Systems and apparatus for reducing signal noise due to pump oscillations

Patent metadata

Field	Value
Publication number	US-9976994-B2
Application number	US-201514839680-A
Country	US
Kind code	B2
Filing date	Aug 28, 2015
Priority date	Aug 28, 2015
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

A system reduces unwanted noise due to pump movement. The system includes a pump including a non-conductive piston extending into a pumping chamber for pumping the sample fluid along an analysis fluid path, a wash chamber, and a seal fluidly separating the pumping chamber from the wash chamber. The system also includes a wash path supplying a wash fluid from a wash reservoir to the wash chamber, an electrical conductor electrically connecting the analysis fluid path to the wash fluid path, and a ground conductor electrically connecting the electrical conductor to ground via a resistor. The electrical conductors and resistor combination between the chambers reduces unwanted noise in the conductivity detector due voltage potentials between the eluent and wash chambers created as the piston moves between the chambers.

First claim

What is claimed is:

1. An apparatus for reducing noise due to pump movement, the apparatus comprising:
a pump for pumping a sample fluid along an analysis fluid path to a conductivity detector, the pump including a pumping chamber, a piston extending into the pumping chamber for pumping the sample fluid along the analysis fluid path, a seal washing chamber, and a seal fluidly separating the pumping chamber from the seal washing chamber, wherein the piston extends through the seal and creates a voltage potential between the pumping chamber and the seal washing chamber as the piston moves;
a wash fluid path supplying a wash fluid from a wash reservoir to the seal washing chamber;
an electrical conductor for reducing noise in the conductivity detector due to pump movement, the electrical conductor electrically connecting the analysis fluid path to the wash fluid path;
a ground conductor electrically connecting the electrical conductor and a ground; and
a resistor between the electrical conductor and the ground.

2. The apparatus according to claim 1 , wherein the piston is formed of sapphire.

3. The apparatus according to claim 1 , wherein the electrical conductor is a platinum wire having a first end in electrical communication with the analysis fluid path and a second end in electrical communication with the wash fluid path.

4. The apparatus according to claim 1 , wherein the resistor has a resistance of at least a megaohm.

5. The apparatus according to claim 1 , wherein the ground is a chassis ground or a low impedance ground.

6. The apparatus according to claim 1 , further comprising a pump body formed of a conductive polyether ether ketone (PEEK) material, wherein the conductive pump body forms the electrical conductor electrically connecting the analysis fluid path to the wash fluid path.

7. The apparatus according to claim 1 , wherein the electrical conductor between the paths reduces unwanted cycling in the conductivity detector by reducing any voltage potential across the pumping chamber and the seal washing chamber as the piston moves.

8. An analysis system comprising:
an analysis fluid path;
a pump for pumping a sample fluid along the analysis fluid path, the pump including a pumping chamber, a non-conductive piston extending into the pumping chamber for pumping the sample fluid along the analysis fluid path, a seal washing chamber, and a seal fluidly separating the pumping chamber from the seal washing chamber, wherein the piston extends through the seal and creates a voltage potential between the pumping chamber and the seal washing chamber as the piston moves;
a conductivity detector fluidly connected to the analysis fluid path downstream of the pump for monitoring the sample fluid;
a wash fluid path supplying a wash fluid from a wash reservoir to the seal washing chamber;
an electrical conductor for reducing noise in the conductivity detector due to pump movement, the electrical conductor electrically connecting the analysis fluid path to the wash fluid path, and
a ground conductor electrically connecting a resistor between the electrical conductor and a ground.

9. The analysis system according to claim 8 , wherein the analysis system is an ion chromatography system.

10. The analysis system according to claim 8 , wherein the piston is formed of sapphire.

11. The analysis system according to claim 8 , wherein the electrical conductor is a platinum wire having a first end in electrical communication with the analysis fluid path and a second end in electrical communication with the wash fluid path.

12. The analysis system according to claim 11 , further comprising a polymeric tee assembly having first and second legs extending along the analysis fluid path between the pump and the conductivity detector, and a third leg positioning the first end of the platinum wire in electrical communication with the analysis fluid path.

13. The analysis system according to claim 11 , further comprising a stainless steel tube forming a portion of the wash fluid path, wherein the second end of the platinum wire is attached to the stainless steel tube.

14. The analysis system according to claim 8 , wherein the resistor has a resistance of at least a megaohm.

15. The analysis system according to claim 8 , wherein the ground is a chassis ground or a low impedance ground.

16. The analysis system according to claim 8 , further comprising a pump body formed of a conductive polyether ether ketone (PEEK) material, wherein the conductive pump body forms the electrical conductor electrically connecting the analysis fluid path to the wash fluid path.

17. The analysis system according to claim 16 , wherein the pump body is formed of ultra-high-molecular-weight polyethylene (UHMWPE) containing carbon.

18. The analysis system according to claim 8 , wherein the electrical conductor reduces unwanted cycling in the conductivity detector by reducing any voltage potential across the pumping chamber and the seal washing chamber as the piston moves.

19. An ion chromatography system comprising:
an analysis fluid path;
an eluent source supplying an eluent to the analysis fluid path for forming a mobile phase for chromatographic analysis;
an injector for introducing a sample containing an analyte into the eluent to form the mobile phase;
a separation column downstream of the injector for separating the analyte;
a pump for pumping the eluent to the separation column, the pump including a non-conductive pump body, a pumping chamber in the pump body, a non-conductive piston extending into the pumping chamber for pumping the eluent along the analysis fluid path, a seal washing chamber within the pump body, and a seal separating the pumping chamber from the seal washing chamber, wherein the piston extends through the seal and creates a voltage potential between the pumping chamber and the seal washing chamber as the piston moves;
a conductivity detector fluidly connected to the analysis fluid path downstream of the pump and the separation column to detect the analyte flowing along the analysis fluid path through the conductivity detector;
a wash fluid path supplying a wash fluid to the seal washing chamber;
an electrical conductor electrically connecting the analysis fluid path to the wash fluid path, wherein the electrical conductor reduces noise in the conductivity detector due to pump movement; and
a ground conductor electrically connecting the electrical conductor to ground via a resistor.

20. The ion chromatography system according to claim 19 , wherein the pump body is formed of a polymeric material.

21. The ion chromatography system according to claim 20 , wherein the polymeric material is polyether ether ketone (PEEK).

22. The ion chromatography system according to claim 19 , wherein the piston is formed of sapphire.

23. The ion chromatography system according to claim 19 , wherein the electrical conductor is a platinum wire having a first end in electrical communication with the analysis fluid path and a second end in electrical communication with the wash fluid path.

24. The ion chromatography system according to claim 23 , further comprising a polymeric tee assembly having first and second legs extending along the analysis fluid path between the pump and the conductivity detector, and a third leg positioning the first end of the platinum wire in electrical communication with the analysis fluid path.

25. The ion chromatography s

Assignees

• Dionex Corp

Inventors

• Mcadams Michael J
• Elzind Ihab

Classifications

• G01N30/96 Primary

  using ion-exchange (G01N30/02, G01N30/90 take precedence) · CPC title

• C02F1/42

  by ion-exchange (ion-exchange in general B01J) · CPC title

• G01N2030/645

  electrical conductivity detectors · CPC title

• B01D15/361

  Ion-exchange · CPC title

• G01N30/64 Primary

  Electrical detectors · CPC title