ISO/TC 147/SC 3/WG 15 - Liquid scintillation counting and proportional counting
Comptage par scintillation liquide et comptage proportionnel
General Information
This document specifies a method for the measurement of 210Pb in all types of waters by liquid scintillation counting (LSC). The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. Filtration of the test sample is necessary. Lead‑210 activity concentration in the environment can vary and usually ranges from 2 mBq l-1 to 300 mBq l-1 [27][28]. Using currently available liquid scintillation counters, the limit of detection of this method for 210Pb is generally of the order of 20 mBq l-1 to 50 mBq l-1, which is lower than the WHO criteria for safe consumption of drinking water (100 mBq lâ’1).[4][6] These values can be achieved with a counting time between 180 min and 720 min for a sample volume from 0,5 l to 1,5 l. Higher activity concentrations can be measured by either diluting the sample or using smaller sample aliquots or both. The method presented in this document is not intended for the determination of an ultra-trace amount of 210Pb. The range of application depends on the amount of dissolved material in the water and on the performance characteristics of the measurement equipment (background count rate and counting efficiency). The method described in this document is applicable to an emergency situation. The analysis of Pb adsorbed to suspended matter is not covered by this method. It is the user’s responsibility to ensure the validity of this test method for the water samples tested.
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This document specifies a method for the measurement of 14C activity concentration in all types of water samples by liquid scintillation counting (LSC) either directly on the test sample or following a chemical separation. The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, marine water, as well as cooling water, industrial water, domestic, and industrial wastewater. The detection limit depends on the sample volume, the instrument used, the sample counting time, the background count rate, the detection efficiency and the chemical recovery. The method described in this document, using currently available liquid scintillation counters and suitable technical conditions, has a detection limit as low as 1 Bqâ™lâ’1, which is lower than the WHO criteria for safe consumption of drinking water (100 Bq·l-1). 14C activity concentrations can be measured up to 106 Bqâ™l-1 without any sample dilution. It is the user’s responsibility to ensure the validity of this test method for the water samples tested.
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This document specifies a test method for the determination of iron-55 (55Fe) activity concentration in samples of all types of water using liquid scintillation counting (LSC). Using currently available liquid scintillation counters, this test method can measure the 55Fe activity concentrations in the range from the limit of detection up to 120 mBq l-1. These values can be achieved with a counting time between 7 200 s and 10 800 s for a sample volume from 0,5 l to 1,5 l. Higher activity concentrations can be measured by either diluting the sample or using smaller sample aliquots or both. NOTE     These performance indicators are wholly dependent on the measurement regimes in individual laboratories; in particular, the detection limits are influenced by amount of stable iron present. The range of application depends on the amount of dissolved material in the water and on the performance characteristics of the measurement equipment (background count rate and counting efficiency). It is the laboratory’s responsibility to ensure the suitability of this test method for the water samples tested.
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