Indirect UV detection of carbohydrates in capillary zone electrophoresis by using tryptophan as a marker

Lü, Bing; Westerlund, Douglas

doi:10.1002/elps.1150170207

Cited by 44 publications

(13 citation statements)

References 23 publications

(20 reference statements)

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“…Based on the fundamental transport equations using the eigenvector approach, Poppe's research group [21,221 have introduced a mathematical model for the simulation of indirect detection electropherograms, in which the analyte peak directions, number and position of system peaks, and magnitudes of detector responses can be predicted based on the results of computational calculations. It has been reported that the simulated data showed deviations from experimental results in some indirect detection systems [16,231. However, studies on the detector response patterns in separations of mixtures containing both cationic and anionic analytes, regarding the influence of the charges of the marker ions and the composition of the BGEs, have not been reported in the literature to date according to our knowledge.…”

Section: Introductionmentioning

confidence: 88%

Response patterns with indirect UV detection in capillary zone electrophoresis

Lü

Westerlund

1998

Electrophoresis

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Capillary zone electrophoresis with indirect UV-detection was used to separate mixtures containing both positively and negatively charged species. In order to understand the dependence of detector response patterns on the changes in compositions of the background electrolytes and the charge of marker ions (UV-absorbing ions), the separations were performed in two different systems. In a three-ion system (analyte ion, coion and counterion) a marker ion was the major ionic component of a buffer solution and in a two-coion or counterion system the marker ion was used as an additive. In the three-ion system the response profile of an analyte was in good agreement with the mathematical treatment based on the Kohlrausch regulation function. In the two-coion or counterion system the response patterns were more complicated; however, the experimental results agree well with data obtained from a computer simulation program. Peak directions of the analytes were not only determined by their relative charge to the marker ion, but were also associated with their relative mobilities to the buffer coion and the marker ion. The analytes with higher effective mobilities compared to the marker ion were detected as positive peaks and the ones with lower effective mobilities as negative peaks. Similarly to the three-ion system, the detector response of an analyte was stronger by applying a marker coion compared to a counterion. An interesting result was obtained in the separation of a mixture of quaternary ammonium ions and sugars by using a cationic marker ion. The highest and most symmetrical peak was not a cation, but raffinose anion, which appeared most closely to the system peak. The observation suggests that the electromigration dispersion in its zone was eliminated by migrating close to the electroosmosis. A system peak with the mobility corresponding to the electroosmotic flow was obtained in both systems, and an additional system peak with a mobility close to that the marker ion was present in the systems using marker ions as additives.

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Section: Introductionmentioning

confidence: 88%

Response patterns with indirect UV detection in capillary zone electrophoresis

Lü

Westerlund

1998

Electrophoresis

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“…For the most challenging case of neutral carbohydrates, a charge can be endowed (i) by simple deprotonation in highly alkaline BGEs (pH > 12), allowing their separation according to their p K a values and size, and their subsequent detection by indirect absorbance using an anionic chromophore (e.g. sorbate , tryptophan or 2,6‐pyridine dicarboxylate ), or amperometry , (ii) by in‐capillary complexation of the carbohydrates with borate anions or alkaline earth cations, allowing their separation according to their complexing ability and size, and their detection under underivatized form by direct absorbance in the low‐UV range (borate complexes) or under appropriate precapillary derivatized form (borate and metal complexes), (iii) by precapillary labeling their reactive reducing end with a charged UV‐absorbing or fluorescent tag (e.g. 2‐aminopyridine, 6‐aminoquiniline, 1‐phenyl‐3‐methyl‐5‐pyrazolone, 8‐aminonaphtalene‐1,3,6‐trisulfonate, 8‐ (or 9‐) aminopyrene‐1,3,6‐ (or 1,4,6‐) trisulfonate (APTS)), allowing both their separation according to their size and sensitive detection .…”

