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)

ElementDetection LimitUpper Limit
Ag210,000
As1-
Au2 ppb30,000 ppb
Ba20100,000
Br0.55000
Ca0.20%-
Ce110,000
Co0.110,000
Cr0.5100,000
Cs0.2-
Eu0.051000
ElementDetection LimitUpper Limit
Fe0.01%-
Hf0.2-
Ir2 ppb-
La0.0510,000
Lu0.01-
Mo210,000
Na0.00%10%
Nd110,000
Ni5010,000
Rb10
Sb0.110,000
ElementDetection LimitUpper Limit
Sc0.01-
Se0.5-
Sm0.0110,000
Sr100-
Ta0.310,000
Tb0.1
Th0.110,000
U0.110,000
W110,000
Yb0.05-
Zn10

 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)

ElementDetection LimitUpper Limit
Pr0.011,000
Gd0.011,000
Dy0.011,000
Ho0.011,000
Er0.011,000
Tm0.011,000

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 a combination simultaneous/sequential Thermo Jarrell-Ash ENVIRO II 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 a Perkin Elmer SCIEX ELAN 6000 ICP/MS using a proprietary sample introduction methodology. Calibration is performed using USGS and CANMET certified reference materials.

 Fusion ICP

OxideDetection
Al2O30.01%
CaO0.01%
Fe2O30.01%
K2O 0.01%
MgO0.01%
MnO0.01%
Na2O0.01%
P2O50.01%
SiO20.01%
TiO20.005%
LOI0.01%

Trace Elements and Detection Limits (ppm)

ElementDetection LimitUpper LimitReported By
Ag0.5100,000ICP/INAA
As2100,000INAA
Au5 ppb30,000 ppbINAA
Ba330,000ICP/INAA
Be110,000ICP
Bi210,000ICP
Br1-INAA
Cd0.55,000ICP
Ce310,000INAA
Co110,000INAA
Cr1100,000INAA
Cs0.5INAA
Cu110,000ICP
Eu0.1-INAA
Hf0.5-INAA
Hg110,000INAA
Ir2 ppb10,000 ppbINAA
La0.510,000INAA
Lu0.051000INAA
Mo510,000INAA
ElementDetection LimitUpper LimitReported By
Nd510,000INAA
Ni110,000ICP
Rb2010,000INAA
S0.00%20%ICP
Sb0.210,000INAA
Sc0.11000INAA
Se310,000INAA
Sm0.110,000INAA
Sr2-ICP
Ta110,000INAA
Tb0.51000INAA
Th0.510,000INAA
U0.510,000INAA
V5-ICP
W310,000INAA
Y110,000ICP
Yb0.1-INAA
Zn210,000ICP
Zr4-ICP

Typical ICP Analysis of some USGS and Canmet Standards (%)

Std.SiO2Al2O3Fe2O3MnOMgOCaONa2OK2OTiO2P2O5
SY359.5111.626.470.322.548.254.174.230.140.52
MRG139.438.5917.930.1713.7414.770.730.183.780.07
DNC146.9118.469.760.1510.0511.271.990.240.470.07
BIR147.7815.4311.520.179.713.751.860.020.950.02
W252.5815.3510.720.166.3710.982.310.641.050.12
G268.7214.952.650.030.711.874.084.480.480.13
STM159.6418.075.240.220.071.098.874.240.130.1

4E-Exploration options:

4E-XRF

4E-ICPMS

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 a Varian Vista 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 a Varian Vista ICP.

 Fusion ICP

OxideDetection
Al2O30.01%
CaO0.01%
Fe2O30.01%
K2O 0.01%
MgO0.01%
MnO0.01%
Na2O0.01%
P2O50.01%
SiO20.01%
TiO20.05%
Loss on Ignition0.01%

Trace Elements and Detection Limits (ppm)

ElementDetection LimitUpper LimitReported By
Ag0.5100,000ICP/INAA
As1100,000INAA
Au1 ppb30,000 ppbINAA
Ba130,000ICP/INAA
Be110,000ICP
Bi210,000ICP
Br0.5-INAA
Cd0.55,000ICP
Ce110,000INAA
Co0.110,000INAA
Cr0.5100,000INAA
Cs0.2INAA
Cu110,000ICP
Eu0.05-INAA
Hf0.2-INAA
Hg110,000INAA
Ir2 ppb10,000 ppbINAA
La0.0510,000INAA
Lu0.011000INAA
Mo210,000INAA
ElementDetection LimitUpper LimitReported By
Nd110,000INAA
Ni110,000ICP
Rb1010,000INAA
S0.00%20%ICP
Sb0.110,000INAA
Sc0.011000INAA
Se0.510,000INAA
Sm0.0110,000INAA
Sr2-ICP
Ta0.310,000INAA
Tb0.11000INAA
Th0.110,000INAA
U0.110,000INAA
V5-ICP
W110,000INAA
Y110,000ICP
Yb0.05-INAA
Zn210,000ICP
Zr4-ICP

 Typical ICP Analysis of some USGS and Canmet Standards (%)

Std.SiO2Al2O3Fe2O3MnOMgOCaONa2OK2OTiO2P2O5
SY359.5111.626.470.322.548.254.174.230.140.52
MRG139.438.5917.930.1713.7414.770.730.183.780.07
DNC146.9118.469.760.1510.0511.271.990.240.470.07
BIR147.7815.4311.520.179.713.751.860.020.950.02
W252.5815.3510.720.166.3710.982.310.641.050.12
G268.7214.952.650.030.711.874.084.480.480.13
STM159.6418.075.240.220.071.098.874.240.130.1

 4E-Research options:

4E-XRF

4E-ICP-MS

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)

ElementDetection LimitUpper Limit
Ga510,000
Nb13,000
Pb51,000
Rb220,000
Sn510,000

Fused sample is diluted and analyzed by Perkin Elmer Sciex ELAN 6000, 6100 or 9000 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)

ElementDetection LimitUpper Limit
Bi0.12,000
Ce0.053,000
Cs0.11,000
Dy0.011,000
Er0.01-
Eu0.005-
Ga110,000
Gd0.011,000
Ge0.510,000
Hf0.1100
ElementDetection LimitUpper Limit
Sn11,000
Ta0.01500
Tb0.01-
Th0.051,000
Tl0.051,000
Tm0.005-
U0.011,000
Yb0.01-
Zr110,000