The customer's sample was returned for investigation.The sample was investigated with a dedicated research toolbox to detect streptavidin interfering factors.A decreased amount of counts was generated with the kit version that contains an additional amount of a given streptavidin blocking agent.This does not indicate the presence of a streptavidin interfering factor.With a research version of the ft3 assay that contains an additional amount of a given iep (interference eliminating protein), a non-significant increase of the ft3 value was measured compared to the value generated with the commercially available assay.Once again, this does not indicate that an streptavidin interfering factor is available in the sample analyzed.Although no interfering factor could be identified during the analysis of the sample, an interfering factor may have been available in the sample.The effect of the latter on the value of the ft3 assay may have been minimalized by the different freeze/thaw cycles of the sample concerned.From the information provided and the analysis thereof, a general reagent issue most likely can be excluded.The investigation did not identify a product problem.The cause of the event could not be determined.
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