JPS5910247B2 - Solvent mixing liquid delivery device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solvent mixing and liquid feeding device, and in particular, to a solvent flow path between a solvent reservoir and a solvent mixing section, air and helium gas in the solvent can be replaced through a synthetic resin membrane. By bringing the helium gas channels into contact with each other, the generation of bubbles during solvent mixing is prevented, thereby making it possible to deliver a fixed amount of liquid using a pump.

Solvents are usually exposed to air, and melting of the air is unavoidable.

On the other hand, in high performance liquid chromatographs and the like, it is necessary to mix solvents and pump them in a fixed amount. For example, when feeding a mixture of water and methanol (or acetonitrile),
When both liquids start mixing, the amount of air dissolved in the mixed liquid is
Because it is smaller than the sum of the dissolved amounts of each solution (see Figure 1),
Air becomes supersaturated and forms bubbles. Therefore, even if a mixed liquid containing such bubbles is supplied to a pump, it is impossible to expect a constant amount of liquid delivery. As a means to solve these problems, it is known to provide a gas-liquid separation section between the solvent mixing section and the pump, but the volume in the separation section causes a delay in composition change, and furthermore, the degassing operation causes problems. Many problems arise in terms of performance, such as compositional fluctuations.

In view of these circumstances, the inventors conducted extensive research, and
Focusing on the phenomenon that various molecules permeate through a thin layer of synthetic resin, they discovered that the thin layer could be used to permeate bubbles generated from a solvent, leading to the completion of this invention. That is, the specific configuration of the present invention includes a plurality of solvent reservoirs, a mixing section for these solvents, and a liquid delivery pump for the mixed solvent, and a solvent flow path between the solvent reservoirs and the mixing section. ,
This is a solvent mixing/liquid feeding device that includes a replacement section for replacing air in the solvent with helium gas.

In other words, in this invention, the solvent flow path between the solvent reservoir and the mixing section has a synthetic resin granule path through which the solvent flows, and a helium gas flow path that covers the outside of the holder. By providing a displacement part in the mixing part, the air dissolved in the solvent is allowed to permeate through the flow path to the helium gas side where the air partial pressure is small, thereby reducing the amount of dissolved air. This prevents the generation of bubbles and enables fixed-quantity liquid delivery.

Of course, helium gas moves through the membrane to the solvent side, but since it has the lowest solubility in various solvents, there is almost no risk of bubbles occurring during mixing. To this invention}
As the synthetic resin flow path that can be used in the process, it is preferable to use a flow path made of tetrafluoroethylene resin, polyethylene resin, etc.
Examples include those made of fluorinated ethylene resin (Teflon: registered trademark) pipes.

The wall thickness of the pipe is 0 in the case of tetrafluoroethylene resin.
．． A value of about 1 to Im is desirable. The inner diameter of these synthetic resin pipes is preferably 0.5 to 2 mmφ. The present invention will be described in detail below based on embodiments shown in the figures. Note that this invention is not limited by this. In FIG. 2, a solvent mixing liquid feeding device 1 has two solvent suction channels 2 and 3.
, a solvent mixing section 4 , and a mixed solvent liquid pump 5 .

The suction channel 2 extends from a methanol solvent reservoir 6 to a solvent mixing section 4 via a helium gas contact section 7 and a time proportional valve 8. The helium gas contact section 7 can also be referred to as a section for replacing air in the solvent with helium gas. A cylindrical stainless steel helium gas channel 9 is coaxially formed. 10 is helium gas inlet, 11
is the exit.

Note that 12 is a filter. On the other hand, the configuration of the suction flow path 3 is the same except that the solvent is water, so the explanation will be omitted. In the solvent mixing liquid feeding device 1, methanol and water are supplied to each solvent reservoir 6 by opening the liquid feeding pump 5 and the time proportional valves 8 and 13.
, 14, mixed, and transferred to a high performance liquid chromatograph.

At this time, for example, when methanol passes through the helium gas contact part 7, there is a helium gas space with almost zero air partial pressure outside the thin layer of tetrafluoroethylene resin in the thin tube, so the air partial pressure difference is large. The air dissolved in methanol passes through the thin layer and escapes to the helium gas flow path side, and is appropriately carried out of the system from the outlet 11 along with the helium gas. Of course, helium gas permeates through the thin layer and dissolves in methanol, replacing it, but its solubility is extremely low. In the case of water, dissolved air escapes to the helium gas side in the same way. Methanol and water, which have a reduced concentration of dissolved air in this way, hardly generate any bubbles when mixed, making it possible to feed the liquid in a fixed amount with great accuracy. Traditional degassing methods that involve bubbling helium gas into the solvent involve direct contact between the helium gas and the solvent, which can result in a significant amount of solvent molecules being lost in the flow of helium gas. In the case of aqueous solutions containing dissolved salts, concentration changes are particularly problematic. However, in the above device, a thin layer of synthetic resin is interposed between the solvent and helium gas, so the solvent concentration (composition)
Changes can be reduced. In order to replace the air steam in the solvent with helium gas, the airtight container is divided by a thin film 21a made of tetrafluoroethylene resin, and one side is used as the solvent flow path 20a and the other side is used as the helium gas flow path 9a. (See Figure 3).

[Brief explanation of the drawing]

Fig. 1 is a graph showing the amount of air dissolved in water and methanol, Fig. 2 is a functional explanatory diagram showing one embodiment of the solvent mixing liquid feeding device of the present invention, and Fig. 3 is a main part showing another embodiment. It is a functional explanatory diagram. 1... Solvent mixing liquid feeding device, 2, 3...
Suction channel, 4... Solvent mixing section, 5...
Liquid feed pump, 6, 14...Solvent reservoir, 7, 15
・・・・・・Helium gas contact part, 9, 18・・・・・・
・Helium gas flow path.

Claims (1)

[Claims] 1. A system comprising a plurality of solvent reservoirs, a mixing section for these solvents, and a liquid delivery pump for the mixed solvent, and further includes a solvent passageway between the solvent reservoirs and the mixing section for supplying air in the solvent. A solvent mixing liquid feeding device that includes a replacement section for replacing helium gas with helium gas. 2. The apparatus according to claim 1, wherein the solvent flow path and the helium gas flow path of the substitution section are in contact with each other via a synthetic resin thin film. 3. The apparatus according to claim 1 or 2, wherein the substitution section is comprised of a synthetic resin solvent channel and a helium gas channel formed to cover the outside of the solvent channel. 4. The device according to any one of claims 1 to 3, using tetrafluoroethylene resin as the synthetic resin.