What is the surrogate?
The surrogate is a set of chemicals (added to the water sample at the laboratory) to ensure that the laboratory equipment is functioning properly. If the percent recovery number (i.e. 95%) falls between the QC limits (70%-130%), it means the laboratory equipment is correctly calibrated and functioning properly. In rare instances, the surrogate value may be slightly above the 130% value, but that is still within acceptable laboratory limits. If the value is below 70% then it is possible that the results are invalid. The surrogate chemicals are not present in your drinking water.
