What are the statistics of your results? Assumed distribution, uncertainty, data at higher results?

The definition of detection varies by discipline. The results are unreliable if the uncertainty approaches the result value.

Hi Paula

Statistically, you're detection limit is in 4-10 targets by reaction, below 4 copies by reaction you have 50% likelihood of have 0 targets. Other different factors can impact in your detection limit as your PCR efficiency, the DNA purification procedure and the efficiency of bacteria recovery from your sample.

On the other hand depending your PCR setup, you must to take some care in order to be sure that PCR signals at high Ct are true amplifications

best regards

Francesc

How was your definition of detection obtained? How do you incorporate PCR efficiency, the DNA purification procedure and the efficiency of bacteria recovery in your determination of detection limit? How do you ensure your PCR setup is appropriate to apply the detection limit?

Does ratio of Base pairs of amplified and original sample greater than x can help. If x is say >10 or 100 or 1000 or so. It's interesting to know about  minimum measurable  limit. What is conservative value of x at which pcr surely did the job. I think 1000 is OK.

Hi Josep

Is very large to respond, however I'll link some references

How was your definition of detection obtained?

  - inspired by the ISO 7218, point 10.3.2.4.1,

How do you incorporate PCR efficiency,

  - one example is https://www.ncbi.nlm.nih.gov/pubmed/23649952

the DNA purification procedure and the efficiency of bacteria recovery in your determination of detection limit?

  - it must to be experimentally evaluated or using internal standards

How do you ensure your PCR setup is appropriate to apply the detection limit?

  - it mus be done during the method validation

How do I calculate the detection limit in qPCR?. Available from: