Wyniki wyszukiwania - Biblioteka Nauki

1

Determination of formaldehyde in aquatic products by micellar electrokinetic capillary chromatography with 2,4-dinitrophenylhydrazine derivatization

100%

Xu L. N. , Gai F. Y. , Mu G. F. , Gao Y. , Liu C. J. , Luan F.

Acta Chromatographica

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2012

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tom Vol. 24, no. 4

519--528

EN

Formaldehyde in aquatic products was determined by micellar electrokinetic capillary chromatography (MEKC) after derivatization with 2,4-dinitrophenylhydrazine. Separation was carried out at 25 °C and 25 kV, using a fused silica capillary (75 µ internal diameter; 50.5 cm effective length) and an ultraviolet detector set at 360 nm. The optimal background electrolyte was 20 mM sodium tetraborate and 20 mM sodium dodecyl sulfate at pH 9.0 with 3 s hydrodynamic injection at 30 mbar. Electrophoretic analysis took approximately 6.5 min. The correlation coefficient of the calibration curve was 0.999 over the concentration range 2.0–100.0 mg L-1 and the LOD and LOQ values were 0.57 and 1.89 µg mL-1, respectively. The recoveries were from 83.7% to 97.2% with steam distillation as the sample pretreatment method.

2

Determination of hexachlorophene in cosmetics by capillary electrophoresis compared with high performance liquid chromatography

100%

Xiaobin L. , Fangfang G. , Huitao L. , Yuan G.

Acta Chromatographica

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2021

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tom Vol. 33, no. 1

44--50

EN

A simple capillary electrophoresis (CE) method with ultraviolet (UV) detection was developed for the determination of hexachlorophene (HCP) in cosmetics. Separation conditions were obtained in 20 mM Na2B4O7, 10% MeOH (pH 9.20), with 25 kV applied voltage and UV detection at 208 nm. Under the selected conditions, electrophoretic analysis was completed in about 4 min, with limit of detection (LOD) of 0.06 mg$mL1 for HCP. The method was successfully applied to determine HCP in three kinds of cosmetics with relative standard deviations (RSD) of 0.52–3.02% and recoveries from 90.0 to 96.4% for the spiked samples. The results indicated that the proposed method was reliable. Comparative experiments were also carried out with high-performance liquid chromatography (HPLC)-UV method described in National Standards of People’s Republic of China. The validation results of the two methods are comparable, but the proposed CE method is simple, rapid, which makes separation and analyte quantification in shorter time with much less reagent consumption.

3

Elektroforeza kapilarna - wysokosprawna technika w analizie farmaceutycznej

100%

Maruszak W.

Przemysł Chemiczny

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2002

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tom T. 81, nr 5

317-323

4

Effect of perfluorinated surfactant as additive of background electrolyte for capillary electrophoresis of inorganic cations

100%

Mori M. , Ikeda T. , Itabashi H.

Acta Chromatographica

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2012

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tom Vol. 24, no. 4

529--542

EN

This study reports the effect of a nonionic perfluorinated surfactant, N-polyoxyethylene-N-propyl perfluorooctane sulfonamide (PFOSA), as additive of background electrolyte on capillary electrophoresis (CE) of common inorganic cations. The association constants (Kass) for PFOSA estimated from the electrophoretic mobility of analyte cations were the order of Mg2+ > Ca2+ > Sr2+ > K+ ≈ NH4+ > Na+ ≈ Li+. The Kass values were larger than those for zwitterionic and nonionic surfactants with hydrocarbon moiety. Use of PFOSA made another essential contribution to the determination of inorganic cations in a protein-containing sample. This was considered because high solubility of PFOSA for proteins functioned as suppressor for protein adsorption to the capillary wall. Four inorganic cations, Na+, K+, Mg2+, and Ca2+, in human saliva sample were successfully determined by sample injection without any pretreatments except for filtration and dilution.

5

Characteristics of humic acids extracted from soils by the capillary electrophoresis

100%

Grzelakowska A. , Christy A.

Polish Journal of Soil Science

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2003

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tom 36

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nr 2

145-152

EN

Humic acids have an important role in the soils. When specific structures of which little is known, are studied, one should use the latest analitycal methods. So far the method of fractionation by electrophoretic mobility has not been very popular in the research studies on humic substances. However, it seems that it is possible to study humification processes and subtle changes in the structure of the material investigated using capillary electrophoresis. On the basis of our experience, some soils representing various types were selected as study material. Electrophoretic separation (by means of buffer solutions with various pH-values) was carried out for the humic acids extracted from the soils selected. The results obtained allowed for the determination of differences in the humic acids structures due to their origin.

