Chromatography systems and methods using them
View Patent ↗Certain embodiments described herein are directed to chromatography systems that include a microfluidic device. The microfluidic device can be fluidically coupled to a switching valve to provide for selective control of fluid flow in the chromatography system. In some examples, the microfluidic device may include a charging chamber, a bypass restrictor or other features that can provide for added control of the fluid flow in the system. Methods of using the devices and methods of calculating lengths and diameters to provide a desired flow rate are also described.
1. A method comprising:
selecting a fluid flow rate to be used in a chromatography system configured to receive a microfluidic device comprising a plurality of ports fluidically coupled to each other through an internal microchannel of the microfluidic device;
determining a dimension of a restrictor in the chromatography system comprising the microfluidic device to provide the selected fluid flow rate; and
placing the restrictor of determined dimension downstream of the microfluidic device.
2. A method comprising:
selecting a fluid flow rate to be used in a chromatography system;
determining a dimension of a restrictor in the chromatography system to provide the selected fluid flow rate, in which the dimension is restrictor internal diameter of the restrictor and the internal diameter is calculated using the following equation
d
c
=
256
·
L
·
p
a
·
η
b
·
π
4
where d r is the internal diameter of the restrictor, L is restrictor length, p a is absolute pressure, η is viscosity of a carrier gas and b is a constant.
3. The method of claim 2 , further comprising configuring the chromatography system with a switching valve comprising a 3-way solenoid valve that is actuated at a frequency of about 10 Hz to about 100 Hz.
4. The method of claim 2 , further comprising balancing pressure in the system by configuring the system with the restrictor between a detector and a microfluidic device.
5. The method of claim 4 , further comprising providing column effluent from a first charging chamber to a first detector fluidically coupled to the microfluidic device and providing the column effluent from a second charging chamber to a second detector fluidically coupled to the microfluidic device, in which the restrictor is between the first detector and the microfluidic device.
6. The method of claim 5 , further comprising configuring each of the first and second charging chambers as internal chambers within the microfluidic device.
7. The method of claim 6 , further comprising configuring a rate of fluid flow from a modulating gas source to be at least five times greater than a rate of fluid flow of column effluent into the first and second charging chambers.
8. The method of claim 4 , further comprising determining a dimension of a second restrictor in the chromatography system to provide a second selected fluid flow rate, and balancing the pressure in the system by configuring the system with the restrictor between a first detector and a microfluidic device and configuring the system with the second restrictor between a second detector and the microfluidic device.
9. A method comprising:
selecting a fluid flow rate to be used in a chromatography system;
determining a dimension of a restrictor in the chromatography system to provide the selected fluid flow rate, in which the dimension is restrictor length and the restrictor length is calculated using the following equation
L
r
=
[
π
×
T
a
×
d
r
4
256
×
F
a
×
p
a
×
(
p
i
2
-
p
or
2
)
-
T
r
2
×
η
r
2
×
L
r
2
]
T
r
1
×
η
r
1
+
L
r
2
where L r1 is the length of the restrictor inside an oven of the chromatography system, L r2 is the length of the restrictor inside a detector of the chromatography system, η r1 is the viscosity of carrier gas at the oven temperature, η r2 is the viscosity of carrier gas at the detector temperature, T r1 is the absolute temperature of the oven, T r2 is the absolute temperature of the detector, p i is the inlet pressure of the restrictor, p or is the outlet pressure of the restrictor, p a is the absolute pressure and Fa is the flow rate.
10. The method of claim 9 , further comprising configuring the chromatography system with a switching valve comprising a 3-way solenoid valve that is actuated at a frequency of about 10 Hz to about 100 Hz.
11. The method of claim 9 , further comprising balancing pressure in the system by configuring the system with the restrictor between a detector and a microfluidic device.
12. The method of claim 11 , further comprising providing column effluent from a first charging chamber to a first detector fluidically coupled to the microfluidic device and providing the column effluent from a second charging chamber to a second detector fluidically coupled to the microfluidic device, in which the restrictor is between the first detector and the microfluidic device.
13. The method of claim 12 , further comprising configuring each of the first and second charging chambers as internal chambers within the microfluidic device.
14. The method of claim 13 , further comprising configuring a rate of fluid flow from a modulating gas source to be at least five times greater than a rate of fluid flow of column effluent into the first and second charging chambers.
15. The method of claim 11 , further comprising determining a dimension of a second restrictor in the chromatography system to provide a second selected fluid flow rate, and balancing the pressure in the system by configuring the system with the restrictor between a first detector and a microfluidic device and configuring the system with the second restrictor between a second detector and the microfluidic device.
16. A method comprising:
selecting a fluid flow rate to be used in a chromatography system;
determining a dimension of a restrictor in the chromatography system to provide the selected fluid flow rate and
configuring the chromatography system with a switching valve upstream of the restrictor, the switching valve configured to actuate between a first position and a second position, the first position permitting fluid flow from a modulating gas source to a first charging chamber of a microfluidic device to provide column effluent from the first charging chamber to a detector fluidically coupled to the microfluidic device, and the second position permitting fluid flow from the modulating gas source to the second charging chamber of the microfluidic device to provide column effluent from the second charging chamber to the detector fluidically coupled to the microfluidic device.
17. The method of claim 16 , further comprising configuring the switching valve as a 3-way solenoid valve that is actuated at a frequency of about 10 Hz to about 100 Hz.
18. The method of claim 16 , further comprising balancing pressure in the system by configuring the system with the restrictor between a detector and the microfluidic device.
19. The method of claim 18 , further comprising providing the column effluent from the first charging chamber to a first detector fluidically coupled to the microfluidic device and providing the column effluent from the second charging chamber to a second detector fluidically coupled to the microfluidic device, in which the restrictor is between the first detector and the microfluidic device.
20. The method of claim 18 , further comprising determining a dimension of a second restrictor in the chromatography system to provide a second selected fluid flow rate, and balancing the pressure in the system by configuring the system with the restrictor between the first detector and the microfluidic device and configuring the system with the second restrictor between the second detector and the microfluidic device.
21. The method of claim 16 , further comprising configuring each of the first and second charging chambers as internal chambers within the microfluidic device.
22. The method of claim 16 , further comprising configuring a rate of fluid flow from the modulating gas source to be at least five times greater than a rate of fluid flow of the column effluent into the first and second charging chambers.