The customer reported a false negative reaction of a patient sample with a known anti-d with cell #4 of biotest cell-i11 plus on tango optimo.The customer returned the supposedly defective product biotest cell-i11 plus, but only the affected cell #4 and not the complete panel.The customer also returned the patient sample that had caused a false negative test result.At the time we received the material provided by customer the supposedly defective product was already expired.Nevertheless our quality control laboratory tested the patient sample with the complaint sample on tango optimo and yielded a correctly positive result.Additionally the patient sample was tested with the current lot of biotest cell-i11 plus.All positive and negative reactions were correct.We did not observe any false negative reaction.The retention sample of the complained lot was tested during its shelf life with different samples and controls e.G.Anti-d.Again, all results were as expected.Testing by our quality control laboratory confirmed that the allegedly defective lot of biotest cell-i11 plus functions correctly.A review of the batch record documentation showed no irregularities which might have negatively affected the quality of the allegedly defective lot.The affected tango optimo was inspected by our field service engineers with no indication for an instrument malfunction.The service engineer confirmed a proper function of the instrument by metrology qualification.Also the ssc ii qc of other testing days was run without any complaint relevant issue.
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