6

Inks analysis by capillary electrophoresis : analytical conditions optimisation

100%

Mania J. , Madej K. , Kościelniak P.

Chemia Analityczna

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2002

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tom Vol. 47, No. 4

585-594

EN

The analytical studies are presented which were aimed at searching optimal conditions for the separation and identification of ink dyes with the use of the PrinCE 550 CE electro-phoresis system. The ultimate task was to establish the minimum sample amount which have to be taken from ink lines on paper to perform a valuable analysis for criminalistic purposes. Micellar electrokinetic capillary chromatography (MEKC) mode was applied to separation of dyes. The examinations were carried out using the standard mixtures of Methyl Violet B, Victoria Blue B and Solvent Black 3, and the sample requirements were evaluated for a black ball-point pen ink extracted from paper. It was stated that the minimum number of micro-dots punched out from examined document was established to be as small as 4. It was also revealed that the identification parameters for components of inks can be migration time as well as ratio of peak areas of dye isomers.

PL

W pracy przedstawiono badania analityczne mające na celu określenie optymalnych warunków rozdziału i identyfikacji barwników materiałów kryjących przy użyciu aparatu do elektroforezy kapilarnej PrinCE 550 CE. Głównym zadaniem badań było ustalenie, jaka ilość próbki powinna być pobrana z linii pisma na papierze aby zapewnić wiarygodną analizę pod względem kryminalistycznym. Do rozdzielania barwników zastosowano technikę micelarnej elektrokinetycznej chromatografii kapilarnej (MEKC). Badania wykonano przy użyciu wzorcowych mieszanin barwników Methyl Yiolet B, Yictoria Blue B i Solvent Black 3, a wymagania co do ilości próbki oceniono dla czarnego tuszu dlugopisowego eks-trahowanego z papieru. Minimalną liczbę mikropróbek (w kształcie kółek) wyciętych z badanego dokumentu określono jako równą4. Wykazano również, że do identyfikacji składników materiałów kryjących może służyć zarówno czas ich migracji, jak i powierzchnie pod pikami izomerów barwników.

7

Determination of glyphosate in water samples with the combination of cation-exchange chromatography and capillary electrophoresis

100%

Khrolenko M. , Dżygiel P. , Wieczorek P.

Ars Separatoria Acta

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2003

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tom No. 2

56-63

EN

An analytical method for determination of pesticide Glyphosate in water as a combination of cation-exchange chromatography and capillary electrophoresis is presented. Pure water was spiked with Glyphosate at concentrations 0.1, 0.25, 0.5 and 1 mM and percolated through a strong cation-exchange column packed with Dowex 50WX4-400 resin in its H+ form. The extract was further analyzed by capillary electrophoresis in indirect detection mode. The calibration curve for the pesticide in the range 0.1–2.5 mM was linear and with high degree of reproducibility. The obtained recoveries for all the studied concentrations amount 85%. Afterwards, the possibility to determine Glyphosate at the concentration 0.001mM (0.17 µg/ml) was checked by percolation of 100 ml of water sample through a column. The calculated recovery was 97.7%

8

Microcapillary Electrophoresis with Fluorescence Detection

100%

Lewandowska N. , Dybko A. , Chudy M. , Wcisło M. , Poboży E. , Brzózka Z.

Polish Journal of Chemistry

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2006

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tom Vol. 80, nr 11

1799-1806

EN

The advantages and application perspectives for microcapillary electrophoresis (mi CE) are presented. The microchip based on a glass plate was fabricated. The separations of three FITC-labeled amino acids carried out with the conventional CE system and in the microchip were compared. The obtained results proved the usability of the microchip for mi CE process.

9

Capillary electrophoresis for diagnosing purine inherited disorders - two complementary approaches

100%

Adam T. , Friedecky D. , Fairbanks L. D. , Bartak P. , Sevcik J.

Cellular and Molecular Biology Letters

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1999

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tom 04

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nr 3

10

Densitometry, video-scanning and capillary electrophoresis for determination of valsartan and amlodipine in a combined dosage form: A comparative study

88%

Inglot T. W. , Gumieniczek A. , Komsta Ł. , Związek R.

