Claims
- 1. Apparatus for generating an eluent and using the same in anion analysis comprising
- (a) a flowthrough first cation exchange bed including exchangeable cations, said first cation exchange bed comprising an upstream bed portion comprising a strongly acidic cation exchange material and an adjacent downstream bed portion comprising a weakly acidic cation exchange material,
- (b) a first electrode in electrical communication with the inlet portion of said first cation exchange bed and a second electrode in electrical communication with the outlet portion thereof,
- (c) a power supply for applying an electrical potential between said first and second electrodes while an aqueous stream is flowing in a first direction therethrough for electrolytically generating hydroxide ions and displacing exchangeable cations into said aqueous stream to form a first eluent comprising a base,
- (d) a sample injection port for injecting a liquid sample stream containing anions to be detected,
- (e) a chromatographic separator having an inlet and an outlet, said inlet being in flulid communication with said sample injection port and said first eluent for separating anions to be detected in a first sample stream flowing through said port and forming a first chromatography effluent exiting from said chromatographic separator, and
- (f) a detector in fluid communication with the outlet of said first chromatographic separator for detecting the separated anions in said first chromatographic effluent.
- 2. The apparatus of claim 1 in which said first and second electrodes are in contact with said first cation exchange bed.
- 3. The apparatus of claim 1 in which said first and second electrodes are in direct contact with said first cation exchange bed.
- 4. The apparatus of claim 1 further comprising
- (g) means for maintaining said chromatography effluent flowing to said detector under pressure.
- 5. The apparatus of claim 1 wherein said power supply includes a variable output potential.
- 6. The apparatus of claim 1 in which said upstream portion has a total ion capacity, at least about 10 times that of said downstream bed portion.
- 7. The apparatus of claim 1 in which said detector comprises an electrical conductivity detector.
- 8. The apparatus of claim 1 in which said first cation exchange bed comprises a first cation exchange resin packed bed.
- 9. The apparatus of claim 1 further comprising
- (g) a flowthrough second cation exchange bed and including exchangeable hydronium ions, said second cation exchange bed being disposed in fluid communication between said chromatographic separator and said detector, said second cation exchange bed being adapted to convert said base in said first chromatography effluent to weakly ionized form, said first chromatography effluent exiting said second cation exchange bed as a first suppressed effluent.
- 10. The apparatus of claim 9 in which said second cation exchange bed includes an inlet and an outlet, and further comprising a third and fourth electrode disposed near said second cation exchange bed inlet and outlet, respectively, wherein said power supply is operable to apply an electric potential between said third and fourth electrodes, while an aqueous stream is flowing through said second cation exchange bed in a second direction opposite said first direction for electrolytically generating hydroxide ions and displacing exchangeable cations in said downstream portion to form a second eluent comprising a base which exits said second cation exchange bed, said apparatus further comprising
- (h) valving for reversing the direction of fluid flow in said first and second cation exchange beds from that of steps (a) and (d).
- 11. The apparatus of claim 1 further comprising
- (g) a second cation exchange bed including hydronium ions exchangeable with the cations of said first eluent, said second cation exchange bed being disposed to receive fluid exiting said detector.
- 12. The apparatus of claim 11 in which said second cation exchange bed includes an inlet and an outlet, said apparatus further comprising a third and fourth electrode disposed near said second cation exchange bed inlet and outlet, respectively, wherein said power supply is operable to apply an electric potential between said third and fourth electrodes while an aqueous stream is flowing through said second cation exchange resin bed in a second direction opposite said first direction for electrolytically generating hydroxide ions for combining with displaced exchangeable cations in said downstream portion to form a second eluent comprising a base which exits said second cation exchange resin bed, said apparatus ftrther comprising
- (h) valving for reversing the direction of fluid flow in said first and second cation exchange beds from that of steps (a) and (d).
