Liquid chromatographic detector and method

• US 4,695,555 A
• Filed: 10/30/1986
• Issued: 09/22/1987
• Est. Priority Date: 06/12/1985
• Status: Expired due to Fees

• Current Assignee: Andrew F O'Keeffe
• Original Assignee: Andrew F O'Keeffe
• Inventors: O'Keeffe, Andrew F.
• Primary Examiner(s): Therkorn, Ernest G.
• Application Number:
  US06/924,119
• Time in Patent Office: 327 Days
• Field of Search: 210/198.2, 422/55, 422/56, 422/57, 422/58, 422/69, 422/70, 422/68, 436/149, 436/150, 436/151, 436/161, 73/61.1 C
• US Class Current: 436/150
• CPC Class Codes: G01N 2030/642 photoionisation detectors
• CPC Class Codes: G01N 2030/8464 Uncharged atoms or aerosols
• CPC Class Codes: G01N 30/64 Electrical detectors

Abstract

The liquid chromatograph detector of the present invention includes a nozzle communicating with a liquid chromatograph column. A piezoelectric element is firmly affixed to the nozzle and is actuated by an alternating current of a frequency appropriate to cause the firing of charged droplets of a predetermined, uniform size from the nozzle. The emitted droplets pass between two planar deflector plates which are maintained at a DC voltage sufficient to produce a transverse electric field between the plates. The electric field causes droplets passing between the plates to be deflected towards one of the plates and away from the other in a manner and to a degree sensitively dependent upon the charge acquired by the droplet upon discharge from the nozzle. A moving recording medium, such as paper, is positioned to receive the droplets passing between the deflector plates. If necessary, the recording surface is then processed so as to make the impinging droplets visible.

Claims

1. An apparatus for detecting the solute burden of an effluent of a liquid chromatograph column comprising:

means for emitting an effluent liquid stream from the chromatograph column, in the form of spherical droplets, through an opening in the liquid chromatograph column at a constant velocity and over a common path, each of said droplets being imparted with an electric charge due to the spray electrification effect occurring on each droplet as each droplet is emitted from the liquid chromatograph column, the amount of said electric charge acquired by each droplet being dependent upon the nature and quantity of the solute carried by said droplet;

means for altering the path over which each of said droplets travels as a function of said electric charge acquired by each droplet;

means for recording the solute burden of each droplet in said series of droplets as a function of the deviation of the droplets from said common path.

2. The apparatus of claim 1 wherein said means for emitting charged spherical droplets comprises:

piezoelectric element firmly affixed to a nozzle of said liquid chromatograph column through which said droplets are emitted.

3. The apparatus of claim 2 wherein said means for altering the path over which each of said droplets travels comprises:

a pair of deflector plates positioned parallel to said common path of travel of said droplets and parallel to each other;

means for creating a transverse electric field between said pair of parallel deflector plates.

4. The apparatus of claim 1 wherein said means for altering the path over which each of said droplets travels comprises:

deflector means positioned parallel to said common path of travel of said droplets so that said droplets travel through said deflector means;

means for creating a transverse electric field between said deflector means;

said deflector means causing each droplet to be deflected from said common path of travel.

5. An apparatus for detecting the solute burden of an effluent of a liquid chromatograph column comprising:

means for emitting an effluent liquid stream from the chromatograph column in the form of spherical droplets, through an opening in the liquid chromatograph column at a constant velocity and over a common path, each of said droplets being imparted with an electric charge, the amount of said electric charge acquired by each droplet being dependent upon the nature and quantity of the solute carried by said droplet, said means for emitting an effluent liquid stream also including a piezoelectric element firmly affixed to a nozzle of said liquid chromatograph column;

deflector means positioned parallel to said common path of travel of said droplets so that said droplets travel through said deflector means;

means for creating a transverse electric field between said deflector means;

said deflector means causing each droplet to be deflected from said common path of travel;

means for recording the solute burden of each droplet in said series of droplets as a function of the deviation of the droplets from said common path.

