What are Laboratory Control Samples?

Laboratory Control Samples and Sample Duplicates (LCS/LCSD) are samples prepared in the laboratory that contain analytes that are representative of the analytes of interest in client submitted samples. Known concentrations of analytes are added to either DI Water or Sand and are processed in the same manner as the client samples. The results of the LCS are used to demonstrate that the laboratory is in control of the processes involved in the preparation and analysis of specific tests. Control charts are maintained with acceptance criteria for each of the LCS analytes. These acceptance criteria must be met before results for client samples can be reported. The criteria include both accuracy or bias (% recovery) and precision (% RPD – or reproducibility) measurements. It is critical that the laboratory be able to not only accurately recover what is present but to be able to reproduce that action as well. A laboratory control sample duplicate (LCSD) is used to demonstrate reproducibility.

The importance of the LCS/LCSD is to provide confidence to you that what the laboratory claims it can recover and reproduce is actual and not hypothetical.