FR2503418A1 - DEVICE FOR PROGRAMMING THE COMPOSITION OF A LIQUID, IN PARTICULAR FOR LIQUID-PHASE CHROMATOGRAPHY - Google Patents

Abstract

THE DEVICE INCLUDES A MIXING CHAMBER AND ELECTROMAGNETIC VALVES CONNECTED TO LIQUID TANKS. IN THE MIXER 1, IN THE DIRECT NEIGHBORHOOD OF THE LIQUID INPUTS 3 TOWARDS THE MIXING CHAMBER 2, SEATS 9 WITH AT LEAST TWO ELECTROMAGNETIC VALVES 10, HAVE SHUTTERS 11 WITH AN UPPER PART OF INVERTED TRUNCONIC SHAPE, OF WHICH THE PART THE WIDEST IS SITUATED BETWEEN THE WALL OF CHAMBER 2 AND THE SEAT 9. MIXER 1 SHOWS THE SHAPE OF A CYLINDER, AND THE INPUTS 3 FOR THE LIQUID TO MIXING CHAMBER 2 ARE LAYED ON THE PERIOD OF THE LATTER.

Description

The subject of the invention is a device for programming the composition

  of a liquid, in particular applicable to the

liquid chromatography.

  Already known, according to US Pat. No. 4,004,884, a provision

  programming section for the composition of a liquid equipped with a reccord, which is, via n double electromagnetic electronically controlled valves, connected to n different liquid tanks, communicating

  with a common source of pressurized gas.

  During the programming of the composition of the liquid, at the set point, only one two-way valve is open for the duration of time proportional to the set rate of

  liquid communicated by it to a mixing chamber.

  The defect of this arrangement consists in the presence of all the n liquids in the mixing chamber, where the various jets of liquid are assembled in a single flow, which

  implies in these conditions the inevitable pollution of the li-

  that of others, who should not be part of the process. In chromatography, this fact can cause the loss of activity of the column or the generation of additional vertices on the chromatogram or the drift of

the zero line.

  Another drawback of this arrangement is that the various liquids are assigned to the tanks

  by the presence of gas under pressure. Because in chromato-

  In general we use high pressures of the order of 50 to 500 atm, the liquid in the tank is responsible for

  gas in minutes. The gas dissolved in the liquid involved

  only adverse changes in its properties and it interferes with the work of the chromatograph due to degassing of the liquid

  in the detector drain pan.

  In addition, in the mixing chamber applied in the

  disposal, the components are not mixed, that is why

  what the process of composition of programmed liquids

  will differ from that recorded at various times.

  In addition, the mounting of the two-way valves and the

  liquid tanks in the pressure side of the device

  sition imposes on these elements a construction capable of withstanding high pressures, The device known until now for programming the composition of a liquid from the so-called American company

  Spectra Physics, includes a four-way valve, common

  connecting on the one hand by pipes with three liquid tanks, and on the other hand by a mixer with the pipe

of a piston pump.

  The mixer has a dead volume of the order of 1.9 ml. The outlet of each of these three conduits communicating the liquid to the valve is equipped with a membrane

  movement by means of an electromagnetic coil.

  At the location of the connection of the three conduits containing each

  cun a different liquid, at all times are present all

  liquids regardless of the quantity of liquids programmed.

  The main drawback of such a device consists in the permanent contact of the proportioned liquids present in

  the tanks placed in communication by the valve. It im-

  plique the pollution of the solution proportioned by the au-

  very liquid, a fact which can cause deactivation of the chromatographic column, drift of the zero line, and other similar disadvantages. In addition, an annoying defect

  also result from the large dead volume of the device,

  finished by connecting the valve, mixer and

the pump.

  The device for programming the composition of a

  liquid, particularly applicable in liquid phase chromatography

  quide, comprising a mixing chamber and solenoid valves

  is characterized according to the invention by the fact that in the mete

  langor, in the immediate vicinity of the liquid inlets to the mixing chamber, provision has been made for the integral mounting of seats of at least two electromagnetic valves, the members

  shutters have a tapered cone-shaped top

  inverted, and in that the widest part of the cone is housed between the wall of the mixing chamber and the seat of

the electromagnetic valve.

  The mixer has the shape of a cylinder, and the

  liquid flows to the mixing chamber are arranged

around its perimeter.

  The electromagnetic valves are of the two-way type.

  The device can work just as well on the discharge side as on the suction side of the pump. When mounted on the discharge side of the pump, the liquid tanks have the form of a screw-wound pipe

unending.

  By construction, the profile of the mixer and that of the

  cylinder-shaped mixing chamber, ensures filling

  maximum sage from the mixing chamber, thus reducing

  the minimum volume of the chamber.