6. The apparatus of claim 5 wherein said deflector means comprises:

a pair of deflector plates positioned parallel to said common path of travel of said droplets and parallel to each other.

7. The apparatus of claim 5 wherein said means for recording the solute burden of each droplet comprises:

recording medium positioned for receiving said droplets emitted from said liquid chromatograph column;

means for moving said recording medium to sequentially record individual droplets of said series of droplets.

8. The apparatus of claim 5 wherein said means for recording the solute burden of each droplet comprises:

moving paper means positioned to sequentially receive droplets emitted from said liquid chromatograph column;

means for applying a toner to said moving paper to cause said received droplets to become visible.

9. An apparatus for detecting the solute burden of effluent of a liquid chromatograph column comprising:

means for emitting an effluent liquid stream from the chromatograph column, in the form of spherical droplets, through an opening in the liquid chromatograph column at a constant rate and over a common path, each of said droplets being imparted with an electric charge, the amount of said electric charge acquired by each droplet being dependent upon the nature and quantity of the solute carried by said droplet;

a helical wire coil positioned relative to said nozzle so that each emitted droplet passes through said helical wire coil and induces a charge in said coil;

means for recording the solute burden of each droplet in said series of droplets as a function of said detected electric charge of each droplet.

10. An apparatus for detecting the solute burden of effluent of a liquid chromatograph column comprising:

means for emitting an effluent liquid stream from the chromatograph column, in the form of spherical droplets, through an opening in the liquid chromatograph column at a constant rate and over a common path, each of said droplets being imparted with an electric charge, the amount of said electric charge acquired by each droplet being dependent upon the nature and quantity of the solute carried by said droplet;

a metal cylinder including a radioactive source positioned relative to said emitting means so that said emitted droplets pass through said cylinder, air within said cylinder being ionized by radiation and becoming conductive thereby permitting the charge from each droplet to be transfered to the cylinder;

means for recording the solute burden of each droplet in said series of droplets as a function of said detected electric charge of each droplet.

11. A method of detecting the solute burden of effluent of a liquid chromatograph column comprising the steps of:

emitting an effluent liquid stream, as uniformly sized spherical droplets, through an orifice in the liquid chromatograph column at a constant rate and over a common path, said emitted droplets being imparted with an electric charge, the amount of said electric charge acquired by each droplet being dependent upon the nature and quantity of the solute carried by said droplet;

passing each of said droplets through an electric field which causes each of said droplets to deflect off said common path by a distance dependent on the solute burden in said droplet;

providing an electrically neutral, relatively non conducting recording medium;

positioning said recording medium so that said droplets passing through the electric field will impinge on said recording medium;

processing said recording medium so as to render said impinging droplets visible.

12. The method of detecting the solute burden of effluent of claim 11 further comprising the step of creating an electric field between said two deflector plates which are oppositely charged, said electric field causing each of said droplets to deflect off its common path.

13. The method of detecting the solute burden of claim 11 wherein said step of emitting droplets at a constant rate and over a common path comprises the steps of:

providing a nozzle, communicating with the liquid chromatograph column, through which droplets are emitted;

firmly affixing a piezoelectric element to said nozzle;

actuating said piezoelectric element with an alternating current of a frequency sufficient to provide the proper emission rate.

14. A method of detecting the solute burden of effluent of a liquid chromatograph column comprising the steps of:

emitting an effluent liquid stream, as uniformly sized spherical droplets, through an orifice in the liquid chromatograph column at a constant rate and over a common path, said emitted droplets being imparted with an electric charge due to the spray electrification effect on each droplet occurring as each droplet is emitted from the liquid chromatograph column, the amount of said electric charge acquired by each droplet being dependent upon the nature and quantity of the solute carried by said droplet;

detecting said electric charge of each droplet of said series of droplets by passing said each droplet through a deflector means positioned parallel to said common path of travel of said droplets so that said droplets travel through said deflector means;

creating a transverse electric field within said deflector means for deflecting each droplet from said common path of travel;

recording the solute burden of each droplet in said series of droplets as a function of said detected electric charge of each droplet.