The Centers for Disease Control and Prevention's (CDC) Environmental Health Laboratory uses modified versions of inductively coupled plasma mass spectrometry (ICP-MS) analytical methods to quantify metals contamination present in items that will come into contact with patient samples during the pre-analytical, analytical, and post-analytical stages. This lot screening process allows us to reduce the likelihood of introducing contamination which can lead to falsely elevated results. This is particularly important when looking at biomonitoring levels in humans which tend to be near the limit of detection of many methods. The fundamental requirements for a lot screening program in terms of facilities and processes are presented along with a discussion of sample preparation techniques used for lot screening. The criteria used to evaluate the lot screening data to determine the acceptability of a particular manufacturing lot is presented as well. As a result of lot testing, unsuitable manufactured lots are identified and excluded from use.