INAA AND MULTI-METHODS
A 1g aliquot is encapsulated in a polyethylene vial and irradiated along with flux wires at a thermal neutron flux of 7 x 10 12 ncm-2 s-1. After a 7-day period to allow Na-24 to decay the samples are counted on a high purity Ge detector with resolution of better than 1.7 KeV for the 1332 KeV Co-60 photopeak. Using the flux wires and control standards, the decay-corrected activities are compared to a calibration developed from multiple certified international reference materials. For values exceeding the upper limits, assays are recommended. One standard is run for every 11 samples. One blank is analyzed per work order. Duplicates are analyzed when sample material is available.
Elements and Detection Limits (ppm)
Element Detection Limit Upper Limit
Ag 2 10,000
As 1 -
Au 2 ppb 30,000 ppb
Ba 20 100,000
Br 0.5 5000
Ca 0.20% -
Ce 1 10,000
Co 0.1 10,000
Cr 0.5 100,000
Cs 0.2 -
Eu 0.05 1000
Element Detection Limit Upper Limit
Fe 0.01% -
Hf 0.2 -
Ir 2 ppb -
La 0.05 10,000
Lu 0.01 -
Mo 2 10,000
Na 0.00% 10%
Nd 1 10,000
Ni 50 10,000
Rb 10
Sb 0.1 10,000
Element Detection Limit Upper Limit
Sc 0.01 -
Se 0.5 -
Sm 0.01 10,000
Sr 100 -
Ta 0.3 10,000
Tb 0.1
Th 0.1 10,000
U 0.1 10,000
W 1 10,000
Yb 0.05 -
Zn 10
Reference:
Hoffman, E.L., 1992. Instrumental Neutron Activation in Geoanalysis. Journal of Geochemical Exploration, volume 44, pp. 297-319.
Option: 4A RES/MS, elements are determined by fusion ICP/MS.
Elements and Detection Limits (ppm)
Element Detection Limit Upper Limit
Pr 0.01 1,000
Gd 0.01 1,000
Dy 0.01 1,000
Ho 0.01 1,000
Er 0.01 1,000
Tm 0.01 1,000
Note: Assays are recommended for values which exceed the upper limits.
INAA Portion
A 1g aliquot is encapsulated in a polyethylene vial and irradiated along with flux wires at a thermal neutron flux of 7 x 10 12 ncm-2 s-1. After a 7-day period to allow Na-24 to decay the samples are counted on a high purity Ge detector with resolution of better than 1.7 KeV for the 1332 KeV Co-60 photopeak. Using the flux wires and control standards, the decay-corrected activities are compared to a calibration developed from multiple certified international reference materials. For values exceeding the upper limits, assays are recommended. One standard is run for every 11 samples. One blank is analyzed per work order. Duplicates are analyzed when sample material is available.
Reference: Hoffman, E.L., 1992. Instrumental Neutron Activation in Geoanalysis. Journal of Geochemical Exploration, volume 44, pp. 297-319.
Total Digestion – ICP
A 0.25 g sample aliquot is digested with a mixture of HClO4, HNO3, HCl, and HF at 200 °C to fuming and is then diluted with aqua regia. This leach is partial for magnetite, chromite, barite and other spinels and potentially massive sulphides.
Major Elements by Fusion ICP-OES
Samples are prepared and analyzed in a batch system. Each batch contains a method reagent blank, certified reference material, and 17% replicates. Samples are mixed with a flux of lithium metaborate and lithium tetraborate and fused in an induction furnace. The molten melt is immediately poured into a solution of 5% nitric acid containing an internal standard, and mixed continuously until completely dissolved (~30 minutes). The samples are then run for major oxides and selected trace elements (Code 4B) on an ICP.
For the ICP analysis, reagent blanks with and without the lithium borate flux are analyzed, as well as the method reagent blank. Interference correction verification standards are analyzed. Calibration is performed using multiple USGS and CANMET certified reference materials. Two of the standards are used during the analysis for every group of ten samples. This standard brackets the group of samples. The sample solution is also spiked with internal standards and is further diluted and introduced into an ICP-MS using a proprietary sample introduction methodology. Calibration is performed using USGS and CANMET certified reference materials.
