Indirect photomeric detection of anions in capillary electrophoresis using dyes as probes and electrolytes buffered with an isoelectric ampholyte

Johns, Cameron; Macka, Mirek; Haddad, Paul R.

doi:10.1002/(sici)1522-2683(20000401)21:7<1312::aid-elps1312>3.0.co;2-9

Cited by 37 publications

(32 citation statements)

References 13 publications

(23 reference statements)

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“…As early as 1997, noise levels as low as ∼10 −5 absorbance units have been reported (105). Over the past decade, LEDs were used in miniaturized photometric detectors for CE, resulting in low baseline noise and detection limits comparable to commercial CE instruments using D 2 lamps (14,15,25,(106)(107)(108)(109)(110); facile estimation of the effective path length and stray light that govern the performance of the detector has been suggested (111).…”

Section: Capillary Scale Absorbance Detectionmentioning

confidence: 99%

Light-Emitting Diodes for Analytical Chemistry

Macka

Piasecki

Dasgupta

2014

Annual Rev. Anal. Chem.

113

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Light-emitting diodes (LEDs) are playing increasingly important roles in analytical chemistry, from the final analysis stage to photoreactors for analyte conversion to actual fabrication of and incorporation in microdevices for analytical use. The extremely fast turn-on/off rates of LEDs have made possible simple approaches to fluorescence lifetime measurement. Although they are increasingly being used as detectors, their wavelength selectivity as detectors has rarely been exploited. From their first proposed use for absorbance measurement in 1970, LEDs have been used in analytical chemistry in too many ways to make a comprehensive review possible. Hence, we critically review here the more recent literature on their use in optical detection and measurement systems. Cloudy as our crystal ball may be, we express our views on the future applications of LEDs in analytical chemistry: The horizon will certainly become wider as LEDs in the deep UV with sufficient intensity become available.

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Section: Capillary Scale Absorbance Detectionmentioning

confidence: 99%

Light-Emitting Diodes for Analytical Chemistry

Macka

Piasecki

Dasgupta

2014

Annual Rev. Anal. Chem.

113

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“…Tartrazine (3-carboxy-5-hydroxy-1-p-sulfophenyl-4-p-sulfophenylazopyrazole trisodium salt) (Fluka, Buchs, Switzerland) was purified by recrystallisation [11] and used to prepare a series of BGEs. A standard solution of methanesulfonate (Sigma, St. Louis, MO, USA) was prepared by dilution of a LR grade solution of methanesulfonic acid.…”

Section: Reagentsmentioning

confidence: 99%

“…The highly absorbing anionic dye tartrazine has been previously used as an anionic probe [11] and also to evaluate detector linearity (Johns et al, submitted). A BGE consisting of tartrazine and the isoelectric carrier ampholyte buffer histidine was used as a model electrolyte during this work.…”

Section: Choice Of Model Bge Systemmentioning

confidence: 99%

“…A BGE consisting of tartrazine and the isoelectric carrier ampholyte buffer histidine was used as a model electrolyte during this work. It has been shown in earlier work [11] that the reversal of electroosmotic flow (EOF) with a cationic surfactant to provide co-EOF separation of anions is not possible due to the formation of a tartrazine-surfactant precipitate when commonly used EOF modifiers such as tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB) were used. To provide the fastest possible separations of anions applying negative polarity at the injection end, the EOF was suppressed by the addition to the BGE of 0.05% hydroxypropylmethylcellulose (HPMC) [11].…”

Section: Choice Of Model Bge Systemmentioning

confidence: 99%

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Optimisation of probe concentration in indirect photometric detection in capillary electrophoresis using highly absorbing dyes

