BioLT

Worked Example

Copy Number Example for qPCR Standard Preparation

Worked example for converting DNA mass into copies and preparing a standard series with enough volume for replicates.

Scenario

You have a quantified DNA standard and need copy number estimates before planning a dilution series.

This example shows how the copy calculation and the dilution plan should be documented together.

Inputs to confirm

Template length must match the actual standard molecule.

Use the measured concentration from the same batch you will dilute, not an older value from a prior prep.

Decide how many replicate wells and reruns the standard series must support.

How a researcher would use the result

First convert the measured mass concentration to copies per unit volume, then design the dilution series backward from the target copy range.

Keep one note line with the molecule length, calculation date, and target copy range so the standard can be defended later.

Common failure points

Using the wrong fragment length after cloning or linearization changes.

Planning the dilution steps without checking whether the starting concentration can realistically support them.

Running the series too close to the lower detection limit without replicate protection.