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1.
Recombinant human erythropoietin-α (rHuEPO-α) has been widely used in clinic for anemia treatment. The detection and quantification of rHuEPO-α is essential for monitoring this widespread recombinant glycoprotein pharmaceutical. In this paper, we developed a new affinity probe capillary electrophoresis/laser-induced fluorescence (APCE/LIF) method for the detection of rHuEPO-α by using a specific single-stranded DNA aptamer probe for the first time. In this method, the complex of aptamer-rHuEPO-α and the free aptamer can be well separated and identified by their migration and fluorescence intensity after systematic optimization. The existence of sodium cation in the sample buffer and running buffer played a critical role for stabilizing complex and enhancing the separation efficiency, additionally, suitable high voltage and sample buffer additives were also important for improving the peak height of the complex. Under the optimized conditions, the method was successfully applied for the quantification of rHuEPO-α in physiological buffer, artificial urine and human serum. The linear range for rHuEPO-α was from 0.2 to 100 nM and the limit of detection was 0.2 nM (i.e. 7.4 ng/mL). Further binding experiments using fluorescein isothiocyanate-labeled rHuEPO-α (F-rHuEPO-α) and N-deglycosylated F-rHuEPO-α demonstrated that the oligosaccharides moiety was of importance in the specific interaction between rHuEPO-α and its aptamer.  相似文献   

2.
A simple, reliable and reproducible method for the separation and determination of five β-casomorphins (β-CMs, namely TPGN, PGPI, TPGI, TPGP and TPPG) based on glass microfluidic chip electrophoresis and laser-induced fluorescence detection is first described in here. The microfluidic chip electrophoresis and laser-induced fluorescence detection system consisted of a home-made glass "double-T" microchip and a simple LIF detector with excitation and emission wavelengths of 473 and 525 nm, respectively. Fluorescein isothiocyanate (FITC) was used as the precolumn derivatization reagent to label fluorophore on five β-CMs, and the optimum conditions of FITC-derivatization reaction and MCE separation were investigated in detail. Under optimum conditions, five β-CMs were completely separated and detected within 30 min with a detection limit of 18.7-75.1 nmol/L and an RSD (n=5) of 3.0-5.9%, respectively. The proposed method has been successfully used to detect β-CMs in real cheese sample with a recovery of 89-109%, suggesting that our method is sensitive and reliable. These features, as well as its low cost, operation convenience, stability and reusability, make it a promising alternative to β-CMs detection methods.  相似文献   

3.
β-Lactoglobulin (βLG) is the main allergenic protein in cow's milk and can cause allergy even when present at very low concentration. The aim of this work is to develop an innovative sample preparation method fully compatible with capillary electrophoresis and laser-induced fluorescence detection for improving the sensitivity when analyzing βLG. Different types of baby food were on purpose contaminated with diverse dairy desserts and submitted to thermal treatment to simulate potential contamination at production. Sample preparation prior to CE analysis was performed by the classical extraction method and by the innovative one, and the results were compared. Analysis was performed by capillary electrophoresis with laser-induced fluorescence detection. The innovative method permitted to detect contaminations as low as 1 part of yoghurt in 10 000 parts of baby food.  相似文献   

4.
The complexation of seven bile salts, present in the small intestine of rat, dog and man, (taurocholate, tauro-β-muricholate, taurodeoxycholate, taurochenodeoxycholate, glycocholate, glycodeoxycholate and glycochenodeoxycholate) with γ-cyclodextrin and the chemically modified 2-hydroxypropyl-γ-cyclodextrin, was studied using affinity capillary electrophoresis (ACE). The cyclodextrins (CDs) were investigated due to their use in drug formulation as excipients for solubilisation of poorly soluble drugs and drug candidates. Using mobility shift ACE, the bile salt cyclodextrin interactions were characterized demonstrating 1:1 binding stoichiometry with stability constants ranging from 2 × 103 to 8 × 104 M?1. The binding constants showed a systematic dependence on the number and position of hydroxyl groups on the steroid skeleton and the stability constants were in general higher for complexation with the native cyclodextrin than with the modified cyclodextrin. Based upon the size of the complexation constants, it was suggested that the interaction between the CDs and the bile salts takes place at the C and D ring of the steroid skeleton. The complexation of bile salts with the γ-cyclodextrins may compete with drug-γ-cyclodextrin complex formation and, thus, potentially affect drug absorption and efficacy.  相似文献   

