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5A, 5B & 5S - INAA

An aliquot 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. For all analytes except Au, a 1g aliquot is used. For Au a 30g size, if available, is used.

 

One standard is run for every 11 samples. One blank is analyzed per work order. Duplicates are analyzed when samples are provided.

   

 

Code 5A Basic Elements and Detection Limits (ppm)

Element

Detection Limit

Upper Limit

Element

Detection Limit

Upper Limit

Element

Detection Limit

Upper Limit

As

2

10,000

Fe

0.02%

75%

Sc

0.5

200

Au

5 ppb

30,000 ppb

Hf

1

5000

Se

5

10,000

Ba

200

100,000

La

1

10,000

Sm

0.1

10,000

Br

2

1000

Lu

0.1

1000

Ta

2

10,000

Ce

5

10,000

Mo

5

10,000

Th

1

10,000

Co

2

10,000

Na

500

100,000

U

2

10,000

Cr

10

100,000

Nd

10

10,000

W

5

10,000

Cs

2

10,000

Rb

50

10,000

Yb

0.5

1000

Eu

0.2

2000

Sb

0.2

10,000

 

 

Code 5B Other Elements and Detection Limits (ppm)

Element

Detection Limit

Upper Limit

Element

Detection Limit

Upper Limit

Element

Detection Limit

Upper Limit

As

1

10,000

Fe

0.01%

75%

Sc

0.1

200

Au

5 ppb

30,000 ppb

Hf

0.5

500

Se

2

10,000

Ba

100

100,000

La

0.1

10,000

Sm

0.01

10,000

Br

0.5

1000

Lu

0.05

1000

Ta

0.5

10,000

Ce

3

10,000

Mo

2

10,000

Th

0.2

10,000

Co

0.5

10,000

Na

100

100,000

U

0.1

10,000

Cr

1

100,000

Nd

5

10,000

W

2

10,000

Cs

0.5

10,000

Rb

20

10,000

Yb

0.2

1000

Eu

0.2

2000

Sb

0.1

10,000

 

Code 5S Short Lived Isotopes (ppm)

Element

Detection Limit

Upper Limit

Element

Detection Limit

Upper Limit

Al

1

100,000

In

0.1

5,000

Br

5

10,000

Mg

0.05%

50%

Cl

100

100,000

Mn

0.1

10,000

Cu

5

2,500

Na

50

200,000

Dy

0.5

5,000

Re

1

5,000

Ga

5

10,000

Ti

50

100,000

I

0.5

5000

V

0.1

10,000

 

 

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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