17

69.14

TiO2

0.666

0.002

0.30

0.66

 

0.555

0.002

0.36

0.48

Al2O3

15.58

0.12

0.77

15.41

 

15.81

0.062

0.39

15.39

Fe2O3

6.27

0.017

0.27

6.21

 

2.56

0.007

0.27

2.66

MnO

0.105

0.0004

0.38

0.108

 

0.033

0.0002

0.61

0.03

MgO

7.57

0.10

1.32

7.60

 

0.77

0.08

10.3

0.75

CaO

6.26

0.02

0.3

6.29

 

2.00

0.005

0.25

1.96

Na2O

3.77

0.13

3.5

3.11

 

5.04

0.26

5.2

4.08

K2O

1.83

0.010

0.55

1.81

 

4.64

0.006

0.13

4.48

P2O5

0.161

0.003

1.9

0.146

 

0.144

0.004

2.8

0.14

Sc

23.4

2.2

9.4

28.5

 

8.6

0.6

7.0

 

V

136.5

13.4

9.8

126

 

33

10

30

36

Cr

420

1.8

0.4

436

 

 

 

 

 

Ni

127

1.3

1.0

130

 

5.8

0.4

6.9

 

Cu

30.1

1.0

3.3

29.7

 

9.9

0.8

8.1

11

Zn

64.0

0.7

1.1

64.7

 

86

1.0

1.2

86

Ga

17.1

0.4

2.3

16.9

 

22.6

0.5

2.2

23

Rb

70.2

0.5

0.7

72.9

 

169.9

0.7

0.41

170

Sr

242.9

0.6

0.3

248

 

479

1.1

0.23

478

Y

17.7

0.3

1.7

18.3

 

10.2

0.4

3.9

11

Zr

112.3

0.7

0.6

116

 

319

1.5

0.47

309

Nb

9.7

1.5

15.5

9.47

 

12.6

0.4

3.2

12

Ba

318.4

1.9

0.6

321

 

1859

5.1

0.27

1880

La

14.1

1.7

5.9

15.8

 

94.8

2.4

2.5

89

Ce

32.1

3

9.4

32.7

 

162.8

2.1

1.3

160

Nd

10.6

7.6

72

13.9

 

63.7

5.7

8.9

55

Hf

1.6

1.1

69

2.86

 

6.5

0.7

10.7

7.9

Pb

19.4

0.3

1.5

19.2

 

31.1

0.6

1.9

30

Th

5.1

0.3

5.9

5.03

 

25.7

0.3

1.2

25

U

1.9

0.5

26

2.21

 

3.0

0.6

20

 

 

 

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 Created and Maintained by Thomas Fleming  Last update 01/20/2004