5.
Heat effects of the dissolution of crystalline γ-aminobutyric acid in water and potassium hydroxide solutions are determined by direct colorimetry at 298.15 K. Standard enthalpies of formation of γ-aminobutyric acid and the products of its dissociation in aqueous solution are calculated.  相似文献   

6.
Based on the fact that some metal ions can catalyze the chemiluminescence(CL)reaction of luminol with K_3Fe(CN)_6,a novel capillary electrophoresis CL method was developed for the determination of Co(Ⅱ)and Cu(Ⅱ).The separation was carried out with a 10 mmol/L sodium acetate solution containing 0.8 mmol/L luminol and 2.0 mmol/Lα-HIBA(adjusted to pH 4.8 by HAc solution).The post-capillary reagent was 2.0 mmol/L K_3Fe(CN)_6 which was adjusted to pH 13.0 by NaOH solution.Under the optimum conditions,the detection limits(S/N=3)for Co(Ⅱ)and Cu(Ⅱ)were 7.5×10~(-11)mol/L and 7.5×10~(-9)mol/L,with the linear range of 7.5×10~(-9)mol/L to 1.0×10~(-6)mol/L and 7.5×10~(-8)mol/L to 5.0×10~(-5)mol/L, respectively.  相似文献   

7.
Summary The separation and determination of β-(3,4-dihydroxyphenyl) lactic acid, protocatechuic acid and protocatechuic aldehyde in RadixSlviae Miltiorrhizae injection were investigated by capillary zone electrophoresis. With boric acid (200 mmol L−1) adjusted to pH 8.11 as a background electrolyte, 28 kV applied voltage and 30°C thermostating temperature, complete separation of β-(3,4-dihydroxyphenyl)lactic acid, protocatechuic acid and protocatechuic aldehyde was readily achieved within 9 min. Results indicate that capillary electrophoresis promises to be applicable to quality control of radixSalviae Miltiorrhiza injection.  相似文献   

8.
Gamma-amino butyric acid (GABA) has antihypertensive and anti-stress effects on human health. High hydrostatic pressure (HHP), a nonthermal treatment, has been documented as a novel approach to enhance the nutritional quality and functional components of plant-based food. In this study, a novel method to convert monosodium glutamate (MSG) to GABA using bee pollen as a natural catalyst was observed, and the GABA yield was improved by HHP treatment. Firstly, GABA production was confirmed by high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS-MS), the highest GABA production was found in lotus bee pollen (LBP) when different varieties of bee pollen were used for the reaction. Secondly, the reaction conditions were utilized, and the optimal reaction condition of the GABA production was determined as described below: 250 mg/mL of bee pollen mixed with 590 mmol/L of MSG that prepared by 80 mmol/L of phosphate buffer (pH 5.8), and incubated at 40 °C for 6 h. For HHP treatment conditions, a treatment of 200 MPa for 10 min at 40 °C was found as the optimal. Under optimal conditions, GABA production reached 508.79 mmol/L (containing GABA from LBP) from 590 mmol/L of MSG. In conclusion, we found and optimized a novel method to convert monosodium glutamate (MSG) to GABA, and proposed the promotion of HHP on GABA bio-conversion.  相似文献   

9.
A new synthetic approach to (3R)-4-amino-3-methylbutyric acid and [(4R)-2-oxo-4-phenylpyrrolidin-1-yl]acetamide [(R)-phenotropil] has been developed. Asymmetric center with a required configuration has been generated via enantioselective addition of diethyl malonate to 1-nitropropene and β-nitrostyrene, catalyzed by Ni(II) complexes with (R,R)- and (S,S)-N,N′-dibenzylcyclohexane-1,2-diamine.  相似文献   

10.
Capillary electrophoresis with a capacitively contactless conductivity detector (CE-C?D) is becoming a significant useful technique for the analysis of analytes in various fields such as pharmaceutical, biomedical, food and environmental. This review is an update describing the recent developments in the application of CE with a C?D detector.  相似文献   

11.
This review gives a wide overview of recent advances and applications of capillary electrophoresis and microchip capillary electrophoresis methods in the fields of proteomics and peptidomics in the period from mid-2018 up to the end of 2022. The methodological topics covering sample preparation and concentration techniques, hyphenation of capillary electrophoresis methods with mass spectrometry, and multidimensional separations by on-line or off-line coupled different capillary electrophoresis and liquid chromatography techniques are described and new developments in both bottom-up and top-down approaches in proteomics are presented. In addition, various applications of capillary electrophoresis methods in proteomic and peptidomic studies are demonstrated. They include monitoring of protein posttranslational modifications and applications in biological and biochemical research, clinical peptidomics and proteomics, and food analysis.  相似文献   

