Permeative amine or acid introduction for very weak acid detection in ion chromatography

Patent metadata

Field	Value
Publication number	US-11714070-B2
Application number	US-202016891901-A
Country	US
Kind code	B2
Filing date	Jun 3, 2020
Priority date	Jan 7, 2016
Publication date	Aug 1, 2023
Grant date	Aug 1, 2023

Abstract

A permeative amine/acid introduction device (PAID) is placed after a conventional KOH eluent suppressed conductometric anion chromatography (SCAC) system. The PAID converts the suppressed eluites from the acid form to the corresponding salt. For example, when the analytes are acids, they are converted to the corresponding ammonium salt (NR2H+HX→NR2H2++X−) and allows very weak acids HX (pKa≥7.0) that cannot normally be detected by SCAC to be measured by a second conductivity detector following the PAID. Permeative reagent introduction is dilutionless, can be operated without pumps and provides good mixing with low band dispersion (as small as 30 μL). An exemplary amine is diethylamine (DEA), which was chosen as the amine source due to its low pKb value (pKb 3.0), high vapor pressure, and low toxicity and low odor.

First claim

The invention claimed is:

1. A device comprising:
(a) an impermeable component defining an internal compartment, comprising;
(i) at least one of a first acid and a first base introduction section fluidically connected with at least one of a first respective weakly dissociating acid and weakly dissociating base extraction section, wherein the at least one of the first acid and the first base introduction section comprises at least one of a first respective acid and a first base inlet port and at least one of a second respective acid and a second base waste outlet port; and
(ii) the at least one of the first respective weakly dissociating acid and the first weakly dissociating base extraction section comprises a water introduction port and at least one of a respective weakly dissociating acid and weakly dissociating base waste outlet port; and

(b) a permeable membrane disposed within a cavity of the internal compartment, wherein the permeable membrane is contiguous with the at least one of the first acid and a first base introduction section and the at least one of the first respective weakly dissociating acid and the first weakly dissociating base extraction section, wherein the permeable membrane is in a tubular configuration having a lumen and is in contact with at least one of a volatile base or acid on an outside of the permeable membrane to only allow passage of an at least one of a volatile acid or a volatile base through the permeable membrane and into the lumen of the permeable membrane;
wherein the device is configured to receive an effluent from a chromatographic medium containing a weakly dissociating acid or a weakly dissociating base such that the weakly dissociating acid or the weakly dissociating base flows in fluidic contact within the lumen of the permeable membrane, and further wherein the permeable membrane is amorphous fluoroplastic, which is gas permeable and liquid impermeable.

2. The device of claim 1 , wherein the volatile acid or volatile base is a volatile amine.

3. The device of claim 1 , wherein the impermeable component and the permeable membrane are spaced apart from each other to facilitate fluid flow between an outer surface of the permeable membrane and an inner surface of the impermeable component.

4. The device of claim 1 , wherein at least one weakly dissociating acid extraction section or weakly dissociating base extraction section is fluidly connected to a detector.

5. A method comprising:
(a) introducing a volatile acid or a volatile base to an acid or base introduction section of a permeable membrane device via an acid or base introduction port, wherein the permeable membrane device is configured for integration downstream of a chromatographic medium of an ion chromatographic separation,
(b) permeating the membrane with the volatile acid or volatile base and contacting a weakly dissociating acid or base within an internal compartment of the membrane of the device;
(c) traversing the weakly dissociating acids or bases along a length of the acid or base introduction section to enter a weak acid or base extraction section of the device;
(d) introducing deionized water into the weak acid or base extraction section of the device, via a water introduction port; and
(e) contacting a surface of the membrane of the device with the deionized water, thereby extracting protonated weakly dissociating acid or deprotonated weakly dissociating base and carrying the protonated weakly dissociating acid or deprotonated weakly dissociating base out of the permeable membrane device and to a detector;
wherein the permeable membrane device comprises:
(i) an impermeable component defining the internal compartment comprising the acid or base introduction section contiguous and fluidically connected with the weak acid or base extraction section, the acid or base introduction section comprising an acid or base inlet port and a respective acid or base waste outlet port, and the weak acid or base extraction section comprising the water introduction port and a respective weakly dissociating acid or weakly dissociating base waster outlet port, and
(ii) the permeable membrane, wherein the permeable membrane is amorphous fluoroplastic, which is gas permeable and liquid impermeable.

6. The device of claim 5 , wherein the volatile acid or volatile base is a volatile amine.

Assignees

• Univ Texas

Inventors

• Dasgupta Purnendu K
• Shelor Charles Philip
• Liao Hongzhu

Classifications

• G01N30/96 Primary

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

• B01D15/24

  relating to the treatment of the fractions to be distributed · CPC title

• B01D15/363

  Anion-exchange · CPC title

• G01N27/44756

  Apparatus specially adapted therefor · CPC title

• B01D15/367

  Ion-suppression · CPC title