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1EPI - Aqua Regia-ICP, INAA

A 30 g sample is analyzed by INAA and with an aqua regia digestion followed by ICP analysis.

 

INAA

INAA is an analytical technique dependent on measuring gamma radiation induced in the sample by irradiation with neutrons. The primary source of neutrons for irradiation is usually a nuclear reactor. Each activated element emits a "fingerprint" of gamma radiation which can be measured and quantified. 

 

A 30 g aliquot, if available, is encapsulated in a polyethylene vial and irradiated with flux wires and an internal standard (1 for 11 samples) at a thermal neutron flux of 7 x 1012 n cm-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, the decay-corrected activities are compared to a calibration developed from multiple certified international reference materials. The standard present is only a check on accuracy and is not used for calibration purposes. From 10-30 % of the samples are rechecked by re-measurement.  For values exceeding the upper limits, assays are recommended.

One standard is run for every 11 samples. One blank is analyzed per work order. Selected duplicates are analyzed when enough material is submitted.

ICP/OES
0.5 g of sample is digested with aqua regia for 2 hours at 95 ° C. Sample is cooled then diluted with deionized water. The samples are then analyzed on a Perkin Elmer ICP for the 35 element suite.  A matrix standard and blank are run every 13 samples.

A series of USGS-geochemical standards are used as controls. This digestion is near total for base metals; however it is only a partial digestion for silicates and oxides.

Code 1EPI (Au + 14) Elements and Detection Limits (ppm)

Element

Detection Limit

Upper Limit

Reported By

 

Element

Detection Limit

Upper Limit

Reported By

Ag *

0.2

10,000

ICP

 

Mn

2

20,000

ICP

As

2

10,000

INAA

 

Mo

2

10,000

ICP

Au

5 ppb

30,000 ppb

INAA

 

Ni

1

10,000

ICP

Ba

50

100,000

INAA

 

Pb

2

5,000

ICP

Cd

0.5

5,000

ICP

 

S+

0.001%

20%

ICP

Cu

1

10,000

ICP

 

Sb

0.2

10,000

INAA

Fe

0.02%

75%

INAA

 

W

4

10,000

INAA

Hg

1

10,000

INAA

 

Zn

1

10,000

ICP

 

 

Code 1EPI Enhanced (Au + 14) Elements and Detection Limits (ppm)

Element

Detection Limit

Upper Limit

Reported By

 

Element

Detection Limit

Upper Limit

Reported By

Ag *

0.2

10,000

ICP

 

Mo

2

10,000

ICP

As

0.5

10,000

INAA

 

Ni

1

10,000

ICP

Au

2 ppb

30,000 ppb

INAA

 

Pb

2

5,000

ICP

Ba

50

50,000

INAA

 

S+

0.001%

20%

ICP

Cd

0.5

5,000

ICP

 

Sb

0.2

10,000

INAA

Cu

1

10,000

ICP

 

W

4

10,000

INAA

Hg

1

10,000

INAA

 

Zn

1

10,000

ICP

Mn

2

20,000

ICP

 

 

 

 

 


Notes:
 
Extraction of each element by Aqua Regia Digestion is dependent on mineralogy.

+ Only sulphide sulphur is extracted.
* Element reported by multiple techniques if one or more technique may not be total.
Assays are recommended for values which exceed the upper limits.

 

Reference :

Hoffman, E.L., 1992. Instrumental Neutron Activation in Geoanalysis. Journal of Geochemical Exploration, volume 44, pp. 297-319.


Activation Laboratories Ltd. | 41 Bittern Street, Ancaster, Ontario, L9G 4V5, Canada | TF: +1.888.228.5227
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