Appendix CRF - Part 3 - Northamptonshire County Council

Job reference number
GAU1278 (Final)
Limits of detection / quantification
For gamma data, limits of quantification, LQ, is calculated as defined by Currie (1968)
and Gilmore & Hemingway (2000)
n C
2
1 100 100 1
LQ
gamma 0. 5
( )
1
1
4 1
2
2m
.
t E Y M g
where is set at 2.00, C is the background counts, n is the number of channels
covering the peak, m is the number of background channels taken either side of the
photopeak, t is the count time in seconds, E is the counting efficiency, Y is the gamma
emission probability and Mg is the mass of sample analysed in grams
Limits of detection for H-3 analyses are quoted as LD as defined by Currie, 1968.
2.
71
4.
65 C 100 100 1
LD
( Bq / g)
t E R M
where C is the background count, t is the count time in seconds, E is the measurement
efficiency, R is the chemical recovery and m is the sample mass in grams.
References
Currie L.A. (1968). Limits of qualitative detection and quantitative determination. Anaytical Chemistry,
40 (3), 586-593.
Gilmore G. and Hemingway J. (2000). Practical gamma-ray spectrometry. John Wiley, Chichester, UK
Geosciences Advisory Unit, National Oceanography Centre, Southampton, European Way, SO14 3ZH
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