A planar microelectrodialytic NaOH generator for eluite conversion after suppressed conductometric detection in ion chromatography

Sjögren, Anna; Dasgupta, Purnendu Κ.

doi:10.1016/s0003-2670(98)00831-9

Cited by 14 publications

(11 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Overall, this performance is at least equal to or better than previous approaches (see Table S1). ,, …”

Section: Resultsmentioning

confidence: 99%

“…Overall, this performance is at least equal to or better than previous approaches (see Table S1). 5,6,11 However, a linear configuration (or a large coil radius as used here) has been reported to be most prone to poor mixing and large dispersion; 12 hence, we coiled the Teflon AF tube in the PAID on a 3.7 mm support rod and thermoset the shape by putting it in boiling water for 30 min. Both the noise and the dispersion decreased to 3.6 ± 0.2 nS/cm and 30.3 ± 0.3 μL, respectively, under the same test conditions.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…A recent review by Karu et al addresses various efforts toward weak acid detection by modified SCAC; the most promising approach identified was strong base (e.g., NaOH) introduction after a conventional hydroxide eluent SCAC system followed by a second conductivity detector (D2). − After NaOH introduction, a fraction f of the eluite acid HX is converted to NaX, f ≤ 1, and increases with decreasing p K a (for example, f will be 0.5 for an acid with a p K a of 10 if the pH after base introduction is 10). The D2 signal is thus negative and equals fC(λ X – – λ OH – ), where C is the eluite concentration in eq/L, and λ X – and λ OH – are the limiting equivalent conductance of X – and OH – , respectively.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Permeative Amine Introduction for Very Weak Acid Detection in Ion Chromatography

Liao

Dasgupta

2016

Anal. Chem.

Self Cite

View full text Add to dashboard Cite

A permeative amine 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 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 (baseline noise 0.8 nS/cm for 27 μM diethylamine) with low band dispersion (as small as 30 μL). Diethylamine (DEA) was chosen as the amine source due to its low pKb value (3.0), high vapor pressure, low toxicity, and low odor. The eluites are thus detected against a low diethylammonium hydroxide (DEAOH) background (5-31 μS/cm) as negative peaks because the equivalent conductance of OH(-) is greater than that of X(-). Reducing the background DEA concentration enhances the detectability of traces of weak acids. Lower background [DEA] will limit the maximum concentration of analyte acids that can be determined; a general concept of peak width measurement at a fixed height is proposed as a solution. Trace impurities formed during electrodialytic suppression play a role in background noise; for the first time, we look at the nature of such impurities. The appearance of silicate in a sample put in a glass container as a function of pH can be readily followed. The maximum silica level in high purity type 1 water is 50 nM (1.40 μg/L Si), which is a measurement challenge in particular. A large injection volume (1 mL) permits detection limits of 21 nM silicate, 3 nM taurine, 3 nM sulfide, and 13 nM cyanide.

show abstract

“…Overall, this performance is at least equal to or better than previous approaches (see Table S1). ,, …”

Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Permeative Amine Introduction for Very Weak Acid Detection in Ion Chromatography

Liao

Dasgupta

2016

Anal. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, very weak acids barely ionize and are undetectable. We have been exploring determination of strong to very weak acids by adding a base after the suppressor as a PCR. − Following base addition, the principal conductive species is OH – . An eluting acid reacts as HX + OH – → H 2 O + X – , the highly mobile OH – is replaced by less conductive X – , producing a negative response.…”

Section: Resultsmentioning

confidence: 99%

Width Based Characterization of Chromatographic Peaks: Beyond Height and Area

et al. 2017

Self Cite

View full text Add to dashboard Cite

The preceding paper ( Anal. Chem. 2017 , 10.1021/acs.analchem.6b04857 ) introduced width-based quantitation (WBQ). The present paper focuses on (1) situations where WBQ is effective while height/area-based linear calibrations fail, e.g., when (a) the detector is in a nonlinear response region, (b) the detector/data system is saturated, causing clipping/truncation of the signal, or (c) the detector signal is not a single-valued function of concentration, as when a fluorescence signal goes into the self-quenched domain. (2) Utilization of WBQ in postcolumn reagent addition methods where the reagent produces a significant detector background. WBQ can minimize added reagent without sacrificing the upper determination limit; a limited reagent amount truncates peaks from high analyte concentrations but does not hamper WBQ at a low height. (3) A description of peak asymmetry via leading/trailing half-widths vs relative height (fraction of maximum height) plots. (4) A holistic description of chromatographic peaks through six parameters describing the two independent generalized Gaussian distributions that underlie the WBQ chromatographic peak model. (5) Characterization of shape by widths at multiple heights and shape-based impurity detection.

show abstract

“…In a subsequent more detailed paper, the dispersion was measured to be 94 μL for a device of 15-mm active length. Further developments led to planar MENG devices that exhibited noise levels as good as 8 nS/cm with band dispersions in the range of 78−90 μL …”

mentioning

confidence: 99%

Two-Dimensional Detection in Ion Chromatography: Sequential Conductometry after Suppression and Passive Hydroxide Introduction

2001

Self Cite

View full text Add to dashboard Cite

An improved method that uses sequential suppressed and nonsuppressed IC for the sensitive detection of both common anions and very weak acid anions is described. After suppressed conductometric detection of an electrolytically generated hydroxide eluent and an electrolytic suppressor, the eluent is passed into a membrane device where KOH is passively introduced into the eluent stream using Donnan forbidden leakage. A second conductivity detector then measures the conductivity of the stream. The background conductance of the second detector is typically maintained at a relatively low level of 20-30 microS/ cm. The weak acids are converted to potassium salts that are fully ionized and are detected against a low KOH background as negative peaks. The applicability of different commercially available cation exchange membranes was studied. Device configurations investigated include planar, tubular, and a filament-filled annular helical (FFAH) device. The FFAH device provided more effective mixing of the penetrated hydroxide with the eluent stream, resulting in a noise level of < or = 7 nS/cm and a band dispersion value of less than 82 microL. Optimal design and performance data are presented.

show abstract

A planar microelectrodialytic NaOH generator for eluite conversion after suppressed conductometric detection in ion chromatography

Cited by 14 publications

References 15 publications

Permeative Amine Introduction for Very Weak Acid Detection in Ion Chromatography

Permeative Amine Introduction for Very Weak Acid Detection in Ion Chromatography

Width Based Characterization of Chromatographic Peaks: Beyond Height and Area

Two-Dimensional Detection in Ion Chromatography: Sequential Conductometry after Suppression and Passive Hydroxide Introduction

Contact Info

Product

Resources

About