Acta Chromatographica

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2013

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tom Vol. 25, no. 1

47-58

EN

Comparison of classical densitometry, video-scanning, and capillary electrophoresis was performed for determination of angiotensin II receptor antagonist, valsartan, and calcium channels blocker, amlodipine, in a combined dosage form. Thin layer chromatography was performed on RP8F254 TLC plates with a mobile phase consisting of acetonitrile-phosphate buffer at pH 9.0 (5:5, v/v) and temperature 20 °C. Densitometry was done in the reflectance mode at 217 nm for valsartan and in the absorbance mode at 370 nm for amlodipine. Video-scanning was elaborated at 254 and 366 nm for valsartan and amlodipine, respectively. For chromatographic analysis, calibration plots were constructed in the range of 0.4–2.8 μg per spot for valsartan and 0.02–0.14 μg per spot for amlodipine. Capillary electrophoresis (CE) was performed using a 75 μm × 94 cm fused silica capillary (72 cm effective length), 0.01 mol L-1 borate buffer at pH 8.0, 20 kV voltage, 30 °C temperature, hydrodynamic injection (10 mbar, 6 s) and UV detection at 237 nm. Calibration plots were constructed in the range of 0.1–0.6 mg mL-1 for valsartan and 0.005–0.03 mg mL-1 for amlodipine. All methods were validated in respect to robustness, specificity, stability, linearity, precision, and accuracy. Generally, statistical comparison between the methods did not show significant differences so all procedures are suitable for pharmaceutical analysis.

11

Ultrasensitive determination of epicatechin, rutin, and quercetin by capillary electrophoresis chemiluminescence

88%

Wang J. , Wang H. , Han S.

Acta Chromatographica

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2012

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tom Vol. 24, no. 4

679--688

EN

An ultrasensitive and rapid method for the determination of epicatechin, rutin, and quercetin was developed using capillary zone electrophoresis with on-line chemiluminescence detection. Under the optimal conditions, the analytes were baseline separated within 12 min. The limits of detection in turn were 0.60 pg mL-1 for epicatechin, 0.50 pg mL-1 for rutin, and 1.0 pg mL-1 for quercetin. The developed method was an easy and reliable method of determining these analytes concentrations in tea, extract Ginkgo biloba, and rutin tablet, demonstrating the feasibility and reliability of the proposed method.

12

Sample Preparation for Determination of Biological Thiols by Liquid Chromatography and Electromigration Techniques

88%

Bald E. , Department o f Environmental Chemistry U. o. L.

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tom 13

PL

Wydrukowano z dostarczonych Wydawnictwu UŁ gotowych materiałów

EN

Majority of the bioanalytical or environmental methods do not use just one chromatografie or electrophoretic step, but rather involve several sample pretreatment steps which simplfy the matrix, and often preconcentrate and chemically modify the analytes. This work surveys typical procedures for sample preparation for most commonly analyzed biofluids with particular emphasis placed on chemical derivatization of sulfur amino acids for their determination by liquid phase separation techniques. Recent author's laboratory contribution to the development of sample preparation procedures is merked.

13

Application of capillary electrophoresis in the analysis of coloring matter on paper

88%

Król M.

Nowa kodyfikacja prawa karnego

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2017

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tom 44

23-40

EN

Modern law enforcement agencies are constantly struggling with crimes against documents. Due to increasing quality of counterfeit documents and different physicochemical properties of inks, such crimes are becoming harder to detect. This situation obliges forensic laboratories for the development and implementation of testing procedures with the use of some modern techniques of chemical analysis. CE opens up numerous possibilities for various analytical applications, mainly due to its numerous advantages, the diversity of its modes and the compatibility with different detection systems. This study focuses on discussing two modes of CE: CZE and MECC and three different detection systems: DAD, LIF and MS. By using them information about substances exhibiting absorption, fluorescence and about molecular mass of analyzed compound can be received. In the Laboratory for Forensic Chemistry many different coloring matters were examined, including ballpoint, fountain pen, gel and stamp pad inks in most popular colors as well as a large group of branded and off-brand printing inks. The obtained results showed the great applicability of CE-DAD method. It has been proved that LIF and MS detections improve the discriminating possibilities of CE providing additional information on samples.

14

Using capillary electrophoresis to study methylation effect on RNA-peptide interaction.

88%

Mucha P. , Szyk A. , Rekowski P. , Agris P. F.

