JPH07159388A - Mixer for supercritical fluid chromatography - Google Patents

Abstract

PURPOSE:To provide a mixer for supercritical fluid chromatography, wherein ineffective time is greatly shortened and homogenization is improved. CONSTITUTION:The mixer has a mixing part 4, wherein two flow paths are combined into one flow path, and a coil-shaped homogenizing flow path 5, wherein the fluid is diffused and homogenized and the change of the composition of the flowing direction is smoothed. The entire mixer is contained in a heating block having a heater and heated to a specified temperature, where the mixed fluid becomes the supercritical state. The mixed fluid flowing out of the mixer is sent into a column 8 and a flow path on the downstream side from the column.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mixer used in supercritical fluid chromatography (SFC).

[0002]

2. Description of the Related Art SFC performed using a mixed fluid of carbon dioxide (CO ₂ ) and various polar organic solvents represented by CH ₃ OH is more polar than CO ₂ alone. However, even in the molecular weight range, the sample to be measured is remarkably expanded, and the versatility is high.

However, in order to realize this, it is necessary to arbitrarily and quantitatively change the composition ratio and the flow rate, and therefore C
A mixer for quantitatively feeding O ₂ and an organic solvent individually and mixing them under high pressure is required. The mixer is configured to mix the CO ₂ and an organic solvent regularly, a minute change in the composition based on the flow rate variation per a minute time (for each repetition stroke of each pump feeding a CO ₂ and an organic solvent) , Smoothing, and at the mixer outlet, a homogeneously mixed fluid must steadily flow out.

Moreover, in the case of elution by the composition gradient method, it is necessary to shorten the ineffective time from the start of the gradient operation to the actual change of the composition in the separation column.

FIG. 1 shows a conventional supercritical fluid chromatograph equipped with a mixer. In FIG. 1, 1 is CO
A pump for supplying ₂ and a pump for supplying CH ₃ OH. CO ₂ and CH sent by pumps 1 and _2
3 OH is sent to the mixer 3 via the flow paths P ₁ and P ₂ . The mixer 3 includes a mixing section 4 for combining the _two flow paths ₁ and P ₂ into one flow path, and a coil shape for smoothing the composition change in the flow direction after the mixed fluid diffuses and becomes homogeneous. The homogenizing flow path 5 is provided. The mixed fluid mixed in the mixer passes through the sample injector 6 and the thermostatic chamber 7
It is sent to the inner column 8. The mixed fluid flowing out of the column 8 is sent to a detector 9 such as a UV detector arranged adjacent to the column 8. The fluid passing through the detector 9 is discharged to the drain 11 via the pressure controller 10.

[0006]

In order to achieve sufficiently good homogeneity in the mixer 3 with such a configuration, it is necessary to set the capacity of the mixing section to a certain level or more. But,
As shown in FIG. 2, when the capacity of the mixing section is large, CO
_{When the} gradient method in which the flow rates of ₂ and CH ₃ OH are changed with time is performed, the dead time t _i from the start of the gradient operation to the actual change in the composition in the separation column as shown by C in FIG. Occurs.

This t _i is the flow velocity of the mixed fluid U (μl /
Min) and the capacity V (μl) of the mixer is t _i =
It is known that the V / U relationship is established. As can be seen from this equation, if V is increased in order to improve the homogeneity, the ineffective time t _i is increased, and in order to reduce the ineffective time t _i , V must be decreased to sacrifice the homogeneity. It was

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a mixer having good homogeneity and capable of reducing the dead time.

[0009]

In order to achieve this object, the present invention is a mixer for supercritical fluid chromatography using a mixed fluid in which plural kinds of fluids are mixed, and a conduit for introducing each fluid individually. A mixing section for mixing each conduit into one flow path and a smoothing flow path for smoothing the mixed fluid, and heating at least the mixing section to a temperature at which the mixed fluid becomes a supercritical state. It is characterized in that a heating means is provided.

[0010]

In the present invention, the mixing portion for mixing the respective fluids is heated so that the mixed fluids are mixed in a supercritical state, so that the ineffective time can be shortened while maintaining high homogeneity. An embodiment of the present invention will be described below in detail with reference to the drawings.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is a block diagram showing an embodiment of the present invention. The embodiment of FIG. 3 is different from the conventional example of FIG. 1 in that the entire mixer 3 including the mixing portion 4 and the homogenizing flow path 5 is housed in a heating block 12 and heated to a predetermined temperature. Is. The heating block 12 has, for example, 25
A heater 13 for heating to a constant temperature of about 0 ° C. is provided.

In the above structure, the entire mixer including the mixing section 4 is maintained at a constant temperature of about 250 ° C. At this temperature, the mixed fluid becomes supercritical by appropriately setting the pressure. FIG. 4 is a graph showing the relationship between the composition X and the density (holding time) of the mixed fluid of CO ₂ and CH ₃ OH, using the temperature as a parameter. From Figure 4, at 250 ° C,
It can be seen that the fluid density of the mixed fluid is significantly reduced. For example, under a pressure of 200 kg / cm ² , CO ₂ : CH ₃ OH
The mixed fluid having a composition of = 1: 1 has a density at a temperature of 250 ° C. of about 1/3 of a density at a temperature of 50 ° C. Due to this decrease in density, the fluid velocity in the mixing section becomes about three times higher than in the conventional case where the supercritical state is not set. This means that the flow velocity U becomes three times larger, so that the ineffective time can be shortened to 1/3 based on the above-mentioned formula.

Further, such an improvement in the flow velocity of the mixed fluid leads to an increase in the vortex flow in the flow path, resulting in an improvement in homogenization. Moreover, it has been known that at a temperature of about 250 ° C., the thermal diffusion coefficient is about twice as large as at room temperature. Therefore, the time required for homogenization is shortened from the viewpoint of heat diffusion, and the time required for mixing and homogenization is 1/2.
Becomes

Further, as described above, since the density decreases when mixed in the supercritical state, even if the diameter of the discharge port of the conduit that has carried CO ₂ and CH ₃ OH in the mixing section 4 is made thinner than before. Since the pressure loss hardly occurs, the diameter of the discharge port can be reduced. If the flow velocity improvement due to the diameter reduction is added to the flow velocity improvement by 3 times due to the decrease in the density described above, a flow velocity improvement of 10 times or more than the conventional one can be realized in total, and the dead time due to the improvement of the flow velocity U Further shortening is possible.

In the above embodiment, the case where two fluids are mixed has been described, but it goes without saying that the same can be applied to the case where three or more kinds of fluids are mixed.

[0016]

As described in detail above, according to the present invention,
Since the fluids are mixed in a supercritical state, a dead time is significantly shortened, and a supercritical fluid chromatograph mixer having improved homogenization is realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a conventional mixer.

FIG. 2 is a diagram for explaining an invalid time when performing a gradient method.

FIG. 3 is a configuration diagram of an embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the composition X and the density (holding time) of a mixed fluid of CO ₂ and CH ₃ OH, using temperature as a parameter.

[Explanation of symbols]

 3 Mixer 4 Mixing part 5 Homogenization channel 12 Heating block 13 Heater

Claims (1)

[Claims] 1. A mixer for supercritical fluid chromatography that uses a mixed fluid in which a plurality of types of fluids are mixed, and a conduit for individually introducing each fluid, and a mixing section for mixing each conduit into one flow path. A smoothing flow path for smoothing the mixed fluid, and a heating means for heating at least the mixing portion to a temperature at which the mixed fluid becomes a supercritical state.