Capillary Electrophoresis-ultraviolet Detection Research Articles

Capillary electrophoretic profiling of in-bone tryptic digests of proteins as a potential tool for the detection of inflammatory states in oral surgery.

The commonly used histological assessment of pathological states of alveolar bone tissues in oral surgery needs laborious and time-consuming processing by an experienced histologist. Therefore, a simpler and faster methodology is required in this field. Following this demand, this paper reports a straightforward approach using the tryptic cleavage of proteins directly in bone without its demineralization, followed by the capillary electrophoresis-ultraviolet detection profiling of the yielded protein digest. Cleavage-derived peptides were separated by capillary electrophoresis in acidic background electrolytes, pH 2.01-2.54. The best resolution of peptide fragments with the highest peak capacity was achieved in the background electrolyte composed of 55mM H3 PO4 , 14mM tris(hydroxymethyl)aminomethan, pH 2.01. The differences in the obtained capillary electrophoresis-ultraviolet detection profiles with characteristic patterns for particular bone samples were subsequently discriminated by linear discriminant analysis over principal components. This approach was first verified on porcine bone tissues as model samples; jawbone and calf bone tissues could be discriminated with an accuracy of 100%. Subsequently, the method was capable of differentiating unequivocally between human healthy and inflammatory alveolar bone tissues obtained from oral surgery. This procedure seems to be promising as complement or even an alternative to the traditional histological discrimination between healthy and inflammatory bone tissues in oral surgery.

Determination of HMF in Vinegar and Soy Sauce Using Two-Step Ultrasonic Assisted Liquid–Liquid Micro-Extraction Coupled with Capillary Electrophoresis-Ultraviolet Detection

A new, rapid, and inexpensive method using two-step ultrasonic assisted liquid–liquid micro-extraction (UALLME) coupled with capillary electrophoresis-ultraviolet (CE-UV) was developed for 5-hydroxymethylfurfural (HMF) analysis in high ion strength samples (like vinegar and soy sauce). The factors affecting the extraction efficiency were optimized such as the extraction volume, the ultrasonic time, and the power density of ultrasonic. Under the optimum conditions, the limit of detection (LOD) and the limit of quantification (LOQ) for HMF were 0.03 and 0.10 mg/L, respectively. The relative standard deviations (RSD %) for HMF were ranging from 0.53 to 3.17%, and the recoveries of HMF were ranging from 91.24 to 109.39%. The results turned out that two-step UALLME-CE-UV was applicable to analyze HMF in vinegar and soy sauce. Eleven brands of vinegar and soy sauce were tested by two-step UALLME-CE-UV, and the results showed that the method had a potential application in analysis of foodstuffs. The two step UALLME method was effective to improve the selectivity and sensitivity of CE-UV method for HMF analysis in vinegar and soy sauce.

Dispersive micro-solid-phase extraction using carbon-based adsorbents for the sensitive determination of verapamil in plasma samples coupled with capillary electrophoresis.

A dispersive micro-solid-phase extraction procedure coupled with capillary electrophoresis ultraviolet detection was developed for determination of verapamil in plasma samples. Graphene oxide/polydopamin was synthesized by a one-step polymerization method, and graphene oxide/Fe3 O4 (magnetic graphene oxide) nanocomposite was prepared by coprecipitation method. Moreover, they were fully characterized. The use of hazardous and water-immiscible solvents was scaled down, and only 500μL of acetone was required as the desorption solvent. The detector response concentration plots were linear in the range of 5-500ng/mL, and the proposed method was validated according to guidelines. The precision and accuracy were less than 15%. Dispersive micro-solid-phase extraction method provides a rapid, environmentally friendly, and sensitive analysis for the verapamil in patient plasma samples, which is adequate for therapeutic drug monitoring and pharmacokinetic studies.