- 13. Apparatus for generating an eluent and using the same in cation analysis comprising
- (a) a flowthrough first anion exchange bed including exchangeable anions, said first anion exchange bed comprising an upstream bed portion comprising a strongly basic anion exchange material and an adjacent downstream portion comprisinig a weakly basic anion exchange material,
- (b) a first electrode in electrical communication with said inlet portion of said first anion exchange bed and a second electrode in electrical communication with said outlet portion thereof,
- (c) a power supply for applying an electrical potential between said first and second electrodes while an aqueous stream is flowing in a first direction therethrough for electrolytically generating hydronium ions and displacing exchangeable anions into said aqueous stream to form a first eluent comprising an acid,
- (d) a sample injection port for injecting a liquid sample stream containing cations to be detected,
- (e) a chromatographic separator having an inlet and an outlet, said inlet being in fluid communication with said sample injection port and said first eluent for separating cations to be detected in a first sample stream flowing through said port and forming a first chromatography effluent exiting from said chromatographic separator, and
- (f) a detector in fluid communication with the outlet of said first chromatographic separator for detecting the separated cations in said first chromatographic effluent.
- 14. The apparatus of claim 13 in which said first and second electrodes are in direct contact with said first anion exchange bed.
- 15. The apparatus of claim 13 further comprising
- (g) means for maintaining said chromatography effluent flowing to said detector under pressure.
- 16. The apparatus of claim 13 wherein said power supply includes a variable output potential.
- 17. The apparatus of claim 13 in which said detector comprises an electrical conductivity detector.
- 18. The apparatus of claim 13 in which said first anion exchange bed comprises a first cation exchange resin packed bed.
- 19. The apparatus of claim 13 in which said upstream portion has a capacity at least about 10 times that of said downstream bed portion anion exchange material.
- 20. The apparatus of claim 13 in which the capacity of said downstream bed portion is from about 0.4 to about 2.4 meq./ml.
- 21. The apparatus of claim 13 further comprising
- (g) a flowthrough second anion exchange bed and including exchangeable hydroxide ions, said second anion exchange bed being disposed in fluid communication between said chromatographic separator and said detector, said second anion exchange bed being adapted to convert said acid in said first chromatography effluent to weakly ionized form, said first chromatography effluent exiting as a first suppressed effluent.
- 22. The apparatus of claim 21 in which said second anion exchange bed includes an inlet and an outlet and further comprising a third and fourth electrode disposed near said second anion exchange bed inlet and outlet, respectively, wherein said power supply is operable to apply an electric potential between said third and fourth electrodes, while an aqueous stream is flowing through said second anion exchange bed in a second direction opposite said first direction for electrolytically generating hydronium ions and displacing exchangeable anions in said downstream portion to form a second eluent comprising an acid which exits said second anion exchange bed, said apparatus further comprising
- (h) valving for reversing the fluid flow in said first and second anion exchange beds from that of steps (a) and (d).
- 23. The apparatus of claim 13 further comprising
- (g) a second anion exchange bed including hydroxide ions exchangeable with the anions of said first eluent, said second anions exchange bed being disposed to receive fluid exiting said detector.
- 24. The apparatus of claim 23 in which said second anion exchange bed includes an inlet and an outlet, said apparatus further comprising a third and fourth electrode disposed in said second anion exchange bed inlet and outlet respectively, wherein said power supply is operable to apply an electric potential between said third and fourth electrodes while an aqueous stream is flowing through said second anion exchange resin bed in a second direction opposite said first direction for electrolytically generating hydronium ions for combining with displaced exchangeable anions in said downstream portion to form a second eluent comprising an acid which exits said second anion exchange bed, said apparatus further comprising
- (h) valving for reversing the direction of fluid flow in said first and second cation exchange beds from that of steps (a) and (d).
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of H. Small U.S. patent application Ser. No. 08/783,317, filed Jan. 15, 1997 now abandoned.
US Referenced Citations (9)
Foreign Referenced Citations (1)
Number |
Date |
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0 180 321 |
May 1986 |
EPX |
Continuation in Parts (1)
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Number |
Date |
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783317 |
Jan 1997 |
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