How would you prepare a 1:10 dilution of a specimen for an assay, and how would you label the dilution?

• A. Mix 1 Part Sample With 9 Parts Diluent To A Total Of 10 Parts; Label As '1:10 Dilution' With Date/Time, Initials, And Patient/Specimen ID.
• B. Mix 10 Parts Sample With 1 Part Diluent; Label As '1:11 Dilution'.
• C. Mix 1 Part Sample With 99 Parts Diluent; Label As '1:1000'.
• D. Dilute With Water Only; Label As 'Water Dilution'.

Answer: (A)

Understanding dilution factors and proper labeling is essential for accurate assay results and traceability. A one-in-ten dilution is made by combining one part of the specimen with nine parts diluent, giving ten parts total and reducing the concentration by a factor of ten. Label the dilution with the dilution expression, such as "1:10," along with the date and time, the initials of the person who prepared it, and the patient or specimen ID. This labeling ensures you know exactly what was prepared, when, and for which sample, which is crucial for reproducibility and proper result interpretation.

The other approaches don’t fit because they mix the sample with a different amount of diluent, giving a different dilution factor (for example, ten parts sample with one part diluent yields a much more concentrated dilution, not a tenfold one). Diluting with ninety-nine parts diluent would reach a one-in-a-hundred dilution. Diluting with water is not appropriate unless water is the specified, validated diluent for the assay, and simply labeling as a water dilution doesn’t communicate the exact dilution or the specimen’s identity.