Section: Introductionmentioning

confidence: 99%

Analysis of underivatized cellodextrin oligosaccharides by capillary electrophoresis with direct photochemically induced UV‐detection

et al. 2015

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Analysis of underivatized cellodextrin oligosaccharides by capillary electrophoresis with direct photochemically induced UV-detectionThis work focuses on the development of a CE method allowing, for the first time, the simultaneous separation of the underivatized first seven cellodextrin oligomers (glucose, cellobiose, cellotriose, cellotetraose, cellopentaose, cellohexaose, and celloheptaose), with a view to analyze the hydrolysates obtained after partial acid depolymerization of nitrocellulose, and eight carbohydrates (ribose, xylose, fructose, mannose, galactose, maltose, lactose, and sucrose), which might be potential interfering compounds in explosives samples. Separation was achieved with a highly alkaline BGE containing sodium chloride and direct mid-UV-absorbance detection was performed after photo-oxidation in the detection window. EOF was reversed to speed up the analysis using a dynamic capillary coating by hexadimethrine bromide. A central composite design was carried out to determine the effects of BGE conductivity and sodium hydroxide concentration on resolutions between neighboring peaks, and analysis time. A desirability analysis on modeled responses was applied to maximize resolutions and to minimize analysis time. The simultaneous analysis in 20 min total runtime of the 15 carbohydrates plus internal reference (naphthalene sulfonate) was carried out at 25°C with a BGE composed of 77.4 mM NaOH and 183 mM NaCl to adjust the conductivity at the optimum value. Finally, the resolution robustness was checked. This new method should also be of interest to monitor food and nonfood crop products. Keywords:Cellodextrins / Capillary electrophoresis / Design of experiments / Direct UV detection / Oligosaccharide DOI 10.1002/elps.201400605Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionCarbohydrates are ubiquitous compounds in the living world, as natural and degradation products, metabolites, or conjugates. They are also widely used as food or beverage additives. This class of compounds of tremendous complexity actually encompasses a variety of molecules differing in size (mono-, oligo-, and polysaccharides), epimerization or isomerization, glycosidic linkage, branching, and functionality , and mixed modes [11,13] have all been commonly employed. Separations have been based on hydrogen bonding, size, complexing ability, and in some cases charge. As far as detection is concerned, great difficulties are encountered due to the lack of a chromophoric moiety. According to the sensitivity requirements and separation mode, different detection strategies have been implemented, namely, without-or with pre-or postcolumn

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“…[14] in CE analysis of inorganic ions. Several groups utilized indirect UV detection in CE of carbohydrates [15][16][17][18][19][20][21]. Several UV-absorbing compounds, such as sorbic acid, riboflavin, 5-sulfosalicylic acid, 1,2,4-tricarboxylbenzoic acid, 1-naphthylacetic acid, and trypotophan, were used as backround chromophores.…”

Section: Introductionmentioning

confidence: 99%

Separation of disaccharides as their borate complexes by capillary electrophoresis with indirect detection in visible range

Plocek

Chmelı́k

1997

Electrophoresis

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Borate complexation was used to make possible the separation of disaccharides by capillary electrophoresis with indirect detection. A high borate concentration did not affect the indirect detection sensitivity in as negative a way as predicted previously. The concentration sensitivity for sucrose was determined to be 2 mM at the borate concentration of 200 mM in running electrolyte. The newly introduced background [corrected] chromophore, p-nitrophenol, allows the monitoring of the separation process in a visible range at 400 nm. This also enables the indirect detection of UV-absorbing compounds in complex mixtures in which they would be impossible to detect with a UV-absorbing background [corrected] chromophore.

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Indirect UV detection of carbohydrates in capillary zone electrophoresis by using tryptophan as a marker

Cited by 44 publications

References 23 publications

Response patterns with indirect UV detection in capillary zone electrophoresis

Response patterns with indirect UV detection in capillary zone electrophoresis

Analysis of underivatized cellodextrin oligosaccharides by capillary electrophoresis with direct photochemically induced UV‐detection

Separation of disaccharides as their borate complexes by capillary electrophoresis with indirect detection in visible range

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