  Thanks to this, one can faithfully program the composition

  tion of the mobile phase, even without the mixture of liquids introduced into the chamber, at least in the range of

concentrations from 10 to 90%.

  We were able to verify experimentally the repeatability and the accuracy of the gradient patterns as a function of the dead volume of the mixing chamber, of the speed of the mobile phase.

  as well as according to the duration of mixing of its components.

  The advantages of the device consist in the elimination

  of the process of mixing liquids, which in said process

  above are not subject to programming, and also to the possibility of programming the composition of the liquid from n components, including the concentration rates of

  various components as a function of time will be arbitrary.

  In addition, the liquid tanks, the electric valves

  tromagnetic and the mixer can be mounted indifferently

  on the discharge or suction side of the pump.

  In addition, there is the possibility of adjusting a suitable volume of the mixing chamber according to the flow of

  the pump and the duration of the programming times of the

  position of the liquid transmitted to the chromatography column

phie.

  An embodiment of the invention is described by way of example with reference to the accompanying drawings o: - Figure 1 shows the device for programming the composition of a liquid in longitudinal section, and

  - Figure 2 is a general block diagram of the chromatography

  phe in liquid phase with the connected programming device

  tion of the composition of a liquid.

  According to the embodiment chosen and shown (Figure 1), the device comprises a mixer 1 in the form of a cylinder with mixing chamber 2, on the periphery of which two liquid inlets 3 have been arranged. The mixing chamber 2 is limited at the top by a piston 4, in the axis of symmetry of which is arranged a channel 5 for discharging the liquid, and it is equipped with a mechanical agitator 6 in the form of a cylinder.

  dre, with drive shaft 7 mounted in a cable gland 8.

  The diameter of the agitator 6 is less than that of the

  bedroom 2 of lmm approximately. In the direct vicinity of the

  inlet 3 of liquid, provision has been made for mounting a seat 9 of a

  two-way electromagnetic valve 10, the component of which

  turateur 11 has at the upper part the profile of an inverted truncated cone, its widest part surmounting the seat 9 of the valve 10. The member 11 is integral with a magnet 12 sliding in the carcass-frame 13 of the valve 10,

  whose inner wall has a channel 14 for inlet of

  which communicates via a line 15 with a reservoir of

  liquid 16. The carcass 13 is equipped with a coil of induc-

  tance 17. The cable gland 8 has a cap 18 and a

sealing ring 19.

  The seat 9 of the valve 10 is sealed between the frame 13 of the valve and the agitator 1 by means of washers 20

  in polytetraflu6rethylene. According to Figure 2, the met-

  langeur 1 communicates with the piston pump 21, while the inductance coils 17 associated with the carcass 13 of the electromagnetic valve 10 are connected to the electronic control circuit 22. The piston pump 21 delivers the

  liquid mixed by the doser 23 and the chromatography column

  writing 24 to a detector 25 which is connected to a recorder

sorrow 26.

  In operation, the pump is first started

  piston 21 and the mechanical stirrer 6. The inductor coils

  ce 17 of the valves 10 are connected to the control circuit 22, and the working program of each valve 10 is adjusted so that they are opened alternately. From the reservoir 16 the pump sucks the liquid which flows through the valve 10 currently open and the inlet 3 towards the mixing chamber 2, where it will be mixed with that present

  in chamber 2 by continuous injection. The rate in

  cent of liquid injected through the open valve 10 is

25034 1 8

  proportional to the duration of its opening. After obtaining the composition of the various liquids with composition consigned in advance in quantity, the solution is transferred by the

  pump 21 and the metering device 23 to the chromatography column 24.

  After passing through the chromatography column 24, the solution is directed to the discharge through the detector 25. The electrical signal from the detector 25 is recorded by

  the recorder 26. The number of valves 10 equipping the

  langeur 1 determines that of the components of the programmed mixture

of the solution.

Claims (3)

RESELL ICATIONS   1. Device for programming the composition of a liquid, in particular for liquid chromatography, comprising a mixing chamber and solenoid valves for communication with liquid reservoirs, characterized in   what we have mounted in mixer 1, in the immediate vicinity   rect inlets (3) of liquids in the mixing chamber   (2), seats (9) of at least two electromagnetic valves   ticks (10), having obturating members (11) with a   upper tie in the shape of an inverted truncated cone, the   widest tie is placed between the wall of the chamber (2)   and the seat (9) of the electromagnetic valve (10).   2. Device according to claim 1, characterized in that the mixer (1) has the shape of a cylinder and in that the inlets (3) of liquids in the mixing chamber   (2) are arranged around its perimeter.   3. Device according to claim 1, characterized in   that the electromagnetic valves (10) are of the type with - two ways.