Radiotracer-diluted samples

In isotope dilution analysis, a known amount of radio-labeled compound with known specific activity is spiked to a known amount of an unknown mixture containing the same compound made up of stable isotopes. Then, the components of the radiotracer-diluted samples are mixed thoroughly to form a homogeneous mixture. This istopically diluted mixture, with known levels of dilution, is then suitably treated to isolate a small amount of the desired constituent. The radioactive isotope content of the isolated portion is determined by measuring its specific activity. From the... 

The method of dilution, with its two variants integration method and injection method with constant flow. Here an appropriate radiotracer is injected in the process, and samples are collected in a point enough downstream to assure a complete mixture. The injection of the tracer and its concentration, both in the injected solution and in the diluted samples, are measured. From these data, the flow can be easily calculated, a. Integration Method the tracer (activity A) is injected during a short interval of time. In a section, situated downstream, we measure in a point the function C(t) representing its passage the flow is given by ... 

In an isotope dilution experiment, chloride was determined by adding 5,0 mg of sodium chloride containing C1 (fj. " 37.3 min) to a sample, The specific activity of the added NaCI was 4.0 x lO cps/mg. What was the total amount of chloride present in the original sample if 400 mg of pure AgCl was isolated and if this material had a counting rate of 35 cps above background 148 min after the addition of the radiotracer ... 

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