Fusion ICP
Oxide Detection
Al2O3 0.01%
CaO 0.01%
Fe2O3 0.01%
K2O 0.01%
MgO 0.01%
MnO 0.01%
Na2O 0.01%
P2O5 0.01%
SiO2 0.01%
TiO2 0.005%
LOI 0.01%
Trace Elements and Detection Limits (ppm)
Element Detection Limit Upper Limit Reported By
Ag 0.5 100,000 ICP/INAA
As 2 100,000 INAA
Au 5 ppb 30,000 ppb INAA
Ba 3 30,000 ICP/INAA
Be 1 10,000 ICP
Bi 2 10,000 ICP
Br 1 - INAA
Cd 0.5 5,000 ICP
Ce 3 10,000 INAA
Co 1 10,000 INAA
Cr 1 100,000 INAA
Cs 0.5 INAA
Cu 1 10,000 ICP
Eu 0.1 - INAA
Hf 0.5 - INAA
Hg 1 10,000 INAA
Ir 2 ppb 10,000 ppb INAA
La 0.5 10,000 INAA
Lu 0.05 1000 INAA
Mo 5 10,000 INAA
Element Detection Limit Upper Limit Reported By
Nd 5 10,000 INAA
Ni 1 10,000 ICP
Rb 20 10,000 INAA
S 0.00% 20% ICP
Sb 0.2 10,000 INAA
Sc 0.1 1000 INAA
Se 3 10,000 INAA
Sm 0.1 10,000 INAA
Sr 2 - ICP
Ta 1 10,000 INAA
Tb 0.5 1000 INAA
Th 0.5 10,000 INAA
U 0.5 10,000 INAA
V 5 - ICP
W 3 10,000 INAA
Y 1 10,000 ICP
Yb 0.1 - INAA
Zn 2 10,000 ICP
Zr 4 - ICP
Typical ICP Analysis of some USGS and Canmet Standards (%)
Std. SiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O TiO2 P2O5
SY3 59.51 11.62 6.47 0.32 2.54 8.25 4.17 4.23 0.14 0.52
MRG1 39.43 8.59 17.93 0.17 13.74 14.77 0.73 0.18 3.78 0.07
DNC1 46.91 18.46 9.76 0.15 10.05 11.27 1.99 0.24 0.47 0.07
BIR1 47.78 15.43 11.52 0.17 9.7 13.75 1.86 0.02 0.95 0.02
W2 52.58 15.35 10.72 0.16 6.37 10.98 2.31 0.64 1.05 0.12
G2 68.72 14.95 2.65 0.03 0.71 1.87 4.08 4.48 0.48 0.13
STM1 59.64 18.07 5.24 0.22 0.07 1.09 8.87 4.24 0.13 0.1
4E-Exploration options:
INAA Portion
A 1g aliquot is encapsulated in a polyethylene vial and irradiated along with flux wires at a thermal neutron flux of 7 x 10 12 ncm-2 s-1. After a 7-day period to allow Na-24 to decay the samples are counted on a high purity Ge detector with resolution of better than 1.7 KeV for the 1332 KeV Co-60 photopeak. Using the flux wires and control standards, the decay-corrected activities are compared to a calibration developed from multiple certified international reference materials. For values exceeding the upper limits, assays are recommended. One standard is run for every 11 samples. One blank is analyzed per work order. Duplicates are analyzed when sample material is available.
Reference: Hoffman, E.L., 1992. Instrumental Neutron Activation in Geoanalysis. Journal of Geochemical Exploration, volume 44, pp. 297-319.
Major Elements Portion
A 0.2g sample is mixed with a mixture of lithium metaborate/lithium tetraborate and fused in a graphite crucible. The molten mixture is poured into a 5% nitric acid solution and shaken until dissolved (~ 30 minutes). The samples are run for major oxides and selected traces on an ICP. Calibration is achieved using a variety of international reference materials. Independent control standards are also analyzed. Results on the international standards run with the samples are appended at the end of the report.
Base Metals and Selected Trace Elements
A 0.25g sample is digested with four acids beginning with hydrofluoric, followed by a mixture of nitric and perchloric acids, heated using precise programmer controlled heating in several ramping and holding cycles which takes the samples to dryness. After dryness is attained, samples are brought back into solution using hydrochloric acid. With this digestion certain phases may be only partially solubilized. These phases include zircon, monazite, sphene, gahnite, chromite, cassiterite, rutile and barite. Ag greater than 100 ppm and Pb greater than 5,000 ppm should be assayed as high levels may not be solubilized. Only sulphide sulfur will be solubilized.
An in-lab standard (traceable to certified reference materials) or certified reference materials are used for quality control. Samples are analyzed using an ICP.
