Franklin & Marshall College Franklin & Marshall College

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Earth and Environment

X-ray Laboratory

Precision and Accuracy

A measure of the total analytical precision for XRF analysis performed June, 2011.

Each analysis listed below is a separate aliquot taken from a singular sample (F30) and prepared independently by Karen Mertzman. These 10 analyses represent all the errors that could accrue from weighing, mixing, preparation of the fusion glass disk and trace element briquette, and the actual peak and background measurements made by the PW2404 Panalytical, Inc. XRF vacuum spectrometer.







Speciman

 F30/1 F30/2 F30/3 F30/4 F30/5 F30/6 F30/7 F30/8 F30/9 F30/10
SiO2 48.78 48.81 48.79 48.71 48.69 48.76 48.74 48.70 48.70 48.74
TiO2 2.40 2.40 2.40 2.40 2.40 2.40 2.40 2.40 2.40 2.40
Al2O3 12.92 12.96 12.94 12.91 12.90 12.91 12.93 12.93 12.92 12.93
Fe2O3T 13.32 13.30 13.31 13.30 13.29 13.30 13.29 13.30 13.29 13.29
MnO 0.178 0.176 0.177 0.176 0.176 0.176 0.176 0.176 0.177 0.177
MgO 10.350 10.372 10.351 10.355 10.364 10.370 10.376 10.358 10.364 10.356
CaO 9.693 9.682 9.670 9.681 9.684 9.683 9.681 9.679 9.689 9.679
Na2O 1.901 1.895 1.895 1.890 1.904 1.898 1.894 1.900 1.899 1.894
K2O 0.386 0.389 0.389 0.387 0.386 0.388 0.389 0.388 0.388 0.388
P2O5 0.264 0.266 0.269 0.265 0.264 0.264 0.265 0.266 0.266 0.264
Total 100.192 100.250 100.191 100.074 100.058 100.149 100.141 100.097 100.093 100.118
                     
Rb 6.2 6.0 5.9 6.5 6.0 5.9 6.2 6.2 6.0 6.3
Sr 297 296 297 299 295 295 298 293 296 301
Y 27.2 27.4 28.0 27.3 27.8 28.1 27.4 27.9 27.7 27.9
Zr 135 136 134 135 134 135 134 134 134 135
V 307 310 307 313 314 310 315 304 303 317
Ni 243 245 243 243 243 243 246 245 245 245
Cr 633 671 650 669 635 638 657 665 648 647
Nb 10.8 11.2 11.8 12.2 11.7 11.2 11.6 11.3 11.3 11.7
Ga 16.2 16.3 16.5 16.5 16.4 16.6 16.5 16.4 16.6 16.5
Cu 133 132 133 133 132 132 132 133 134 133
Zn 106 106 105 105 105 106 106 106 107 106
Co 57 58 57 58 57 58 59 59 57 59
Ba 89 101 96 109 76 89 81 91 86 88
La 14 14 15 16 16 15 15 16 15 16
Ce 29 31 30 27 32 29 30 31 30 31
U <0.5 0.9 1.1 1.7 <0.5 0.5 0.7 2.0 0.7 <0.5
Th 3.0 <0.5 2.2 <0.5 1.8 2.0 0.9 1.4 2.6 1.5
Sc 34 33 33 34 34 33 34 33 33 33
Pb <1 <1 <1 <1 2 3 1 2 1 <1

A measure of the accuracy of the current XRF major and trace element calibration being utilized in F&M College X-ray laboratory using geochemical standard BHVO-2 performed June, 2011.

A singular glass fusion disk for the major elements and a singular sample powder / copolywax briquette were each analyzed 10 times and compiled in the table below. Also listed is the geochemical analysis of BHVO-2 that can be currently found at the USGS web site.


 

Specimen BHVO-2 BHVO-2 BHVO-2 BHVO-2 BHVO-2 BHVO-2 BHVO-2 BHVO-2 BHVO-2 BHVO-2 BHVO-2 Accepted
SiO2 49.94 50.02 49.97 49.94 49.83 49.95 50.00 49.92 49.97 49.95 49.90
TiO2 2.72 2.73 2.73 2.72 2.72 2.73 2.73 2.73 2.73 2.72 2.73
Al2O3 13.63 13.66 13.66 13.65 13.61 13.62 13.65 13.62 13.64 13.66 13.50
Fe2O3T 12.43 12.45 12.41 12.42 12.40 12.43 12.42 12.42 12.43 12.43 12.30
MnO 0.165 0.165 0.165 0.165 0.165 0.165 0.164 0.166 0.165 0.165 0.165
MgO 7.299 7.292 7.285 7.294 7.291 7.309 7.304 7.290 7.289 7.290 7.230
CaO 11.473 11.482 11.485 11.490 11.473 11.505 11.491 11.486 11.488 11.479 11.400
Na2O 2.196 2.190 2.197 2.200 2.202 2.191 2.190 2.199 2.192 2.197 2.220
K2O 0.505 0.507 0.507 0.505 0.504 0.504 0.505 0.507 0.508 0.507 0.520
P2O5 0.265 0.267 0.267 0.266 0.267 0.266 0.266 0.268 0.268 0.266 0.270
Total 100.623 100.763 100.676 100.650 100.462 100.670 100.720 100.606 100.680 100.664 100.235
                       
Rb 8.3 7.8 7.5 7.2 7.3 8.5 7.8 8.1 8.6 7.9 7.9
Sr 371 380 384 380 380 380 379 378 383 385 385
Y 26.0 25.9 25.9 25.6 25.7 25.4 26.1 25.3 25.5 25.2 25.2
Zr 167 169 165 170 166 164 167 168 164 168 168
V 327 331 328 328 323 325 324 326 324 327 327
Ni 122 122 123 122 122 122 123 121 121 123 123
Cr 312 327 310 319 312 322 331 342 324 314 314
Nb 16.5 17.6 16.8 17.0 17.9 17.0 16.5 16.8 17.2 16.9 16.9
Ga 17.8 17.7 18.1 18.1 17.7 17.8 17.8 17.9 17.9 17.9 17.9
Cu 128 126 130 128 130 127 128 120 121 122 122
Zn 91 92 91 92 92 92 92 91 91 91 91
Co 45 45 47 46 44 48 45 46 45 45 45
Ba 121 112 124 111 118 115 104 128 120 107 107
La 15 13 15 17 17 16 15 16 17 17 17
Ce 29 29 29 31 29 28 28 29 30 30 30
U 1.1 0.8 1.1 1.7 1.5 0.5 1.5 1.9 2.0 0.8 0.8
Th <0.5 <0.5 1.3 <0.5 1.4 0.5 <0.5 <0.5 <0.5 1.8 1.8
Sc 34 34 35 34 33 33 34 33 33 34 34
Pb 1 1 1 <1 <1 2 1 1 2 1 1