Johns¹,

Macka²,

Haddad³

2002

Electrophoresis

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In indirect photometric detection in capillary electrophoresis, the concentration of the absorbing probe ion in the background electrolyte should be as high as possible in order to increase the dynamic range of the detection method. For relatively low absorptivity probes (epsilon < 2000 L mol(-1)cm(-1)) used under typical conditions (75 microm ID capillary) the maximum probe concentration is normally limited by the separation current. However, for medium (epsilon approximately/= 2000-15000 L mol(-1)cm(-1)) and especially for high (epsilon > 15000 L mol(-1)cm(-1)) absorptivity probes such as dyes, the maximum concentration may be limited by the background absorbance of the electrolyte which must fall within the linearity range of the detector. In this work, it is shown that another practical factor limiting the probe concentration is the adsorption of probe onto the capillary wall at higher concentrations, resulting in unstable baseline and increased noise. Use of a zwitterionic surfactant to suppress adsorption enabled the concentration of a model probe anion (tartrazine) to be increased by a factor of six times (to 3 mM). This resulted in significant improvements in peaks shapes, resolution between peaks, detection sensitivity and linear calibration range for the analyte anions. Baseline separation of a test mixture was maintained up to 7.5 mM total concentration of sample coions injected (13.7 nL) for the 3 mM electrolyte, with detection limits ranging from 0.63 to 0.94 microM. Peak height reproducibility (over 20 consecutive injections) was improved (values ranging from 1.1 to 1.9%) compared with electrolytes containing lower concentrations of the probe. Overall, the optimised, higher concentration probe electrolyte provided the sensitivity benefits of highly absorbing probes with the additional benefits of ruggedness and improved stacking, peak shapes and resolution.

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“…However, it is impossible to meet the requirement with a single probe for separating C2-C18 ACAs, which have the effective electrophoretic mobilities ranging from 0.98 to 3.86610 -4 cm 2 s -1 V -1 in aqueous solution [33]. To solve this problem, the use of multiple probes or adding co-ions has been developed [21,34,35]. The latter is more easily carried out because suitable probes are difficult to find in NACE-ILIF.…”

Section: Role Of Co-ionsmentioning

confidence: 99%

Indirect fluorescence of aliphatic carboxylic acids in nonaqueous capillary electrophoresis using merocyanine 540

Chiu

Huang

et al. 2002

Electrophoresis

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A method for the analysis of aliphatic carboxylic acids (ACAs) in nonaqueous capillary electrophoresis (NACE) in conjunction with indirect laser-induced fluorescence (ILIF) using merocyanine 540 (MC 540) is described. Performing the analysis in organic solvent is advantageous when using MC 540, because of its greater quantum yield in aprotic solvent. To achieve a high dynamic reserve (DR) and optimize resolution, we have tested a number of aqueous mixtures containing alcohols and acetonitrile (ACN). The optimum buffer for the analysis of C2-C18 ACAs, in terms of sensitivity, resolution, and speed, is an aqueous mixture of 40% ACN, 30% ethanol, and 1 mM Tris at apparent pH 7.4 (adjusted with ascorbic acid). Under this condition, the DR is greater than 1000, thereby the limits of detection for acids are in the range of sub-microM to microM. Linear plots show that the dynamic ranges for the analysis of ACAs are at least two decades in concentration, with regression coefficients all greater than 0.98. The relative standard deviations of the migration times and peak heights for all ACAs are less than 2.0%. Furthermore, this simple and cost-effective method has been applied to the analysis of marine lipid concentrate, with the concentrations of 1.67+/-0.03 and 4.50+/-0.05 mM (n = 5) for C14 and C16 acids, respectively, in a tablet of marine lipid concentrate sample.

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Indirect photomeric detection of anions in capillary electrophoresis using dyes as probes and electrolytes buffered with an isoelectric ampholyte

Cited by 37 publications

References 13 publications

Light-Emitting Diodes for Analytical Chemistry

Light-Emitting Diodes for Analytical Chemistry

Optimisation of probe concentration in indirect photometric detection in capillary electrophoresis using highly absorbing dyes

Indirect fluorescence of aliphatic carboxylic acids in nonaqueous capillary electrophoresis using merocyanine 540

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