Material in a supply chain is tracked by a method of applying a DNA taggant set to a first batch of the material produced by a first supplier of the material. The DNA taggant set corresponds to a tag string corresponding to the first supplier. The first batch is aggregated with a second batch to create an aggregated lot. A sample is selected from the aggregated lot and tested to determine a DNA taggant set of the sample. After selecting a sample from the aggregated lot, the sample may be labeled with a grade and then placed in a receptacle corresponding to the grade.