Acta Biochimica Polonica

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2003

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tom 50

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nr 3

857-864

EN

Methylation of RNA and proteins is one of a broad spectrum of post-transcriptional/translational mechanisms of gene expression regulation. Its functional signification is only beginning to be understood. A sensitive capillary electrophoresis mobility shift assay (CEMSA) for qualitative study of the methylation effect on biomolecules interaction is presented. Two RNA-peptide systems were chosen for the study. The first one consists of a 17-nucleotide analogue (+27-+43) of the yeast tRNAPhe anticodon stem and loop domain (ASLPhe) containing three of the five naturally occurring modifications (2'-O-methylcytidine (Cm32), 2'-O-methylguanine (Gm34) and 5-methylcytidine (m5C40)) (ASLPhe-Cm32,Gm34,m5C40) and a 15-amino-acid peptide (named tF2 : Ser1-Ile-Ser-Pro-Trp5-Gly-Phe-Ser-Gly-Leu10-Leu- Arg-Trp-Ser-Tyr15) selected from a random phage display library (RPL). A peptide-concentration-dependent formation of an RNA-peptide complex was clearly observable by CEMSA. In the presence of the peptide the capillary electrophoresis (CE) peak for triply methylated ASLPhe shifted from 18.16 to 20.90 min. Formation of the complex was not observed when an unmethylated version of ASLPhe was used. The second system studied consisted of the (+18)-(+44) fragment of the trans-activation response element of human immunodeficiency virus type 1 (TAR RNA HIV-1) and a 9-amino-acid peptide of the trans-activator of transcription protein (Tat HIV-1) Tat(49-57)-NH2 (named Tat1 : Arg49-Lys-Lys-Arg52-Arg-Gln-Arg-Arg- Arg57-NH2). In the presence of Tat(49-57)-NH2 a significant shift of migration time of TAR from 18.66 min to 20.12 min was observed. Methylation of a residue Arg52→Arg(Me)2, crucial for TAR binding, strongly disrupted formation of the complex. Only at a high micromolar peptide concentration a poorly shaped, broad peak of the complex was observed. CE was found to be an efficient and sensitive method for the analysis of methylation effects on interaction of biomolecules.

15

Capillary electrophoresis for the determination of N-Acetyltyrosine and N-acetylcysteine in products for parenteral nutrition: Method development and comparison of two CE systems

88%

Jaworska M. , Szulińska Z. , Wilk M. , Anuszewska E.

Acta Chromatographica

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2011

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tom Vol. 23, no. 4

595--602

EN

Because of the problems with stability and solubility, some of the amino acids (AAs) used in parenteral nutrition products are often replaced by their acetylated forms. These include N-acetyltyrosine (NAT) and N-acetylcysteine (NAC). This leads to a need to develop new analytical methods for rapid and easy determination of these substances in the presence of common AAs. Capillary electrophoresis (CE) is one of the techniques that have been successfully applied to the assay of multi-component samples containing AAs and their derivatives. This paper discusses a new CE method for the simultaneous determination of two acetylated AAs in solutions for parenteral nutrition. A background electrolyte (BGE) was developed based on borate buffer with alkaline pH. The method is selective and enables the separation and assay of analytes without special sample pretreatment. Validation parameters confirmed sufficient precision and accuracy of the method. Its applicability was verified by testing several medicinal products from various manufacturers. Moreover, the flexibility of the method was checked using two brands of CE equipment. Appropriate adjustment of instrumental parameters turned out to be essential for method transferability. The method could be used in routine testing of parenteral nutrition medicinal products containing AAs.

16

Application of Isotachophoresis for Determination of Anionic Forms of Phosphonic Acids

88%

Górecki H. , Szczygieł B. , Drela I.

Polish Journal of Chemistry

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2004

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tom Vol. 78 / nr 9

1691-1702

EN

Using a capillary electrophoresis analyser, the concentrations of anionic forms of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and N-trismethylenephosphonic acid (NTMP) were determined by the isotachophoresis method. The measurements were performed at pH = 4.2, 6.0 and 8.0. In each case the proper leading/terminating electrolyte system was selected on the basis of literature and authors'own research. The results of isotachophoretic analyses were found to be in good agreement with the results derived from dissociation constants determined by potentiometric method. Considerable difficulties were encountered in interpretation of the results obtained for pH = 8.0 since individual steps in the isotachopherograms were fuzzy and distorted probably due to incomplete separation of the analysed sample into zones. Knowledge of the kind and concentration of ligand forms of chelating compounds, to which PBTC and NTMP belong, can be useful for reclamation of soils polluted with heavy metals.

