Abstract: Using the actual process of spiking standard recovery experiments and computing model, the total uncertainty of lead measurement using graphite furnace atomic absorption spectrometry pig,s liver was evaluated. The results shows that the repeatable uncertainty of an average recovery rate composes only 16% of the total uncertainty; standard stock solution composes only 38% of the uncertainty of the spiked dilution process, which is 0.5% of the average recovery rate, whereas the uncertainty of plus scalar observations composes major part of the total uncertainty, accounting for 81%, mainly from the curve fitting the concentration uncertainty. There are higher rigor and relevance if the assessment of recovery rate bases on actual process and computing models.

Key words: chemical detection, food inspection, measuring deviation, recovery, uncertainty