Fusion ICP
Oxide Detection
Al2O3 0.01%
CaO 0.01%
Fe2O3 0.01%
K2O 0.01%
MgO 0.01%
MnO 0.01%
Na2O 0.01%
P2O5 0.01%
SiO2 0.01%
TiO2 0.05%
Loss on Ignition 0.01%
Trace Elements and Detection Limits (ppm)
Element Detection Limit Upper Limit Reported By
Ag 0.5 100,000 ICP/INAA
As 1 100,000 INAA
Au 1 ppb 30,000 ppb INAA
Ba 1 30,000 ICP/INAA
Be 1 10,000 ICP
Bi 2 10,000 ICP
Br 0.5 - INAA
Cd 0.5 5,000 ICP
Ce 1 10,000 INAA
Co 0.1 10,000 INAA
Cr 0.5 100,000 INAA
Cs 0.2 INAA
Cu 1 10,000 ICP
Eu 0.05 - INAA
Hf 0.2 - INAA
Hg 1 10,000 INAA
Ir 2 ppb 10,000 ppb INAA
La 0.05 10,000 INAA
Lu 0.01 1000 INAA
Mo 2 10,000 INAA
Element Detection Limit Upper Limit Reported By
Nd 1 10,000 INAA
Ni 1 10,000 ICP
Rb 10 10,000 INAA
S 0.00% 20% ICP
Sb 0.1 10,000 INAA
Sc 0.01 1000 INAA
Se 0.5 10,000 INAA
Sm 0.01 10,000 INAA
Sr 2 - ICP
Ta 0.3 10,000 INAA
Tb 0.1 1000 INAA
Th 0.1 10,000 INAA
U 0.1 10,000 INAA
V 5 - ICP
W 1 10,000 INAA
Y 1 10,000 ICP
Yb 0.05 - INAA
Zn 2 10,000 ICP
Zr 4 - ICP
Typical ICP Analysis of some USGS and Canmet Standards (%)
Std. SiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O TiO2 P2O5
SY3 59.51 11.62 6.47 0.32 2.54 8.25 4.17 4.23 0.14 0.52
MRG1 39.43 8.59 17.93 0.17 13.74 14.77 0.73 0.18 3.78 0.07
DNC1 46.91 18.46 9.76 0.15 10.05 11.27 1.99 0.24 0.47 0.07
BIR1 47.78 15.43 11.52 0.17 9.7 13.75 1.86 0.02 0.95 0.02
W2 52.58 15.35 10.72 0.16 6.37 10.98 2.31 0.64 1.05 0.12
G2 68.72 14.95 2.65 0.03 0.71 1.87 4.08 4.48 0.48 0.13
STM1 59.64 18.07 5.24 0.22 0.07 1.09 8.87 4.24 0.13 0.1
4E-Research options:
Add-Ons:
The trace elements analyses are done on pressed powder pellets made from 6.5g of sample. Spectral interferences are corrected from pre-calculated interfering factors. Because of the trace level (< 1,000 ppm) of the analytes, only the mass absorptions are corrected for matrix effects. The mass absorption coefficients are derived from measuring the Compton scatter of the Rh-tube (e.g., Nisbet et al., 1979. Fortschr. Miner., volume 57, pp. 264-279). The background and mass absorption corrected intensities are then calculated against the calibrations constructed from 24 international geological reference materials. In general, the limits of detection are between 1 to 5 ppm.
Elements and Detection Limits (ppm)
Element Detection Limit Upper Limit
Ga 5 10,000
Nb 1 3,000
Pb 5 1,000
Rb 2 20,000
Sn 5 10,000
Fused sample is diluted and analyzed by ICP-MS. Three blanks and five controls (three before sample group and two after) are analyzed per group of samples. Duplicates are fused and analyzed every 15 samples. Instrument is recalibrated every 40 samples.
Elements and Detection Limits (ppm)
Element Detection Limit Upper Limit
Bi 0.1 2,000
Ce 0.05 3,000
Cs 0.1 1,000
Dy 0.01 1,000
Er 0.01 -
Eu 0.005 -
Ga 1 10,000
Gd 0.01 1,000
Ge 0.5 10,000
Hf 0.1 100
Element Detection Limit Upper Limit
Sn 1 1,000
Ta 0.01 500
Tb 0.01 -
Th 0.05 1,000
Tl 0.05 1,000
Tm 0.005 -
U 0.01 1,000
Yb 0.01 -
Zr 1 10,000