12.
A flow injection–capillary electrophoresis system with contactless conductivity detection and hydrostatic-pressure-generated flow was used for the fast and sensitive speciation of Se(IV) and Se(VI). The sample throughput was 25 samples per hour using a background electrolyte solution containing 8.75 mM l-histidine (His) adjusted to pH 4.00 with acetic acid. The repeatability of peak areas (n=8) was better than 1.41% and the limits of detection were 190 g L–1 and 7.5 g L–1 for Se(IV) and Se(VI), respectively. The interference from carbonate, typically present in water samples, was eliminated by using a low-pH electrolyte in which carbonate is uncharged and migrates at the EOF front. The method was applied to the analysis of Se(IV) and Se(VI) in soil samples that were spiked with both selenium species and the results for recovery of both selenium species were in good agreement with their introduced concentrations.  相似文献   

13.
The detection of the major active component of cannabis, Δ9-tetrahydrocannabinol (THC), becomes increasingly relevant due to its widespread abuse. For control purposes, some easy-to-use, sensitive and inexpensive test methods are needed. We have developed a fluorescence immunoassay utilising THC–fluorescein conjugate as tracer. Fluorescence spectroscopy of the conjugate revealed an unusual property: The relatively weak fluorescence of a dilute tracer solution was increased by a factor of up to 5 after binding of a THC-specific antibody. Fluorescence lifetime measurements in aqueous solutions suggested two different tracer conformations both associated with quenching of fluorescein fluorescence by the intramolecular THC moiety. After antibody binding, the tracer enters a third conformation in which fluorescence quenching of fluorescein is completely suppressed. Utilising this property, we established a homogeneous competitive immunoassay (homogeneous increasing fluorescence immunoassay) with low detection limits. The test requires only two reagents, the new tracer molecule and an anti-THC antibody. A single test takes only 8 min. The dynamic detection range for THC is 0.5 to 20 ng/mL in buffer, with a limit of detection (LOD) of 0.5 ng/mL. The test also works in diluted saliva samples (1:10 dilution with buffer) with an LOD of 2 ng/mL and a dynamic range of 2–50 ng/mL.  相似文献   

14.
A CE method was developed for the determination of total (free and weakly bound) cyanide in electroplating solutions based on the use of a cationic surfactant (TTAB) and complexation with Ni(II)-NH3 solutions to Ni(CN)4 2–. Both direct complexation and cyanide distillation combined with complexation were tested. Under optimized conditions, this method is time-saving compared to standard methods. Total cyanide determined by CE had detection limits (with respect to the initial sample concentration) of 0.5 μg/mL for direct complexation and 50 ng/mL for distillation combined with complexation. Total cyanide and cyanide not amenable by chlorination (CNAC) were determined in real samples from spent electroplating baths.  相似文献   

15.
A laboratory-built automated instrument is reported for on-line, near real-time monitoring of nine haloacetic acids species (HAA9) in drinking water. The device uses anion-exchange chromatography to separate the HAA9 species, followed by post-column reaction with nicotinamide in basic solution with fluorescence detection. Method detection limits for HAA9 species ranged from 0.6 to 10.1 μg L−1, mean % recovery values ranged from 58 to 161%, and % relative standard deviation ranged from 3.5 to 32% while operating within a factor of 2.5-5 of the method detection limit. The bias between the proposed method and United States Environmental Protection Agency Method 552.3 was measured during two separate on-line studies and using grab samples collected from different distribution systems. In general, the two methods showed good agreement with biases for HAA9 of less than 10 μg L−1.  相似文献   

16.
In our recent studies, the reversal of the enantiomer migration order (EMO) was observed with heptakis (2,3-dimethyl-6-sulfo)-β-CD (HDMS-β-CD) when aqueous electrolyte was changed with nonaqueous electrolyte in CE. One-dimensional rotating frame nuclear Overhauser effect spectroscopy experiments prevailed that an inclusion complex was formed between the analyte and the chiral selector in the aqueous buffer, whereas an external complex resulted when a methanolic electrolyte was employed. In the case of the similarly substituted heptakis (2,3-diacetyl-6-sulfo)-β-CD (HDAS-β-CD), the external complex was observed in the aqueous buffer but an inclusion complex was formed in methanolic electrolyte. In contrast to heptakis (2,3-dimethyl-6-sulfo)-β-CD, no reversal of the enantiomer migration order was observed with HDAS-β-CD. In the present study, further mechanisms of enantioselective recognition and separation of propranolol enantiomers with HDAS-β-CD were investigated by using different techniques of nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. To the best of our knowledge, enantioselective nuclear Overhauser effect was observed for the first time in this study.  相似文献   

