Methods for real-time sampling of reaction products

1. A method for analyzing sample components in a microfluidic device comprising a chamber, a load channel that leads from the chamber to a load waste well, a separation channel that leads from a separation head well to a separation waste well and intersects the load channel, and a preload channel that leads from the load channel at a position between the chamber and the load channel/separation channel intersection to a preload waste well, wherein:

the length of the load channel from the chamber to load channel/separation channel intersection is distance A, the length of the load channel from the load channel/preload channel junction to the load channel/separation channel intersection is distance B, and distance A and distance B satisfy the following conditions:

(1) ν fast (T 1 )<distance A;

(2) ν slow (2·T 1 +T 2 )>distance A;

(3) ν slow (T 1 )>distance B;

wherein ν fast is the electrokinetic velocity of the fastest component of interest in the sample, and ν slow is the electrokinetic velocity of the slowest component of interest in the sample;

the method comprising the steps of:

(a) adding an assay solution to the chamber;

(b) applying a first voltage across the chamber and the load waste well for a first length of time T 1 to move (i) a first set of sample components removed from the assay solution at a first time and previously moved into the load channel into a load channel/separation channel intersection region and (ii) a second set of sample components removed from the assay solution at a second time from the chamber into the load channel;

(c) subsequent to step (b), applying a second voltage across the chamber and the preload waste well for a second length of time T 2 to continue to move the second set of sample components removed from the assay solution at a second time from the chamber and in the load channel towards the preload waste well; and

(d) subsequent to step (b), applying a third voltage across the separation head well and separation waste well for a third length of time T 3 to inject the first set of sample components from the load channel/separation channel intersection region into the separation channel and to perform an analysis of the first set of sample components in the separation channel.

2. The method according to claim 1 , wherein the distance A is 0.1-2 cm.

3. The method according to claim 2 , wherein the distance A is 0.3-0.8 cm.

4. The method according to claim 1 , wherein the distance B is 0.01-0.2 cm.

5. The method according to claim 1 , wherein steps (c) and (d) at least partially overlap in time.

6. The method according to claim 5 , wherein step (c) begins when step (b) ends.

7. The method according to claim 6 , wherein step (d) begins when step (b) ends.

8. The method according to claim 5 , wherein step (b) is repeated after step (d) ends.

9. The method according to claim 8 , wherein the cycle of steps (b), (c), and (d) is repeated at least 10 times.

10. The method according to claim 1 , wherein the sample components move by electrophoresis.

11. The method according to claim 1 , further comprising performing at least one nucleic acid amplification reaction in the chamber after step (a).

12. The method according to claim 11 , wherein the following series of steps (b)-(e) is repeated at least twice:

step (b);

step (c);

step (d); and

(e) performing at least one amplification cycle beginning at the end of step (c);

wherein:

the first time the series of steps is performed, step (d) is optionally omitted;

the subsequent series of steps begins after step (d) and step (e) end; and

optionally, the last time the series of steps is repeated, the series of steps only includes step (b) and step (d).

13. The method according to claim 12 , wherein:

steps (c) and (d) begin when each step (b) ends; and

one amplification cycle is performed in each step (e), which begins at the end of each step (c).

14. The method according to claim 1 , wherein the sample components comprise at least one polynucleotide.