The experimental laboratory intercomparison tests (‘round robin’ test) reported here were twofold: (i) analysis of HTO in different waters and (ii) analysis of HTO plus 14CH3OH in mixtures in different waters. The first test sequence was organized by Norway while the second was arranged by Vietnam.

11.1. LABORATORY INTERCOMPARISON TEST ON HTO ANALYSIS

11.1.1. Preparation of samples

The following series of samples were prepared at IFE, Norway:

• Series 1, samples 1A-1E: Distilled tap water with added and calibrated quantities of HTO. Sample volume was 100 mL each.

• Series 2, samples 2A-2E: Distilled tap water with a quenching agent added and calibrated quantities of HTO. Sample volume was 100 mL each.

• Series 3, samples 3A-3E: Artificial Gullfaks (Norwegian oilfield) formation water with added and calibrated quantities of HTO. Sample volume was 250 mL each.

• Series 4, samples 4A-4E: Real formation water (Tordis oilfield, Norway) which has been in contact with ‘live’ oil. A calibrated quantity of HTO was added. Sample volume was 250 mL each. For the concentration of some main ions, see Table 17.

The samples were calibrated with certified Wallac and Packard secondary standard tablets using Quantulus 1220 liquid scintillation counting equipment. Six packages of 20 water samples each were shipped to the various participating laboratories on 18 May 2006. Results were requested by 15 September 2006.