17.
The photo-oxidation reaction of phenothiazine has been studied in the presence of-cyclodextrin (-CD) and 2-hydroxypropyl-cyclodextrin (HP -CD). The influence of these organized media on the formation of the oxidation photoproduct upon UV irradiation has been investigated. Phenothiazine forms an inclusion complex with the cyclodextrins. The stoichiometry and formation constant of the complex formed with 2-hydroxypropyl -CD have been calculated using the changes of the fluorescence emission signal and of the absorbance of the drug upon inclusion. An increase of the fluorescence intensity of the photogenerated product is attained when it becomes included inside the cyclodextrin cavity.  相似文献   

18.
So far, the potential of capillary electrophoresis in the application fields has been increasingly excavated due to the advantages of simple operation, short analysis time, high-resolution, less sample consumption, and low cost. This review examines the implementations and advancements of capillary electrophoresis in different application fields (environmental, pharmaceutical, clinical, and food analysis) covering the literature from 2019 to 2021. In addition, ultrasmall sample injection volume (nanoliter range) and short optical path lead to relatively low concentration sensitivity of the most frequently used ultraviolet-absorption spectrophotometric detection, so the pretreatment technology being developed has been gradually utilized to overcome this problem. Despite the review being focused on the development of capillary electrophoresis in the fields of environmental, pharmaceutical, clinical, and food analysis, the new sample pretreatment techniques of microextraction and enrichment fit excellently to capillary electrophoresis in recent three years are also described briefly.  相似文献   

19.
Δ9‐Tetrahydrocannabinol is the primary psychoactive component in cannabis, one of the most commonly used illicit drugs in the world. This paper describes a simple and rapid method for direct analysis of major metabolites of Δ9‐tetrahydrocannabinol; 11‐nor‐Δ9‐tetrahydrocannabinol‐9‐carboxylic acid and its glucuronide in urine by capillary electrophoresis/mass spectrometry. The only pretreatment needed for a urine sample was dilution with methanol containing an internal standard and centrifugation. Electrophoresis was carried out in an untreated fused‐silica capillary (50 µm i.d. × 85 cm) filled with 40 m m ammonium formate (pH 6.4). An analysis could be completed within 10 min. For both compounds, the assay was linear over the range 0.1 ? 10 µg/mL in urine with correlation coefficients (r2) > 0.99 and the limit of detection was 0.5 pg (10 nL injection). The detection yields and reproducibilities were determined at three different concentrations (0.1, 0.5 and 2 µg/mL in urine). The mean detection yields were 60 ? 99%. The intra‐ and inter‐day relative standard deviations of migration times were 0.063 ? 0.19 and 0.18 ? 0.36%, and those of peak areas were 4.2 ? 18 and 5.9 ? 25%, respectively. The proposed method successfully analyzed the urine samples of cannabis users. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

20.
The antitumoral effect of cisplatin [cis-diamminodichloroplatinum(II)] in mammals is related to its binding to DNA components. However, there is a lack of specific chemical methods to selectively detect those adducts formed in vivo at low concentrations. In this work, a new sensitive and selective method of determining cisplatin–DNA adducts based on the use of element-selective mass spectrometry is proposed, and the method is then applied to detect cisplatin adducts induced in vivo in somatic cells of Drosophila melanogaster. The bioanalytical strategy proposed here allows the determination of the most important DNA adduct formed between adjacent guanine units of the same DNA strand with cisplatin, and it is based on the coupling of capillary liquid chromatography (cap-LC) to inductively coupled plasma mass spectrometry (ICP-MS). This set-up allows the simultaneous monitoring of the Pt (from the drug) and P (from the DNA components) present in these adducts, once they have been cleaved by enzymatic hydrolysis of the DNA samples. Using this instrumental set-up, the adducts of cisplatin formed in vivo when D. melanogaster flies are exposed to different cisplatin concentrations can be detected and their concentration determined. The results obtained show a direct correlation between the concentration of cisplatin adducts, the induced genotoxic damage (measured as DNA strand breaks using the Comet assay) and the cisplatin concentration. Figure The work illustrates the complementary use of bioanalytical and biological information to study cisplatin interactions with DNA is vivo at biologically relevant concentrations of the drug  相似文献   

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