Purification chemistries and formats for sanger dna sequencing reactions on a micro-fluidics device

An apparatus for reducing sequencing contaminants in a single-stranded DNA sequencing reaction, the apparatus comprising:

• a microfluidics chip comprising a microfluidic conduit in the microfluidic chip, the microfluidic conduit comprising a flow channel, an inlet to the flow channel, and an outlet from the flow channel, and a flow path defined through the flow channel from the inlet to the outlet;
• a first plurality of beads trapped in a first section of the flow path along a length of the flow channel, the first plurality of beads coated with a first reagent and a second reagent, the first reagent comprising an anion-exchange reagent configured to capture negatively-charged single-stranded DNA fragments, the second reagent comprising a size-exclusion reagent configured to prevent single-stranded DNA fragments larger than a preselected size from being captured;
• a second plurality of beads trapped in a second section of the flow path along the length of the flow channel, the second plurality of beads coated with a third reagent, the third reagent comprising a cation-exchange reagent configured to capture positively-charged single-stranded DNA fragments;
• and
• retention structures in the flow channel located at each of the first and second sections of the flow path, the retention structures configured to trap the first plurality of beads in the first section and the second plurality of beads in the second section,
• wherein the first section is upstream of the second section along the flow path, and the length is an unbranched segment of the flow channel.