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2B - Vegetation - INAA

Ground vegetation samples weighing 6 to 15 g are compressed under 30 tons of pressure to form a briquette (smaller samples are weighed in vials). Briquettes are stacked with flux wires and an internal standard (1 for 29 samples) and irradiated at a thermal flux of 7 x 10 12 n cm-2 s-1 for 15 minutes. 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 analyzed for every 29 samples. Duplicates are analyzed when provided.

Required Preparation: Code  B2 (drying and macerating vegetation in a Retsch mill with sieving to 1 mm)

 

Code 2B (Vegetation) Elements and Detection Limits (ppm)

Element

Detection Limit

Element

Detection Limit

Element

Detection Limit

Element

Detection Limit

Ag

0.3

Cs

0.05

Mo

0.05

Sr

100

As

0.01

Eu

0.05

Na

1

Ta

0.05

Au

0.1 ppb

Fe

0.005%

Nd

0.3

Tb

0.1

Ba

5

Hf

0.05

Ni

2

Th

0.1

Br

0.01

Hg

0.05

Rb

1

U

0.01

Ca

0.01%

Ir

0.1 ppb

Sb

0.005

W

0.05

Ce

0.1

K

0.01%

Sc

0.01

Yb

0.005

Co

0.1

La

0.01

Se

0.1

Zn

2

Cr

0.3

Lu

0.001

Sm

0.001

 

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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