User manual

2 | Droplet Digital
™
PCR Applications Guide
ddPCR has the following benefits for nucleic acid quantification:
■
Unparalleled precision — the massive sample partitioning afforded by ddPCR enables
small fold differences in target DNA sequence between samples to be reliably measured
■
Increased signal-to-noise — enrich for rare targets by reducing competition that comes
from high-copy templates
■
Removal of PCR efficiency bias — error rates are reduced by removing the amplification
efficiency reliance of PCR, enabling accurate quantification of targets
■
Simplified quantification — a standard curve is not required for absolute quantification
QX100/QX200 Workflow
Bio-Rad’s QX100 or QX200 ddPCR system (Figure 1.1) combines water-oil emulsion
droplet technology with microfluidics. The QX200 droplet generator partitions samples
into 20,000 droplets (Figure 1.2). PCR amplification is carried out within each droplet
using a thermal cycler. After PCR, droplets are streamed in single file on a QX200 droplet
reader, which counts the fluorescent positive and negative droplets to calculate target
DNA concentration.
Droplet Digital
™
PCR
Fig. 1.1. QX200 ddPCR system with associated consumables.
Fig. 1.2. In ddPCR, a single PCR sample is partitioned into 20,000 discrete droplets.