SPSFAM Heavy Metals ERP - Arsenic

8. The sensitivities reported in Table 4 are troubling. The sensitivity for As(III) is ~15% lower than that of MMAs and As(V), and the sensitivity for DMAs is 10% higher than that of MMAs and As(V). This strongly suggests that there are either impurities in standards (possible) or that the integrations are not correct (more likely). The sensitivities for all species should be identical, and this is an important QA measure to control. When this method was published on the FDA website, there were some chromatogram posted as well, and they showed some As(III) tailing into the DMAs, and the integration for DMAs was being biased, causing high-bias for DMA. Based on the sensitivities listed in Table 4, this could be happening with this method.