Ion pair hollow fiber liquid–liquid–liquid microextraction combined with capillary electrophoresis-ultraviolet detection for the determination of thyroid hormones in human serum

In this study, a novel, inexpensive, sensitive and selective analytical method that combines ion pair hollow fiber liquid–liquid–liquid microextraction (IP-HF-LLLME) with capillary electrophoresis-ultraviolet detection (CE-UV) was developed for the simultaneous determination of six thyroid hormones (including diiodothyronine (T2), 3,3,5-triiodo-l-thyronine (T3), 3,5,3,5-tetraiodolthyronine (T4), 3,3,5-triiodothyronine (rT3), monoiodotyrosine (MIT) and diiodotyrosine (DIT)) in human serum samples. By the addition of a low concentration of sodium dodecyl sulfate (SDS) into the donor phase as an ion pair reagent, octanol as the organic extraction solvent and 30mmol/L Na2CO3 as acceptor phase, six analytes with different polarity and water solubility were successfully extracted simultaneously using HF-LLLME. To the best of our knowledge, this is the first time that a liquid phase microextraction technique was proposed for the extraction of thyroid hormones in real samples. The CE separations were investigated in detail. When 20kV of voltage was applied, the six compounds were separated within 13min in 25mmol/L phosphate buffer (pH 2.15) containing 10% (v/v) acetonitrile and 0.5% (m/v) polyethylene glycol (PEG). Under the optimized conditions, enrichment factors (EFs) ranging from 183- to 366-fold were obtained and the limits of detection (at a signal-to-noise ratio of 3) were at sub μg/L level. The established IP-HF-LLLME-CE-UV method was successfully applied to simultaneous determination of thyroid hormones and relative compounds in human serum samples with good recoveries for the spiked samples.

Membrane-supported liquid–liquid–liquid microextraction combined with anion-selective exhaustive injection capillary electrophoresis-ultraviolet detection for sensitive analysis of phytohormones

A novel method based on off-line membrane-supported liquid–liquid–liquid microextraction (MS-LLLME) combined with on-column anion-selective exhaustive injection (ASEI) capillary electrophoresis–ultraviolet (CE–UV) detection was established for the analysis of seven phytohormones (abscisic acid (ABA), jasmonic acid (JA), 2,4-dichlorophenoxyacetic acid (2,4-D), 1-naphthalene acetic acid (NAA), indole-3-acetic acid (IAA), salicylic acid (SA) and gibberellic acid (GA)). In MS-LLLME, the target phytohormones were extracted from the acid donor phase to the alkaline acceptor phase, and the acceptor solutions were directly analyzed by ASEI-CE–UV. Under the optimal experimental conditions, the analytical performance of the method was evaluated. The limits of detection (LODs) of ABA, JA, 2,4-D, NAA, IAA, SA and GA were determined to be 1.00, 2.21, 0.33, 0.17, 0.67, 0.05 and 16.5ng/mL, respectively. The relative standard deviations (RSDs, n=7) ranged from 4.7% to 12.9%, and the enrichment factors were in the range of 307 to 20,160. The proposed method was successfully applied for the determination of multiple phytohormones in banana, cabbage and cucumber extracts, and ABA, IAA and SA were detected in these samples. The recoveries for the spiked samples were in the range of 79.0 to 116.4%. The proposed method was demonstrated to be suitable for the simultaneous quantification of multiple phytohormones with high sensitivity and good sample cleanup ability.

Off-line hyphenation of molecularly imprinted magnetic nanoparticle-based extraction with large volume sample stacking capillary electrophoresis for high-sensitivity detection of trace chloro-phenols

The present work developed a sensitive and selective method for the determination of 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) in an environmental water sample by molecularly imprinted magnetic nanoparticle (Fe3O4@MIP) based extraction coupled with capillary electrophoresis (CE). The highly selective, fast and effective sample pretreatment method with Fe3O4@MIPs can overcome the low sensitivity of the highly efficient capillary electrophoresis-ultraviolet detection method (CE-UV). In order to further improve the detection sensitivity, the analytes eluted from the Fe3O4@MIPs were analyzed by the on-line sample preconcentration large volume sample stacking (LVSS) technique with MEKC. Under optimal concentration conditions, signal enhancements of 781, 3276 and 8916-fold were achieved for 4-CP, 2,4-DCP and 2,4,6-TCP, respectively. The average recoveries of the three analytes in spiked water samples were 99.33–104.5% with a relative standard deviation (RSD) below 6.8%. The detection limits for 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol were 1.1 × 10−3, 2.13 × 10−4 and 6.68 × 10−5 μg mL−1, respectively.

