Mathematics of quantitative kinetic PCR and the application of standard curves

Nucleic Acids Res. 2003 Aug 15;31(16):e93. doi: 10.1093/nar/gng093.


Fluorescent monitoring of DNA amplification is the basis of real-time PCR, from which target DNA concentration can be determined from the fractional cycle at which a threshold amount of amplicon DNA is produced. Absolute quantification can be achieved using a standard curve constructed by amplifying known amounts of target DNA. In this study, the mathematics of quantitative PCR are examined in detail, from which several fundamental aspects of the threshold method and the application of standard curves are illustrated. The construction of five replicate standard curves for two pairs of nested primers was used to examine the reproducibility and degree of quantitative variation using SYBER Green I fluorescence. Based upon this analysis the application of a single, well- constructed standard curve could provide an estimated precision of +/-6-21%, depending on the number of cycles required to reach threshold. A simplified method for absolute quantification is also proposed, in which quantitative scale is determined by DNA mass at threshold.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA / genetics
  • DNA / metabolism
  • Kinetics
  • Linear Models
  • Mathematics
  • Polymerase Chain Reaction / methods*
  • Polymerase Chain Reaction / standards*
  • Reference Standards
  • Reproducibility of Results


  • DNA