Surrogate Spike
  Surrogate spikes are  used in organic analysis to determine if an analysis hasgone wrong. They are compounds that are similar in chemical compo  sitionand have similar behavior during sample preparation and analysis. Forex ample, a deuterated analog of the analyte is an ideal surrogate during GC-MS analysis.

  It behaves like the analyte and will not be present in thesample originally. The surrogate spike is added to the samples, the stand ards, the blanks, and the matrix spike. The surrogate recovery is computedfor each run. Unusually high or low recovery indicates a problem, such  ascontamination or instrument malfunction. For example, consider a set ofsamples to be analyzed for gasoline contamination by purge and trap. Deuterated toluene is added as a surrogate to all the samples, standards, andblanks. The recovery of the deuterated toluene in each is checked. If therecovery in a certain situation is unusually high or low, that particularanalysis is rejected.