17

Determination of lanthanum(III) and europium(III) – lactate interaction constants by capillary electrophoresis for environmental applications

88%

Bortolus S. , Varenne A. , Draye M. , Gareil P. , Czerwiński K. , Cote G.

Ars Separatoria Acta

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2003

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tom No. 2

29-35

EN

In the present work, we investigated the ability of electrophoresis to determine the stability constant of the complex formed between lactate ions (a simple model of natural organic matter), and lanthanum (III) and europium (III), two model metal cations of actinides. The effect of lactate on lanthanide’s effective mobility is studied, and conditional metal ion-ligand interaction constants are determined on the basis of the variation in the effective mobilities (log βn = 2.23 for lanthanum (III) and 2.39 for europium (III), at 25°C and I=0.015 M). The originality of this contribution lies in the fact that we have chosen to detect the metal ion instead of the ligand by an indirect UV-visible detection and using a chromophoric compound (creatinine).

18

Analysis of polyphenols in Valeriana wallichii DC by capillary electrophoresis with amperometric detection

88%

Chu Q. , Zhang H. , Zhang D. , Ye J.

Acta Chromatographica

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2010

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tom Vol. 22, no. 4

623--635

EN

High-performance capillary electrophoresis with amperometric detection (CE-AD) has been used for analysis of eight bioactive components of the leaves, stems, and roots of Valeriana wallichii DC, after a relatively simple extraction procedure with ethanol. Under the optimum conditions, the eight components can be well separated or (apigenin and luteolin) separated nearly to baseline within 23 min by use of 50 mM borax (pH 9.2) as running buffer and a separation potential of 16 kV. Linearity was excellent over two orders of magnitude of concentration and detection limits ( S/N = 3) ranged from 1.7 × 10 −7 to 1.8 × 10 -8 g mL -1. This method was used for comparison of the concentrations of the bioactive compounds in different parts of the plant on the basis of their electropherograms or ‘characteristic electrochemical profiles’. Assay results were satisfactory.

19

Using capillary electrophoresis to study methylation effect on RNA-peptide interaction

88%

Mucha P. , Szyk A. , Rekowski P. , Agris P. F.

Acta Biochimica Polonica

|

2003

|

tom 50

|

nr 3

EN

Methylation of RNA and proteins is one of a broad spectrum of post-trans- criptional/translational mechanisms of gene expression regulation. Its functional signification is only beginning to be understood. A sensitive capillary electrophoresis mobility shift assay (CEMSA) for qualitative study of the methylation effect on biomolecules interaction is presented. Two RNA-peptide systems were chosen for the study. The first one consists of a 17-nucleotide analogue (+27-+43) of the yeast tRNA Phe anticodon stem and loop domain (ASL Phe) containing three of the five naturally occurring modifications (2'-O-methylcytidine (Cm32), 2'-O-methylguanine (Gm34) and 5-methylcytidine (m5 C40)) (ASL Phe -Cm32,Gm34,m5 C40) and a 15-amino-acid peptide (named tF 2: Ser1 -Ile-Ser-Pro-Trp5 -Gly-Phe-Ser-Gly-Leu10 -Leu- Arg-Trp-Ser-Tyr15 ) selected from a random phage display library (RPL). A pep- tide-concentration-dependent formation of an RNA-peptide complex was clearly observable by CEMSA. In the presence of the peptide the capillary electrophoresis (CE) peak for triply methylated ASL Phe shifted from 18.16 to 20.90 min. Formation of the complex was not observed when an unmethylated version of ASL Phe was used. The second system studied consisted of the (+18)-(+44) fragment of the trans-activation response element of human immunodeficiency virus type 1 (TAR RNA HIV-1) and a 9-amino-acid peptide of the trans-activator of transcription protein (Tat HIV-1) Tat(49–57)-NH2 (named Tat1: Arg49-Lys-Lys-Arg52-Arg-Gln-Arg-Arg- Arg57-NH2). In the presence of Tat(49–57)-NH2 a significant shift of migration time of TAR from 18.66 min to 20.12 min was observed. Methylation of a residue Arg52->Arg(Me)2, crucial for TAR binding, strongly disrupted formation of the complex. Only at a high micromolar peptide concentration a poorly shaped, broad peak of the complex was observed. CE was found to be an efficient and sensitive method for the analysis of methylation effects on interaction of biomolecules.

20

GA3 content in young and mature antheridia of Chara tomentosa estimated by capillary electrophoresis

88%

Kazmierczak A. , Stepinski D.

Folia Histochemica et Cytobiologica

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2005

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tom 43

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nr 1