Control system and method for flash separation
Provided are methods and apparatus for determining conditions for performing chromatography, particularly flash chromatography. The methods may be utilized for separating compounds in a sample in a column chromatography system. The method includes determining at least two retention factors corresponding to the TLC performance of a target compound and an adjacent compound and defining a sample loading amount and a solvent gradient profile using at least two solvents that will result in differential elution of the target and adjacent compounds from a chromatography column. The chromatography system and loading parameters may be selected to provide satisfactory separation of the target compound from adjacent compounds.
1. A method of separating compounds in a sample using a column chromatography system, the method comprising:
receiving data input sufficient for determining;
at least two retention factors (R f ) corresponding to a primary compound and a secondary compound exposed to an initial solvent system; and
a proportion of each solvent in the initial solvent system;
generating a solvent ratio profile based on the received inputs including;
a starting point corresponding to a starting solvent ratio;
an ending point corresponding to an ending solvent ratio; and
a transitional phase during which the solvent ratio increases from the starting solvent ratio to the ending solvent ratio; and
introducing separation solvent system having the starting solvent ratio at a solvent flow rate into an upstream end of a chromatography column having a column volume;
introducing a sample including the primary compound and the secondary compound into an upstream end of a chromatography column;
varying the solvent ratio of the separation solvent system being introduced into the upstream end of the chromatography column in accord with the solvent ratio profile; and
carrying at least the primary compound to a downstream end of the chromatography column.
2. The method of separating compounds in a sample according to claim 1 , wherein:
the transitional phase has a duration of at least 8 column volumes.
3. The method of separating compounds in a sample according to claim 2 , wherein:
the final solvent ratio includes the strong solvent at a solvent concentration of 2C S .
4. The method of separating compounds in a sample according to claim 1 , wherein:
the initial solvent system includes a strong solvent and a weak solvent, the strong solvent being present at a concentration of C S in the initial solvent system; and
the starting solvent ratio including the strong solvent at a solvent ratio of (0.25)C S .
5. The method of separating compounds in a sample according to claim 1 , wherein:
the initial solvent system includes a strong solvent and a weak solvent, the strong solvent being present at a concentration of C S in the initial solvent system; and
the final solvent ratio includes the strong solvent at a solvent concentration of 2C S .
6. The method of separating compounds in a sample according to claim 1 , wherein:
the strong solvent exhibits greater polarity than the weak solvent.
7. The method of separating compounds in a sample according to claim 6 , wherein:
the retention factors differ by at least 0.1.
8. The method of separating compounds in a sample according to claim 1 , wherein:
at least one retention factor is between 0.1 and 0.9.
9. The method of separating compounds in a sample according to claim 1 , wherein:
the separation solvent system solvent ratio varies in substantially linear fashion between the starting solvent ratio and the ending solvent ratio.
10. The method of separating compounds in a sample according to claim 1 , wherein:
the separation solvent system solvent ratio varies in a linear fashion between the starting solvent ratio and the ending solvent ratio.
11. The method of separating compounds in a sample according to claim 1 , wherein:
the separation solvent system solvent ratio varies in a step-wise fashion between the starting solvent ratio and the ending solvent ratio.
12. The method of separating compounds in a sample according to claim 1 , wherein:
the separation solvent system is a solution of miscible solvents.
13. The method of separating compounds in a sample according to claim 1 , wherein:
the separation solvent system includes at first solvent from a first selectivity group and a second solvent from a different selectivity group.
14. The method of claim 1 further comprising:
determining a Δ column volume for the elution of the primary and secondary compounds based on the retention factors.
15. The method of claim 1 further comprising:
determining a sample mass, a column size, and a separation solvent system flow rate to provide a Δ column volume of at least 0.1 between the primary and secondary compounds.
16. The method of claim 1 further comprising:
determining a sample mass, a column size, and a separation solvent system flow rate to provide a Δ column volume of at least 0.8 between the primary and secondary compounds.
17. The method of claim 1 further comprising:
determining a Δ column volume for the elution of the target and adjacent compounds based on the retention factors; and
adjusting the solvent ratio profile to provide a Δ column volume of at least 0.1 between the primary and secondary compounds.
18. The method of claim 17 further comprising:
determining a target sample loading mass as a function of the Δ column volume and the chromatography column.
19. The method of claim 17 , wherein:
the initial solvent system has a polar/non-polar solvent ratio of 1:99 to 99:1.
20. The method of claim 1 , wherein:
the initial solvent system has a polar/non-polar solvent ratio of 1:99 to 99:1.