Ionic liquid‐based dispersive liquid–liquid microextraction with back‐extraction coupled with capillary electrophoresis to determine phenolic compounds

Ionic liquid (IL) based dispersive liquid-liquid microextraction (DLLME) with back-extraction coupled with capillary electrophoresis ultraviolet detection was developed to determine four phenolic compounds (bisphenol-A, β-naphthol, α-naphthol, 2, 4-dichlorophenol) in aqueous cosmetics. The developed method was used to preconcentrate and clean up the four phenolic compounds including two steps. The analytes were transferred into room temperature ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate, [C(8) MIM][PF(6) ]) rich-phase in the first step. In the second step, the analytes were back-extracted into the alkaline aqueous phase. The effects of extraction parameters, such as type and volume of extraction solvent, type and volume of disperser, extraction and centrifugal time, sample pH, salt addition, and concentration and volume of NaOH in back-extraction were investigated. Under the optimal experimental conditions, the preconcentration factors were 60.1 for bisphenol-A, 52.7 for β-naphthol, 49.2 for α-naphthol, and 18.0 for 2, 4-dichlorophenol. The limits of detection for bisphenol-A, β-naphthol, α-naphthol and 2, 4-dichlorophenol were 5, 5, 8, and 100 ng mL(-1), respectively. Four kinds of aqueous cosmetics including toner, soften lotion, make-up remover, and perfume were analyzed and yielded recoveries ranging from 81.6% to 119.4%. The main advantages of the proposed method are quick, easy, cheap, and effective.

Optimization of ascorbic and uric acid separation in human plasma by free zone capillary electrophoresis ultraviolet detection

Optimization of ascorbic and uric acid separation in human plasma by free zone capillary electrophoresis ultraviolet detection

Fast determination of paraquat residues in water by an optical immunosensor and validation using capillary electrophoresis-ultraviolet detection

A solid-phase fluoroimmunoassay combined with an optical transducer chemically modified with an analyte derivative coupled to a FIA system was used [A. Brecht, A. Klotz, C. Barzen, G. Gauglitz, R. Harris, G. Quigley, J. Wilkinson, P. Sztajnbok, R. Abuknesha, J. Gascón, A. Oubiña, D. Barceló, Anal. Chim. Acta 362 (1998) 69]. Excitation and collection of fluorescence from fluorescently labelled anti-paraquat antibodies locally bound at the planar interface allows the measurement of the fluorescent signal which is indirectly related to the paraquat concentration of the sample. Matrix effects on the immunosensor response were observed, thus leading to the following detection limits, 0.01 and 0.06 μg l −1, when analyzing paraquat in MilliQ and in river water, respectively. The validation of the biosensor was carried out analyzing paraquat samples by capillary zone electrophoresis with ultraviolet detection (CZE-UV) at 214 nm. Preconcentration of the samples prior to their injection in the capillary electrophoresis were performed using the automated solid-phase extraction system (ASPEC-XL). Paraquat samples were adjusted at pH 9 and were percolated through a silica cartridge, subsequent elution was carried out using a mixture of hydrochloric acid and methanol and afterwards samples were evaporated and injected. This optical immunosensor, also called RIver ANAlyzer (RIANA) with an optical immunosensor can be applied for fast monitoring of paraquat in river water samples being the total analysis time of 15 min.

Analysis of atrazine, terbutylazine and their N-dealkylated chloro and hydroxy metabolites by solid-phase extraction and gas chromatography–mass spectrometry and capillary electrophoresis–ultraviolet detection

Solid-phase extraction (SPE) with the styrene–divinylbenzene adsorbent LiChrolut EN was investigated for the extraction of the s-triazine herbicides atrazine and terbutylazine, their polar N-dealkylated degradation products deethylatrazine (DEA), deisopropylatrazine (DIA) and deethylterbutylazine (DET) and for the hydrophilic hydroxytriazine degradation products (HTDPs) hydroxyatrazine (HA), hydroxyterbutylazine (HT), deethylhydroxyatrazine (DEHA), deisopropylhydroxyatrazine (DIHA) and deethyldeisopropylhydroxyatrazine (ameline). The optimum pH value for the extraction of the HTDPs from fortified tap water at 2 μg/l is 3.0. Recovery values with 200 mg LiChrolut EN are >80% for HA, HT, DEHA and 30% for DIHA from 200 ml spiked tap and river water. Atrazine, terbutylazine, DEA, DIA and DET are quantitatively extracted by LiChrolut EN. The chlorotriazines are analyzed by GC–MS and the HTDPs by capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC) with an acetate buffer at pH 4.6 or a sodium borate–sodium dodecyl sulfate buffer at pH 9.3. The combined method of SPE enrichment and CE analysis allows the determination of HTDPs in the low μg/l range.